Renal pump

Abstract

To provide an apparatus and a method including a step of recognizing a subject as suffering from a state selected from the group consisting of cardiac dysfunction, congestive heart failure, reduced renal blood flow, increased renal vascular resistance, arterial hypertension, and renal dysfunction.SOLUTION: By installing a blood pump 150 in the inside of a renal vein 32 of a subject and by moving an impeller so as to pump blood from the renal vein into a vena cava of the subject, a blood pressure in the renal vein of the subject is reduced. Other application examples are also described.SELECTED DRAWING: Figure 21A

Description

Related Applications

[0001] Cross - References to Related Applications This application claims priority to U.S. Provisional Patent Application No. 61 / 779,803, entitled "Renal pump", filed on March 13, 2013 by Schwammenthal, and U.S. Provisional Patent Application 61 / 914,475, entitled "Renal pump", filed on December 11, 2013 by Schwammenthal.

Technical Field

[0002] This application is related to International Patent Application PCT / IL2013 / 050495, entitled "Prosthetic renal valve", filed on June 6, 2013 by Tuval, which was published as WO13 / 183060 and claims priority to U.S. Provisional Patent Application No. 61 / 656,244, entitled "Prosthetic renal valve", filed on June 6, 2012 by Tuval.

[0003] All of the applications listed above are hereby incorporated by reference into this specification.

[0004] Some applications of the present invention generally relate to medical devices. Specifically, some applications of the present invention relate to devices and methods associated with installing a pump in one or more of the renal veins of a subject.

Background Art

[0005] It is often seen that cardiac dysfunction or congestive heart failure progresses to renal dysfunction, and that it causes the symptoms of congestive heart failure to develop or worsen. Typically, systolic and / or diastolic cardiac dysfunction causes systemic venous congestion, resulting in increased renal venous pressure and interstitial pressure. The increased pressure causes increased fluid retention by the body due to both renal dysfunction and renal neurohormonal activation, both of which typically develop as a result of increased renal venous pressure and interstitial pressure. The resulting fluid retention causes congestive heart failure to develop or worsen by causing an overload of blood volume in the heart and / or by increasing systemic resistance. Similarly, it is often seen that renal dysfunction and / or renal neurohormonal activation progress to cardiac dysfunction and / or congestive heart failure. In this pathophysiological cycle, cardiac dysfunction and / or congestive heart failure lead to renal dysfunction and / or renal neurohormonal activation, or renal dysfunction and / or renal neurohormonal activation lead to cardiac dysfunction and / or congestive heart failure, and each dysfunction leads to the worsening of the other dysfunction. This pathophysiological cycle is called cardiorenal syndrome.

[0006] Increased renal venous pressure has been experimentally shown to cause azotemia, as well as reduced glomerular filtration rate, renal blood flow, urine output, and sodium excretion. It has also been shown to increase plasma renin and aldosterone, as well as protein excretion. Venous congestion may also contribute to anemia via three different pathways: reduction of erythropoietin production in the kidney, hemodilution due to fluid retention, and an inflammatory response that leads to reduced gastrointestinal iron uptake.

[0007] Mechanistically, increased renal venous pressure may cause an increase in intracapsular pressure and subsequently interstitial peritubular pressure. The increase in peritubular pressure is the pressure of Bowman's capsule By increasing it, it may affect renal tubular function (reducing sodium excretion) and reduce glomerular filtration.

[0008] In patients with heart failure, increased renal venous pressure may result not only from increased central venous (right atrial) pressure but also from intra-abdominal fluid retention (ascites) that directly exerts pressure on the renal vein. Reduction of intra-abdominal pressure in patients with heart failure by removal of fluid (e.g., via paracentesis and / or ultrafiltration) has been shown to reduce plasma creatinine levels.

Summary of the Invention

Problems to be Solved by the Invention

[0009] An increase in venous return resulting from activation of the "calf muscle pump" during physical activity such as walking may, among other things, increase the systemic venous pressure in patients with heart failure and result in retrograde flow into the renal vein.

Means for Solving the Problems

[0010] According to some applications of the present invention, a blood pump including an impeller is placed inside the renal vein of a subject to provide acute treatment for a subject suffering from cardiac dysfunction, congestive heart failure, low renal blood flow, high renal vascular resistance, arterial hypertension, and / or kidney dysfunction, and the impeller is moved to pump blood from the renal vein to the large vein of the subject. For example, the impeller can be placed inside the renal vein of the subject for a period exceeding 1 hour (e.g., exceeding 1 day), a period less than 1 week (e.g., less than 4 days), and / or a period between 1 hour and 1 week (e.g., between 1 day and 4 days).

[0011] The pump is typically configured to pump blood in a downstream direction and reduce the pressure in the renal vein. Typically, due to the reduction in the pressure in the renal vein caused by pumping blood in the downstream direction, the perfusion of the kidney increases. And this can cause the pressure in the renal vein to rise relative to the pressure in the renal vein immediately after the start of pumping due to the increased blood flow into the renal vein. Typically, even after the perfusion of the kidney has increased, the pump is configured to maintain the pressure in the renal vein at a value lower than the pressure in the renal vein before the start of pumping.

[0012] Typically, the subject's renal vein is protected from being damaged by the impeller by placing a cage around the impeller into the renal vein, and the cage separates the wall of the renal vein from the impeller. In some applications, the cage and the impeller are engaged with each other by an engagement mechanism, and in response to the cage being compressed radially, the impeller is compressed radially, thereby causing the cage to maintain the separation between the wall of the renal vein and the impeller.

[0013] According to some applications, a pump and an occlusion element (e.g., a valve) are placed inside the subject's renal vein to provide acute treatment for subjects suffering from cardiac dysfunction, congestive heart failure, low renal blood flow, high renal vascular resistance, arterial hypertension, and / or kidney dysfunction. For example, the pump and the occlusion element can be placed inside the subject's renal vein for a period exceeding 1 hour (e.g., exceeding 1 day), for a period less than 1 week (e.g., less than 4 days), and / or for a period between 1 hour and 1 week (e.g., between 1 day and 4 days).

[0014] The occlusion element is configured to occlude the renal vein at the occlusion site. The pump is configured to pump blood in a downstream direction from a site in fluid communication with the upstream side of the occlusion element to a site in fluid communication with the downstream side of the occlusion element. When pumping, the pump reduces the pressure in the renal vein. The occlusion element is configured to protect the renal vein from backflow of blood from the vena cava to the renal vein.

[0015] Typically, due to the reduction in pressure in the renal vein caused by pumping blood in the downstream direction, the renal perfusion of the kidney increases. And this can cause the pressure in the renal vein to rise with respect to the pressure in the renal vein immediately after the start of pumping, due to the increased blood flow into the renal vein. Typically, even after the renal perfusion of the kidney has increased, the pump is configured to maintain the pressure in the renal vein at a value lower than the pressure in the renal vein before the start of pumping.

[0016] According to some applications of the present invention, a blood-impermeable sleeve is installed in the vena cava of the subject, and the downstream end of the sleeve is connected to the wall of the vena cava at a first location downstream of all the renal veins of the subject, and the upstream end of the sleeve is connected to the wall of the vena cava at a second location upstream of all the renal veins of the subject. Typically, a coupling structure, such as a rigid coupling structure (e.g., a stent), is configured to connect the upstream and downstream ends of the sleeve to the vena cava.

[0017] The pump pumps blood from a location outside the sleeve to a location in fluid communication with the inside of the sleeve (e.g., a location in the vena cava upstream or downstream of the sleeve). Thus, the pump pumps blood from the renal vein of the subject into the vena cava of the subject. The sleeve prevents backflow of blood from the vena cava into the renal vein.

[0018] Thus, according to some applications of the present invention, identifying a subject as suffering from a condition selected from the group consisting of cardiac dysfunction, congestive heart failure, reduced renal blood flow, increased renal vascular resistance, arterial hypertension, and kidney dysfunction; In response, reducing the blood pressure in the renal vein of interest by placing an impeller inside the renal vein of interest and moving the impeller to pump blood from the renal vein to the vena cava of interest. A method is provided that includes.

[0019] In some applications, the step of moving the impeller to pump blood from the renal vein into the vena cava includes enhancing the rate of blood flow from the renal vein into the vena cava without causing a substantial change in the direction of blood flow compared to the direction of blood flow from the renal vein into the vena cava when the pump is not operating.

[0020] In some applications, the step of moving the impeller to pump blood from the renal vein into the vena cava includes moving the impeller to pump blood directly from the renal vein into a portion of the vena cava adjacent to the renal vein.

[0021] In some applications, the step of moving the impeller to pump blood from the renal vein into the vena cava includes moving the impeller to pump blood from the renal vein into the vena cava without removing blood from the venous system of interest into a non-venous receptacle.

[0022] In some applications, the step of placing the impeller inside the renal vein includes protecting the renal vein of interest from being damaged by the impeller by placing the impeller into the renal vein with a cage disposed around the impeller and the cage separating the inner wall portion of the renal vein from the impeller.

[0023] In some applications, the step of installing the impeller into the renal vein with the cage disposed around the impeller includes the step of installing the impeller into the renal vein with the cage disposed around the impeller, wherein the cage and the impeller are engaged with each other by an engagement mechanism, and in response to the cage being compressed radially, the impeller is lengthened axially, and the cage is configured to maintain a separation between the wall of the renal vein and the impeller.

[0024] According to some applications of the present invention, there is provided an apparatus including an impeller, the impeller comprising an impeller frame including a proximal end portion and a distal end portion, and a plurality of helical elongated elements that curve from the proximal end portion to the distal end portion; a material, the material being connected to the helical elongated elements, and the helical elongated elements to which the material is connected being configured to define at least one blade of the impeller; and the apparatus further includes.

[0025] In some applications, the impeller includes a biocompatible impeller configured to be inserted into a blood vessel of a subject.

[0026] In some applications, the plurality of elongated elements include a plurality of helical strips.

[0027] In some applications, at least one of the helical elongated elements has a variable pitch, and the pitch of at least one of the elongated elements varies along the length of the helical elongated element.

[0028] In some applications, the impeller is configured to pump blood through a blood vessel by being disposed inside the target blood vessel and rotated with respect to the blood vessel, and the device further includes a radially expandable cage configured to be disposed between the impeller and the inner wall portion of the blood vessel and to separate the blood vessel wall portion from the impeller.

[0029] In some applications, the proximal end portion and the distal end portion include a proximal ring and a distal ring.

[0030] In some applications, at least one of the proximal end portion and the distal end portion defines a notch at its edge, and the notch is configured to facilitate the connection of material to a helical elongated element.

[0031] In some applications, the impeller further includes a suture thread coupled around a helical elongated element, and the suture thread is configured to facilitate the connection of material to the helical elongated element.

[0032] In some applications, the plurality of helical elongated elements includes three helical elongated elements that curve from the proximal end portion to the distal end portion.

[0033] In some applications, when the impeller is in its unconstrained configuration, the length of each helical elongated element, measured along the longitudinal axis of the impeller, is greater than 5 mm. In some applications, when the impeller is in its unconstrained configuration, the length of each helical elongated element, measured along the longitudinal axis of the impeller, is less than 14 mm.

[0034] In some application examples, when the impeller is in its unconstrained configuration, the span of the impeller in a direction perpendicular to the longitudinal axis of the impeller is greater than 8 mm. In some application examples, the span of the impeller is greater than 10 mm. In some application examples, the span of the impeller is less than 15 mm. In some application examples, the span of the impeller is less than 12 mm.

[0035] In some application examples, the plurality of helical elongated elements includes two helical elongated elements that curve and progress from a proximal end portion to a distal end portion.

[0036] In some application examples, the radius of each of the two helical elongated elements is within 20 percent of each other. In some application examples, the radius of each of the two helical elongated elements is similar to each other. In some application examples, the pitch of each of the two helical elongated elements is within 20 percent of each other. In some application examples, the pitch of each of the two helical elongated elements is similar to each other. In some application examples, the longitudinal axes of each of the two helical elongated elements are parallel to each other and parallel to the longitudinal axis of the impeller.

[0037] In some application examples, the material includes a continuous film of material supported by the helical elongated elements.

[0038] In some application examples, each of the helical elongated elements defines at least one-eighth of a turn of the helix. In some application examples, each of the helical elongated elements defines less than half of a turn of the helix.

[0039] In some application examples, A helical elongated element defines its proximal end and distal end, and the helical elongated element is configured to support material between the proximal end and the distal end of the helical elongated element. The impeller does not include an additional support member for supporting material between the proximal end and the distal end of the helical elongated element.

[0040] In some applications, the impeller is configured such that rotational movement is imparted from the proximal end portion of the impeller to the distal end portion of the impeller substantially only through the helical elongated element of the impeller.

[0041] In some applications, by not including an additional support member for supporting material between the proximal end and the distal end of the helical elongated element, the impeller is configured to be radially compressible to a smaller diameter than if the impeller included an additional support member for supporting material between the proximal end and the distal end of the helical elongated element.

[0042] In some applications, by not including an additional support member for supporting material between the proximal end and the distal end of the helical elongated element, the impeller is configured to be more flexible than if the impeller included an additional support member for supporting material between the proximal end and the distal end of the helical elongated element.

[0043] In some applications, between the proximal end and the distal end of the helical elongated element By not including an additional support member for supporting material, the force required to lengthen the impeller axially is less than a predetermined amount compared to what would be required if the impeller included an additional support member for supporting material between the proximal end and the distal end of the helical elongated element. The impeller is configured.

[0044] According to some application examples of the present invention, Cutting the tube so as to define a structure having first and second end portions at the proximal and distal ends of the structure, wherein the end portions are connected to each other by a plurality of elongated elements; Compressing the structure axially to cause the elongated elements to expand radially and form helical elongated elements; Connecting a material to the helical elongated elements such that the helical elongated elements to which the material is connected define at least one blade of the impeller; Thereby, a method for manufacturing an impeller is additionally provided.

[0045] In some application examples, the step of cutting the tube includes cutting the tube by laser.

[0046] In some application examples, the step of manufacturing the impeller includes manufacturing a biocompatible impeller configured to be inserted into a target blood vessel.

[0047] In some application examples, the step of cutting the tube is a step of cutting the tube so as to define a structure having first and second end portions at the proximal and distal ends of the structure, wherein the end portions are connected to each other by a plurality of strips.

[0048] In some application examples, the step of causing the elongated elements to expand radially and form helical elongated elements includes causing at least one of the helical elongated elements to have a variable pitch, wherein at least one pitch of the elongated elements varies along the length of the helical elongated elements.

[0049] In some applications, the step of cutting the tube such that the cut tube defines a structure having first and second end portions at the proximal and distal ends of the structure includes the step of cutting the tube such that the cut tube defines a structure having first and second rings at the proximal and distal ends of the structure.

[0050] In some applications, the step of cutting the tube further includes the step of forming a notch in at least one edge of the end portion, the notch being configured to facilitate the connection of material to a helical elongated element.

[0051] In some applications, the method further includes the step of tying a suture around a helical elongated element, the suture being configured to facilitate the connection of material to the helical elongated element.

[0052] In some applications, the step of cutting the tube is the step of cutting the tube such that the cut tube defines a structure having first and second end portions at the proximal and distal ends of the structure, the end portions being connected to each other by three elongated elements and the step of causing the elongated elements to expand radially and form a helical elongated element includes the step of causing the elongated elements to form three helical elongated elements.

[0053] In some applications, the step of cutting the tube includes cutting the tube such that, in the absence of axial compression applied to the structure, the structure has a length greater than 15 mm as measured along the longitudinal axis of the structure. In some applications, the step of cutting the tube includes cutting the tube such that, in the absence of axial compression applied to the structure, the length of the structure as measured along the longitudinal axis of the structure is less than 25 mm. In some applications, the step of cutting the tube includes cutting the tube such that, in the absence of axial compression applied to the structure, each of the elongated elements has a length greater than 14 mm as measured along the longitudinal axis of the structure. In some applications, the step of cutting the tube includes cutting the tube such that, in the absence of axial compression applied to the structure, the length of each of the elongated elements as measured along the longitudinal axis of the structure is less than 22 mm.

[0054] In some applications, the step of axially compressing the structure includes axially compressing the structure such that the structure defines a length greater than 8 mm as measured along the longitudinal axis of the structure. In some applications, the step of axially compressing the structure includes axially compressing the structure such that the length measured along the longitudinal axis of the structure is less than 18 mm. In some applications, the step of axially compressing the structure includes axially compressing the structure such that each of the elongated elements defines a length greater than 5 mm as measured along the longitudinal axis of the structure. In some applications, the step of axially compressing the structure includes axially compressing the structure such that the length of each of the elongated elements as measured along the longitudinal axis of the structure is less than 14 mm.

[0055] In some application examples, the step of axially compressing the structure includes axially compressing the structure such that the span of the structure in a direction perpendicular to the longitudinal axis of the structure is greater than 8 mm. In some application examples, the step of axially compressing the structure includes axially compressing the structure such that the span of the structure is greater than 10 mm. In some application examples, the step of axially compressing the structure includes axially compressing the structure such that the span of the structure is less than 15 mm. In some application examples, the step of axially compressing the structure includes axially compressing the structure such that the span of the structure is less than 12 mm.

[0056] In some application examples, the step of connecting the material to the helical elongated element includes immersing at least a portion of the structure into the material while the material is in its liquid state and drying the material while the material is supported by the helical elongated element. In some application examples, the step of drying the material includes the step of curing the material.

[0057] In some application examples, the step of cutting the tube is a step of cutting the tube such that the cut tube defines a structure having first and second end portions at the proximal and distal ends of the structure, the end portions being connected to each other by two elongated elements, and the step of causing the elongated elements to expand radially and form a helical elongated element includes the step of causing the elongated elements to form two helical elongated elements.

[0058] In some application examples, the step of drying the liquid material while the material is supported by the helical elongated element is a step of causing the material to form a continuous film between the helical elongated elements, the continuous film being supported by the helical elongated element.

[0059] In some applications, the step of cutting the tube is a step of cutting the tube such that the cut tube defines a structure having first and second end portions at the proximal and distal ends of the structure, the end portions being connected to each other by two elongated elements, and the step of causing the elongated elements to expand radially and form helical elongated elements includes the step of causing the elongated elements to form two helical elongated elements.

[0060] In some applications, the step of causing the elongated elements to form two helical elongated elements is a step of causing the elongated elements to form two helical elongated elements, both of the two helical elongated elements originating from the first end portion and terminating at the second end portion, and the radii of the helical elongated elements being similar to each other. In some applications, the step of causing the elongated elements to form two helical elongated elements is a step of causing the elongated elements to form two helical elongated elements, both of the two helical elongated elements originating from the first end portion and terminating at the second end portion, and the radii of the helical elongated elements being within 20 percent of each other.

[0061] In some applications, the step of causing an elongated element to form two helical elongated elements is the step of causing an elongated element to form two helical elongated elements, wherein both of the two helical elongated elements originate from a first end portion and terminate at a second end portion, and the pitch of the helical elongated elements is similar to each other. In some applications, the step of causing an elongated element to form two helical elongated elements is the step of causing an elongated element to form two helical elongated elements, wherein both of the two helical elongated elements originate from a first end portion and terminate at a second end portion, and the pitch of the helical elongated elements is within 20 percent of each other.

[0062] In some applications, the step of causing an elongated element to form two helical elongated elements is the step of causing an elongated element to form two helical elongated elements, wherein the longitudinal axes of both of the helical elongated elements are parallel to each other and parallel to the longitudinal axis of the impeller.

[0063] In some applications, the step of causing an elongated element to form two helical elongated elements is the step of causing an elongated element to form two helical elongated elements, wherein each of the helical elongated elements defines at least one-eighth of a turn of the helix. In some applications, the step of causing an elongated element to form two helical elongated elements is the step of causing an elongated element to form two helical elongated elements, wherein each of the helical elongated elements defines less than one-half of a turn of the helix.

[0064] In some applications, the step of cutting the tube is such that the cut tube defines a structure having first and second rings at the proximal and distal ends of the structure, and the first and second ends of each of the elongated elements are disposed at an angle with respect to the peripheral portion of the ring such that the angle is greater than 50 degrees. In some applications, the step of cutting the tube is such that the first and second ends of each of the elongated elements are disposed at an angle with respect to the peripheral portion of the ring such that the angle is greater than 70 degrees. In some applications, the step of cutting the tube is such that the first and second ends of each of the elongated elements are disposed at an angle with respect to the peripheral portion of the ring such that the angle is greater than 90 degrees.

[0065] In some applications, the step of cutting the tube is such that the cut tube defines a structure having first and second rings at the proximal and distal ends of the structure, and the first and second ends of each of the elongated elements are disposed at an angle with respect to the peripheral portion of the ring such that the angle is less than 180 degrees. In some applications, the step of cutting the tube is such that the first and second ends of each of the elongated elements are disposed at an angle with respect to the peripheral portion of the ring such that the angle is less than 150 degrees. In some applications, the step of cutting the tube is such that the first and second ends of each of the elongated elements are disposed at an angle with respect to the peripheral portion of the ring such that the angle is less than 110 degrees.

[0066] In some applications, the step of connecting a material to a helical elongated element includes connecting the material to the helical elongated element such that the material is supported by the helical elongated element between the proximal end and the distal end of the helical elongated element, when there is no additional support member for supporting the material between the proximal end and the distal end of the helical elongated element.

[0067] In some applications, the step of connecting a material to a helical elongated element includes configuring the impeller such that rotational movement is imparted from the proximal end portion to the distal end portion substantially only through the helical elongated element of the impeller, when there is no additional support member for supporting the material between the proximal end and the distal end of the helical elongated element.

[0068] In some applications, the step of connecting a material to a helical elongated element includes configuring the impeller such that it is radially compressible to a smaller diameter than if the impeller included an additional support member for supporting the material between the proximal end and the distal end of the helical elongated element, when there is no additional support member for supporting the material between the proximal end and the distal end of the helical elongated element.

[0069] In some applications, the step of connecting a material to a helical elongated element includes configuring the impeller such that it is more flexible than if the impeller included an additional support member for supporting the material between the proximal end and the distal end of the helical elongated element, when there is no additional support member for supporting the material between the proximal end and the distal end of the helical elongated element.

[0070] In some applications, when there is no additional support member for supporting the material between the proximal end and the distal end of the helical elongated element, the material The step of connecting includes configuring the impeller such that the force required to lengthen the impeller in the axial direction is less than a predetermined amount than would be required if the impeller included additional support members for supporting material between the proximal and distal ends of the helical elongated element.

[0071] According to some applications of the present invention, In a radially expanded configuration, an impeller configured to pump fluid by rotating, and A radially expandable cage disposed around the impeller, wherein in the radially expanded configuration of the impeller and the cage, the impeller is configured to be separated from the inner surface of the cage, the cage; An engagement mechanism configured to engage the impeller with the cage, wherein in response to the cage being compressed radially, the engagement mechanism elongates the impeller in the axial direction and keeps the impeller separated from the inner surface of the cage, the engagement mechanism An apparatus is further provided that includes.

[0072] In some applications, The cage and the impeller define a configuration elongated in their axial direction, and the cage is configured to accommodate the impeller inside the cage while in the configuration elongated in its axial direction, while the impeller is in the configuration elongated in its axial direction, The cage includes struts, and at least some of the struts include a portion of the strut that is wavy at least when the cage is in a configuration radially expanded. The level of undulation of the wavy portion of the strut when the cage is in a radially expanded configuration is greater than the level of undulation of the wavy portion of the strut when the cage is in a configuration elongated in its axial direction.

[0073] In some applications, the engagement mechanism is configured to allow rotation of the impeller while the cage is maintained in a position fixed in the rotational direction.

[0074] In some applications, the engagement mechanism is configured to lengthen the impeller axially by applying longitudinal movement caused by longitudinal movement of the cage in response to the cage being compressed radially to the impeller.

[0075] In some applications, the impeller includes a biocompatible impeller and is configured to be placed inside a blood vessel and pump blood through the blood vessel by rotating, and the cage is configured to be disposed between the impeller and the inner wall of the blood vessel and to separate the impeller from the blood vessel wall.

[0076] In some applications, the cage includes struts shaped to define cells, and the cage is configured to separate the impeller from the blood vessel wall even if the blood vessel wall protrudes through the cells of the cage.

[0077] In some applications, the impeller is connected to the cage such that the longitudinal axis of the impeller is aligned with the longitudinal axis of the cage, the cage defines a generally cylindrical central portion thereof, and generally the outer surface of the cage in the generally cylindrical portion is parallel to the longitudinal axis of the cage.

[0078] In some applications, the impeller is configured to be placed inside a blood vessel and pump blood through the blood vessel by rotating, and the cage is configured to be disposed between the impeller and the inner wall of the blood vessel and to separate the impeller from the inner wall of the blood vessel.

[0079] In some applications, the cage is configured to expand radially inside a blood vessel, and the outer surface of the cage in the generally cylindrical portion of the cage is adapted to engage the inner wall portion of the blood vessel, whereby the cage is oriented within the blood vessel such that the longitudinal axis of the cage is parallel to the local longitudinal axis of the blood vessel.

[0080] According to some applications of the present invention, In a radially expanded configuration, an impeller configured to pump blood through the blood vessel by rotation, and A radially expandable cage disposed around the impeller Installing inside the target blood vessel; Radially expanding the cage and the impeller inside the blood vessel such that the impeller is separated from the inner wall portion of the blood vessel by the cage, The impeller is engaged with the cage, and in response to the cage being radially compressed, the impeller is elongated in the axial direction and remains separated from the inner wall portion of the blood vessel; Operating a control unit to pump blood through the blood vessel by rotating the impeller, A method is additionally provided that includes.

[0081] In some applications, the blood vessel includes a renal vein, and operating the control unit to pump blood through the blood vessel includes operating the control unit to pump blood toward the vena cava of the subject away from the subject's kidney.

[0082] In some applications, the method Measuring the pressure in the target blood vessel at a first location in the blood vessel upstream of the impeller and at a second location in the blood vessel downstream of the impeller, and controlling the rotation of the impeller in response to pressures measured at a first and a second location; further comprising operating a control unit to control the rotation of the impeller.

[0083] In some applications, the step of placing the cage and the impeller inside the blood vessel includes placing the cage and the impeller inside the blood vessel while the cage and the impeller are in an axially elongated configuration, and while the axially elongated cage encloses the impeller inside the cage, and while the impeller is in an axially elongated configuration. The cage includes struts defining the cage, at least some of the struts including a portion of the strut that is wavy when at least the cage is in a radially expanded configuration. The step of radially expanding the cage includes radially expanding the cage such that the level of undulation of the wavy portion of the strut is greater than the level of undulation of the wavy portion of the strut when the cage is in its axially elongated configuration.

[0084] In some applications, the step of operating the control unit to rotate the impeller includes operating the control unit to rotate the impeller while the cage is maintained in a fixed position in the rotational direction.

[0085] In some applications, the cage includes struts shaped to define cells, and the step of radially expanding the cage includes radially expanding the cage to separate the impeller from the vessel wall portion even if the vessel wall portion protrudes through the cells of the cage.

[0086] In some applications, The step of installing the impeller and the cage inside the blood vessel is the step of installing the impeller and the cage inside the blood vessel, and includes the step that the impeller is connected to the cage such that the longitudinal axis of the impeller is aligned with the longitudinal axis of the cage. The cage includes a cage defining a central portion having a generally cylindrical shape, and an outer surface of the cage in the generally cylindrical portion of the cage is parallel to the longitudinal axis of the cage. The step of radially expanding the cage inside the blood vessel includes the step of engaging the outer surface of the cage in the generally cylindrical portion of the cage with the inner wall portion of the blood vessel, whereby the cage is radially expanded inside the blood vessel such that the longitudinal axis of the cage is parallel to the local longitudinal axis of the blood vessel.

[0087] In some applications, the blood vessel has a predetermined diameter in the absence of the cage. The step of radially expanding the cage includes the step of expanding a portion of the blood vessel such that the diameter of a portion of the blood vessel is greater than the predetermined diameter. The step of radially expanding the impeller includes the step of radially expanding the impeller such that the span of the impeller is at least equal to the predetermined diameter.

[0088] In some applications, the method includes measuring the flow through the blood vessel and controlling the rotation of the impeller in response to the measured flow, and further includes operating a control unit.

[0089] In some application examples, the step of operating the control unit to measure the flow through the blood vessel is the step of operating the control unit to measure the blood flow through a thermal flow sensor disposed in the housing, wherein the housing is configured such that the blood flow through the housing is in a direction substantially parallel to the local longitudinal axis of the blood vessel.

[0090] According to some application examples of the present invention, In a radially expanded configuration, a radially expandable impeller configured to pump fluid by rotating, and A radially expandable cage disposed around the impeller, wherein in the radially expanded configuration of the impeller and the cage, the impeller is separated from the inner surface of the cage. An apparatus comprising: The impeller is connected to the cage such that the longitudinal axis of the impeller is aligned with the longitudinal axis of the cage. The cage defines a central portion having a generally cylindrical shape, and the outer surface of the cage in the generally cylindrical portion of the cage is parallel to the longitudinal axis of the cage. Further provided is an apparatus.

[0091] In some application examples, The cage and the impeller define an axially elongated configuration, and the cage is configured to accommodate the impeller inside the cage while the cage is in the axially elongated configuration. On the other hand, the impeller is in the axially elongated configuration. The cage includes struts, and at least some of the struts include a portion of the strut that is wavy at least when the cage is in a radially expanded configuration. When the cage is in a configuration where it is radially expanded, the undulation level of the corrugated portion of the strut is greater than the undulation level of the corrugated portion of the strut when the cage is in a configuration where it is lengthened in its axial direction.

[0092] In some applications, the impeller defines a proximal ring and a distal end at its proximal end and distal end, respectively, the cage defines a proximal ring and a distal ring at its proximal end and distal end, respectively, The impeller The proximal rings of the impeller and the cage are installed on the first support element such that the proximal rings of the impeller and the cage are aligned with each other, and The distal rings of the impeller and the cage are installed on the second support element such that the distal rings of the impeller and the cage are aligned with each other, whereby the longitudinal axis of the impeller is connected to the cage so as to be aligned with the longitudinal axis of the cage.

[0093] In some applications, the device further includes an engagement mechanism configured to engage the impeller with the cage, and in response to the cage being radially compressed, the engagement mechanism lengthens the impeller axially so that the impeller remains separated from the inner surface of the cage.

[0094] In some applications, the engagement mechanism is configured to allow rotation of the impeller while the cage is maintained in a fixed position in the rotational direction.

[0095] In some applications, the engagement mechanism is configured to lengthen the impeller axially by imparting to the impeller a longitudinal movement caused by a longitudinal movement of the cage in response to the cage being radially compressed.

[0096] In some applications, the impeller is a biocompatible impeller, and the biocompatible impeller is configured to be installed inside a blood vessel and to pump blood through the blood vessel by rotating, and the cage is configured to be disposed between the impeller and the inner wall portion of the blood vessel and to separate the blood vessel wall portion from the impeller.

[0097] In some applications, the cage includes struts shaped to define cells, and the cage is configured to separate the blood vessel wall portion from the impeller, even if the blood vessel wall portion protrudes through the cells of the cage. See, even if the blood vessel wall portion protrudes through the cells of the cage, the cage is configured to separate the blood vessel wall portion from the impeller.

[0098] In some applications, the impeller is a biocompatible impeller, and the biocompatible impeller is configured to be installed inside a blood vessel and to pump blood through the blood vessel by rotating, and the cage is configured to be disposed between the impeller and the inner wall portion of the blood vessel and to separate the blood vessel wall portion from the impeller.

[0099] In some applications, the cage is configured to expand radially inside the blood vessel, and the outer surface of the cage in the generally cylindrical portion of the cage is adapted to engage the inner wall portion of the blood vessel, whereby the cage is oriented within the blood vessel such that the longitudinal axis of the cage is parallel to the local longitudinal axis of the blood vessel.

[0100] According to some applications of the present invention, In a radially expanded configuration, an impeller configured to pump blood through a blood vessel by rotating, and A radially expandable cage disposed around an impeller, the impeller being connected to the cage such that the longitudinal axis of the impeller is aligned with the longitudinal axis of the cage, the cage defining a central portion having a generally cylindrical shape, and an outer surface of the cage in the generally cylindrical portion of the cage being parallel to the longitudinal axis of the cage, the radially expandable cage and placing it inside the target blood vessel; such that the impeller is separated from the inner wall of the blood vessel by the cage, and such that an outer surface of the cage in the generally cylindrical portion of the cage engages the inner wall of the blood vessel, whereby the cage is oriented within the blood vessel such that the longitudinal axis of the cage is parallel to the local longitudinal axis of the blood vessel; radially expanding the cage and the impeller inside the blood vessel; operating a control unit to pump blood through the blood vessel by rotating the impeller. A method is further provided that includes:

[0101] In some applications, the method further includes measuring the pressure in the target blood vessel at a first location in the blood vessel upstream of the impeller and at a second location in the blood vessel downstream of the impeller, and operating the control unit to control the rotation of the impeller in response to the pressures measured at the first and second locations. The method further includes:

[0102] In some applications the blood vessel has a predetermined diameter in the absence of the cage, and the step of radially expanding the cage includes expanding a portion of the blood vessel such that the diameter of the portion of the blood vessel is greater than the predetermined diameter. The step of radially expanding the impeller includes radially expanding the impeller such that the span of the impeller is at least equal to a predetermined diameter.

[0103] In some applications, the method measures the flow through the blood vessel and controls the rotation of the impeller in response to the measured flow, and further includes operating a control unit.

[0104] In some applications, the step of operating the control unit to measure the flow through the blood vessel is the step of operating the control unit to measure the blood flow via a thermal flow sensor disposed within the housing, where the housing is configured such that the blood flow through the housing is in a direction substantially parallel to the local longitudinal axis of the blood vessel.

[0105] According to some applications of the present invention, a radially expandable impeller configured to pump fluid by rotating in a radially expanded configuration, and a radially expandable cage disposed around the impeller, where in the radially expanded configuration of the impeller and the cage, the impeller is separated from the inner surface of the cage, comprising an apparatus, the cage and the impeller define an axially elongated configuration, and the cage is configured to accommodate the impeller inside the cage while in the axially elongated configuration, while the impeller is in the axially elongated configuration, the cage includes struts, and at least some of the struts include a portion of the strut that is wavy when at least the cage is in the radially expanded configuration of the cage, The device further provides that when the cage is in a radially expanded configuration, the undulation level of the corrugated portion of the strut is greater than the undulation level of the corrugated portion of the strut when the cage is in a configuration elongated in its axial direction.

[0106] In some applications, for each strut including the corrugated portion, the strut The shortest distance from the first longitudinal end of the strut to the second longitudinal end of the strut when the cage is in a configuration elongated in its axial direction, and The shortest distance from the first longitudinal end of the strut to the second longitudinal end of the strut when the cage is in a radially expanded configuration is configured such that the ratio is greater than 1.05:1.

[0107] In some applications, the ratio is less than 1.4:1. In some applications, the ratio is greater than 1.15:1. In some applications, the ratio is greater than 1.2:1.

[0108] In some applications, the device is an engagement mechanism configured to engage an impeller with the cage, and in response to the cage being elongated in the axial direction, the impeller is elongated in the axial direction and remains separated from the inner surface of the cage, and further includes the engagement mechanism.

[0109] In some applications, the engagement mechanism is configured to allow rotation of the impeller while the cage is maintained in a fixed position in the rotational direction.

[0110] In some applications, the engagement mechanism is configured to elongate the impeller in the axial direction by applying to the impeller the longitudinal movement caused by the longitudinal movement of the cage in response to the cage being elongated in the axial direction.

[0111] In some applications The cage and the impeller are biocompatible, and the impeller is arranged inside the cage, and while the cage and the impeller are configured to be elongated in their axial directions, they are configured to be inserted into a blood vessel. The impeller is configured to expand radially inside the blood vessel and to pump blood through the blood vessel by rotating. The cage is configured to expand radially inside the blood vessel and is disposed between the impeller and the inner wall of the blood vessel to separate the inner wall of the blood vessel from the impeller. In some applications, the struts of the cage are shaped to define cells, and the cage is configured to separate the blood vessel wall from the impeller even if the blood vessel wall protrudes through the cells of the cage.

[0112] In some applications,

[0113] the impeller is connected to the cage such that the longitudinal axis of the impeller is aligned with the longitudinal axis of the cage. The cage defines a generally cylindrical central portion thereof, and the outer surface of the cage in the generally cylindrical portion of the cage is parallel to the longitudinal axis of the cage.

[0114] In some applications, the impeller is biocompatible, the impeller is configured to be installed inside the blood vessel and to pump blood through the blood vessel by rotating, the cage is configured to be disposed between the impeller and the inner wall of the blood vessel, and the cage is configured to separate the inner wall of the blood vessel from the impeller.

[0115] ​In some applications, the cage is configured to radially expand inside a blood vessel, and the outer surface of the cage in the generally cylindrical portion of the cage is adapted to engage the inner wall portion of the blood vessel, whereby the cage is oriented within the blood vessel such that the longitudinal axis of the cage is parallel to the local longitudinal axis of the blood vessel.

[0116] According to some applications of the present invention, In a radially expanded configuration, an impeller configured to pump blood through the blood vessel by rotation, and A radially expandable cage disposed around the impeller, the cage defining struts, the cage Installing the cage inside the target blood vessel, While the cage and the impeller are configured to be elongated in their axial directions, and while the cage is configured to be elongated in its axial direction, while accommodating the impeller inside the cage, and while the impeller is configured to be elongated in its axial direction, the step of installation is carried out, the step and Radially expanding the cage and the impeller inside the blood vessel such that the cage and the impeller are configured to radially expand and such that the impeller is separated from the inner wall portion of the blood vessel by the cage, Operating the control unit to pump blood through the blood vessel by operating the impeller, The cage includes struts, and at least some of the struts include a wavy portion of the struts that is wavy at least when the cage is configured to radially expand in the radial direction of the cage, The step of radially expanding the cage includes radially expanding the cage such that the level of the undulation of the wavy portion of the struts is greater than the level of the undulation of the wavy portion of the struts when the cage is configured to be elongated in its axial direction, the step and A method is additionally provided that includes.

[0117] In some applications, the step of operating the control unit to pump blood through the blood vessel, where the blood vessel includes the renal vein, includes operating the control unit to pump blood away from the target kidney and towards the vena cava of the subject.

[0118] In some applications, the method includes measuring the pressure in the blood vessel of the subject at a first location in the blood vessel upstream of the impeller and at a second location in the blood vessel downstream of the impeller, and operating the control unit to control the rotation of the impeller in response to the pressure measured at the first and second locations. The method further includes operating the control unit.

[0119] In some applications, the blood vessel has a predetermined diameter when there is no cage, the step of radially expanding the cage includes expanding a portion of the blood vessel such that the diameter of the portion of the blood vessel becomes larger than the predetermined diameter, the step of radially expanding the impeller includes radially expanding the impeller such that the span of the impeller is at least equal to the predetermined diameter.

[0120] In some applications, the step of radially expanding the cage includes, for each of the struts including the wavy portion, the shortest distance from the first longitudinal end of the strut to the second longitudinal end of the strut when the cage is in a configuration elongated in its axial direction, and the shortest distance from the first longitudinal end of the strut to the second longitudinal end of the strut when the cage is in a configuration radially expanded, and the ratio of these distances is greater than 1.05:1, and the step of radially expanding the cage includes this.

[0121] In some applications, the step of radially expanding the cage includes radially expanding the cage such that the ratio is less than 1.4:1 for each of the struts including the wavy portion. In some applications, the step of radially expanding the cage includes radially expanding the cage such that the ratio is greater than 1.15:1 for each of the struts including the wavy portion. In some applications, the step of radially expanding the cage includes radially expanding the cage such that the ratio is greater than 1.2:1 for each of the struts including the wavy portion.

[0122] In some applications, the method measures the flow through the blood vessel and controls the rotation of the impeller in response to the measured flow and further includes operating a control unit.

[0123] In some applications, the step of operating the control unit to measure the flow through the blood vessel is the step of operating the control unit to measure the blood flow via a thermal flow sensor disposed within the housing, the housing being configured such that the blood flow through the housing is in a direction substantially parallel to the local longitudinal axis of the blood vessel.

[0124] According to some applications of the present invention, installing a radially expandable structure inside a target blood vessel, the blood vessel having a predetermined diameter in the absence of the radially expandable structure, expanding a portion of the blood vessel by expanding the radially expandable structure inside the portion of the blood vessel such that the diameter of the portion of the blood vessel becomes larger than the predetermined diameter, installing an impeller inside the portion of the blood vessel, the impeller including impeller blades, the span of the impeller blades being at least equal to the predetermined diameter. The method further provides a step of operating a control unit to pump blood through a blood vessel by rotating an impeller relative to the blood vessel.

[0125] In some applications, the step of expanding the radially expandable structure includes expanding a radially expandable cage disposed around the impeller such that the impeller is separated from the inner wall portion of the blood vessel by the cage.

[0126] In some applications, the blood vessel includes a renal vein, and the step of operating the control unit to pump blood through the blood vessel includes operating the control unit to pump blood away from the target kidney and towards the vena cava of the subject.

[0127] In some applications, the method measures the pressure in the blood vessel at a first location upstream of the impeller and at a second location downstream of the impeller, and operates the control unit to control the rotation of the impeller in response to the pressures measured at the first and second locations. The method further includes a step of operating the control unit.

[0128] In some applications, the method measures the flow through the blood vessel, and operates the control unit to control the rotation of the impeller in response to the measured flow. The method further includes a step of operating the control unit.

[0129] In some application examples, the step of operating the control unit to measure the flow through a blood vessel is the step of operating the control unit to measure the blood flow via a thermal flow sensor disposed within the housing, where the housing is configured such that the blood flow through the housing is in a direction substantially parallel to the local longitudinal axis of the blood vessel.

[0130] In some application examples, the step of expanding a portion of a blood vessel includes expanding a radially expandable structure inside a portion of the blood vessel such that the diameter of the portion of the blood vessel becomes greater than 105 percent of a predetermined diameter. In some application examples, the step of expanding a portion of a blood vessel includes expanding a radially expandable structure inside a portion of the blood vessel such that the diameter of the portion of the blood vessel becomes greater than 115 percent of a predetermined diameter. In some application examples, the step of expanding a portion of a blood vessel includes expanding a radially expandable structure inside a portion of the blood vessel such that the diameter of the portion of the blood vessel becomes less than 125 percent of a predetermined diameter.

[0131] According to some application examples of the present invention, A blood pump configured to pump blood through a target blood vessel, the blood pump comprising An elongated element, and An impeller disposed at the distal end of the elongated element, the impeller being configured to pump blood through the blood vessel by rotating. A blood pump including the impeller, A thermal flow sensor configured to measure the flow of the pumped blood, the thermal flow sensor including an upstream temperature sensor, a heating element, and a downstream temperature sensor disposed continuously along a portion of the length of the elongated element. An elongated element including a housing, the housing being configured to house a thermal flow sensor, the housing being configured such that blood flow through the housing is in a direction substantially parallel to the local longitudinal axis of the blood vessel, and the elongated element An apparatus is further provided that includes

[0132] In some applications, the housing includes a portion of the outer surface of the elongated element shaped to define a recess therein, with an upstream temperature sensor, a heating element, and a downstream temperature sensor disposed in series along the recess.

[0133] In some applications, the ratio of the length of the recess to the width of the recess is greater than 4:1.

[0134] In some applications, the apparatus further includes a cover, the cover being connected to the elongated element and disposed to cover the thermal sensor.

[0135] In some applications, the housing includes a housing disposed on the outer surface of the elongated element, with an upstream temperature sensor, a heating element, and a downstream temperature sensor disposed in series along the inside of the housing.

[0136] In some applications, the housing includes a compressible tube disposed on the outer surface of the elongated element.

[0137] In some applications, the ratio of the length of the housing to the width of the housing is greater than 4:1. In some applications, the ratio of the length of the housing to the height of the housing is greater than 4:1.

[0138] According to some applications of the present invention, Installing a blood pump into a target blood vessel, the blood pump comprising an elongated element, and An impeller disposed at a distal end of an elongated element including a step; operating a control unit to measure the flow of blood being pumped using a thermal flow sensor, the thermal flow sensor including an upstream temperature sensor, a heating element, and a downstream temperature sensor disposed continuously along a portion of the length of the elongated element; the elongated element including a housing configured to house the thermal flow sensor, the housing being configured such that blood flow through the housing is in a direction substantially parallel to the local longitudinal axis of the blood vessel; operating a control unit to pump blood through a blood vessel by rotating the impeller at least partially in response to the measured flow; and a method is additionally provided.

[0139] According to some applications of the present invention, a pump configured to pump a fluid, the pump including: an elongated element; and an impeller disposed at a distal end of the elongated element, the impeller being configured to pump the fluid by rotating; a thermal flow sensor configured to measure the flow of the fluid being pumped, the thermal flow sensor including an upstream temperature sensor, a heating element, and a downstream temperature sensor disposed continuously along a portion of the length of the elongated element; an elongated element including a housing configured to house the thermal flow sensor, the housing being configured such that fluid flow through the housing is in a direction substantially parallel to the local longitudinal axis of the elongated element; and an elongated element including a housing configured to house the thermal flow sensor, the housing being configured such that fluid flow through the housing is in a direction substantially parallel to the local longitudinal axis of the elongated element; An apparatus is further provided that includes

[0140] In some applications, the housing includes a portion of the outer surface of an elongate element shaped to define a recess therein, and an upstream temperature sensor, a heating element, and a downstream temperature sensor are disposed continuously along the recess.

[0141] In some applications, the ratio of the length of the recess to the width of the recess is greater than 4:1.

[0142] In some applications, the apparatus further includes a cover that is coupled to the elongate element and is disposed to cover the thermal sensor.

[0143] In some applications, the housing includes a housing disposed on the outer surface of the elongate element, and an upstream temperature sensor, a heating element, and a downstream temperature sensor are disposed continuously along the inside of the housing.

[0144] In some applications, the housing includes a compressible tube disposed on the outer surface of the elongate element.

[0145] In some applications, the ratio of the length of the housing to the width of the housing is greater than 4:1. In some applications, the ratio of the length of the housing to the height of the housing is greater than 4:1.

[0146] According to some applications of the present invention, A method for use with a plurality of tributary veins supplying a main vein, the method comprising: mechanically isolating blood in the plurality of veins into a compartment separated from the blood flow in the main vein; controlling blood flow from the plurality of veins to the main vein by pumping blood from the compartment to the main vein A method is further provided that includes

[0147] In some applications, the method further includes the step of performing ultrafiltration on the pumped blood.

[0148] In some applications, the step of isolating a plurality of veins includes installing a blood-impermeable sleeve and a helical support element disposed around the sleeve into the main vein, and connecting the sleeve to the wall of the main vein using the helical support element. The step of pumping blood from the compartment to the main vein includes guiding the distal portion of the blood pump into the compartment using the helical support element and pumping the blood using the blood pump.

[0149] In some applications, the step of isolating a plurality of veins includes installing a blood-impermeable sleeve and a helical portion of the blood pump into the main vein, the helical portion being disposed around the sleeve and configured to support the sleeve, and connecting the sleeve to the wall of the main vein and the step of pumping blood from the compartment to the main vein includes pumping the blood into the inlet aperture of the blood pump defined by the helical portion of the blood pump.

[0150] In some applications, the step of isolating the blood in a plurality of veins into a compartment separated from the blood flow in the main vein includes isolating the blood in the target renal vein into a compartment separated from the blood flow in the target vena cava by placing a blood-impermeable sleeve into the target vena cava, wherein the downstream end of the sleeve is connected to the wall of the vena cava at a first location downstream of all of the target renal veins, and the upstream end of the sleeve is connected to the wall of the vena cava at a second location upstream of all of the target renal veins. The step of pumping blood from the compartment to the main vein includes operating a pump to pump blood from the compartment to a location in fluid communication with the interior of the sleeve.

[0151] In some applications, the step of pumping blood from the compartment includes withdrawing blood in a downstream direction through the renal vein.

[0152] In some applications, the step of placing the sleeve into the vena cava includes placing the sleeve into the vena cava for less than one week, and the step of operating the pump includes operating the pump for less than one week.

[0153] In some applications, the method further includes identifying a subject as a subject suffering from a condition selected from the group consisting of cardiac dysfunction, congestive heart failure, reduced renal blood flow, increased renal vascular resistance, arterial hypertension, and kidney dysfunction, and the step of operating the pump includes reducing the blood pressure in the renal vein of the subject by operating the pump in response to identifying the subject as suffering from the condition.

[0154] In some applications, the step of placing the sleeve into the target vena cava includes anchoring the sleeve to the vena cava by operating a pump to cause the vena cava to constrict around at least a portion of the sleeve.

[0155] In some applications, the step of operating the pump to pump blood from the compartment to a location in fluid communication with the interior of the sleeve includes operating the pump to pump blood from the compartment to a site in the vena cava upstream of the sleeve.

[0156] In some applications, the step of operating the pump to pump blood from the compartment to a location in fluid communication with the interior of the sleeve includes operating the pump to pump blood from the compartment to a site in the vena cava downstream of the sleeve.

[0157] In some applications, the step of placing the sleeve into the vena cava includes placing into the vena cava a stent shaped to define its enlarged upstream and downstream ends, the upstream and downstream ends being enlarged relative to the central portion of the stent, and a blood-impermeable sleeve connected to the stent, the sleeve defining its flared upstream and downstream ends, the upstream and downstream ends being connected respectively to the enlarged upstream and downstream ends of the stent; in response to the blood pressure against at least one first side of at least one flared end of the sleeve being greater than the blood pressure against a second side of at least one flared end of the sleeve, causing blood to flow between the outside of at least one flared end of the sleeve and the inner wall of the blood vessel, and In response to the blood pressure applied to the first side of at least one flared end of the sleeve being less than the blood pressure applied to the second side of at least one flared end of the sleeve, at least one flared end of the sleeve contacts the inner wall portion of the blood vessel, thereby occluding the blood flow between the outside of at least one flared end of the sleeve and the inner wall portion of the blood vessel. connecting the stent to the blood vessel comprises.

[0158] In some applications, the step of placing the sleeve into the vena cava a sleeve, the sleeve being shaped to define its flared end and a narrow central portion between the flared ends, a stent, the stent a sleeve support frame, the sleeve support frame being shaped to define its expanded end and a narrow central portion between the expanded ends that is narrower than the expanded end of the stent, the sleeve being connected to the sleeve support frame of the stent, and a blood vessel wall support frame, the blood vessel wall support frame being connected to the narrow central portion of the sleeve support frame and protruding radially from the sleeve support frame a stent shaped to define comprises placing the stent into the vena cava.

[0159] In some applications, the step of pumping blood from the compartment comprises pumping blood from a site between the outside of the sleeve and the inner wall portion of the vena cava.

[0160] In some applications, the method further comprises inserting a pump into the compartment through an opening in the sleeve through which the pump is insertable.

[0161] In some applications, the step of inserting the pump through the opening includes inserting the pump through an opening having a diameter between 2 mm and 10 mm.

[0162] In some applications, the step of inserting the pump through the opening includes inserting the pump through the opening such that the opening forms a seal around the pump.

[0163] In some applications, the method further includes inserting the pump into the compartment through a pump receiving sleeve protruding from the sleeve.

[0164] In some applications, the step of inserting the pump into the compartment through the pump receiving sleeve includes inserting the pump into the compartment through a pump receiving sleeve having a diameter between 2 mm and 10 mm.

[0165] In some applications, the step of inserting the pump into the compartment through the pump receiving sleeve includes inserting the pump into the compartment through the pump receiving sleeve such that the pump receiving sleeve forms a seal around the pump.

[0166] According to some applications of the present invention, a blood-impermeable sleeve, at least one support structure configured to connect the first and second ends of the sleeve to a blood vessel of a subject, a pump configured to pump blood from outside the sleeve to a location in fluid communication with the inside of the sleeve are further provided.

[0167] In some applications, the pump is configured to perform ultrafiltration on blood.

[0168] In some applications, the pump is configured to anchor the structure to the blood vessel by causing the blood vessel to constrict around at least a portion of the structure.

[0169] In some applications, the structure includes a stent, and the stent is shaped to define an enlarged end thereof that is enlarged compared to the central portion of the stent, the sleeve includes a sleeve coupled to the stent, the sleeve defines a flared end thereof that is coupled to the enlarged end of the stent, at least one of the flared ends of the sleeve is configured to act as a valve by at least partially separating from the enlarged end of the stent to which it is coupled in response to pressure being applied to the flared end of the sleeve.

[0170] In some applications, the support structure includes a helical support element disposed around the sleeve, the distal portion of the blood pump is configured to be guided to be disposed around the outside of the sleeve using the helical support element.

[0171] In some applications, the support structure includes a helical portion of the blood pump, the helical portion is disposed around the sleeve and is configured to support the sleeve, the pump is configured to pump blood from outside the sleeve by pumping blood into an inlet aperture of the pump defined by the helical portion of the blood pump. configured.

[0172] In some applications, the sleeve is shaped to define a flared end thereof and a narrow central portion of the width between the flared ends, The structure includes a stent, and the stent is a sleeve support frame, which is shaped to define its enlarged end and a narrow central portion between the enlarged ends that are narrower than the enlarged end of the stent, and the sleeve is connected to the sleeve support frame of the stent, and a vascular wall support frame, which is connected to the narrow central portion of the sleeve support frame and projects radially from the sleeve support frame, the vascular wall support frame is shaped to define.

[0173] In some applications, a pump is configured to pump blood from a site between the outside of the sleeve and the inner wall of the blood vessel by being installed between the outside of the sleeve and the vascular wall support frame.

[0174] In some applications, the structure is configured to isolate the blood in the subject's renal veins into a compartment separated from the blood flow in the subject's vena cava by connecting the downstream end of the sleeve to the wall of the vena cava at a first location downstream of all of the subject's renal veins and connecting the upstream end of the sleeve to the wall of the vena cava at a second location upstream of all of the subject's renal veins.

[0175] In some applications, the sleeve is configured to be connected to the vena cava for less than one week, and the pump is configured to operate for less than one week.

[0176] In some applications, the pump is configured to reduce the blood pressure in the subject's renal veins by pumping blood.

[0177] In some applications, the pump is configured to pump blood from the compartment to a site in the vena cava.

[0178] In some applications, the pump is configured to pump blood from the compartment to a site in the vena cava upstream of the sleeve.

[0179] In some applications, the pump is configured to pump blood from the compartment to a site in the vena cava downstream of the sleeve.

[0180] In some applications, the sleeve is shaped to define an opening through which the pump can be inserted.

[0181] In some applications, the diameter of the opening is between 2 mm and 10 mm.

[0182] In some applications, the opening is sized to form a seal around the pump.

[0183] In some applications, the device further includes a pump receiving sleeve protruding from the blood-impermeable sleeve, the pump receiving sleeve being configured to accommodate insertion of the pump therethrough to the outside of the blood-impermeable sleeve. to the outside of the blood-impermeable sleeve.

[0184] In some applications, the inner diameter of the pump receiving sleeve is between 2 mm and 10 mm.

[0185] In some applications, the pump receiving sleeve is sized to form a seal around the pump.

[0186] According to some applications of the present invention, at the stent installation site, the step of installing the stent inside the blood vessel; by applying a suction force into the blood vessel to cause the blood vessel to shrink around at least a portion of the stent, at the installation site, the step of at least partially anchor-fixing the stent to the blood vessel; A method is additionally provided that includes

[0187] In some applications, the blood vessel includes a blood vessel having a predetermined diameter at the installation site, and the step of installing a stent inside the blood vessel includes the step of installing a stent having a diameter smaller than the predetermined diameter inside the blood vessel.

[0188] In some applications, the step of causing the blood vessel to contract around at least a portion of the stent includes reducing the degree to which the stent is anchored to the blood vessel, thanks to over-sizing the stent, compared to the case where the blood vessel could not be made to contract around at least a portion of the stent.

[0189] According to some applications of the present invention, a stent configured to be installed inside a blood vessel at the installation site of the stent, and a pump configured to anchor the stent to the blood vessel at the installation site by applying a suction force in the blood vessel to cause the blood vessel to contract around at least a portion of the stent An apparatus is further provided that includes

[0190] In some applications, the blood vessel includes a blood vessel having a predetermined diameter at the installation site, and the stent includes a stent having a diameter smaller than the predetermined diameter. According to some applications of the present invention, a stent configured to be installed inside a blood vessel, the stent being shaped to define an enlarged end thereof that is enlarged compared to the central portion of the stent, and a blood-impermeable sleeve coupled to the stent, the sleeve defining a flared end thereof that is coupled to the enlarged end of the stent, At least one of the flared ends of the sleeve is configured to act as a valve by at least partially separating from the enlarged end of the stent to which it is connected in response to pressure being applied to the flared end of the sleeve, a blood-impermeable sleeve and An apparatus is additionally provided that includes

[0191] According to some applications of the present invention, A stent shaped to define its enlarged upstream and downstream ends, enlarged compared to the central portion of the stent, and A blood-impermeable sleeve connected to the stent, the sleeve defining its flared upstream and downstream ends respectively connected to the enlarged upstream and downstream ends of the stent, a blood-impermeable sleeve Installing into the target blood vessel, and In response to the blood pressure on the first side of at least one flared end of the sleeve being greater than the blood pressure on the second side of at least one flared end of the sleeve, blood flows between the outside of at least one flared end of the sleeve and the inner wall of the blood vessel, and In response to the blood pressure on the first side of at least one flared end of the sleeve being less than the blood pressure on the second side of at least one flared end of the sleeve, at least one flared end of the sleeve contacts the inner wall of the blood vessel to occlude the blood flow between the outside of at least one flared end of the sleeve and the inner wall of the blood vessel, Connecting the stent to the blood vessel and A method is further provided that includes

[0192] According to some applications of the present invention, A blood-impermeable sleeve, the blood-impermeable sleeve defining a flared end portion thereof and a narrow central portion between the flared end portions, and A stent configured to be placed inside a blood vessel, the stent A sleeve support frame, the sleeve support frame shaped to define an enlarged end portion thereof and a narrow central portion between the enlarged end portions that are narrower than the enlarged end portions of the stent, the sleeve being connected to the sleeve support frame of the stent, and A vessel wall support frame, the vessel wall support frame being connected to the narrow central portion of the sleeve support frame and projecting radially from the sleeve support frame, the vessel wall support frame Shaped to define a stent An apparatus is additionally provided that includes

[0193] In some applications, the apparatus further includes a blood pump, the blood pump configured to pump blood from between the outer side of the sleeve and the inner wall portion of the blood vessel by being placed between the outer side of the sleeve and the vessel wall support frame.

[0194] In some applications, the diameter of the narrow central portion of the sleeve is between 8 mm and 35 mm.

[0195] In some applications, the maximum diameter of the flared end portion of the sleeve is between 10 mm and 45 mm.

[0196] In some applications, the ratio of the maximum diameter of the flared end portion of the sleeve to the diameter of the narrow central portion of the sleeve is between 1.1:1 and 2:1.

[0197] In some applications, the maximum diameter of the vessel wall support frame is between 10 mm and 50 mm.

[0198] In some application examples, the ratio of the maximum diameter of the wall support frame to the diameter of the narrow central portion of the sleeve support frame is between 1.1:1 and 5:1. In some application examples, the ratio is greater than 1.5:1.

[0199] In some application examples, the length of the sleeve is greater than 6 mm. In some application examples, the length of the sleeve is less than 80 mm. In some application examples, the length of each of the flared ends of the sleeve is greater than 3 mm. In some application examples, the length of each of the flared ends of the sleeve is less than 40 mm. In some application examples, the length of the narrow central portion of the sleeve is greater than 3 mm. In some application examples, the length of the narrow central portion of the sleeve is less than 70 mm.

[0200] According to some application examples of the present invention, A blood-impermeable sleeve, the blood-impermeable sleeve defining a flared end and a narrow central portion between the flared ends. A stent, the stent comprising A sleeve support frame, the sleeve support frame being shaped to define its enlarged end and a narrow central portion between the enlarged ends that are narrower than the enlarged end of the stent, the sleeve being connected to the sleeve support frame of the stent, and A blood vessel wall support frame, the blood vessel wall support frame being connected to the narrow central portion of the sleeve support frame and protruding radially from the sleeve support frame. The stent being shaped to define Installing the stent into the blood vessel of the subject, and There is additionally provided a method including connecting the stent to the blood vessel such that the blood vessel wall support frame of the stent supports the wall of the blood vessel to keep the blood vessel open and the sleeve support frame supports the sleeve in the blood vessel.

[0201] In some applications, the method further includes pumping blood from a site between the outer side of the sleeve and the inner wall portion of the blood vessel by installing a pump between the outer side of the sleeve and the blood vessel wall support frame.

[0202] In some applications, the step of installing the sleeve into the blood vessel includes the step of installing the sleeve into the blood vessel, wherein the diameter of the narrow central portion of the sleeve is between 8 mm and 35 mm.

[0203] In some applications, the step of installing the sleeve into the blood vessel includes the step of installing the sleeve into the blood vessel, wherein the maximum diameter of the flared end portion of the sleeve is between 10 mm and 45 mm.

[0204] In some applications, the step of installing the sleeve into the blood vessel includes the step of installing the sleeve into the blood vessel, wherein the ratio of the maximum diameter of the flared end portion of the sleeve to the diameter of the narrow central portion of the sleeve is between 1.1:1 and 2:1.

[0205] In some applications, the step of installing the stent into the blood vessel includes the step of installing the stent into the blood vessel, wherein the maximum diameter of the blood vessel wall support frame is between 10 mm and 50 mm.

[0206] In some applications, the step of installing the stent into the blood vessel includes the step of installing the stent into the blood vessel, wherein the ratio of the maximum diameter of the wall support frame to the diameter of the narrow central portion of the sleeve support frame is between 1.1:1 and 5:1. In some applications, the step of installing the stent into the blood vessel includes the step of installing the stent into the blood vessel, wherein the ratio is greater than 1.5:1.

[0207] In some application examples, the step of installing the sleeve into the blood vessel includes the step of installing the sleeve into the blood vessel, where the length of the sleeve is greater than 6 mm. In some application examples, the step of installing the sleeve into the blood vessel includes the step of installing the sleeve into the blood vessel, where the length of the sleeve is less than 80 mm. In some application examples, the step of installing the sleeve into the blood vessel includes the step of installing the sleeve into the blood vessel, where the length of each of the flare-shaped ends of the sleeve is greater than 3 mm. In some application examples, the step of installing the sleeve into the blood vessel includes the step of installing the sleeve into the blood vessel, where the length of each of the flare-shaped ends of the sleeve is less than 40 mm. In some application examples, the step of installing the sleeve into the blood vessel includes the step of installing the sleeve into the blood vessel, where the length of the narrow central portion of the sleeve is greater than 3 mm. In some application examples, the step of installing the sleeve into the blood vessel includes the step of installing the sleeve into the blood vessel, where the length of the narrow central portion of the sleeve is less than 70 mm.

[0208] According to some application examples of the present invention, there is provided a method for operating a blood pump disposed inside a target blood vessel, the method comprising: installing an occlusion element into the blood vessel, the occlusion element having an occluded state and a non-occluded state, wherein in the occluded state, the occlusion element occludes the blood vessel, and in the non-occluded state, the occlusion element does not occlude the blood vessel; drawing blood in a downstream direction from a site in fluid communication with the upstream side of the occlusion element; pumping blood into a site of the target vasculature in fluid communication with the downstream side of the occlusion element; and the step of pumping blood into the target vasculature is performed in a manner that maintains the occlusion element in its occluded state, wherein in the occluded state, the occlusion element occludes the blood vessel.

[0209] In some applications, the method further includes the step of performing ultrafiltration on the blood before pumping the blood into a site of the target vascular system.

[0210] In some applications, the step of placing an occlusion element in a blood vessel includes the step of placing the occlusion element in the blood vessel for less than one week, and the step of pumping blood includes the step of pumping blood into the vascular system for less than one week. In some applications, the step of placing an occlusion element in a blood vessel includes the step of placing the occlusion element in the blood vessel for one week or more, and the step of pumping blood includes the step of pumping blood into the vascular system for less than one week.

[0211] In some applications, the method further includes the step of identifying a subject as a subject suffering from a condition selected from the group consisting of cardiac dysfunction, congestive heart failure, reduced renal blood flow, increased renal vascular resistance, arterial hypertension, and kidney dysfunction, the blood vessel includes the renal vein of the subject, and the step of withdrawing blood in a downstream direction from a site that is in fluid communication upstream of the occlusion element includes reducing the blood pressure in the renal vein of the subject by withdrawing blood in a downstream direction in response to the step of identifying the subject as a subject suffering from the condition.

[0212] In some applications, the step of pumping blood into the vascular system of the subject in a manner that maintains the occlusion element in its occluded state is the dynamic pressure includes the step of pumping blood into the vascular system of the subject so as to maintain the occlusion element in its occluded state.

[0213] In some applications, the step of placing an occlusion element in a blood vessel includes the step of placing a valve having valve leaflets in the blood vessel, and the step of pumping blood into the subject's vascular system such that the hydrodynamic pressure of the blood being pumped into the subject's vascular system maintains the occlusion element in its occluded state includes the step of pumping blood into the subject's vascular system such that the blood being pumped into the subject's vascular system directly impinges downstream of the valve leaflets.

[0214] In some applications, the step of placing a valve in a blood vessel in response to the blood pressure upstream of the valve leaflets exceeding the pressure downstream of the valve leaflets, blood flows in the forward direction between the tips (cusps) of the valve leaflets and the inner wall of the blood vessel, and in response to the blood pressure downstream of the valve leaflets exceeding the pressure upstream of the valve leaflets, the valve occludes retrograde blood flow by the tips of the valve leaflets contacting the inner wall of the blood vessel, includes the step of placing a valve in the blood vessel.

[0215] In some applications, the step of pumping blood into the subject's vascular system such that the blood being pumped into the subject's vascular system directly impinges downstream of the valve leaflets includes the step of reducing thrombus in the valve leaflets by flushing the valve leaflets.

[0216] In some applications, the method further includes the step of pumping an anticoagulant into the subject's vascular system along with the blood being pumped into the subject's vascular system such that the anticoagulant directly impinges on the valve leaflets.

[0217] In some applications, the step of placing a valve in a blood vessel includes maintaining a portion of the valve leaflet in contact with the wall of the blood vessel by inflating a balloon.

[0218] In some applications, the step of placing a valve in a blood vessel includes maintaining a portion of the valve leaflet in contact with the wall of the blood vessel by radially expanding a portion of a slit tube.

[0219] In some applications, the step of pumping blood such that the blood directly impacts the downstream side of the valve leaflet includes pumping blood into the subject's vascular system through an aperture shaped to direct the blood toward the downstream side of the valve leaflet.

[0220] In some applications, the step of pumping blood such that the blood directly impacts the downstream side of the valve leaflet is a step of pumping blood into the subject's vascular system through a pump catheter, the pump catheter being shaped to define a radially projecting portion therefrom, the radially projecting portion being concave and curved toward the distal end of the catheter, the radially projecting portion being configured to direct the blood being pumped into the vascular system toward the valve leaflet.

[0221] In some applications, the step of pumping blood such that the blood directly impacts the downstream side of the valve leaflet is disposed adjacent to the base of the valve leaflet and includes pumping blood into the subject's vascular system through an aperture.

[0222] In some applications, the step of pumping blood such that the blood directly impinges on the downstream side of the valve leaflet includes pumping blood into the subject vascular system through an aperture disposed adjacent to a location below an intermediate point between the tip of the leaflet and the base of the leaflet along the length of the leaflet.

[0223] According to some applications of the present invention, an apparatus for use with a subject blood vessel, the apparatus comprising: An occlusion element configured to be placed within the blood vessel, the occlusion element having an occluded state and a non-occluded state, in the occluded state, the occlusion element occludes the blood vessel, and in the non-occluded state, the occlusion element does not occlude the blood vessel; and A blood pump, the blood pump configured to: Withdraw blood in a downstream direction from a site in fluid communication with the upstream side of the occlusion element; and Pump blood into the subject vascular system at a site in fluid communication with the downstream side of the occlusion element, The pump being configured to pump blood into the blood vessel in a manner that maintains the occlusion element in its occluded state. An apparatus is further provided that includes the above.

[0224] In some applications, the blood pump is configured to perform ultrafiltration of the blood prior to pumping the blood into the subject vascular system.

[0225] In some applications, the occlusion element is configured to be placed within the blood vessel for less than one week, and the pump is configured to pump blood into the vascular system for less than one week. In some applications, the occlusion element is configured to be placed within the blood vessel for one week or more, and the pump is configured to pump blood into the vascular system for less than one week.

[0226] In some applications, the pump is configured to pump blood into the target vascular system in a manner that maintains the occlusion element in its occluded state by pumping blood into the target vascular system such that the hydrodynamic pressure of the blood being pumped into the target vascular system maintains the occlusion element in its occluded state.

[0227] In some applications, the occlusion element includes a valve having a valve leaflet, and the pump is configured to pump blood into the target vascular system such that the blood being pumped into the target vascular system directly impacts downstream of the valve leaflet, and the hydrodynamic pressure of the blood maintains the occlusion element in its occluded state by pumping blood into the target vascular system.

[0228] In some applications, in response to the blood pressure upstream of the valve leaflet exceeding the pressure downstream of the valve leaflet, blood flows in the antegrade direction between the tip of the valve leaflet and the inner wall of the blood vessel, and in response to the blood pressure downstream of the valve leaflet exceeding the pressure upstream of the valve leaflet, the valve closes due to the tip of the valve leaflet contacting the inner wall of the blood vessel. The valve is configured.

[0229] In some applications, the pump is configured to reduce thrombus in the valve leaflet by flushing the valve leaflet by pumping blood into the target vascular system such that the blood being pumped into the target vascular system directly impacts downstream of the valve leaflet.

[0230] In some applications, the device is for use with an anticoagulant, and the pump is configured to pump the anticoagulant into the subject's vascular system along with the blood being pumped into the subject's vascular system such that the anticoagulant impinges directly on the valve leaflet.

[0231] In some applications, the device further includes a balloon, and the balloon is configured to, when inflated, maintain a portion of the valve leaflet in contact with the wall of the blood vessel.

[0232] In some applications, the device further includes a slit tube configured to be inserted into the blood vessel, and the slit tube is configured to maintain a portion of the valve leaflet in contact with the wall of the blood vessel by radially outwardly expanding a portion of the slit tube between the slits.

[0233] In some applications, the blood pump is configured to be coupled to the valve, the blood pump includes an outlet orifice, and the outlet orifice is shaped such that when the blood pump is coupled to the valve, the outlet orifice directs blood downstream of the valve leaflet into the subject's vascular system.

[0234] In some applications, the blood pump is configured to be coupled to the valve, the blood pump includes a blood pump catheter that defines a radially projecting portion that is concave and curved towards the distal end of the catheter, and the radially projecting portion is configured to direct blood being pumped into the vascular system towards the valve leaflet when the blood pump is coupled to the valve.

[0235] In some applications, the blood pump is configured to be coupled to a valve. The blood pump includes an outlet orifice through which blood is pumped into the subject's vasculature. The outlet orifice is disposed on the blood pump and, when the blood pump is coupled to the valve, the orifice is disposed adjacent to the base of the valve leaflet.

[0236] In some applications, the outlet orifice is disposed on the blood pump and, when the blood pump is coupled to the valve, the outlet orifice is disposed adjacent to a location along the length of the valve leaflet that is below the midpoint between the tip of the leaflet and the base of the leaflet.

[0237] According to some applications of the present invention, an apparatus for use with a subject's blood vessel, the apparatus comprising: a blood pump configured to draw blood downstream through the blood vessel into the pump; a valve including a rigid portion configured to couple the valve to the blood vessel, the valve being configured to couple to the distal portion of the blood pump and to prevent blood from flowing retrograde through the valve; is further provided.

[0238] In some applications, the valve further includes a flexible valve leaflet coupled to the rigid portion of the valve. According to some applications of the present invention, providing an artificial valve defining a valve leaflet; in response to the blood pressure upstream of the valve leaflet exceeding the pressure downstream of the valve leaflet, blood flows in a forward direction between the tip of the valve leaflet and the inner wall of the blood vessel, and In response to the blood pressure on the downstream side of the valve leaflet exceeding the pressure on the upstream side of the valve leaflet, the valve closes as the tip of the valve leaflet contacts the inner wall of the blood vessel. A step of installing a valve into a blood vessel is additionally provided.

[0239] According to some applications of the present invention, an apparatus including an artificial valve including a flexible valve leaflet and a rigid valve frame, wherein the valve leaflet In response to the pressure on the first side of the valve leaflet exceeding the pressure on the second side of the valve leaflet, the leaflet opens as the tip of the valve leaflet separates from the rigid frame, and In response to the blood pressure on the second side of the valve leaflet exceeding the pressure on the first side of the valve leaflet, the valve closes as the tip of the leaflet contacts the rigid frame. is further provided, which is connected to the valve frame.

[0240] According to some applications of the present invention, an apparatus including a blood pump, wherein the blood pump a tube, a first and a second one-way valve respectively disposed at the proximal and distal ends of the tube, a membrane that is connected inside the tube and divides the tube into a first compartment that is in fluid communication with the valve and a second compartment that is not in fluid communication with the valve, a pumping mechanism configured to pump fluid through the tube by increasing and then decreasing the size of the first compartment by moving the membrane relative to the tube is additionally provided.

[0241] In some applications, the tube includes a stent and a material disposed on the stent.

[0242] In some applications, the occluding element is configured to be placed within a blood vessel for less than one week.

[0243] In some applications, one of the valves is configured to prevent backflow of blood from the tube into the blood vessel, and a second one of the valves is configured to prevent backflow of blood from the blood vessel into the tube.

[0244] In some applications, a blood pump is configured to be placed within a subject's renal vein and to pump blood in a downstream direction from the renal vein to the subject's vena cava.

[0245] In some applications, a blood pump is configured to occlude backflow of blood from the vena cava to the renal vein.

[0246] According to some applications of the present invention, connecting the tube to the inner wall portion of the subject's blood vessel, wherein first and second one-way valves are disposed at the proximal and distal ends of the tube, respectively, a membrane is connected inside the tube and divides the tube into a first compartment in fluid communication with the valve and a second compartment not in fluid communication with the valve, operating a pumping mechanism to pump blood through the tube by moving the membrane with respect to the tube to increase and then decrease the size of the first compartment, A method is additionally provided that includes.

[0247] In some applications, the tube includes a stent and a material disposed on the stent, and the step of connecting the tube to the inner wall portion of the blood vessel includes the step of connecting the stent and the material to the inner wall portion of the blood vessel.

[0248] In some applications, the step of connecting the tube to the inner wall portion of the blood vessel includes the step of connecting the tube to the inner wall portion of the blood vessel over a period of less than one week.

[0249] In some applications, the step of operating the pumping mechanism includes operating the pumping mechanism such that one of the valves prevents backflow of blood from the tube into the blood vessel and a second one of the valves prevents backflow of blood from the blood vessel into the tube.

[0250] In some applications, the step of connecting the tube to the inner wall portion of the blood vessel includes the step of connecting the tube to the inner wall portion of the target renal vein, and the step of operating the pumping mechanism includes the step of pumping blood in a downstream direction from the renal vein to the target vena cava.

[0251] In some applications, the step of connecting the tube to the inner wall portion of the renal vein includes the step of occluding backflow of blood from the vena cava to the renal vein.

[0252] In some applications, the method further includes identifying a subject as a subject suffering from a condition selected from the group consisting of cardiac dysfunction, congestive heart failure, reduced renal blood flow, increased renal vascular resistance, arterial hypertension, and kidney dysfunction, and the step of operating the pump includes reducing the blood pressure in the renal vein of the subject by operating the pump to pump blood in a downstream direction from the renal vein to the vena cava in response to identifying the subject as a subject suffering from the condition.

[0253] According to some applications of the present invention, Operating the blood pump to pump blood downstream through the first vein, wherein the first vein is a tributary of the second vein and forms a junction with the second vein; Preventing backflow of blood from the second vein to the first vein by covering the ostium at the junction with an umbrella for covering the inlet portion disposed in the second vein; A method is further provided that includes.

[0254] In some applications, the step of operating the blood pump includes performing ultrafiltration on the pumped blood.

[0255] In some applications, when the umbrella for covering the inlet portion is in an open configuration, it includes an umbrella for covering the inlet portion having a diameter greater than 6 mm, and the step of covering the inlet portion with the umbrella includes covering the inlet portion with an umbrella having a diameter greater than 6 mm.

[0256] In some applications, the step of operating the blood pump includes causing the umbrella for covering the inlet portion to be sealed against the wall of the second vein surrounding the inlet portion.

[0257] In some applications, the first vein includes the renal vein of the subject, the second vein includes the vena cava of the subject, and the step of pumping blood downstream includes pumping blood downstream from the renal vein towards the vena cava.

[0258] In some applications, the step of preventing backflow of blood from the second vein to the first vein includes preventing backflow of blood from the vena cava to the renal vein.

[0259] In some applications, the method further includes identifying a subject as a subject suffering from a condition selected from the group consisting of cardiac dysfunction, congestive heart failure, reduced renal blood flow, increased renal vascular resistance, arterial hypertension, and kidney dysfunction, and the step of operating the pump includes reducing the blood pressure in the renal vein of the subject by operating the pump to pump blood in a downstream direction from the renal vein to the vena cava in response to identifying the subject as suffering from the condition.

[0260] According to some applications of the present invention, an apparatus for use with a first vein of a subject, the first vein being a tributary of a second vein and forming a junction with the second vein, the apparatus comprising: a catheter configured to be placed in the first vein, the distal end of the catheter being configured to pump blood in a downstream direction through the first vein into the catheter; an umbrella for an inlet cover, the umbrella for the inlet cover being disposed around the outside of the catheter and configured to be placed in the second vein at the junction, the umbrella for closing the inlet covering the inlet at the junction from a location in the second vein so that the umbrella prevents backflow of blood from the second vein to the first vein; and the apparatus is further provided.

[0261] In some applications, the catheter is configured such that pumping the blood causes the umbrella for the inlet cover to be sealed against the wall of the second vein surrounding the inlet.

[0262] In some applications, the umbrella for the inlet cover has a diameter greater than 6 mm when in an open configuration.

[0263] In some applications, the first vein includes the renal vein of the subject, the second vein includes the vena cava of the subject, and the catheter is configured to pump blood by pumping blood in a downstream direction from the renal vein.

[0264] In some applications, an umbrella for occluding the inlet portion covers the inlet portion at the junction of the renal vein and the vena cava from a location within the vena cava, and the umbrella for covering the inlet portion is configured to prevent backflow of blood from the vena cava to the renal vein.

[0265] According to some applications of the present invention, a catheter, a pumping mechanism configured to suck fluid into the distal end of the catheter, an umbrella for covering the inlet portion disposed around the outside of the catheter, the umbrella having a diameter of at least 6 mm when in its open configuration, and the umbrella for covering the inlet portion are further provided with a device.

[0266] In some applications, the diameter of the umbrella for covering the inlet portion is between 10 mm and 20 mm. In some applications, the diameter of the umbrella for covering the inlet portion is between 15 mm and 25 mm.

[0267] According to some applications of the present invention, a method for measuring the flow in a blood vessel, the method comprising: occluding the blood vessel with an occlusion element; pumping blood from upstream of the occlusion element to downstream of the occlusion element; measuring the blood pressure upstream and downstream of the occlusion element; adjusting the pumping so that the pressure downstream of the occlusion element is equal to the pressure upstream of the occlusion element; measuring the blood flow rate through the pump when the pressure downstream of the occlusion element is equal to the pressure upstream of the occlusion element; Specifying the measured flow rate as the baseline flow rate, and then, measuring the flow rate of blood passing through the pump in comparison with the baseline flow rate are additionally provided.

[0268] In some applications, the method further includes specifying a baseline measurement of the subject's vascular resistance in response to the step of specifying the baseline flow rate, and then measuring the subject's vascular resistance in comparison with the baseline vascular resistance.

[0269] The present invention will be more fully understood from the following detailed description of its embodiments based on the drawings.

Brief Description of the Drawings

[0270]

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Mode for Carrying Out the Invention

[0271] Here, referring to FIGS. 1A to 1B, FIGS. 1A to 1B are schematic diagrams of the heart of a healthy subject during diastole and systole, respectively. As shown in FIG. 1A, during diastole, blood flows from the right atrium (RA) 20 of the subject to the right ventricle (RV) 22 of the subject. As shown in FIG. 1B, during systole, when the right ventricle pumps blood towards the lungs of the subject, the tricuspid valve 24 separating the right atrium from the right ventricle closes. During the longitudinal contraction of the right ventricle in systole, the right atrium is filled with blood from the vena cava 26, and the right atrium expands to draw blood into the right atrium.

[0272] FIG. 1C is a set of graphs showing the central venous flow velocity profile and the central venous pressure profile of a healthy subject with respect to the ECG cycle of the subject. The flow velocity profile is characterized by a biphasic forward flow, and the flow during systole is larger than the flow during diastole. Typically, during atrial contraction, a small amount of reverse flow AR is present. The central venous pressure profile is characterized by a relatively low pressure over the duration of the cardiac cycle, and the A wave (i.e., the pressure during atrial contraction) is typically larger than the V wave (i.e., the pressure during systole).

[0273] Referring now to FIGS. 2A-2B, FIGS. 2A-2B are schematic views of the heart of a subject suffering from congestive heart failure during diastole and systole, respectively. As shown in FIG. 2A, during diastole, as in a healthy heart, blood flows from the right atrium 20 of the subject into the right ventricle 22 of the subject. As shown in FIG. 2B, during systole, due to the right atrial pressure being too high, the filling of the right atrium of the subject is prematurely cut off, and the high atrial pressure is transmitted to the large vein, causing an increase in pressure in the large vein 26. In some cases (e.g., in the case of very high right atrial pressure, tricuspid regurgitation, or atrial fibrillation), due to the premature cutoff of the filling of the right atrium, there may be a retrograde flow of blood from the right atrium into the large vein 26 and / or into the tributaries of the large vein.

[0274] FIG. 2C is a set of graphs showing the central venous flow velocity profile and the central venous pressure profile of a subject suffering from congestive heart failure with respect to the ECG cycle of the subject. The flow velocity profile is characterized by an increased retrograde flow AR at the end of diastole and a lower antegrade flow during systole than during diastole. For example, in some subjects, there may be zero flow or reverse flow during systole. The central venous pressure profile is characterized by a relatively high pressure over the duration of the cardiac cycle, with the V wave being particularly high compared to the V wave of a healthy heart and also particularly high compared to the A wave of the subject.

[0275] Referring now to FIG. 3A, FIG. 3A is a schematic diagram of blood flowing in a retrograde direction towards the kidneys 30 of a subject suffering from congestive heart failure via the left and right renal veins 32 of the subject. FIG. 3B is a set of graphs showing the central venous flow velocity profile and the renal vein pressure profile of a subject suffering from congestive heart failure with respect to the ECG cycle of the subject. It is noted that the graphs shown in FIG. 3B are the same as the graphs shown in FIG. 2C, except that the pressure profile shown in FIG. 3B is the pressure profile of the renal vein, while the pressure profile shown in FIG. 2C is the central venous pressure profile. As shown, typically, in the absence of a device (such as implemented according to some applications of the present invention) placed in the renal vein, and assuming that the renal vein is at the same height as the central venous system, the renal vein pressure profile is identical to the central venous pressure profile . The renal vein pressure profile is characterized by a relatively high pressure over the duration of the cardiac cycle, and the V wave is particularly high compared to the V wave of a healthy heart.

[0276] Referring now to FIG. 4A, FIG. 4A is a schematic diagram of a blood pump 34 and an occlusion element 36 disposed within the left and right renal veins 32 of a subject suffering from congestive heart failure, according to some applications of the present invention. To provide acute treatment for a subject suffering from cardiac dysfunction, congestive heart failure, low renal blood flow, high renal vascular resistance, arterial hypertension, and / or renal dysfunction, the pump and occlusion element are typically disposed inside the subject's renal vein. For example, the pump and occlusion element can be disposed inside the subject's renal vein for a period exceeding 1 hour (e.g., exceeding 1 day), for a period less than 1 week (e.g., less than 4 days), and / or for a period between 1 hour and 1 week (e.g., between 1 day and 4 days). In some applications, to provide long-term treatment for a subject suffering from cardiac dysfunction, congestive heart failure, low renal blood flow, high renal vascular resistance, arterial hypertension, and / or renal dysfunction, the pump and occlusion element are permanently disposed inside the subject's renal vein. In some applications, a series of treatments are applied to the subject over a period of weeks, months, or years, and in the series of treatments, the pump and occlusion element are intermittently disposed inside the subject's renal vein, and the subject is intermittently treated according to the techniques described herein. For example, the subject can be intermittently treated at intervals of several days, weeks, or months.

[0277] The occlusion element is configured to occlude the renal vein at the occlusion site. The pump is configured to pump blood in the downstream direction from a site in fluid communication with the upstream side of the occlusion element to a site in fluid communication with the downstream side of the occlusion element. In doing so, the pump reduces the pressure within the renal vein. The occlusion element is configured to protect the renal vein from backflow of blood from the vena cava into the renal vein.

[0278] Typically, due to the reduction in pressure within the renal vein caused by pumping blood in the downstream direction, the perfusion of the kidney increases. And this can cause the pressure within the renal vein to rise relative to the pressure within the renal vein immediately after the start of pumping, due to the increased blood flow into the renal vein. Typically, even after the perfusion of the kidney has increased, the pump is configured to maintain the pressure within the renal vein at a value lower than the pressure within the renal vein before the start of pumping. In some applications, in addition to reducing the subject's renal vein pressure and / or increasing the perfusion of the subject's kidney, the blood pump performs ultrafiltration on the subject's blood.

[0279] In some applications, it is noted that due to the reduction in pressure within the renal vein caused by pumping blood in the downstream direction, the renal vascular resistance of the subject decreases according to the physiological mechanism described, for example, in the article titled "Effect of elevation of intraluminal pressure on renal vascular resistance" by Haddy et al. (Circulation Research, 1956), which is incorporated herein by reference. It is further noted that a treatment for increasing renal perfusion by increasing the blood pressure within the subject's renal artery typically does not result in the above-described physiological mechanism.

[0280] Typically, when a blood pump as described herein is used to reduce the pressure within the subject's renal vein, it is expected that there will be an improvement in the subject's responsiveness to the administration of a diuretic due to the reduction in renal vein pressure. Thus, in some applications, a reduced dosage of the diuretic can be administered to the subject as compared to the dosage of the diuretic that would be administered to the subject if the techniques described herein were not implemented. Alternatively, the normal dosage of the diuretic can be administered to the subject, but the reduction in renal vein pressure Due to this, the diuretic can have a greater effect on the subject.

[0281] High central venous pressure leads to high levels of blood pressure in the heart, and it leads to the release of atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) by the subject, both of which serve as natural diuretics. Typically, when a blood pump as described herein is used to reduce the pressure in the renal vein of a subject, due to the reduction in renal vein pressure, an improvement in the subject's reactivity to the release of natural diuretics by the subject is expected. In some applications, since the central venous pressure of the subject cannot be reduced using the blood pump described herein, even while the renal vein pressure of the subject is reduced by the use of the blood pump described herein, the subject is expected to continue to release atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP). Thus, in some applications, using the blood pump described herein can result in the subject continuing to release atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP), and also results in the effectiveness of the natural diuretic described above being greater than the effectiveness of the diuretic in the absence of the use of the blood pump.

[0282] In some applications, a pressure sensor and / or a flow sensor is disposed at the distal end of the catheter, and the suction pressure applied to the renal vein by the pump is adjusted in response to feedback from the pressure sensor and / or the flow sensor. For example, a first pressure sensor 35 may be disposed on the side of the occlusion element closer to the kidney, and a second pressure sensor 37 may be disposed on the side of the occlusion element closer to the vena cava. When the pumping of the pump is started, the flow rate of the pumping is adjusted (e.g., automatically adjusted or manually adjusted), causing the pressure measured by the first sensor (which indicates the pressure in the renal vein) to be equal to the pressure measured by the second sensor (which indicates the central venous pressure). When the pressure measured by the first sensor is equal to the pressure measured by the second sensor, the pump control unit interprets that the flow rate of the pumping indicates the natural blood flow from the target renal vein to the target vena cava. The reason is that before the occlusion element is inserted into the renal vein, the renal vein pressure was equal to the central venous pressure. In some applications, the pump control unit designates the measured flow rate described above as the baseline flow rate. Thereafter, when the pump is operated and the pressure in the renal vein is reduced relative to the central venous pressure, the pump control unit measures the flow rate of the blood being pumped and compares it to the designated baseline flow rate.

[0283] In some applications, a third sensor (e.g., a non-invasive blood pressure sensor, or an invasive blood pressure sensor) is used to measure the arterial blood pressure of the subject. As described above, when the pumping of the pump is initiated, the flow rate of the pumping is adjusted to cause the pressure measured by the first sensor to be equal to the pressure measured by the second sensor. When the pressure measured by the first sensor is equal to the pressure measured by the second sensor, the pump control unit measures the difference between the measured arterial pressure and the venous pressure, and divides that difference by the baseline flow rate to determine a baseline measurement of the subject's renal vascular resistance. Thereafter, when the pump is operated to lower the pressure in the renal vein relative to the central venous pressure, the pump control unit measures the current renal vascular resistance relative to the specified baseline renal vascular resistance, (based on the current difference between the measured arterial pressure and the venous pressure, and the current flow rate).

[0284] Figure 4B shows a blood pump 34 and an occlusion element in the left and right renal veins 32 of the subject Subsequent to the placement of the pump 36, a set of graphs showing the central venous flow velocity profile and the renal venous pressure profile of a subject suffering from congestive heart failure with respect to the subject's ECG cycle. The renal venous pressure graph shows the original venous pressure profile as a dotted curve and also shows two curves representing the renal venous pressure subsequent to the placement of the pump and occlusion element into the vein and subsequent to the operation of the pump. Typically, subsequent to the placement of the pump and occlusion element into the vein and subsequent to the operation of the pump, the height of the venous pressure curve depends on the pumping rate that the operator applies to the renal vein via the pump. Thus, two curves are shown with respect to the renal venous pressure subsequent to the placement of the pump and occlusion element into the vein and subsequent to the operation of the pump. As shown, the placement of the pump and occlusion element into the vein and the operation of the pump typically cause the renal venous pressure profile to decrease and flatten even if the subject's central venous pressure increases. In some applications, the renal venous pressure profile is not completely flattened. This is because the pump applies a constant suction pressure to the renal vein throughout the duration of the subject's cardiac cycle, but small periodic changes in blood pressure are transmitted to the renal vein via the renal capillary system. Alternatively, subsequent to the placement of the pump and occlusion element into the vein and subsequent to the operation of the pump, the renal venous pressure profile can be flattened.

[0285] Referring now to FIGS. 5A - 5D, FIGS. 5A - 5D are schematic views of the reversing valve 40 disposed around the blood pump catheter 42 according to some applications of the present invention. The reversing valve 40 is an example of the occlusion element 36 described above with reference to FIGS. 4A - 4B, and the blood pump catheter 42 is an example of the blood pump 34 described above with reference to FIGS. 4A - 4B.

[0286] The reversal valve 40 typically includes a rigid frame 44 configured to anchor the reversal valve to the renal vein 32. (In FIGS. 5A-5B, the reversal valve 40 is shown inside the left renal vein, but the scope of the invention includes placing the reversal valve 40 and the blood pump catheter 42 inside the right renal vein, and typically and commonly, placing the reversal valve 40 and the blood pump catheter 42 inside each of the target renal veins.) The reversal valve 40 also includes valve leaflets 46. In response to the blood pressure upstream of the valve leaflets exceeding the pressure downstream of the valve leaflets, the valve leaflets are configured to open by separating from the vessel wall (and typically, by separating from the rigid frame of the valve), allowing blood to flow in the antegrade direction between the tip of the valve leaflets and the inner wall of the vessel. In this sense, the reversal valve is reversed relative to a normal vascular valve, with its leaflets opening by the tips of the leaflets separating from each other and being configured to allow blood flow between the leaflets in response to the blood pressure upstream of the valve leaflets exceeding the pressure downstream of the valve leaflets. Moreover, a typical vascular valve is disposed within a vessel with the valve leaflets converging towards each other in the downstream direction, while, as shown in FIGS. 5A-5B, the leaflets 46 of the valve 40 diverge from each other in the downstream direction.

[0287] FIG. 5A shows the reversal valve in the open state, with arrow 48 indicating the antegrade blood flow between the tip of the valve leaflets and the inner wall of the renal vein 32. Typically, when the reversal valve 40 and the blood pump catheter 42 are placed inside the renal vein and the blood pump catheter is not being moved, the valve leaflets will open, allowing blood flow from the renal vein to the vena cava in response to the blood pressure in the renal vein exerting pressure upstream of the leaflets 46.

[0288] Figure 5B shows the inversion valve 40 in the closed state. As shown, in the closed state of the valve, the valve blocks the blood flow from the renal vein to the vena cava by the tip of the valve leaflet 46 that contacts the inner wall of the renal vein at the occlusion site 49. In some applications, in the closed state of the valve, the tip of the valve leaflet contacts a portion of the rigid frame of the valve. Typically, the valve closes in response to the blood pressure downstream of the valve leaflet exceeding the pressure upstream of the valve leaflet. When the catheter blood pump is operating, the pump draws blood downstream from a site in fluid communication with the upstream side of the valve and pumps the blood back into the venous system at a site in fluid communication with the downstream side of the valve, such as a site in the vena cava or a site in the renal vein. For example, the catheter blood pump can define an inlet orifice 50 that is in fluid communication with the upstream side of the valve, and blood is pumped into the pump through the inlet orifice 50. Also, the catheter blood pump can further define an outlet orifice 52 that is disposed in fluid communication with the downstream side of the valve, and blood is pumped through the outlet orifice 52 into the renal vein or the vena cava. In some applications, the catheter blood pump uses an impeller 54 to pump the blood, and the impeller 54 is disposed inside the lumen 56 defined by the catheter blood pump as shown.

[0289] In some applications, the blood pump catheter 42 is connected to the frame 44 of the valve 40 before the blood pump catheter 42 and the valve 40 are inserted into the body of interest. The pump is connected to the valve frame and, when installed inside the renal vein, the inlet aperture 50 is in fluid communication with the upstream side of the valve leaflet 46 and the outlet aperture 52 is disposed in fluid communication with the downstream side of the valve. In some applications, the valve 40 and the blood pump catheter 42 are inserted separately into the renal vein of interest. For example, the valve can be inserted into the renal vein and then the blood pump catheter can be inserted through the valve and the blood pump catheter can be connected to the valve frame 44. Alternatively, the blood pump catheter can be inserted into the renal vein and then the valve can be inserted into the renal vein over the blood pump catheter. Typically, the blood pump catheter and the valve frame define a coupling mechanism that couples the blood pump catheter to the valve frame such that the inlet aperture 50 is in fluid communication with the upstream side of the valve leaflet 46 and the outlet aperture 52 is disposed in fluid communication with the downstream side of the valve.

[0290] Typically, the blood pump catheter 42 is configured to pump blood into the renal vein in a manner that causes the reversal valve 40 to assume its occluded state and / or to maintain the reversal valve 40 in its occluded state. For example, the blood flowing out of the outlet orifice 52 directly impinges on the downstream side of the valve leaflet 46, whereby the tip of the leaflet comes into contact with the inner wall of the renal vein and / or in a manner that causes it to be maintained, the blood pump catheter can be configured to pump blood from the outlet orifice. Thus, the dynamic pressure of the blood being pumped into the vasculature of the subject causes the tip of the leaflet to come into contact with the inner wall of the renal vein and / or to be maintained. In some applications, the blood pump catheter is structurally configured to pump blood from the outlet orifice in the manner described above, for example, according to an application of the present invention described hereinbelow with reference to FIGS. 6B - 6D. Typically, the valve 40 and the blood pump catheter 42 are configured such that the valve leaflet 46 opens in response to the blood pump catheter 42 becoming inactive (e.g., due to loss of power to the pump), and in response to pressure being exerted on the upstream side of the valve leaflet by the blood in the subject's renal vein, to allow blood flow from the renal vein to the vena cava.

[0291] As described above, in some applications, the blood pump catheter 42 is configured to pump blood from the outlet aperture 52 in such a manner that the blood flowing out of the outlet aperture impinges directly on the downstream side of the valve leaflet 46. In some applications, pumping blood directly against the downstream side of the valve leaflet has an antithrombotic effect, which is that the blood pumped against the leaflet flushes the leaflet and reduces the accumulation of thrombus and / or tissue growth on the valve leaflet, as compared to the case where the blood is not pumped directly against the valve leaflet. Alternatively or additionally, the blood pump catheter pumps an anticoagulant directly towards the leaflet, together with the blood being pumped directly towards the leaflet. In some applications, by pumping an anticoagulant directly towards the leaflet, a higher dosage of the anticoagulant is provided to the leaflet, for example, than when the anticoagulant is administered systemically to the subject. Thus, the dosage of the anticoagulant administered to the subject can be reduced as compared to the case where the anticoagulant is administered systemically to the subject, and / or the anticoagulant can be more effective in reducing thrombus and / or tissue growth in the leaflet as compared to the case where the anticoagulant is administered systemically to the subject. In some applications, the valve leaflet defines small apertures therethrough, and the small apertures are configured to permit flow of the anticoagulant to the upstream side of the valve leaflet.

[0292] According to the description of FIGS. 5A-5B, thus, the combination of the reversal valve 40 and the blood pump catheter 42 is configured such that (a) when the blood pump is inactive, the reversal valve opens in response to the pressure exerted on the upstream side of the valve leaflet by the blood in the renal vein, and (b) when the blood pump is active, pumping blood into the renal vein on the downstream side of the leaflet 46 maintains the valve in its closed state.

[0293] Figures 5C to 5D are schematic views from respective viewpoints of the upstream end of the inversion valve 40 and the blood pump catheter 42, showing the valve in its non-occluded state and occluded state, respectively. As shown in Figure 5C, when the valve is in its non-occluded state, the tip 58 of the leaflet 46 separates from the valve frame, enabling blood flow between the tip of the valve leaflet and the inner wall of the blood vessel (the blood vessel is not shown). It should be noted that in some applications, the structure of the valve frame is different from that shown in Figures 5C to 5D. For example, the valve frame can have a structure as shown in Figures 5A to 5B, and even when the valve is in its occluded state, the tip of the leaflet does not directly contact a part of the valve frame but contacts the inner wall of the blood vessel.

[0294] Referring now to Figures 6A to 6G, Figures 6A to 6G are schematic views of the configuration of the blood pump catheter 42 used with the inversion valve 40 according to some applications of the present invention.

[0295] Figure 6A shows the pump control unit 60, which is used to control the pumping of the blood pump catheter 42. The dotted box 62 indicates the location of the blood pump motor according to each application of the present invention. In some applications, the blood pump motor is disposed at the location indicated by the box 62A, which is outside the subject's body and near the pump control unit (e.g., within the same housing as the pump control unit). In some applications, the fact that the motor is disposed outside the subject's body allows the use of a catheter with a smaller diameter than would be required if the motor were disposed inside the catheter with respect to the blood pump catheter. Alternatively, the blood pump motor is disposed at the location indicated by box 62B such that when the distal end of the blood pump catheter is disposed inside the renal vein 32, the motor is adapted to be disposed within the vena cava. In some applications, the fact that the motor is disposed within a portion of the catheter disposed within the vena cava allows the distal portion of the catheter disposed inside the renal vein to be smaller than would be required if the motor were disposed inside the distal portion of the catheter. Alternatively, the blood pump motor is disposed at the location indicated by box 62C, which is within the distal portion of the catheter disposed inside the renal vein. In some applications, the blood pump motor is disposed near the impeller 54 (e.g., at the location indicated by box 62C) such that the pump motor is adapted to more efficiently impart rotational motion to the impeller as compared to the case where the blood pump motor is disposed at a greater distance from the impeller 54.

[0296] Figures 6B - 6D are schematic views of the blood pump catheter 42, the pump being structurally configured to pump blood from the outlet orifice 52 in a manner that maintains the reversal valve 40 in its closed state.

[0297] As shown in FIG. 6B, in some applications, the blood pump catheter is disposed (e.g., connected) through the valve, and when the inlet aperture 50 is disposed in fluid communication upstream of the valve, the outlet aperture is positioned adjacent to the base 64 of the valve leaflet 46. For example, the outlet aperture of the pump may be disposed adjacent to a location below the midpoint between the tip 58 of the leaflet and the base 64 of the leaflet along the length of the valve leaflet. Typically, due to the disposition of the outlet aperture relative to the valve leaflet, blood flowing out of the outlet aperture flows against the downstream side of the valve leaflet 46, thereby causing the tip of the leaflet to maintain contact with the inner wall of the renal vein, i.e., thereby maintaining the valve in a closed state (i.e., the closed position).

[0298] In some applications, the blood pump catheter is shaped to define a radially projecting portion 66 therefrom, and the radially projecting portion 66 curves concave toward the distal end of the catheter as shown in FIG. 6C. The curvature and disposition of the projecting portion 66 typically result in the first end of the projecting portion connected to the catheter being disposed proximal to the outlet aperture 52 and the other end of the radially projecting portion being disposed distal to the outlet aperture. Typically, blood flowing out of the outlet aperture is directed by the radially projecting portion 66 toward the downstream side of the valve leaflet 46, thereby causing the tip of the leaflet to maintain contact with the inner wall of the renal vein, i.e., thereby maintaining the valve in a closed state (i.e., the closed position).

[0299] In some applications, the outlet orifice 52 is shaped to direct blood distally from the orifice (i.e., toward the upstream end of the catheter pump). For example, as shown in FIG. 6D, the surface 68 defining the orifice can curve toward the distal end of the pump catheter. Thus, the blood flowing out of the outlet orifice is directed toward the downstream side of the valve leaflet 46, thereby causing the tip of the leaflet to maintain contact with the inner wall of the renal vein, i.e., thereby maintaining the valve in a closed state (i.e., the closed position).

[0300] FIGS. 6E-6G show a support structure that is used to support the inversion valve 40 within the renal vein as an alternative to, or in addition to, the frame 40 (e.g., shown in FIGS. 5A-5D).

[0301] In some applications, the valve 40 is a three - leaflet valve. Alternatively, the valve can be a two - leaflet valve or can have four or more leaflets. The leaflets are maintained in contact with the renal vein at the junctions of the valve leaflets. Between the junctions of the valve leaflets, when the valve is in the closed state of the valve, the tips of the valve leaflets are in contact with the renal vein wall, and when the valve is in the non - closed state of the valve, the tips of the valve leaflets are separated from the renal vein wall and are adapted to permit blood flow between the valve leaflet and the renal vein wall.

[0302] In some applications (e.g., as shown in FIGS. 5A-5D), the leaflet is connected to the valve frame 48 at the seam of the valve leaflet, and the valve frame maintains the seam of the valve leaflet in contact with the renal vein wall. Alternatively or additionally, as shown in FIG. 6E, a slit tube 72 is advanced over the blood pump catheter 42. The tube is configured such that when the distal end of the tube is pushed towards the distal end of the catheter, a portion of the tube between the slits expands radially outward. The radially expanded portion of the tube is configured to maintain the seam of the valve leaflet in contact with the renal vein wall.

[0303] Further alternatively or additionally, a balloon 74 having a star-shaped cross-section (e.g., a 3-vertex star cross-section as shown) is disposed around a portion of the blood pump catheter 42 disposed inside the valve 40. Views of the balloon 74, the blood pump catheter 42, and the valve 40 are shown in FIGS. 6F-6G. In some applications, the three-dimensional shape of the balloon 74 is similar to that of a calabola (i.e., star fruit) when the balloon is in its inflated state. Typically, the balloon is inflated at the vertices of the star of the cross-section of the balloon such that the balloon maintains the seam of the valve leaflet in contact with the renal vein wall.

[0304] As described above, typically, the inversion valve 40 and the blood pump catheter 42 are used to apply acute treatment to a subject. For example, the inversion valve and the blood pump catheter can be placed inside the renal vein of the subject over a period of more than 1 hour (e.g., more than 1 day), less than 1 week (e.g., less than 4 days), and / or between 1 hour and 1 week (e.g., between 1 day and 4 days). In some applications, using the slit tube 72 or the balloon 74 to maintain the valve seam in contact with the renal vein wall promotes the removal of the valve from the renal vein following the end of the treatment. For example, to remove the valve from the renal vein, the slit tube can be retracted, a portion of the radially expanded tube can radially contract, and the valve leaflet is no longer maintained in contact with the renal vein wall and / or the balloon 74 can be deflated so that the valve leaflet is no longer maintained in contact with the renal vein wall.

[0305] Referring now to FIGS. 7A-7B, FIGS. 7A-7B are schematic views of the blood pump catheter 42 and the non-inversion valve 80, showing the non-inversion valve in its closed and non-closed states, respectively, according to some applications of the present invention. In some applications, as an alternative to being installed through the inversion valve, the blood pump catheter 42 is inserted through the non-inversion valve as shown in FIGS. 7A-7B. The non-inversion valve 80 is an example of the occlusion element 36 described above with reference to FIGS. 4A-4B. The non-inversion valve typically includes a rigid frame 82 and a valve leaflet 84.

[0306] Typically, the blood pump catheter 42 is used to pump blood downstream from a site in fluid communication upstream of the valve leaflet 84 to a site in the venous system in fluid communication downstream of the valve leaflet, such as a site in the vena cava or a site in the renal vein. The valve 80 is configured to prevent backflow of blood by the tip 86 of the valve leaflet in contact with the catheter in response to the pressure downstream of the valve leaflet exceeding the pressure upstream of the valve leaflet. The valve 80 is further configured to allow flow of blood across the valve by the tip of the leaflet separated from the catheter in response to the pressure upstream of the valve leaflet exceeding the pressure downstream of the valve leaflet, thereby allowing blood to flow in the direction of arrow 88 (FIG. 7A) between the leaflet and the blood pump catheter.

[0307] In some applications, initially, a combination of a valve (e.g., a reversing valve as shown in FIGS. 5A - 5D and FIGS. 6A - 6G, or a non - reversing valve as shown in FIGS. 7A - 7B) and a pump is used to treat a subject. Thereafter (e.g., after a period exceeding 1 hour, a period less than 1 week, and / or after a period between 1 hour and 1 week), the pump is removed from the subject's renal vein and the valve is left in place in the renal vein. Even in the absence of the pump, the valve is configured to reduce the pressure in the subject's renal vein compared to the renal vein pressure in the subject in the absence of the valve by preventing backflow of blood from the subject's vena cava into the subject's renal vein and allowing flow of blood from the subject's renal vein into the subject's vena cava. Thus, in some applications, the valve remains inside the renal vein and is adapted to provide long - term treatment to the subject even after the acute treatment of the subject (using a pump in combination with the valve) has ended.

[0308] Referring now to FIGS. 8A - 8B, FIGS. 8A - 8B are schematic views of the blood pump 90 from respective perspectives according to some application examples of the present invention. The pump 90 is an example of both the occlusion element 36 and the pump 34 described above with reference to FIGS. 4A - 4B. The reason is that the pump 90 is configured both to occlude the renal vein when installed in the target renal vein and to pump blood downstream from a site in fluid communication with the upstream side of the pump to a site in fluid communication with the downstream side of the pump.

[0309] The pump 90 includes an outer tube 92, and the outer surface of the tube is configured to contact the inner wall portion of the renal vein. Typically, the outer tube 92 includes a stent on which a material (typically a blood - impermeable material) is disposed. First and second one - way valves 94 and 96 are disposed at respective ends of the tube, and the valves simply allow blood to flow in the downstream direction into and out of the tube. A membrane 98 is connected inside the tube, and the membrane divides the tube into a first compartment 100 and a second compartment 102. The first compartment 100 is in fluid communication with the valves, and the second compartment 102 is not in fluid communication with the valves. A pumping mechanism 104, for example, an electromagnetically - driven pumping mechanism, periodically drives the membrane to move relative to the tube so that the relative sizes of the first and second compartments change.

[0310] Referring now to FIGS. 9A - 9D, FIGS. 9A - 9D are schematic views of respective stages of the cycle of operation of the blood pump 90 according to some application examples of the present invention. FIG. 9A shows the blood pump at an arbitrary starting point in the cycle of operation of the blood pump, at which point both valve 94 and valve 96 are closed. As shown in the transition from FIG. 9A to FIG. 9B and the transition from FIG. 9B to FIG. 9C, the pump mechanism 104 The movement of the membrane 98 is caused, for example, by a pumping fluid (e.g., air or saline) of a pumping mechanism coming out of the second compartment, such that the volume of the first compartment 100 increases. The increase in the volume of the first compartment causes the pressure inside the first compartment to decrease relative to the pressure upstream of the first valve 94, causing the valve 94 to open and blood to be drawn into the first compartment. Thereafter, the pumping mechanism moves the membrane, increasing the volume of the second compartment, for example, by pumping fluid into the second compartment as shown in the transition from FIG. 9C to FIG. 9D and the transition from FIG. 9D to FIG. 9A. The movement of the membrane causes the volume of the first compartment to decrease and the pressure in the first compartment to increase. The pressure in the first compartment causes the valve 94 to close and also causes the valve 96 to open, causing the blood that was inside the first compartment to flow downstream of the pump 90.

[0311] Referring now to FIGS. 10A - 10D, FIGS. 10A - 10D are schematic views of a blood-impermeable sleeve 110 configured to occlude blood flow from a subject's vena cava 26 to the subject's renal vein 32 according to some applications of the present invention. Typically, the sleeve is placed within the vena cava, with the downstream end 112 of the sleeve connected to the wall of the vena cava at a first location 114 downstream of all of the subject's renal veins (e.g., the left and right renal veins in a typical subject having two renal veins), and the upstream end 116 of the sleeve connected to the wall of the vena cava at a second location 118 upstream of all of the subject's renal veins. Thus, the sleeve isolates the blood in the renal veins into a compartment that is separated from the blood flow through the vena cava. Typically, a rigid structure, such as a stent 120 as shown, is configured to connect the upstream and downstream ends of the sleeve to the vena cava.

[0312] The pump 122 is configured to pump blood from a location outside the sleeve 110 (i.e., from an isolated compartment) to a location in fluid communication with the interior of the sleeve (e.g., a location in the vena cava upstream or downstream of the sleeve). Thus, the pump pumps blood from the subject's renal vein into the subject's vena cava. The sleeve prevents backflow of blood from the vena cava into the renal vein.

[0313] In some applications, as shown, the stent 120 defines its flared end portion. Also, the sleeve 110 defines its flared end portion. The flared end portion of the sleeve is configured to occlude the flow of blood from the vena cava to the renal vein by contacting the wall of the vena cava when the pressure in the vena cava is greater than or equal to the pressure in the renal vein. In some applications, at least one of the flared end portions of the sleeve is configured to act as a valve by providing blood flow from the outside of the sleeve into the vena cava, for example, to relieve the pressure and / or overflow of blood outside the sleeve. In response to the blood pressure in the renal vein exceeding the blood pressure in the vena cava, the flared end portion of the sleeve is configured to at least partially separate from the wall of the vena cava, and blood is allowed to flow between the outside of the flared end portion of the sleeve and the inner wall of the vena cava. In some applications, the upstream and downstream ends of the sleeve are configured to act as valves in the manner described above, with any changes as may be appropriate. FIG. 10A shows the sleeve when the upstream and downstream ends of the sleeve are closed and configured to occlude the flow of blood between the outside of the sleeve and the wall of the vena cava. FIG. 10B shows the sleeve when the upstream and downstream ends of the sleeve are open and configured to allow the flow of blood from the renal vein to the vena cava between the outside of the sleeve and the wall of the vena cava.

[0314] As shown in FIGS. 10A - 10B and 10D, in some application examples, the pump receiving sleeve 124 protrudes from outside one of the flared ends of the sleeve 110 (e.g., the downstream flared end of the sleeve 110 as shown). The pump receiving sleeve is shaped to facilitate insertion of the pump 122 therethrough. The pump receiving sleeve is configured to form a seal around the pump such that there is minimal or zero blood flow between the outside of the pump and the inside of the pump receiving sleeve. In some application examples (not shown), rather than using the pump receiving sleeve to form a seal around the outside of the pump, the flared end of the sleeve defines an opening (e.g., a hole) through which the pump is inserted, and the opening is sized such that the contact surface between the outside of the pump and the distal flared end of the sleeve is sealed.

[0315] The pump receiving sleeve is shown protruding from outside the upstream flared end of the sleeve, but it is noted that in some application examples, the pump is inserted through the downstream flared end of the sleeve, and the downstream flared end of the sleeve defines the pump receiving sleeve or a hole through which the pump is inserted. Generally, the scope of the present invention includes inserting the blood pump and the occluding element described herein toward the renal vein from above or below the renal vein by approaching the renal vein through the vena cava. For example, the renal vein can be approached through the vena cava from upstream via the femoral vein or from downstream via the jugular vein.

[0316] According to each application example, the pump 122 pumps blood into the large vein at a site upstream or downstream of the sleeve. In some application examples, the pump pumps blood into the large vein at a site downstream of the sleeve, and is configured to reduce the blood flow through the sleeve compared to the case where the pump pumps blood into the large vein at a site upstream of the sleeve. In some application examples, since the sleeve serves as a resistor for the blood flow through the sleeve, it is advantageous to reduce the blood flow through the sleeve in the above-described manner. As described above, and as shown, for example, in FIG. 10D, in some application examples, the pump pumps blood into the large vein at a site upstream of the sleeve.

[0317] In some application examples, the sleeve 110 and the stent 120 are inserted into the target large vein, while the guide wire 126 is disposed inside the pump housing sleeve 124. Following the anchoring of the sleeve 110 and the stent 120 to the large vein, the pump 122 is inserted through the pump housing sleeve by advancing the pump over the guide wire.

[0318] As shown in FIG. 10C, in some application examples, the stent 120 is shaped to define a sleeve support frame 128, and the sleeve support frame 128 is generally shaped to conform to the shape of the sleeve. Typically, the sleeve support frame is shaped to define an enlarged end 130 and a narrow central portion 132 extending between the enlarged ends, and the flare-shaped ends extend from the ends of the narrow central portion. In addition, the stent defines a vessel wall support frame 134, and the vessel wall support frame 134 is connected to the narrow central portion of the sleeve support frame, and the vessel wall support frame 134 projects radially outward from the side of the narrow central portion of the sleeve support frame.

[0319] In some applications, pumping blood by pump 122 from the outside of the sleeve causes the wall of the large vein to be pulled inward. Vascular wall support frame 134 supports the inner wall of the large vein and prevents the inner wall of the large vein from collapsing around the narrow central portion 132 of the width of the stent's sleeve support frame 128. Typically, during operation of the pump, the pump head including the inlet hole 125 of the pump head is disposed in the gap between the narrow central portion of the width of the stent's sleeve support frame (the stent supports the sleeve) and the vascular wall support frame (the vascular wall support frame supports the wall of the large vein).

[0320] As described above, in some applications, pumping blood by pump 122 from the outside of the sleeve causes the wall of the large vein to contract by being pulled inward. In some applications, the pump is configured to anchor stent 120 to the large vein by causing the large vein to contract around at least a portion of the stent by applying a suction force to the large vein. In some applications, a stent that is not substantially oversized relative to the large vein and / or a stent having a diameter smaller than the diameter of the large vein is anchored to the large vein due to the suction force applied to the large vein by the pump causing the large vein to contract around at least a portion of the stent.

[0321] As described above, typically, the sleeve support frame 128 is shaped to generally conform to the shape of the sleeve. The sleeve and the sleeve support frame define a narrow central portion diameter D1 (Figure 10C) and a maximum diameter D2 at the end of the flared distal end of the sleeve. In some applications, D1 is greater than 8 mm and less than 35 mm, and / or between 8 mm and 35 mm. In some applications, D2 is greater than 10 mm and less than 45 mm, and / or between 10 mm and 45 mm. In some applications, the ratio of D2:D1 is greater than 1.1:1 and less than 2:1, and / or between 1.1:1 and 2:1. In some applications, the overall length L1 of the sleeve is greater than 6 mm and less than 80 mm, and / or between 6 mm and 80 mm. In some applications, the length L2 of the flared end of the sleeve (i.e., the length from where the sleeve begins to flare to the end of the sleeve) is greater than 3 mm and less than 40 mm, and / or between 3 mm and 40 mm. In some applications, the length L3 of the narrow central portion of the sleeve and the sleeve support frame is greater than 3 mm and less than 70 mm, and / or between 3 mm and 70 mm.

[0322] In some applications, the maximum diameter D3 of the vessel wall support frame 134 of the stent 120 is greater than 10 mm and less than 50 mm, and / or between 10 mm and 50 mm. In some applications, the ratio of D3:D1 is greater than 1.1:1 (e.g., greater than 1.5:1 or greater than 2:1), less than 5:1, and / or between 1.1:1 and 5:1.

[0323] In some applications, the inner diameter D4 (FIG. 10A) of the pump receiving sleeve 124 is greater than 2 mm, less than 10 mm, and / or between 2 mm and 10 mm. In an application where the sleeve 110 defines an opening through which the pump 122 is inserted, the diameter of the opening through which the pump is inserted is typically greater than 2 mm, less than 10 mm, and / or between 2 mm and 10 mm.

[0324] In some applications, the pump 122 is generally similar to the catheter blood pump 42 described above with reference to FIGS. 5A-5D. For example, as shown in FIG. 10D, the blood pump can include an impeller 123 for pumping blood. Blood is drawn into the catheter from the renal vein through the inlet aperture 125, which is disposed between the outside of the sleeve and the wall of the vena cava, and the blood is pumped into the vena cava through the outlet aperture 127, which is disposed in the vena cava at a location upstream of the sleeve, for example, as shown in FIG. 10D.

[0325] Referring now to FIGS. 10E - 10F, FIGS. 10E - 10F are schematic views of a blood - impermeable sleeve 135 connected to the vena cava 26 using a helical support element 136 configured to occlude blood flow from a target vena cava to a target renal vein 32 according to some application examples of the present invention. According to each application example, the helical support element is either an inflatable helical support element (e.g., a helical balloon) or a helical support element made of a shape - memory alloy such as Nitinol. Typically, the helical support element will be connected to the vena cava, with the downstream end of the helical support element being connected to the wall of the vena cava at a first location 114 downstream of all of the target's renal veins (e.g., the left renal vein and the right renal vein in a typical target having two renal veins), and the upstream end of the helical support element being connected to the wall of the vena cava at a second location 118 upstream of all of the target's renal veins. Thus, the helical support element isolates the blood in the renal veins into a compartment outside the sleeve that is separated from the blood flow through the vena cava. It is noted that the sleeve 135 does not necessarily have a flared - shaped end configured to occlude blood flow from the vena cava to the renal vein by contacting the wall of the vena cava. Rather, as shown, the helical support element can occlude the flow of blood from the vena cava to the renal vein by contacting the wall of the vena cava. Alternatively, the sleeve 135 has a shape generally similar to the sleeve 110 described above with reference to FIGS. 10A - 10D, and the sleeve defines a flared - shaped end configured to contact the wall of the vena cava.

[0326] Typically, the blood pump catheter 137 is inserted into the large vein via a delivery device 138 (FIG. 10F). As shown in the transition from FIG. 10E to FIG. 10F, in some applications, the blood pump catheter is guided into the compartment outside the sleeve by being advanced over a helical support element. In some applications, the distal portion of the blood pump catheter is configured to automatically assume a helical shape when advanced out of the delivery device. Alternatively, by being advanced over a helical support element, the distal portion of the blood pump catheter is caused to assume a helical shape. Typically, the blood pump catheter defines an inlet aperture 139 along most of the length of the distal portion of the blood pump catheter (i.e., the portion of the blood pump catheter disposed inside the compartment outside the sleeve by being advanced over a helical support element) (e.g., 50 percent or more, or 75 percent or more of the length). The blood pump catheter pumps blood from the compartment outside the sleeve (i.e., from the renal vein) into the inlet aperture. The blood pump typically defines an outlet aperture (not shown), which is configured to be disposed in the large vein in fluid communication with the inside of the sleeve (e.g., at the location of the large vein upstream or downstream of the sleeve). The pump pumps blood into the large vein through the outlet aperture.

[0327] Referring now to FIG. 10G, FIG. 10G is a schematic view of a blood-impermeable sleeve 141 coupled to a helical blood pump catheter 143, according to some applications of the present invention, showing that the sleeve and the blood pump catheter are configured to occlude blood flow from the subject's large vein 26 to the subject's renal vein 32. Typically, the sleeve 141 is shaped to define its flared end 145 as shown. Typically, the sleeve 141 is described above with reference to FIGS. 10A-10D It has generally the same shape as the described sleeve 110, and the sleeve defines a flared end configured to contact the wall of the vena cava.

[0328] The sleeve 141 and the blood pump catheter 143 are inserted into the vena cava through the delivery device 149. The distal end of the catheter 143 (i.e., the end of the catheter that is furthest from the insertion site and through which the catheter is inserted into the subject's body) is connected at the coupling location 147 to the distal end of the sleeve (e.g., the downstream end of the sleeve as shown). The blood pump catheter is pre-shaped such that when advanced from the distal end of the insertion device, the distal portion of the catheter assumes a helical shape disposed around the outside of the sleeve. Typically, by assuming a helical shape, the distal portion of the catheter keeps the sleeve axially open (i.e., prevents the sleeve from collapsing axially). In some applications, a ring 151 made of a shape memory material (e.g., nitinol) is connected to the proximal end of the sleeve and is configured to support the proximal end of the sleeve. Typically, the blood pump catheter defines an inlet aperture 153 along most of the length of the distal portion of the blood pump catheter (i.e., the helical portion of the blood pump catheter disposed around the sleeve) (e.g., 50 percent or more, or 75 percent or more of the length). The blood pump catheter pumps blood from outside the sleeve (i.e., from the renal vein) into the inlet aperture. Typically, the sleeve is installed in the vena cava and the downstream end of the sleeve is connected to the wall of the vena cava at a first location 114 downstream of all of the subject's renal veins (e.g., the left and right renal veins in a typical subject having two renal veins), and the upstream end of the sleeve is connected to the wall of the vena cava at a second location 118 upstream of all of the subject's renal veins. More typically, pumping blood into the inlet aperture causes the vena cava to constrict around the outside of the sleeve, such that blood in the renal vein is isolated into a compartment outside the sleeve that is separated from the blood flow through the vena cava.

[0329] The blood pump typically defines an outlet aperture (not shown) that is configured to be disposed within the vena cava in fluid communication with the interior of the sleeve (e.g., at a location of the vena cava upstream of the sleeve or at a location of the vena cava downstream of the sleeve). The pump pumps blood into the vena cava via the outlet aperture.

[0330] In FIGS. 10E-10G, the blood pump is shown as being inserted from the upstream end of the sleeve to the outside of the sleeve, but it is noted that in some applications, the pump may be inserted from the downstream end of the sleeve to the outside of the sleeve. Generally, the scope of the present invention includes inserting the blood pump and the occluding element described herein into the renal vein from above or below the renal vein by approaching the renal vein via the vena cava. For example, the renal vein can be approached through the vena cava from upstream via the femoral vein or from downstream via the jugular vein.

[0331] Referring now to FIGS. 11A-11C, FIGS. 11A-11C are schematic views of a blood pump catheter 42 disposed within a target renal vein 32 according to some applications of the present invention, showing that an umbrella 140 for an inlet cover is disposed around the outside of the catheter and within the vena cava and that the umbrella 140 for the inlet cover is configured to cover the inlet at the junction 142 between the target vena cava 25 and the renal vein 32. Although the umbrella for the inlet cover is described as an "umbrella," the scope of the present invention includes any inlet cover element configured to be disposed around the outside of the catheter and made from a flexible portion (e.g., a flexible tissue portion) and a rigid support element that provides shape and structure to the inlet cover element to cover the inlet. It should be noted that it includes the following. The umbrella 140 for the inlet cover is an example of the occlusion element 36 described above with reference to FIGS. 4A to 4B, and the blood pump catheter 42 is an example of the blood pump 34 described above with reference to FIGS. 4A to 4B. (In FIGS. 11A to 11C, the umbrella 140 for the inlet cover is shown covering the left renal vein inlet, but the scope of the present invention includes covering the right renal vein inlet with the umbrella 140 for the inlet cover, and typically, although it is common, it includes installing the umbrella for the inlet cover at the inlet of the junction of each of the left renal vein and the right renal vein with the vena cava.)

[0332] As shown in FIGS. 11A to 11C, the blood pump catheter 42 and the umbrella 140 for the inlet cover are inserted into the vena cava 26 through the insertion device 144. During insertion, the umbrella for the inlet cover is typically in its closed state. The blood pump catheter and the umbrella for the inlet cover are advanced from the insertion device, and the umbrella for the inlet cover opens in response to being advanced from the distal end of the insertion device (FIG. 11B). The umbrella for the inlet cover is installed near the junction 142. The blood pump catheter is moved to pump blood downstream through the renal vein into the inlet hole 50 at the distal end of the blood pump catheter. Typically, due to the suction force of the blood pump, the umbrella for the inlet cover is pulled against the wall of the vena cava surrounding the inlet at the junction 142 (FIG. 11C).

[0333] Typically, the umbrella 140 for the inlet cover is pushed against the wall of the vena cava surrounding the inlet at the junction 142 in response to blood flowing from the vena cava to the renal vein, thereby occluding the backflow of blood from the vena cava to the renal vein. More typically, while the blood pump is active, the umbrella for the inlet cover is sealed against the wall of the vena cava surrounding the inlet at the junction 142 due to the suction force generated by the blood pump, whereby the umbrella for the inlet cover occludes both the blood flow from the renal vein to the vena cava and the blood flow from the vena cava to the renal vein. In response to the pump 42 becoming inactive (e.g., due to loss of power of the pump), the umbrella surrounding the inlet at the junction 142 allows blood to flow from the renal vein to the vena cava in the direction of arrow 146 (Figure 11B). The reason is that when the pump is inactive, the umbrella is not sealed against the wall of the vena cava.

[0334] In some applications, the diameter D5 of the umbrella 140 for the inlet cover is greater than 5 mm (e.g., greater than 10 mm or greater than 20 mm), less than 30 (e.g., less than 25 mm or less than 20 mm), and / or between 5 mm and 30 mm (e.g., between 10 mm and 20 mm or between 15 mm and 25 mm) when the umbrella for the inlet cover is in its open state.

[0335] Referring now to FIGS. 12Ai-12Aii and 12B, FIGS. 12Ai-12Aii and 12B are schematic views of a blood pump 150 including an impeller 152 disposed inside a radially expandable impeller cage 154 according to some application examples of the present invention. FIGS. 12Ai and 12Aii show respective views of the blood pump 150. Further referring to FIGS. 12C-12D, FIGS. 12C-12D are side views of the blood pump 150 disposed inside the renal vein 32 when the cage 154 is in its relatively radially expanded configuration and its radially compressed configuration, respectively, according to some application examples of the present invention. Also, referring to FIG. 12E, FIG. 12E shows an end view of the impeller 152 combined with a cross-sectional view of the strut 204 of the cage 154 and a cross-sectional view of the renal vein 32 when the blood pump 150 is disposed inside the renal vein 32 according to some application examples of the present invention.

[0336] It is noted that the term "impeller" is used herein to represent a bladed rotor as shown in FIGS. 12Ai-12E. When a bladed rotor is installed and rotated inside a blood vessel (e.g., the renal vein 32, etc.), the bladed rotor functions as an impeller by increasing the flow of blood through the blood vessel and / or by generating a pressure difference between the upstream end and the downstream end of the impeller.

[0337] In some application examples, the blood pump 150 is installed in one or both (or all) of the subject's renal veins and is used to pump blood in the downstream direction towards the vena cava through the renal vein, so as to reduce the renal vein pressure and / or enhance the perfusion of the subject's kidney.

[0338] To provide acute treatment for a subject suffering from cardiac dysfunction, congestive heart failure, low renal blood flow, high renal vascular resistance, arterial hypertension, and / or kidney dysfunction, the blood pump 150 is typically placed inside the subject's renal vein. For example, the pump can be placed inside the subject's renal vein for a period exceeding 1 hour (e.g., exceeding 1 day), for a period less than 1 week (e.g., less than 4 days), and / or for a period between 1 hour and 1 week (e.g., between 1 day and 4 days). In some applications, to provide long-term treatment for a subject suffering from cardiac dysfunction, congestive heart failure, low renal blood flow, high renal vascular resistance, arterial hypertension, and / or kidney dysfunction, the pump is permanently placed inside the subject's renal vein. In some applications, a series of treatments is applied to the subject over several weeks, months, or years, and in the series of treatments, the pump is intermittently placed inside the subject's renal vein and the subject is intermittently treated according to the techniques described herein. For example, the subject can be intermittently treated at intervals of several days, weeks, or months.

[0339] Typically, the effect of pumping blood through the renal vein of a subject suffering from cardiac dysfunction, congestive heart failure, low renal blood flow, high renal vascular resistance, arterial hypertension, and / or kidney dysfunction is generally similar to that described with reference to FIG. 4B. That is, pumping causes the subject's renal vein pressure profile to decrease and flatten even as the subject's central venous pressure increases. According to the description of FIG. 4B above, the renal vein pressure graph shows the original venous pressure profile as a dotted curve and also shows two curves representing the renal vein pressure following the operation of the blood pump. Typically, during pumping of blood through the renal vein, the height of the venous pressure curve depends on the amount of pumping applied to the renal vein by the operator via the pump, as shown by the two solid curves in FIG. 4B, and the curves represent the renal vein pressure profile at each rate of pumping of blood pump 150. In some applications, as shown, the renal vein pressure profile is not completely flattened. This is because small periodic changes in blood pressure are transmitted to the renal vein via the renal capillary system.

[0340] Typically, due to the reduction in pressure within the renal vein caused by downstream pumping of blood by pump 150, renal perfusion of the kidney increases. And this can cause the pressure within the renal vein to increase relative to the pressure within the renal vein immediately after initiation of pumping, due to the increased blood flow into the renal vein. Typically, even after renal perfusion of the kidney has increased, the pump is configured to maintain the pressure within the renal vein at a value lower than the pressure within the renal vein prior to initiation of pumping. In some applications, in addition to reducing the subject's renal vein pressure and / or increasing the subject's renal perfusion, the blood pump performs ultrafiltration on the subject's blood.

[0341] In some applications, pumping blood downstream by pump 150 Due to the resulting reduction in pressure within the renal vein, it is noted that, for example, according to the physiological mechanisms described in the article titled "Effect of elevation of intraluminal pressure on renal vascular resistance" by Haddy et al. (Circulation Research, 1956), which is incorporated herein by reference, the renal vascular resistance of the subject decreases. It is further noted that increasing the blood pressure within the renal artery of the subject typically does not result in the above-described physiological mechanism for increasing renal blood flow.

[0342] As described above, typically when the blood pump 150 is used to reduce the pressure within the renal vein of the subject, it is expected that there will be an improvement in the subject's responsiveness to the administration of a diuretic due to the reduction in renal vein pressure. Thus, in some applications, a reduced dosage of the diuretic that would otherwise be administered to the subject in the absence of implementing the techniques described herein may be administered to the subject. Alternatively, the normal dosage of the diuretic may be administered to the subject, but due to the reduction in renal vein pressure, the diuretic may be capable of having a greater effect on the subject.

[0343] Elevated central venous pressure leads to a high level of blood pressure in the heart, and it leads to the release by the subject of atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP), both of which serve as natural diuretics. Typically, when blood pump 150 is used to reduce the pressure in the subject's renal vein, an improvement in the subject's responsiveness to the release of natural diuretics by the subject is expected due to the reduction in renal vein pressure. In some applications, since the subject's central venous pressure cannot be reduced using blood pump 150, it is expected that the subject continues to release atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) even while the subject's renal vein pressure is reduced by the use of blood pump 150. Thus, in some applications, using blood pump 150 can result in the subject continuing to release atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP), and also results in the effectiveness of the natural diuretics described above being greater than the effectiveness of the diuretics in the absence of the use of blood pump 150.

[0344] Typically, blood pump 150 pumps blood in a manner that enhances the flow rate of blood flow into the large vein through the renal vein, but it is noted that it does not cause a substantial change in the direction of blood flow with respect to the natural direction of flow through the renal vein, or the natural direction of flow from the renal vein to the large vein (i.e., with respect to the blood flow in the absence of pumping by the pump). In other words, for example, rather than pumping blood from the renal vein into a different part of the subject's vein (such as an upstream location in the large vein), the blood pump pumps blood directly downstream through the renal vein and then into a portion of the large vein adjacent to the renal vein. More typically, blood pump 150 enhances the blood flow through the renal vein without removing blood from the subject's venous system into a non-venous receptacle such as the artificial lumen of the blood pump.

[0345] Typically, the cage 154 defines a radially expanded configuration without restraint and a radially compressed configuration. In the absence of any force applied to the cage, the cage assumes the radially expanded configuration without restraint. When the cage is elongated axially, the cage assumes the radially compressed configuration. Similarly, typically, the impeller 152 defines a radially expanded configuration without restraint and a radially compressed configuration. In the absence of any force applied to the impeller, the impeller assumes the radially expanded configuration without restraint. When the impeller is elongated axially it assumes the radially compressed configuration.

[0346] Typically, during insertion of the cage 154 and the impeller 152 into the target renal vein, by elongating the cage and the impeller axially, the cage and the impeller are crimped and are adapted to be radially compressed. The cage and the impeller are inserted into the renal vein while being maintained in the radially compressed configuration by an insertion device 155, such as a catheter. The cage and the impeller are advanced into the renal vein from the distal end of the insertion device. In response to being advanced from the distal end of the insertion device, the cage and the impeller automatically expand radially and contract axially.

[0347] Typically, the cage 154 is configured to keep the inner wall portion of the renal vein open and to separate the inner wall portion of the renal vein from the impeller so that the renal vein cannot be damaged by the impeller. More typically, the blood pump 150 includes an engagement mechanism 156, and the engagement mechanism 156 is configured to engage the impeller with the cage. FIG. 12B shows a cross-sectional view of the impeller and the cage. For example, as shown in FIG. 12B, the proximal and distal bearings 250P and 250D are disposed adjacent to the proximal and distal ends of the impeller 152 and are configured to impart a rotational movement to the impeller. The engagement mechanism 156 is disposed between a ring 202 (described below with reference to FIG. 17) disposed at the distal end of the cage and a surface 252 of the distal bearing 250P, such that when the ring 202 moves distally, the ring pushes the engagement mechanism distally and the engagement mechanism pushes the distal bearing distally. The distal bearing is connected to a distal ring 164 of the impeller (described below with reference to FIGS. 13A-13D), and the distal movement of the distal bearing pulls the distal ring of the impeller distally, thereby elongating the impeller in the axial direction.

[0348] Accordingly, the engagement mechanism engages the impeller with the cage, and in response to the cage being radially contracted and axially elongated (e.g., in response to the renal vein exerting a radial pressure on the cage), the impeller is axially elongated and radially contracted. For example, as shown in the transition from FIG. 12C to FIG. 12D, in response to the renal vein exerting a pressure P on the cage 154, the cage will be partially radially compressed, for example, causing the cage to be elongated as the distal end of the cage moves in the direction of arrow 160. The engagement mechanism 156 causes the impeller to be elongated in response to the cage being elongated. Elongating the impeller causes the impeller to radially contract.

[0349] Typically, the engagement mechanism 156 is configured such that, even at the circumferential location where the separation S1 between the impeller and the inner surface of the cage (FIGS. 12C and 12D) is minimized, and even if the cage contracts radially, the separation between the impeller and the inner surface of the cage is maintained (i.e., the impeller and the inner surface of the cage remain separated from each other). Even further, at the circumferential location where the separation S2 between the impeller and the outer surface of the cage is minimized, and even if the cage contracts radially, the engagement mechanism maintains the separation between the impeller and the outer surface of the cage (i.e., the impeller and the outer surface of the cage remain separated from each other). Since the inner wall portion of the renal vein is supported by the outer surface of the cage, the separation S2 between the impeller and the outer surface of the cage is typically also the separation between the impeller and the inner wall portion of the renal vein at the location where the inner wall portion of the renal vein is closest to the impeller. Thus, even at the location where the inner wall portion of the renal vein is closest to the impeller, and even when the renal vein exerts pressure on the cage such that the cage contracts radially, the engagement mech anism maintains the separation between the impeller and the inner wall portion of the renal vein.

[0350] In response to the renal vein exerting pressure P on the cage 154 and in response to causing the cage to contract radially, the separation S1 between the impeller and the inner surface of the cage and / or the separation S2 between the impeller and the outer surface of the cage may decrease. It is noted, however, that the engagement mechanism is adapted to cause the inner surfaces of the impeller and the cage to remain separated from each other even if the cage contracts radially. Thus, the cage protects the renal vein from being damaged by the impeller even if the renal vein contracts. The inner wall portion of the renal vein is supported by the outer surface of the cage, and it is further noted that the cage typically includes struts defining cells and that the wall portion of the renal vein may typically project into the cage through the cells. By maintaining the separation S1 between the impeller and the inner surface of the cage, the engagement mechanism protects the inner wall portion of the renal vein from the impeller even if the inner wall portion of the renal vein projects into the cage.

[0351] When the blood pump 150 is disposed inside a blood vessel such as the renal vein 32, the cage 154 expands against the inner wall portion of the blood vessel and is adapted to be fixed in the rotational direction with respect to the inner wall portion of the blood vessel. The cage is fixed in the rotational direction with respect to the wall portion of the blood vessel, but the impeller 152 rotates and is adapted to pump blood through the blood vessel. The engagement mechanism 156 is configured to engage the impeller with the cage and (a) when the cage is compressed radially, the impeller is compressed radially, (b) when the cage is lengthened axially, the impeller is lengthened axially, and (c) the impeller is able to rotate even if the cage is fixed in the rotational direction in the proper position. The engagement mechanism is configured to allow rotation of the impeller by allowing rotation of the distal bearing 250D in the engagement mechanism even if the cage is fixed in the rotational direction in the proper position.

[0352] Typically, to insert the cage and impeller into the blood vessel, the cage is installed inside the insertion device 155 in a crimped configuration. Typically, crimping the cage so that it takes an axially elongated configuration automatically causes the impeller to take an axially elongated configuration. The reason is that the engagement mechanism imparts longitudinal movement of the distal end of the cage to the distal end of the impeller in the manner described above.

[0353] For example, as shown in FIGS. 12C-12D, in some applications, pressure sensors 157 and 159 are disposed upstream and downstream of the blood pump 150. When the blood pump 150 is disposed inside the renal vein, as shown in FIGS. 12C-12D, for example, the pressure measured by the upstream pressure sensor 157 represents the blood pressure upstream of the blood pump in the renal vein, and the pressure measured by the downstream pressure sensor 159 represents the central venous pressure. In some applications, one or more additional sensors 161 are disposed on the blood pump (e.g., downstream of the blood pump as shown in FIGS. 12C-12D, or upstream of the blood pump) and are configured to measure one or more additional parameters such as the flow through the renal vein and / or the oxygen saturation in the renal vein. Alternatively or additionally, a thermal flow sensor is used to measure the flow through the renal vein. For example, a thermal flow sensor 260 can be used to measure the flow through the renal vein of interest, as described below with reference to FIGS. 22Ai-22Cii.

[0354] FIG. 12E is a cross-sectional view of the strut 204 of the cage 154 and a cross-sectional view of the renal vein 32 when the blood pump 150 is disposed inside the renal vein 32 according to some applications of the present invention. The end view of the impeller 152 combined with it is shown. The cross-sectional views of the cage and the renal vein are in a plane perpendicular to the longitudinal axis 222 of the cage at a longitudinal location in the center of the longitudinal axis of the cage. Typically, at this location, the diameter of the cage perpendicular to the longitudinal axis of the cage is at its maximum. Further typically, at this location, the span SP of the impeller perpendicular to the longitudinal axis 224 of the impeller is also at its maximum. In some applications, the outer edge of the impeller and the inner surface of the struts of the cage are minimally separated from each other at this longitudinal location, and the outer edge of the impeller and the outer surface of the struts of the cage are minimally separated from each other at this longitudinal location.

[0355] The cage includes struts 204, and since the struts 204 are shaped to define cells, the cage typically allows blood flow through the cage by allowing blood flow through the cells defined by the cage. As shown in FIG. 12E, typically, when the cage and the impeller are in a radially expanded configuration inside a blood vessel such as the renal vein 32, there is a minimum separation S1 between the outer edge of the impeller and the struts 204, and there is a minimum separation S2 between the outer edge of the impeller and the outer surface of the struts 204 of the cage (which is typically also the minimum separation between the outer edge of the impeller and the inner wall of the blood vessel). Further typically, there is a space between the blades of the impeller. Typically, even if the impeller does not actively pump blood through the blood vessel, blood can flow through the blood pump by flowing through the cells defined by the cage, and through the separation between the impeller and the cage, through the separation between the impeller and the blood vessel wall, and / or through the separation between the blades of the impeller.

[0356] It should be noted that the blood pump 150 typically does not include an occlusion element (such as a sealing element, etc.) to prevent retrograde flow of blood through the blood pump. In some applications, while the blood pump is pumping blood in the anterograde direction, some retrograde flow of blood exists through the separation between the impeller and the cage, through the separation between the impeller and the vessel wall portion, and / or through the separation between the blades of the impeller (e.g., near the center of the impeller). Alternatively or additionally, while the blood pump is pumping blood in the downstream direction, some anterograde flow of blood exists through the separation between the impeller and the cage, through the separation between the impeller and the vessel wall portion, and / or through the separation between the blades of the impeller (e.g., directed towards the center of the impeller). Typically, whether the flow of blood through the above-described regions is in the retrograde direction or the anterograde direction, the flow of blood through these regions reduces the tendency for blood to stagnate in these regions.

[0357] In some applications, when the impeller is in a configuration where it is unrestrained and radially expanded (as shown in FIG. 12E), the span SP of the impeller in a direction perpendicular to the longitudinal axis of the impeller is greater than 8 mm, less than 15 mm, and / or between 8 mm and 15 mm. For example, the span SP can be greater than 8 mm, less than 12 mm, and / or between 8 mm and 12 mm. Or the span SP can be greater than 10 mm, less than 15 mm, and / or between 10 mm and 15 mm.

[0358] Referring now to FIGS. 13A - 13D, FIGS. 13A - 13D are schematic views of respective stages of a method of manufacturing an impeller (i.e., a rotor with blades) 152 according to some application examples of the present invention. In some application examples, a tube 162 (e.g., a nitinol, stainless steel, or plastic tube) is cut along the dotted line shown in FIG. 13A (e.g., by laser cutting), and the cut tube (FIG. 13B) is adapted to define a structure 165, and the structure 165 has, at the ends of the structure, first and second end portions, e.g., rings 164, and the rings are connected to each other by a plurality of (e.g., two as shown in FIG. 13B, or three or more) elongated elements 166 (e.g., elongated strips as shown). The first and second ends of each of the elongated elements are typically arranged at an angle alpha with respect to the periphery of the ring relative to each other. Typically, the angle alpha is greater than 5 degrees (e.g., greater than 50 degrees, or greater than 70 degrees, or greater than 90 degrees), less than 360 degrees (e.g., less than 180 degrees, or less than 150 degrees, or less than 110 degrees), and / or between 5 degrees and 360 degrees (e.g., between 50 degrees and 180 degrees, or between 70 degrees and 150 degrees, or between 90 degrees and 110 degrees).

[0359] Although the elongated element 166 is described and shown as a strip, it is noted that the scope of the present invention includes using elongated elements having other structures, such as elongated tubular structures, elongated rod structures, etc., without departing from what should be changed.

[0360] The structure 165 is axially compressed, for example, by pushing two rings towards each other, and the elongated element 166 is adapted to expand radially as shown in the transition from FIG. 13B to FIG. 13C. Typically, before the structure is axially compressed (i.e., in the configuration of the axially elongated structure), the length L4 of the structure measured along the longitudinal axis of the structure is greater than 15 mm and less than 25 mm, and / or between 15 mm and 25 mm. Before the structure is axially compressed (i.e., in the configuration of the axially elongated structure), the respective length L5 of each elongated element measured along the longitudinal axis of the structure is greater than 14 mm and less than 22 mm, and / or between 14 mm and 22 mm. Typically, when the impeller 152 is axially elongated, the length of the impeller 154 and the length of the elongated element 166 measured along the longitudinal axis of the impeller are the same as the lengths L4 and L5, respectively. More typically, when the impeller 152 is axially elongated, the length of the impeller blade 168 measured along the longitudinal axis of the impeller is the same as L5.

[0361] Typically, the structure is in a shape set to the state of the axially compressed structure. The structure 165 forms the frame of the impeller 152. More typically, in the state of the axially compressed structure, each of the elongated elements 166 of the structure 165 forms a helical shape. Each of the helical elongated elements originates from the first of the end portions (e.g., ring 164) and terminates at the second of the end portions (e.g., ring 164). The pitch of each of the helical elongated elements is typically within 20 percent of each other, and the helical elongated elements typically have the same pitch as each other. In some applications, the pitch of the helical elongated elements varies along the length of the helical elongated elements. The radius of each of the helical elongated elements is typically within 20 percent of each other, and typically, the helical elongated elements have the same radius as each other. In some applications, the helixes defined by two elongated elements are not symmetric with respect to each other. The longitudinal axis of each of the helical elongated elements is typically parallel to the longitudinal axis of the other helical elongated element and typically parallel to the longitudinal axis of the impeller. In some applications, each of the elongated elements defines more than one-eighth and / or less than half of the turn of the helix, for example, defining between one-eighth and half of the turn of the helix.

[0362] Each of the elongated elements has been described as being helical, but in some applications, although the elongated elements do not define a mathematically exact helix, each of the elongated elements generally defines a helical shape in that the elongated element extends radially outward in a spiral as it extends axially away from the first of the end portions (e.g., ring), and then extends radially inward in a spiral toward the second of the end portions as it extends axially toward the second of the end portions.

[0363] Typically, it is noted that cutting the tube 162 such that the angle alpha is as described above facilitates shaping of the elongate element 166 into the desired helical shape. In some applications, the tube is cut such that the angle alpha is not as described above, and yet, the elongate element 166 is shaped into the desired helical shape by twisting the structure 165 while applying the shaping process to the structure 165. Typically, all other conditions being equal, cutting the tube 162 such that the angle alpha is as described above promotes shaping of the elongate element 166 into the desired helical shape while reducing the stress on the elongate element 166 as compared to the stress on the elongate element if the elongate element were shaped into the desired helical shape without cutting the tube such that the angle alpha is as described above.

[0364] Typically, in a configuration of a structure compressed axially, the length L6 of the structure measured along the longitudinal axis of the structure is greater than 8 mm and less than 18 mm, and / or between 8 mm and 18 mm. Further typically, in a configuration of a structure compressed axially, the respective length L7 of each elongate element measured along the longitudinal axis of the structure is greater than 5 mm and less than 14 mm, and / or between 5 mm and 14 mm. Typically, when the impeller 152 is in a configuration expanded radially in its uncompressed state, the length of the impeller 154 and the length of the elongate element 166, measured along the longitudinal axis of the impeller, are each the same as the length L6 and the length L7, respectively. Further typically, when the impeller 152 is in a configuration expanded radially without restraint, the length of the impeller blade 168 measured along the longitudinal axis of the impeller is typically the same as L7.

[0365] Following compression of the structure 165 in the axial direction, a material 168 (e.g., a flexible polymeric material such as silicone, polyurethane, and / or polyester) is coupled to at least a portion of the structure 165, e.g., to the helical elongate elements of the structure 165. Typically, the material 168 is coupled to a portion of the structure 165 by immersing the structure 165 into the material 168 while the material 168 is in its liquid state. For example, the structure 165 can be immersed into liquid silicone, a silicone-based elastomer, and / or a different elastomer. Thereafter, the material is dried (e.g., by a curing and / or polymerization process) such that a film of the material supported by the helical elongate elements of the structure 165 is formed. In some applications, techniques are used to facilitate formation of the film on the structure 165 and / or coupling of the material to the helical elongate elements of the structure 165, as described below. In some applications, while drying the material 168, the structure 165 is rotated about its longitudinal axis to facilitate formation of a film of the material 168 having a uniform thickness. In some applications, the material 168 is coupled to the structure 165 in a manner different from the above-described manner, e.g., by stitching and / or electrospinning a flexible polymeric material (e.g., silicone, polyurethane, and / or polyester) to the helical elongate elements of the structure 165. is coupled to the structure 165.

[0366] The helical elongate element 166 to which the material is connected defines an impeller blade. As shown in FIG. 13D, the tube 162 is cut to define a structure that defines two helical elongate elements between the rings 164 to form an impeller 152 with a single blade. (The impeller shown in FIG. 13D could alternatively be described as an impeller with two blades, noting that each of these elongate elements to which the material is connected defines a blade. For example, in the end view of the impeller shown in FIG. 18Ai, a portion of the impeller on each side of the ring 164 could each be considered a blade. Nevertheless, in the context of this application, an impeller including two helical elongate elements as shown in FIG. 13D is described as having a single blade.) In some applications, an impeller with three blades is formed by cutting the tube 162 to define a structure that defines three elongate elements between the rings 164, and when the structure is axially compressed, the structure is configured to define three helical elongate elements, as described below with reference to FIGS. 16A - 16B for example. Alternatively or additionally, impellers with different numbers of blades, for example, 4 - 8 blades, are used.

[0367] Typically, the material 168 is connected to the structure 165 such that the material forms a continuous layer (e.g., a continuous film) between the elongate elements 166. It is further noted that, typically, while the material is being dried (e.g., by a curing or polymerization process), the material 168 is shaped to form one or more blades, thanks to being supported by the helical elongate elements 166 and without the need for the use of any tool configured to shape the blade, such as a shaping mandrel.

[0368] As shown in FIG. 13D, the impeller blade is typically formed from a continuous film of material 168 supported by helical elongated elements 166, which typically form the outer edge of the blade of the impeller. Typically, it is noted that the impeller does not include an axial support member (such as a shaft, etc.) along the axis of the impeller between the proximal and distal ends of the helical elongated elements to provide support for the film of material. More generally, the impeller typically does not include any support member (such as a shaft, etc.) for providing support to the film of material 168 between the proximal and distal ends of the helical elongated elements. Thus, typically, there is no support member that breaks the continuity of the film of material disposed between the helical elongated elements. Moreover, the rotational movement is imparted from the proximal end portion (such as proximal ring 164) of the impeller to the distal end portion (such as distal ring 164) of the impeller through the helical elongated elements of the impeller (for example, substantially only through the helical elongated elements) and without passing through an axial support member (such as a shaft, etc.).

[0369] During insertion of the impeller through the insertion device 155 (FIG. 12Ai), the impeller is radially compressed by elongating the structure 165 axially such that the helical elongated elements 166 are straightened. Typically, since there is no additional support member providing support to the material 168 between the proximal and distal ends of the helical elongated elements, the film of material 168 follows the shape change that the helical elongated elements undergo during axial elongation of the structure 165. More typically, all other conditions being equal, the absence of an axial support member (such as a shaft, etc.) between the proximal and distal ends of the helical elongated elements means that the impeller To promote radial compression, the maximum diameter of the impeller when the impeller is in a configuration where it is radially compressed to its maximum extent is the same in all other aspects but smaller than the maximum diameter of an impeller that includes an axial support member. That is, the impeller is configured to be radially compressible to a smaller diameter than if it included an additional support member for supporting material between the proximal and distal ends of the helical elongated element.

[0370] In some applications, all other conditions being equal, due to the absence of an axial support member (such as a shaft, etc.) between the proximal and distal ends of the helical elongated element, the impeller is more flexible than an impeller that includes an axial support member (such as a shaft, etc.) in all other aspects. During insertion into the renal vein, the impeller and the cage are typically inserted through a vascular junction that forms a relatively acute angle (e.g., an angle greater than 70 degrees) with each other and are disposed at a relatively short distance from each other. For example, the impeller and the cage can be passed through the femoral vein, the iliac vein, into the vena cava, and then into the renal vein. The flexibility of the impeller typically facilitates the insertion of the impeller into the renal vein.

[0371] Moreover, all other conditions being equal, the absence of an axially extending support member (e.g., a shaft) between the proximal and distal ends of the helical elongate element promotes lengthening of the impeller axially by a predetermined length using a smaller force than would be required to lengthen an impeller that includes an axially extending support member (e.g., a shaft) between the proximal and distal ends of the helical elongate element by the same predetermined length. The reason is that lengthening an impeller that includes an axially extending support member typically requires lengthening the axially extending support member (e.g., via axial extension of the support member). Similarly, all other conditions being equal, when a predetermined force is applied to the impeller to lengthen it axially, the axial elongation of the impeller is greater than the axial elongation that would be experienced by a generally similar impeller that includes an axially extending support member (e.g., a shaft) between the proximal and distal ends of the helical elongate element.

[0372] In some alternative applications of the present invention, the impeller material 168 itself is shaped to facilitate insertion of an axially extending support member therethrough. For example, an elastomer (e.g., silicone, or a silicone-based elastomer) may be used as the material 168, and the elastomer may be shaped to form a hollow central lumen therethrough. The axially extending support member may be coupled to the impeller by being passed through the hollow central lumen defined by the elastomer.

[0373] Referring now to FIGS. 14A-14B, FIGS. 14A-14B are schematic views of a structure 165 according to some applications of the present invention, showing that the impeller 152 is formed from the structure 165, and the structure has a suture 170 that is joined around a portion of the structure. Also referring to FIG. 15, FIG. 15 is a schematic view of an impeller 152 according to some applications of the present invention.

[0374] As described above, typically, material 168 is coupled to at least a portion of structure 165 by immersing structure 165 into material 168 while material 168 is in its liquid state. For example, structure 165 can be immersed into liquid silicone. Thereafter, the material is dried (e.g., by a curing and / or polymerization process) to form a film of the material supported by the helical elongated elements of structure 165. In some applications, a suture 170 is coupled around a portion of structure 165 to facilitate formation of a film of material 168 over structure 165 and / or to facilitate coupling of material 168 to the helical elongated elements 166 of structure 165. For example, the suture can be coupled around the helical elongated elements 166 of structure 165 as shown in FIG. 14A, which shows suture 170 coupled around the helical elongated elements 166 of structure 165 prior to material 168 being coupled to structure 165.

[0375] In some applications, the suture increases the surface area contacted by the material 168 while the material 168 is in its liquid state. Alternatively or additionally, the surface of the suture is rougher and / or more porous than that of the elongate element 166 (which is typically made of nitinol). Thus, the material 168 becomes connected to the suture with a connection strength stronger than that of the connection between the material 168 and the elongate element 166. In some applications, the suture serves as an intermediate material between the material from which the elongate element is made (which typically has a relatively high rigidity (and is typically nitinol)) and the material 168 (which is typically an elastomer with a relatively low rigidity). Thereby, when the material dries, the suture strengthens the strength of the connection between the material 168 and the helical elongate element 166. In some applications, by strengthening the strength of the connection between the material 168 and the helical elongate element 166, the suture prevents a gap from being formed between the material and the helical elongate element 166 during and / or after the drying of the material 168. Thus, the suture facilitates the formation of a continuous film of the material 168 between the helical elongate elements. FIG. 14B shows the impeller 152 following the formation of the film of the material 168 on the structure 165, the film being supported by the helical elongate elements 166 of the structure 165.

[0376] Alternatively or additionally, to facilitate film formation of the material 168 onto the structure 165, the edge of the end portion (e.g., the ring 164) of the structure 165 closest to the helical elongated element 166 defines a notch 180 therein, as shown in FIG. 15. As described above, typically, the material 168 is coupled to at least a portion of the structure 165 by immersing the structure 165 into the material 168 while the material 168 is in its liquid state. For example, the structure 165 can be immersed into liquid silicone. Typically, some of the liquid material has entered into the notch 180 in the end portion (e.g., the ring 164), such that the contact area between the material and the structure is increased as compared to the case where the end portion does not define a notch. Thus, when the material is subsequently dried, the strength of the connection of the material to the structure 165 is enhanced.

[0377] Referring now to FIGS. 16A-16B, FIGS. 16A-16B are schematic views of an impeller 152 according to some application examples of the present invention, showing that the impeller defines three blades 190. Typically, impeller 152 is manufactured to have three blades using generally the same techniques as described above with reference to the impellers described with reference to FIGS. 13A-13D. However, rather than cutting the tube 162 (FIG. 13A) to define two elongated elements 166 (FIG. 13B), the tube 162 is cut to define three elongated elements. The tube is then axially compressed so that the elongated elements form three helical shapes, and the tube is shaped in an axially compressed configuration. Material 168 is then coupled to at least a portion of the structure 165. Typically, the material is coupled to at least a portion of the structure 165 by immersing the structure 165 into the material 168 while the material 168 is in its liquid state. For example, the structure 165 can be immersed into liquid silicone. Typically the material is dried on the helical elongated elements (e.g., by curing and / or polymerization), and the helical elongated elements to which the material is coupled form an impeller with three blades, as shown in FIGS. 16A-16B. The helical elongated elements to which it is coupled form an impeller with three blades, as shown in FIGS. 16A-16B.

[0378] Typically, it is noted that the three-bladed impeller shown in FIGS. 16A-16B does not include an axial support member (e.g., a shaft, etc.) for providing support to material 168 between the proximal and distal ends of the helical elongated element and along the axis of the impeller. More generally, typically, the impeller does not include a support member (e.g., a shaft, etc.) for providing support to material 168 in addition to the helical elongated element between the proximal and distal ends of the helical elongated element. Moreover, the rotational movement is provided from the proximal end portion (e.g., proximal ring 164) of the impeller to the distal end portion (e.g., distal ring 164) of the impeller through the helical elongated element of the impeller (e.g., substantially only through the helical elongated element) and without passing through an axial support member (e.g., a shaft, etc.).

[0379] During insertion of the impeller through the insertion device 155 (FIG. 12Ai), the impeller is radially contracted by elongating the impeller axially such that the helical elongated element 166 is straightened. Typically, since there is no additional support member (e.g., a shaft, etc.) for providing support to material 168 between the proximal and distal ends of the helical elongated element, the material 168 follows the shape change that the helical elongated element undergoes while the structure 165 is axially elongated. Further typically, all other conditions being equal, the absence of an axial support member (e.g., a shaft, etc.) between the proximal and distal ends of the helical elongated element promotes radial compression of the impeller, and the maximum diameter of the impeller when the impeller is in its maximally radially compressed configuration is smaller than the maximum diameter of an impeller that is otherwise the same but includes an axial support member, i.e., the impeller is configured to be radially compressible to a smaller diameter than if the impeller included an additional support member for supporting material between the proximal and distal ends of the helical elongated element.

[0380] In some applications, all other things being equal, the impeller is more flexible than an impeller that is otherwise the same but includes an axial support member (e.g., a shaft) due to the absence of an axial support member (e.g., a shaft) between the proximal and distal ends of the helical elongate element. During insertion into the renal vein, the impeller and cage are typically inserted through a vascular junction that forms a relatively acute angle (e.g., an angle greater than 70 degrees) with each other and are disposed at a relatively short distance from each other. For example, the impeller and cage can be inserted into the renal vein by being passed through the femoral vein, the iliac vein, into the vena cava, and then into the renal vein. The flexibility of the impeller typically facilitates insertion of the impeller into the renal vein.

[0381] Moreover, as described above, the absence of an axial support member (e.g., a shaft) between the proximal and distal ends of the helical elongate element facilitates lengthening the impeller axially by a predetermined length using less force than would be required to lengthen by a predetermined length an impeller that includes an axial support member (e.g., a shaft) between the proximal and distal ends of the helical elongate element. Similarly, all other things being equal, if a predetermined force is applied to the impeller to lengthen it axially, the axial elongation of the impeller will be greater than the axial elongation that a generally similar impeller that includes an axial support member (e.g., a shaft) between the proximal and distal ends of the helical elongate element would experience.

[0382] ​In some alternative applications of the present invention, the impeller material 168 itself is shaped to facilitate its insertion through an axial support member. For example, an elastomer (e.g., silicone, or a silicone-based elastomer) can be used as the material 168, and the elastomer can be shaped to form a hollow central lumen therethrough. The axial support member can be coupled to the impeller by being passed through the hollow central lumen defined by the elastomer.

[0383] Referring now to FIG. 17, FIG. 17 is a schematic view of a protective cage 154 of a blood pump 150 according to some applications of the present invention. Typically, the cage includes a proximal ring and a distal ring 202. Between the proximal ring and the distal ring, the cage includes struts 204, and the struts 204 are shaped to define cells. In some applications, in the configuration of the cage that is expanded radially without being compressed (i.e., when no arbitrary force is applied to the cage), between the proximal ring and the distal ring, the cage generally defines a spherical or oval shape as shown in FIG. 17. The engagement mechanism 156 (FIG. 12B) typically engages the impeller to the cage 154 via a ring 164 of the impeller (FIGS. 13A - 13D), a ring 202 of the cage, and a distal bearing 250D (FIG. 12B).

[0384] In some application examples, when the cage 154 is in a configuration where it is expanded in its radial direction, the length L8 of the cage, measured along the longitudinal axis of the cage and including the ring 202 of the cage, is greater than 17 mm, less than 26 mm, and / or between 17 mm and 26 mm. The length L9 of the cage, measured along the longitudinal axis of the cage and not including the ring 202 of the cage, is greater than 12 mm, less than 21 mm, and / or between 12 mm and 21 mm. In some application examples, when the cage is elongated in the axial direction and compressed in the radial direction by being crimped (a configuration not shown), the length of the cage, measured along the longitudinal axis of the cage and including the ring 202 of the cage, is greater than 22 mm, less than 35 mm, and / or between 22 mm and 35 mm. Typically, in such application examples, when the cage is elongated in the axial direction by being crimped (a configuration not shown), the length of the cage, measured along the longitudinal axis of the cage and excluding the ring 202 of the cage, is greater than 18 mm, less than 30 mm, and / or between 18 mm and 30 mm. In some application examples, when the cage 154 is in a configuration where it is expanded in its radial direction, the diameter D7 of the cage is greater than 8 mm, less than 20 mm, and / or between 8 mm and 20 mm. For example, the diameter D7 can be greater than 8 mm, less than 15 mm, and / or between 8 mm and 15 mm. Alternatively, the diameter D7 can be greater than 13 mm, less than 19 mm, and / or between 13 mm and 19 mm.

[0385] The cage is typically inserted into the blood vessel (e.g., into the renal vein) in its crimped configuration (i.e., with the cage elongated axially and compressed radially relative to its uncompressed configuration). As described above, during insertion of the impeller into the blood vessel, the impeller is radially contracted by elongating the structure 165 axially, and the helical elongated elements 166 are straightened. Typically, the film of material 168 follows the shape change that the helical elongated elements undergo during elongation of the impeller. More typically, the impeller 152 is already disposed inside the cage during insertion of the blood pump into the blood vessel. Thus, during insertion of the blood pump 150 into the blood vessel, the impeller -152 is disposed inside the cage in a state where the cage is in its crimped configuration and the impeller is in its axially elongated configuration, and the helical elongated elements of the impeller are straightened. Typically, in response to being released from the insertion device inside the blood vessel, the cage automatically assumes its radially expanded configuration that is not compressed. Similarly, the impeller typically automatically expands radially inside the cage in response to the cage and the impeller being released from the insertion device, and assumes its radially expanded configuration that is not compressed.

[0386] Referring now to FIGS. 18Ai through 18Aiii, FIGS. 18Ai through 18Aiii are schematic views of examples of the structure 165 forming the frame of the impeller 152 according to some applications of the present invention.

[0387] As shown by the inner dotted circular shape 194, the inner dotted circular shape 194 is the same size in both FIGS. 18Ai to 18Aiii, and the impellers shown in FIGS. 18Ai and 18Bi respectively rotate so as to encompass circular regions of the same size. Thus, as shown by the outer dotted circular shape 196, the outer dotted circular shape 196 is the same size in both FIGS. 18Ai to 18Aiii, and the impellers shown in FIGS. 18Ai and 18Bi respectively are suitable for being installed inside a blood vessel having a predetermined cross-sectional area, and as described above, there is a separation between the inner wall portion of the blood vessel and the impeller. (The outer dotted circle represents the cross-section of the inner wall portion of the blood vessel, and the impeller is installed therein.) Although similarly sized and suitable for installation in a blood vessel, the impeller structure 165 shown in FIGS. 18Bi to 18Biii is configured such that the blades of the impeller formed from the structure extend to a larger cross-sectional area than the impeller blades formed from the structure 165 as shown in FIGS. 18Ai to 18Aiii. In other words, when viewed from the end of the impeller (as shown in FIGS. 18Ai and 18Bi), the blades of the impeller frame shown in FIGS. 18Bi to 18Biii extend to a larger cross-sectional area (i.e., the area in the transverse direction with respect to the axis of the impeller) than the cross-sectional area extended by the blades of the impeller frame shown in FIGS. 18Ai to 18Aiii. Similarly, when viewed from the end of the impeller (as shown in FIGS. 18Ai and 18Bi), each of the blades of the impeller frame shown in FIGS. 18Bi to 18Biii defines an angle theta around the longitudinal axis of the impeller, which is smaller than that defined by each of the blades of the impeller frame shown in FIGS. 18Ai to 18Aiii.

[0388] Typically, all other conditions being equal, for an impeller disposed inside a blood vessel having a given diameter, the propulsive force of the blood passing through the blood vessel at a given rotational rate of the impeller increases as the cross-sectional area of the blood vessel across which the blades of the impeller extend (i.e., the area of the blood in the direction transverse to the longitudinal axis of the blood vessel) increases (and thus the efficiency of the impeller increases). For an impeller as shown in FIGS. 18Ai-18iii and FIGS. 18Bi-18iii, the efficiency of the impeller typically increases as the angle theta defined by the impeller blades around each side of the longitudinal axis of the impeller increases. Thus, for FIGS. 18Ai-18Aiii and FIGS. 18Bi-18Biii, all other conditions being equal, the impeller shown in FIGS. 18Bi-18Biii will typically pump blood more efficiently than that shown in FIGS. 18Ai-18Aiii. However, as will be explained in more detail below, when the impeller is lengthened in the axial direction and all other conditions are equal, an impeller defining blades that extend to a larger cross-sectional area will typically be longer than an impeller defining blades that extend to a smaller cross-sectional area.

[0389] In some applications, it is noted that a single-bladed impeller as described herein is used and the value of theta (i.e., the angle defined by the blades of the impeller around each side of the longitudinal axis of the impeller) is greater than 5 degrees (e.g., greater than 50 degrees, greater than 70 degrees, or greater than 90 degrees), less than 360 degrees (e.g., less than 180 degrees, less than 150 degrees, or less than 110 degrees), and / or between 5 degrees and 360 degrees (e.g., between 50 degrees and 180 degrees, between 70 degrees and 150 degrees, or between 90 degrees and 110 degrees).

[0390] While inserting the blood pump 150 into a blood vessel, the impeller 152 is typically disposed inside the cage 154 while the cage is in a crimped configuration elongated in the axial direction and while the impeller is in a crimped configuration elongated in its axial direction. Thus, the length defined by the impeller when the impeller is in its axially elongated crimped configuration is typically less than the length of the cage when the cage is in its axially elongated crimped configuration. And the dimensions of the cage are limited. The reason is that the diameter of the cage in a radially expanded configuration is limited based on the size of the blood vessel into which the blood pump is to be installed.

[0391] In some applications, the cage is configured to include struts 204, which are shaped to include undulating portions 210 as shown in FIG. 18C (which is described in more detail below). Typically, the undulation level of the undulating portion of the strut of the cage when the cage is in its radially expanded configuration is greater than the undulation level of the undulating portion of the strut when the cage is in its axially elongated configuration. In some applications, by including struts with undulating portions, a cage having a given diameter and / or outer profile in its radially expanded configuration can be elongated to define a greater length than a similar diameter and / or outer profile cage that does not include struts with undulating portions when the cage is elongated. Thus, the cage can (a) accommodate the impeller, which is longer in its axially elongated configuration than what can be accommodated by a cage that does not include struts with undulating portions (and thus, in its radially expanded configuration, it defines a larger cross-sectional area), but (b) the diameter and / or outer profile of the cage in its radially expanded configuration is generally similar to a cage that does not include struts with undulating portions.

[0392] A more detailed description of FIGS. 18A1 to 18C follows.

[0393] As described above, the impeller structure 165 shown in FIGS. 18B1 to 18B3 is configured such that the blades of the impeller formed from the structure extend to a larger cross-sectional area than the impeller blades formed by the structure 165 as shown in FIGS. 18A1 to 18A3. FIGS. 18A2 and 18B2 show side views of two examples of the structure 165, and FIGS. 18A3 and 18B3 show views of examples of the structure 165 configured to be elongated in the axial direction, with the helical elongated elements of the structure being straightened. As described above, during insertion of the blood pump 150 into a blood vessel, the impeller is typically configured to be elongated in the axial direction as shown in FIGS. 18A3 and 18B3. To allow the impeller blades to extend to a larger cross-sectional area (as shown in FIG. 18B1), the length of the elongated element 166 is typically longer than the length of an impeller having blades that extend to a smaller cross-sectional area (as shown in FIG. 18A1). Thus, when the impeller is configured to be elongated in its axial direction, the length LB of the impeller shown in FIGS. 18B1 to 18B3 is greater than the length LA of the impeller shown in FIGS. 18A1 to 18A3. Accordingly, when the impeller is configured to be elongated in its axial direction, the length LB of the impeller shown in FIGS. 18B1 to 18B3 is greater than the length LA of the impeller shown in FIGS. 18A1 to 18A3.

[0394] Referring now to FIG. 18C, FIG. 18C is a schematic view of a cage 154 according to some applications of the present invention, the cage including at least some struts 204, the struts 204 being shown as having its corrugated portion 210. Also, referring to FIG. 18D, FIG. 18D is a schematic end view of a radially expanded cage 154 according to some applications of the present invention, one of the cages 154 including struts 204 having its corrugated portion 210 (left cage), and the other of the cages 154 being shown as not including struts having its corrugated portion (middle cage). Alternatively, the right side of FIG. 18D shows a cage including struts having its corrugated portion being superimposed on a cage not including struts having its corrugated portion, the struts including the corrugated portion being shown by solid lines, and the corresponding struts of the second cage not including the corrugated portion being shown by dashed lines. As can be observed in a portion of FIG. 18D showing the superimposed cages, including a corrugated portion in some of the struts does not change the outer profile of the cage. However, the corrugated portion of the strut adds length to the strut, and, all other conditions being equal, the overall axially elongated length of a stent including struts having the corrugated portion is greater than the overall axially elongated length of a stent not including struts having the corrugated portion.

[0395] As described above, typically, the length of an impeller when the impeller is in an axially elongated and crimped configuration is less than the length of a cage when the cage is in an axially elongated and crimped configuration, and the crimped cage is adapted to accommodate the axially elongated impeller. And, and, the dimensions of the cage are limited. The reason is that the diameter of a cage configured as a radially expanded cage is limited based on the size of the blood vessel into which the blood pump is to be installed. For a cage having a structure as shown in FIG. 17, a cage having a longer crimped length typically expands to have a larger maximum diameter inside the blood vessel, which may not be desirable.

[0396] In some applications, a cage as shown in FIG. 18C is used to increase the length of the axially elongated cage without increasing the diameter of the cage in a radially expanded cage configuration. The cage shown in FIG. 18C includes struts that include a corrugated portion 210. During crimping of the cage, the corrugated portion is configured to be at least partially straightened, thereby increasing the length of the crimped cage as compared to the case where portion 210 was not corrugated. When the cage radially expands inside a blood vessel, the corrugated portion becomes corrugated, but does not increase the diameter of the cage, or otherwise does not change the outer profile of the cage as compared to the case where the corrugated portion is straight. Thus, generally, the excess length provided to the cage by the corrugated portion when the cage is in its crimped configuration does not increase the diameter of the cage when the cage expands inside a blood vessel.

[0397] As described, during insertion of the cage into the renal vein, the corrugated portion of the struts of the cage is at least partially straightened. When the cage takes on a radially expanded configuration inside the renal vein, the level of undulation of the corrugated portion of the struts of the cage increases. In some applications, for each of the struts that define the corrugated portion, the strut is (a) the shortest distance from the first longitudinal end of the strut to the second longitudinal end of the strut when the cage is in its axially elongated configuration (i.e., when the corrugated portion is at least partially straightened) or from the first longitudinal end of the strut to the second longitudinal end of the strut, and (b) the shortest distance from the first longitudinal end of the strut to the second longitudinal end of the strut when the cage is in its radially expanded configuration (i.e., when the corrugated portion is at the level of undulation at which the strut was shaped) is configured to be greater than 1.05:1, for example greater than 1.15:1, or greater than 1.2:1.

[0398] In some applications, the above ratio is less than 1.4:1. For example, the ratio can be between 1.05:1 and 1.4:1, between 1.15:1 and 1.4:1, or between 1.2:1 and 1.4:1.

[0399] Referring now to FIGS. 19A - 19B, FIGS. 19A - 19B are schematic views of an impeller cage 154 according to some applications of the present invention, showing that the cage is shaped to define a central portion having a generally cylindrical shape in the absence of any forces applied to the cage. The outer surface of the cage in the generally cylindrical portion of the cage is parallel to the longitudinal axis 222 of the cage. FIG. 19A shows the cage itself, and FIG. 19B shows the cage disposed inside a blood vessel, e.g., the renal vein 32.

[0400] FIG. 19B shows the cage 154, which is radially expanded inside a blood vessel (e.g., the inner renal vein 32) such that the cage is anchored to the blood vessel. As described above, the impeller 152 (FIG. 12Ai) of the blood pump 150 is configured to pump blood axially through the blood vessel by rotating inside the blood vessel. Typically, it is desirable for the longitudinal axis 224 of the impeller to be aligned with the longitudinal axis 226 of the blood vessel in order for the impeller to efficiently pump blood through the blood vessel. More typically, the ring 164 of the impeller 152 is aligned with the ring 202 of the cage 154 such that the longitudinal axes of the impeller and the cage are aligned with each other. For example, as shown in FIG. 12B, (a) both the proximal rings of the impeller and the cage are placed around a first support element (e.g., the proximal bearing 250P, etc.) such that the proximal rings of the impeller and the cage are aligned with each other, and (b) both the distal rings of the impeller and the cage are placed around a second support element (e.g., the distal bearing 250D, etc.) such that the distal rings of the impeller and the cage are aligned with each other, whereby the longitudinal axes of the impeller and the cage can be aligned with each other.

[0401] As shown in FIG. 19B, the generally cylindrical central portion 220 of the cage 154 is anchored to the blood vessel such that the longitudinal axis of the cage is aligned with the longitudinal axis of the blood vessel. Since the longitudinal axes of the impeller and the cage are aligned with each other, the generally cylindrical central portion of the cage causes the impeller to be disposed within the blood vessel such that the longitudinal axis of the impeller is aligned with the longitudinal axis of the blood vessel.

[0402] As used in this application, including as used in the claims, the "longitudinal axis" of a structure is the set of all centroids of the cross-sectional sections of the structure along the structure. Thus, the cross-sectional sections are locally perpendicular to the longitudinal axis running along the structure. (When the structure has a circular cross-section, the centroid corresponds to the center of the circular cross-section.) Referring now to FIG. 20, which is a schematic view of an impeller cage 154 configured to be disposed inside a blood vessel (e.g., renal vein 32), and where a portion of the blood vessel has an increased diameter compared to the diameter of the blood vessel in the absence of the impeller cage. As shown in FIG. 20, in some applications, the cage is configured to expand a blood vessel having a diameter D6 in the absence of the cage such that a portion of the blood vessel has a diameter greater than D6. For example, the cage is capable of expanding the blood vessel such that when the blood vessel is expanded, the diameter of the blood vessel is greater than 105 percent of diameter D6, or for example, greater than 110 percent of diameter D6, or greater than 115 percent of diameter D6. In some applications, the cage expands the blood vessel such that when the blood vessel is expanded, the diameter of the blood vessel is less than 125 percent of diameter D6. For example, the expanded diameter can be between 105-125 percent, 110-125 percent, and / or 115-125 percent of diameter D6. In some applications, the impeller 152 of the blood pump 150 is configured to expand to a diameter at least equal to the diameter D6 of the blood vessel. Typically, all other factors being equal, the larger the diameter the impeller expands to, the greater the flow rate the impeller can pump blood through the blood vessel.

[0403] Referring now to FIG. 21A, FIG. 21A is a schematic view of an impeller-based blood pump 150 inserted into the left and right renal veins 32 of a subject through the subject's femoral vein 230, according to some applications of the present invention. Although the details of the blood pump 150 are not shown in FIG. 21A, it is noted that the pump is generally as described above. Typically, the blood pump is inserted into the left and right renal veins through respective catheters 155, both of which are inserted through the femoral vein. Alternatively (not shown), the blood pump is inserted through a single catheter that passes from an access point in the femur to the subject's vena cava.

[0404] Typically, the impeller of the blood pump 150 is coupled to a motor 232, which provides rotational movement to the impeller. According to each application, the motor is disposed outside the subject's body (as shown) or is installed inside the subject's body (not shown). Typically, a control unit 234 and a user interface 236 are disposed outside the subject's body. More typically, the control unit receives inputs from pressure sensors 157 and 159, which are disposed upstream and downstream of the blood pump as described above with reference to FIGS. 12C-12D. When the blood pump 150 is disposed inside the renal vein (as shown in FIG. 21A, for example), the pressure measured by the upstream pressure sensor 157 represents the blood pressure upstream of the blood pump inside the renal vein, and the pressure measured by the downstream pressure sensor 159 represents the central venous pressure. In some applications, the control unit receives inputs from additional sensors 161 (such as flow sensors and / or oxygen saturation sensors), which are disposed on the blood pump (downstream of the blood pump, as shown in FIG. 12Ai, for example). Alternatively or additionally, the control unit receives inputs from a thermal flow sensor, such as the thermal flow sensor 260 described below with reference to FIGS. 22Ai-22Cii.

[0405] In some applications, the control unit 234 controls the rotation of the impeller 152 by controlling the motor 232 in response to one or more of the above inputs. Typically, the user interface 236 displays the current renal venous pressure and central venous pressure of the subject based on the pressures measured by the sensors 157 and 159. Typically, based on the current values of the subject's renal venous pressure and central venous pressure, a user (e.g., a healthcare provider, etc.) inputs a target value for the subject renal venous pressure via the user interface. In response, the control unit 234 controls the speed of rotation of the impeller and reduces the renal venous pressure towards the target level as indicated by the user, at the flow rate at which the impeller is configured to pump from the renal vein towards the vena cava. In some applications, in response to a signal received from the downstream sensor 159 indicating that the central venous pressure is at the target renal venous pressure, the control unit stops the rotation of the impeller. Generally, the control unit typically controls the speed of rotation of the impeller in response to inputs from the pressure sensors 157 and 159. In some applications, the control unit controls the speed of rotation of the impeller in response to inputs from an additional sensor 161 and / or a thermal flow sensor 260 (shown in FIGS. 22Ai - 22Cii).

[0406] It should be noted that the "control unit" as described in the specification and claims in this application includes any type of processor (such as a computer processor, etc.) configured to execute the actions described in this specification. The "user interface" includes any type of user interface configured to receive input from a user and / or provide output to a user. For example, the user interface can include one or more input devices (such as a keyboard, mouse, trackball, joystick, touch screen monitor, touch pad, voice command interface, smartphone, tablet computer, and / or other types of input devices known in the art, etc.), and / or one or more output devices (such as a monitor, audio output device, smartphone, tablet computer, and / or other types of output devices known in the art, etc.).

[0407] Referring now to FIG. 21B, FIG. 21B is a schematic diagram of an impeller-based blood pump 150 inserted into the left and right renal veins 32 of a subject through the subject's subclavian vein 240 according to some application examples of the present invention. Although the details of the blood pump 150 are not shown in FIG. 21B, it should be noted that the pump is generally as described above. Typically, the blood pump is inserted into the left and right renal veins through respective catheters, both of which are inserted through the subclavian vein. Alternatively (not shown), the blood pump is inserted through a single catheter that passes from an access point under the clavicle to the subject's vena cava. Apart from the fact that it is inserted into the renal veins through different veins, the blood pump 150 as shown in FIG. 21B is generally similar to the blood pump 150 as shown in FIG. 21A in all other respects.

[0408] Referring now to FIGS. 22Ai-22Cii, FIGS. 22Ai-22Cii are schematic views of a thermal flow sensor 260 for use with a blood pump 150 according to some applications of the present invention. The thermal flow sensor typically includes an upstream temperature sensor 262, a downstream temperature sensor 264, and a heating element 266 disposed between the upstream temperature sensor and the downstream temperature sensor. As indicated by the flow arrows shown in the enlarged view of the thermal flow sensor in FIG. 22Ai, the blood flow passes through the upstream temperature sensor and reaches the heating element. The heating element heats the blood as the blood flows through the heating element. The heated blood then flows to the downstream temperature sensor. The degree to which the blood flowing through the downstream temperature sensor is heated by the heating element depends on the flow rate of the blood. Thus, the thermal flow sensor measures the change in blood temperature between the upstream temperature sensor and the downstream temperature sensor and determines the blood flow responsively thereto.

[0409] As described with reference to FIGS. 21A-21B, in some applications, the control unit controls the speed of rotation of the impeller responsively to the input from the thermal flow sensor 260. Typically, measuring the axial component of the blood flow through the renal vein, i.e., the axial component of the blood flow parallel to the local longitudinal axis of the renal vein, is of interest. The reason is that this determines the flow rate of the blood leaving the subject's kidney. However, due to the rotation of the impeller, the blood flow downstream of the impeller typically includes components other than the axial component (e.g., rotational and radial components). In some applications, the thermal flow sensor is disposed inside a housing 268, and the housing is configured such that the blood flow through the housing is substantially axial and components other than the axial component of the blood flow (e.g., rotational and radial components) are reduced compared to the blood flow through the renal vein outside the housing. That is, measuring the axial component of the blood flow parallel to the local longitudinal axis of the renal vein is of interest. The reason is that this determines the flow rate of the blood leaving the subject's kidney. However, due to the rotation of the impeller, the blood flow downstream of the impeller typically includes components other than the axial component (e.g., rotational and radial components). In some applications, the thermal flow sensor is disposed inside a housing 268, and the housing is configured such that the blood flow through the housing is substantially axial and components other than the axial component of the blood flow (e.g., rotational and radial components) are reduced compared to the blood flow through the renal vein outside the housing.

[0410] Referring now to FIGS. 22Ai and 22Aii, FIGS. 22Ai and 22Aii are schematic cross-sectional and top views, respectively, of a thermal flow sensor 260 and a housing 268 according to some applications of the present invention. Typically, the impeller 152 and cage 154 of the blood pump 150 are disposed at the ends of an elongated element 270 (e.g., a tube) of the blood pump. In some applications, the elongated element 270 defines a recess, and the thermal flow sensor is housed inside the recess, and thus, the outer surface of the elongated element 170 defining the recess includes the housing 168. As shown, the upstream temperature sensor 262, the heating element 266, and the downstream temperature sensor 264 are typically disposed continuously along the length of the recess. Typically, the ratio of the length LI of the recess to the width WI of the recess is greater than 4:1 and / or less than 8:1, e.g., between 4:1 and 8:1. The ratio of the length LI to the width WI is typically such that the blood flow through the recess is in a direction that is substantially parallel to the local longitudinal axis of the renal vein (and parallel to the local longitudinal axis of the elongated element), and components other than the axial component of the blood flow (e.g., rotational and radial components) are reduced compared to the blood flow through the renal vein outside the housing. Since the thermal sensor is housed inside the recess, the thermal flow sensor measures the blood flow in a direction that is substantially parallel to the local longitudinal axis of the renal vein (and parallel to the local longitudinal axis of the elongated element).

[0411] In some applications (not shown), a single thermistor is used to measure flow. The single thermistor is installed inside the housing and, using techniques as described with reference to FIGS. 22Ai through 22Cii, is modified such that the blood flow through the housing is in a direction that is substantially parallel to the local longitudinal axis of the renal vein (and parallel to the local longitudinal axis of the elongate element), and such that components other than the axial component of the blood flow (e.g., the rotational and radial components) are reduced compared to the blood flow through the renal vein outside the housing. Typically, the housing is such that. In such applications, the ratio of the length of the housing to the width of the housing is typically greater than 1:1, e.g., greater than 4:1, and / or less than 8:1, e.g., between 4:1 and 8:1. In such applications, when a housing as shown in FIGS. 22Ci through 22Cii is used, the ratio of the length of the housing to the height of the housing is typically greater than 1:1, e.g., greater than 4:1, and / or less than 8:1, e.g., between 4:1 and 8:1.

[0412] Referring now to FIGS. 22Bi and 22Bii, FIGS. 22Bi and 22Bii are schematic cross-sectional and top views, respectively, of a thermal flow sensor 260 and a housing 268 according to some applications of the present invention. In addition to being housed inside a recess in the elongate element 270, the thermal sensor shown in FIGS. 22Bi through 22B is covered by a cover 272, except that the housing 268 as shown in FIGS. 22Bi through 22Bii is generally similar to that shown in FIGS. 22Ai through 22Aii. In other aspects, the thermal sensor and housing 268 are as generally described with reference to FIGS. 22Ai through 22Aii.

[0413] Referring now to FIGS. 22Ci - 22Cii, FIGS. 22Ci - 22Cii are schematic cross-sectional views of a thermal flow sensor 260 and a housing 268, respectively, according to some application examples of the present invention. In some application examples, the housing 268 houses the thermal sensor 260 and includes a housing such as a tube connected to the outer surface of the elongated element 270 of the blood pump 150. Typically, the housing is compressible and is adapted to be compressed during insertion of the blood pump 150 into a target blood vessel via the insertion device 155.

[0414] As shown, the upstream temperature sensor 262, the heating element 266, and the downstream temperature sensor 264 are typically disposed continuously along the length of the housing within the housing. Typically, the ratio of the length LH of the housing to the width WH of the housing is greater than 4:1 and / or less than 8:1, for example, between 4:1 and 8:1. Further typically, the ratio of the length LH of the housing to the height HH of the housing is greater than 4:1 and / or less than 8:1, for example, between 4:1 and 8:1. The ratio of the length LH to the width WH and the ratio of the length LH to the height HH are such that the blood flow through the housing is substantially in a direction parallel to the local longitudinal axis of the renal vein (and parallel to the local longitudinal axis of the elongated element), and components other than the axial component of the blood flow (e.g., rotational and radial components) are reduced compared to the blood flow through the renal vein outside the housing. Since the thermal sensor is housed inside the recess, the thermal flow sensor measures the blood flow substantially in a direction parallel to the local longitudinal axis of the renal vein (and parallel to the local longitudinal axis of the elongated element).

[0415] It should be noted that in FIG. 22Cii, for illustrative purposes, the interior of the elongated element 270 is hatched. However, typically, the elongated element 270 stores a control mechanism for controlling the movement of the impeller 152 and the cage 154.

[0416] Experimental results Referring now to FIG. 23, FIG. 23 shows a graph depicting the results of an experiment performed on a healthy pig using an impeller-based blood pump 150 according to some applications of the present invention. Throughout the experiment, the left renal venous pressure of the pig was measured directly using a pressure sensor disposed within the left renal vein of the pig. In addition, the right renal venous pressure of the pig was measured using a pressure sensor in the inferior vena cava at the level of the renal vein. Also, the left renal blood flow and the baseline level of urine output from the left and right kidneys were measured, and the above-described parameters were re-measured at specific points at appropriate times during the experiment.

[0417] A balloon was inflated in the inferior vena cava of the pig downstream of the junction between the inferior vena cava and both the left and right renal veins. The balloon was inflated to cause an increase in blood pressure in the inferior vena cava of the pig downstream of the renal vein by partially occluding the blood flow through the inferior vena cava downstream of the renal vein. Simultaneously with the balloon being inflated inside the inferior vena cava of the pig, the impeller-based blood pump was operated to pump blood through the left renal vein of the pig as described herein, while no assistance was provided to the blood flow through the right renal vein of the pig. While the balloon was still inflated, the blood pump in the left renal vein was temporarily switched off for a period of time and then switched on again. Thereafter, the balloon in the inferior vena cava was deflated and the blood pump was switched off.

[0418] The upper graph in Figure 23 shows the left renal vein pressure and the right renal vein pressure as measured during the experiment. The left renal vein pressure is shown by the solid line curve, and the right renal vein pressure is shown by the dotted line curve. To more clearly show the left renal vein pressure measurement and the right renal vein pressure measurement, it is noted that at the places where the left renal vein pressure measurement and the right renal vein pressure measurement are the same (for example, between approximately 12:35 and 13:28), the two curves are slightly separated. In addition, small changes in venous pressure are ignored. As shown, initially, during the baseline period, the left renal vein pressure and the right renal vein pressure were similar to each other at approximately 8 mmHg. Thereafter, at 13:28, the balloon was inflated and the impeller-based blood pump was moved within the left renal vein. As a result of the balloon being inflated, the pressure in the vena cava increased, and thus the right renal vein pressure increased to approximately 22 mmHg. Despite the increase in the pressure in the vena cava, the left renal vein pressure did not increase due to the pumping of blood through the left renal vein. At approximately 14:10, the blood pump within the left renal vein was switched off, and as a result, the left renal vein pressure increased to the level of the venous pressure in the vena cava. Thereafter, at approximately 14:40, the pump was switched on again, and as a result, the pressure within the left renal vein decreased. Thereafter, at 15:24, the balloon was deflated, and the venous pressure in the vena cava, and thus the right renal vein pressure, decreased. These results indicate that an impeller-based blood pump as described herein can effectively reduce renal vein pressure, even if the central venous pressure of the subject increases.

[0419] The middle graph in FIG. 23 shows renal blood flow as measured within the left renal vein. As shown, the baseline value of left renal blood flow was approximately 360 ml / min. Left renal blood flow was measured again when the balloon was inflated within the vena cava and the blood pump was operating within the left renal vein. As shown, due to the pumping of blood by the blood pump, left renal blood flow increased to approximately 440 ml / min. Thereafter, while the balloon was inflated within the vena cava and while the blood pump was switched off, left renal blood flow was measured and renal blood flow dropped to approximately 380 ml / min. Thereafter, when the blood pump was switched on again, left renal blood flow was measured again and left renal blood flow increased to approximately 340 ml / min. These results indicate that an impeller-based blood pump as described herein is capable of effectively increasing renal blood flow even if the central venous pressure of the subject increases.

[0420] It is noted that for illustrative purposes, the change in renal blood flow between one data point and the next is shown on the graph as occurring at a constant rate. However, the inventor hypothesizes that the change in renal blood flow is substantially due to the blood pump being switched on and off inside the left renal vein and / or due to the inflation of the balloon inside the vena cava, and that most of the change in renal blood flow will occur in accordance with the occurrence of the above events.

[0421] The lower graph in FIG. 23 shows the urine output measured in the left kidney (shown by the solid line curve) and the right kidney (shown by the dotted line curve) of a pig at specific times during the experiment. It is noted that generally, the rate of blood flow through the kidneys is known to have an impact on the rate of urine output. As shown, when measured during the baseline period, urine production from the left and right kidneys was approximately 21 ml per 10 minutes. Thereafter, the balloon was inflated inside the vena cava During the period in which it was inflated and while the blood pump was operating inside the left renal vein, urine output was measured at approximately 14:00. As shown, urine output from the left kidney increased while urine production from the right kidney decreased. These results indicate that increasing renal blood flow by pumping blood using a blood pump (as performed within the left renal vein) can increase urine output even when central venous pressure increases (which can lead to a reduction in urine output as indicated by urine output from the right kidney).

[0422] Subsequently, while the balloon was still inflated inside the large vein but while the blood pump was switched off, urine output from the left and right kidneys was measured at approximately 14:35. At this point, urine production in the right kidney continued to decline while urine output from the left kidney also decreased. Subsequently, while the large vein balloon was still inflated and after the blood pump was switched on again, urine output from the right kidney plateaued at approximately 14 ml per 10 minutes while urine output from the right kidney increased to substantially 48 ml per 10 minutes.

[0423] It is noted that for illustrative purposes, the change in urine production between one data point and the next is shown on the graph as occurring at a constant rate. However, the inventor hypothesizes that the change in urine production is substantially due to the blood pump being switched on and off inside the left renal vein and / or due to the inflation of the balloon inside the large vein and that most of the change in urine production occurred in accordance with the occurrence of the above events.

[0424] In further experiments, an impeller-based blood pump as described herein was used to pump blood through the renal veins of different pigs over a continuous period of 3 hours. During this time period, no occurrence of either thrombus or abnormal levels of hemolysis occurred. This indicates that an impeller-based blood pump as described herein can increase blood flow through the renal vein of a subject, thereby reducing the pressure in the renal vein, without causing a risk of abnormal levels of thrombus and / or hemolysis. It is noted that anticoagulants were administered to the pigs during the above-described experiments. Nevertheless, in a typical procedure performed on a human subject using an impeller-based blood pump as described herein, the subject will be administered anticoagulants, so this result still shows that an impeller-based blood pump as described herein can increase blood flow through the renal vein of a subject, thereby reducing the pressure in the renal vein, without causing a risk of hemolysis and / or thrombus.

[0425] Generally, in the above-described experiments and in additional experiments conducted by the inventors of the present application with a blood pump in pigs, the following observations were made. 1. The blood pump 150 was smoothly placed and retrieved in less than 1 minute.

[0426] 2. The renal vein pressure was effectively and continuously reduced from about 20 mmHg to a preselected target value of 8 mmHg within the minimum margin of change. 3. An increase in venous pressure in the large vein causes a decrease in urine output, creatinine clearance, and fractional sodium excretion in untreated kidneys, but does not cause them in kidneys treated with the blood pump 150. These results indicate that the use of the blood pump 150 has a favorable effect on glomerular and tubular renal function.

[0427] 4. Even when the venous pressure in the large vein increased, the use of the blood pump 150 protected and restored renal blood flow, urine output, and sodium excretion. 5. The blood pump 150 was successfully operated in a closed-loop mode, and in the closed-loop mode, the pressure in the renal vein was maintained constant for over 3 hours.

[0428] 6. No thrombus was observed in any part of the blood pump or the catheter. 7. No clinically significant hemolysis was observed for over 3 hours during which the pump was operating.

[0429] Although some of the pumps and / or occlusion elements described herein are shown as being inserted into a given one of the subject's renal veins, it is noted that the scope of the present invention includes inserting the pump and occlusion element into either the left renal vein or the right renal vein, or into both of the subject's renal veins. Moreover, the scope of the present invention includes inserting the pump and occlusion element into more than three renal veins of a subject having more than three renal veins, as in the case of some people.

[0430] Although some of the pumps and / or occlusion elements described herein are shown as being inserted into the subject's renal vein, it is noted that the scope of the present invention includes inserting the pump and occlusion element into other blood vessels of the subject, with modifications where necessary. For example, in order to reduce the venous pressure in a vein and / or to reduce the pressure in an organ from which the vein draws blood (e.g., to reduce a congested liver), the reversal valve 40 (Figs. 5A - 5D, and Figs. 6A - 6F) can be installed in the subject's hepatic vein, intestinal vein, or adrenal vein.

[0431] Alternatively or additionally, to reduce venous pressure in a vein and / or to reduce pressure in an organ from which the vein draws blood (e.g., to reduce a congested liver), a blood pump 90 (Figs. 8A-8B and 10A-10D) can be placed into a hepatic vein, mesenteric vein, or adrenal vein of a subject. Or, to reduce intracranial pressure by draining cerebrospinal fluid from a chamber, a blood pump 90 can be placed into a chamber inside a fluid-filled brain. Alternatively or additionally, by being placed into a subject's aorta and pumping blood away from the left ventricle, a blood pump 90 can be used as an assist device for the left ventricle. Further alternatively or additionally, a blood pump 90 can be placed into a urethra and is configured to keep a subject's prostate open and to drain the subject's bladder.

[0432] Generally, a sleeve 110 (Figs. 10A-10C) can be used to isolate blood in a plurality of tributary veins feeding into a main vein from the blood flow in the main vein into separate compartments, and then a pump 122 can be used to control the flow of blood from the compartments into the main vein.

[0433] In some applications, an umbrella 140 (Figs. 11A-11C) for an inlet cover can be used to cover an inlet at the junction between a hepatic vein, mesenteric vein, or adrenal vein of a subject and another vein, and a blood pump catheter 42 is used to control the flow of blood from the hepatic vein, mesenteric vein, or adrenal vein to another vein to reduce venous pressure in the vein and / or to reduce pressure in an organ from which the vein draws blood (e.g., to reduce a congested liver).

[0434] In some applications, a blood pump 150 (Figs. 12Ai-12E) is placed into an artery supplying a peripheral limb, e.g., gangrene To treat the limbs, the perfusion of the amputated limbs has been enhanced. Alternatively or additionally, a blood pump, such as blood pump 150, is placed within an artery, such as the descending aorta, to propel blood away from the heart, to reduce afterload, and / or, otherwise, to improve cardiac function.

[0435] Generally, in the specification and claims of this application, the terms "proximal" and related terms should be construed to mean the end of a device or a part thereof when used with reference to the device or a part thereof, and that end is typically closer to the location where the device is inserted through it into the body of the subject when the device is inserted into the body of the subject. The terms "distal" and related terms should be construed to mean the end of a device or a part thereof when used with reference to the device or a part thereof, and that end is typically farther from the location where the device is inserted through it into the body of the subject when the device is inserted into the body of the subject.

[0436] Generally, in the specification and claims of this application, the terms "downstream" and related terms should be construed to mean a location within a blood vessel or a part of a device configured to be placed within a blood vessel when used with reference to the blood vessel or a part of a device, and that is downstream with respect to the direction of antegrade blood flow through the blood vessel as compared to a different location within the blood vessel. The terms "upstream" and related terms should be construed to mean a location within a blood vessel or a part of a device configured to be placed within a blood vessel when used with reference to the blood vessel or a part of a device, and that is upstream with respect to the direction of antegrade blood flow through the blood vessel as compared to a different location within the blood vessel.

[0437] Accordingly, in accordance with some application examples of the present invention, the following inventive concepts are provided. Inventive Concept 1 A method for use with a plurality of tributary veins supplying a main vein, the method comprising: mechanically isolating blood in the plurality of veins into a compartment separated from the blood flow in the main vein; and controlling blood flow from the plurality of veins to the main vein by pumping blood from the compartment to the main vein. A method comprising the steps of:

[0438] Inventive Concept 2 The method according to Inventive Concept 1, further comprising subjecting the pumped blood to ultrafiltration.

[0439] Inventive Concept 3 The method according to Inventive Concept 1, wherein the step of isolating the plurality of veins comprises: installing a blood-impermeable sleeve and a helical support element disposed around the sleeve into the main vein; and connecting the sleeve to the wall of the main vein using the helical support element. The method further comprises: The step of pumping blood from the compartment to the main vein comprises guiding a distal portion of a blood pump into the compartment using the helical support element and pumping the blood using the blood pump. A method comprising the steps of:

[0440] Inventive Concept 4 The method according to Inventive Concept 1, wherein the step of isolating the plurality of veins comprises: A step of placing a blood-impermeable sleeve and a helical portion of a blood pump into the main vein, wherein the helical portion is disposed around the sleeve and is configured to support the sleeve. A step of connecting the sleeve to the wall portion of the main vein comprising The step of pumping blood from the compartment into the main vein includes the step of pumping blood into an inlet hole of the blood pump defined by the helical portion of the blood pump. A method.

[0441] Inventive Concept 5 A method according to any one of Inventive Concepts 1 to 4, The step of isolating blood in the plurality of veins into a compartment separated from the blood flow in the main vein includes isolating blood in the renal vein of the subject into a compartment separated from the blood flow in the main vein of the subject by placing a blood-impermeable sleeve into the main vein of the subject, wherein a downstream end of the sleeve is connected to the wall portion of the main vein at a first location downstream of all of the renal veins of the subject, and an upstream end of the sleeve is connected to the wall portion of the main vein at a second location upstream of all of the renal veins of the subject. The step of pumping blood from the compartment into the main vein includes operating a pump to pump blood from the compartment to a location in fluid communication with the interior of the sleeve. A method.

[0442] Inventive Concept 6 A method according to Inventive Concept 5, wherein the step of pumping blood from the compartment includes the step of drawing blood downstream through the renal vein.

[0443] Inventive Concept 7 The method according to inventive concept 5, wherein the step of installing the sleeve into the vena cava includes the step of installing the sleeve into the vena cava over a period of less than one week, and the step of operating the pump includes the step of operating the pump over a period of less than one week.

[0444] Inventive concept 8 The method according to inventive concept 5, further comprising the step of identifying the subject as a subject suffering from a condition selected from the group consisting of cardiac dysfunction, congestive heart failure, reduced renal blood flow, increased renal vascular resistance, arterial hypertension, and kidney dysfunction, wherein the step of operating the pump includes reducing the blood pressure in the renal vein of the subject by operating the pump in response to the step of identifying the subject as suffering from the condition.

[0445] Inventive concept 9 The method according to inventive concept 5, wherein the step of installing the sleeve into the vena cava of the subject causes the vena cava to contract around at least a portion of the sleeve, thereby including the step of anchoring the sleeve to the vena cava. The method includes the step of anchoring the sleeve to the vena cava by causing the vena cava to contract around at least a portion of the sleeve.

[0446] Inventive concept 10 The method according to inventive concept 5, wherein the step of operating the pump to pump blood from the compartment to the location in fluid communication with the interior of the sleeve includes the step of operating the pump to pump blood from the compartment to the site of the vena cava upstream of the sleeve.

[0447] Inventive concept 11 The method according to inventive concept 5, wherein the step of operating the pump to pump blood from the compartment to the location in fluid communication with the interior of the sleeve is the step of operating the pump to pump blood from the compartment to the site of the vena cava downstream of the sleeve, method.

[0448] Inventive concept 12 The method according to inventive concept 5, wherein the step of installing the sleeve in the vena cava A stent shaped to define its enlarged upstream and downstream ends, the upstream and downstream ends being enlarged relative to the central portion of the stent, and A blood-impermeable sleeve connected to the stent, the sleeve defining its flared upstream and downstream ends, the upstream and downstream ends being connected to the enlarged upstream and downstream ends of the stent, respectively, blood-impermeable sleeve installing into the vena cava; and In response to the blood pressure on at least one first side of the flared end of the sleeve being greater than the blood pressure on a second side of the at least one flared end of the sleeve, blood flows between the outside of the at least one flared end of the sleeve and the inner wall of the blood vessel, and In response to the blood pressure on the first side of the at least one flared end of the sleeve being less than the blood pressure on the second side of the at least one flared end of the sleeve, the at least one flared end of the sleeve contacts the inner wall of the blood vessel to close the blood flow between the outside of the at least one flared end of the sleeve and the inner wall of the blood vessel, connecting the stent to the blood vessel; and including method.

[0449] Invention concept 13 The method according to invention concept 5, wherein the step of placing the sleeve into the vena cava comprises a sleeve, the sleeve being shaped to define a flared end portion thereof and a narrow central portion of the width between the flared end portions a stent, the stent comprising a sleeve support frame, the sleeve support frame being shaped to define an enlarged end portion thereof and a narrow central portion of the width between the enlarged end portions that is narrower than the enlarged end portion of the stent, the sleeve being connected to the sleeve support frame of the stent, and a blood vessel wall support frame, the blood vessel wall support frame being connected to the narrow central portion of the sleeve support frame and protruding radially from the sleeve support frame a stent shaped to define and placing the same into the vena cava. A method comprising the step of

[0450] Invention concept 14 The method according to invention concept 13, wherein the step of pumping blood from the compartment comprises pumping blood from a site between the outside of the sleeve and the inner wall portion of the vena cava.

[0451] Invention concept 15 The method according to invention concept 5, further comprising inserting the pump into the compartment through an opening in the sleeve through which the pump is insertable.

[0452] Invention concept 16 The method according to inventive concept 15, wherein the step of inserting the pump through the opening comprises inserting the pump through an opening having a diameter between 2 mm and 10 mm.

[0453] Inventive concept 17 The method according to inventive concept 15, wherein the step of inserting the pump through the opening comprises inserting the pump through the opening such that the opening forms a seal around the pump.

[0454] Inventive concept 18 The method according to inventive concept 5, wherein the method further comprises inserting the pump into the compartment through a pump receiving sleeve protruding from the sleeve.

[0455] Inventive concept 19 The method according to inventive concept 18, wherein the step of inserting the pump into the compartment through the pump receiving sleeve comprises inserting the pump into the compartment through a pump receiving sleeve having a diameter between 2 mm and 10 mm.

[0456] Inventive concept 20 The method according to inventive concept 18, wherein the step of inserting the pump into the compartment through the pump receiving sleeve comprises inserting the pump into the compartment through the pump receiving sleeve such that the pump receiving sleeve forms a seal around the pump.

[0457] Inventive concept 21 A blood-impermeable sleeve, At least one support structure configured to connect the first and second ends of the sleeve to a blood vessel of a subject, A pump configured to pump blood from outside the sleeve to a location in fluid communication with the inside of the sleeve An apparatus comprising

[0458] Inventive concept 22 An apparatus according to inventive concept 21, wherein the pump is configured to perform ultrafiltration on the blood.

[0459] Inventive concept 23 An apparatus according to inventive concept 21, wherein the pump is configured to anchor the structure to the blood vessel by causing the blood vessel to constrict around at least a portion of the structure.

[0460] Inventive concept 24 An apparatus according to inventive concept 21, wherein the structure includes a stent, and the stent is shaped to define an enlarged end thereof that is enlarged compared to a central portion of the stent. The sleeve includes a sleeve connected to the stent. The sleeve is connected to the enlarged end of the stent and defines a flared end thereof. At least one of the flared ends of the sleeve is configured to act as a valve by at least partially separating from the enlarged end of the stent to which it is connected in response to pressure being applied to the flared end of the sleeve.

[0461] Inventive concept 25 An apparatus according to inventive concept 21, The support structure includes a helical support element disposed around the sleeve. The distal portion of the blood pump is configured to be guided to be disposed around the outside of the sleeve using the helical support element.

[0462] Inventive concept 26 An apparatus according to inventive concept 21, The support structure includes the helical portion of the blood pump, the helical portion being disposed around the sleeve and configured to support the sleeve. An apparatus, wherein the pump is configured to pump blood from outside the sleeve by pumping blood into an inlet hole of the pump defined by the helical portion of the blood pump.

[0463] Inventive concept 27 An apparatus according to any one of inventive concepts 21 - 24, wherein the sleeve is shaped to define its flared end and a narrow central portion between the flared ends. The structure includes a stent, the stent being a sleeve support frame shaped to define its enlarged end and a narrow central portion between the enlarged ends that is narrower than the enlarged ends of the stent, the sleeve being connected to the sleeve support frame of the stent, and a blood vessel wall support frame, the blood vessel wall support frame being connected to the narrow central portion of the sleeve support frame and protruding radially from the sleeve support frame. An apparatus shaped to define the same.

[0464] Inventive concept 28 An apparatus according to inventive concept 27, wherein the pump is configured to pump blood from a site between the outside of the sleeve and the inner wall of the blood vessel by being installed between the outside of the sleeve and the blood vessel wall support frame.

[0465] Inventive concept 29 The device according to any one of inventive concepts 21 to 26, wherein the structure is configured to isolate the blood in the renal veins of the subject into a compartment separated from the blood flow in the vena cava of the subject by connecting the downstream end of the sleeve to the wall of the vena cava at a first location downstream of all of the renal veins of the subject and by connecting the upstream end of the sleeve to the wall of the vena cava at a second location upstream of all of the renal veins of the subject.

[0466] Inventive concept 30 The device according to inventive concept 29, wherein the sleeve is configured to be connected to the vena cava for less than one week and the pump is configured to operate for less than one week.

[0467] Inventive concept 31 The device according to inventive concept 29, wherein the pump is configured to reduce the blood pressure in the renal veins of the subject by pumping blood.

[0468] Inventive concept 32 The device according to inventive concept 29, wherein the pump is configured to pump blood from the compartment to a site in the vena cava.

[0469] Inventive concept 33 The device according to inventive concept 32, wherein the pump is configured to pump blood from the compartment to a site in the vena cava upstream of the sleeve.

[0470] Inventive concept 34 The device according to inventive concept 32, wherein the pump is configured to pump blood from the compartment to a site in the vena cava downstream of the sleeve.

[0471] Inventive concept 35 The device according to any one of inventive concepts 21 to 26, wherein the sleeve is shaped to define an opening, and the pump is insertable through the opening.

[0472] Inventive concept 36 The device according to inventive concept 35, wherein the diameter of the opening is between 2 mm and 10 mm.

[0473] Inventive concept 37 The device according to inventive concept 35, wherein the opening is sized to form a seal around the pump.

[0474] Inventive concept 38 The device according to any one of inventive concepts 21 to 26, further comprising a pump receiving sleeve protruding from the blood-impermeable sleeve, the pump receiving sleeve being configured to accommodate insertion of the pump through it to the outside of the blood-impermeable sleeve.

[0475] Inventive concept 39 The device according to inventive concept 38, wherein the inner diameter of the pump receiving sleeve is between 2 mm and 10 mm.

[0476] Inventive concept 40 The device according to inventive concept 38, wherein the pump receiving sleeve is sized to form a seal around the pump.

[0477] Inventive concept 41 At the stent installation site, the step of installing the stent inside the blood vessel, By applying a suction force into the blood vessel to cause the blood vessel to contract around at least a portion of the stent, at the installation site, the step of at least partially anchoring the stent to the blood vessel A method comprising.

[0478] Inventive concept 42 The method according to inventive concept 41, wherein the blood vessel includes a blood vessel having a predetermined diameter at the installation site, and the step of installing the stent inside the blood vessel includes installing a stent having a diameter smaller than the predetermined diameter inside the blood vessel.

[0479] Inventive concept 43 The method according to inventive concept 41, wherein the step of causing the blood vessel to shrink around at least a portion of the stent includes reducing the degree to which the stent is anchored to the blood vessel, thanks to over-sizing the stent, as compared to the case where the blood vessel could not be shrunk around at least a portion of the stent.

[0480] Inventive concept 44 A stent configured to be installed inside a blood vessel at the installation site of the stent, A pump configured to anchor the stent to the blood vessel at the installation site by applying a suction force in the blood vessel to cause the blood vessel to shrink around at least a portion of the stent and including.

[0481] Inventive concept 45 The apparatus according to inventive concept 44, wherein the blood vessel includes a blood vessel having a predetermined diameter at the installation site, and the stent includes a stent having a diameter smaller than the predetermined diameter.

[0482] Inventive concept 46 A stent configured to be installed inside a blood vessel, the stent being shaped to define an enlarged end thereof, which is enlarged as compared to the central portion of the stent. A blood-impermeable sleeve connected to the stent, The sleeve is connected to the enlarged end of the stent and defines its flared end. At least one of the flared ends of the sleeve is configured to act as a valve by at least partially separating from the enlarged end of the stent to which it is connected in response to pressure being applied to the flared end of the sleeve, a blood-impermeable sleeve An apparatus comprising.

[0483] Inventive concept 47 A stent shaped to define its enlarged upstream and downstream ends, which are enlarged compared to the central portion of the stent, and A blood-impermeable sleeve connected to the stent, the sleeve defining its flared upstream and downstream ends, which are respectively connected to the enlarged upstream and downstream ends of the stent, a blood-impermeable sleeve Installing into the blood vessel of a subject; In response to the blood pressure on the first side of at least one of the flared ends of the sleeve being greater than the blood pressure on the second side of the at least one flared end of the sleeve, blood flows between the outside of the at least one flared end of the sleeve and the inner wall of the blood vessel, and In response to the blood pressure on the first side of the at least one flared end of the sleeve being less than the blood pressure on the second side of the at least one flared end of the sleeve, the at least one flared end of the sleeve conta...

Claims

1. identifying a subject as suffering from a condition selected from the group consisting of cardiac dysfunction, congestive heart failure, reduced renal blood flow, increased renal vascular resistance, arterial hypertension, and kidney dysfunction; in response thereto, reducing the blood pressure in the renal vein of the subject by placing an impeller inside the renal vein of the subject and moving the impeller to pump blood from the renal vein to the vena cava of the subject; A method comprising:

2. The method according to claim 1, wherein the step of moving the impeller to pump blood from the renal vein into the vena cava comprises enhancing the rate of blood flow from the renal vein into the vena cava without causing a substantial change in the direction of the blood flow as compared to the direction of blood flow from the renal vein into the vena cava when the pump is not operating.

3. The method according to claim 1, wherein the step of moving the impeller to pump blood from the renal vein into the vena cava comprises moving the impeller to pump blood directly from the renal vein into a portion of the vena cava adjacent to the renal vein.

4. The method according to claim 1, wherein the step of moving the impeller to pump blood from the renal vein into the vena cava comprises moving the impeller to pump blood from the renal vein into the vena cava without removing blood from the venous system of the subject into a non-venous receptacle.

5. The method according to any one of claims 1 to 4, wherein the step of placing the impeller inside the renal vein comprises protecting the renal vein of the subject from being damaged by the impeller by placing the impeller into the renal vein with a cage disposed around the impeller and the cage separating the inner wall of the renal vein from the impeller.

6. The method according to claim 5, wherein the step of installing the impeller into the renal vein with the cage disposed around the impeller comprises the step of installing the impeller into the renal vein with the cage disposed around the impeller, wherein the cage and the impeller are engaged with each other by an engagement mechanism, and in response to the cage being compressed radially, the impeller is lengthened axially, and the cage is configured to maintain a separation between the wall portion of the renal vein and the impeller.

7. An apparatus including an impeller, wherein the impeller includes a proximal end portion and a distal end portion, and an impeller frame including a plurality of helical elongated elements that bend and proceed from the proximal end portion to the distal end portion; a material, wherein the material is connected to the helical elongated elements, and the helical elongated elements to which the material is connected are configured to define at least one blade of the impeller; and the apparatus.

8. The apparatus according to claim 7, including a biocompatible impeller configured to be inserted into a target blood vessel.

9. The apparatus according to claim 7, wherein the plurality of elongated elements include a plurality of helical strips.

10. The apparatus according to claim 7, wherein at least one of the helical elongated elements has a variable pitch, and the at least one pitch of the elongated element varies along the length of the helical elongated element.

11. The apparatus according to claim 7, wherein the impeller is configured to be installed inside a target blood vessel and to pump blood through the blood vessel by rotating with respect to the blood vessel, and the apparatus further includes a radially expandable cage configured to be disposed between the impeller and the inner wall portion of the blood vessel and to separate the blood vessel wall portion from the impeller.

12. The device according to claim 7, wherein the proximal end portion and the distal end portion include a proximal ring and a distal ring.

13. The device according to claim 7, wherein at least one of the proximal end portion and the distal end portion defines a notch at its edge, and the notch is configured to facilitate the connection of the material to the helical elongated element.

14. The device according to claim 7, wherein the impeller further includes a suture thread coupled around the helical elongated element, and the suture thread is configured to facilitate the connection of the material to the helical elongated element.

15. The device according to claim 7, wherein the plurality of helical elongated elements include three helical elongated elements that curve from the proximal end portion to the distal end portion.

16. The device according to any one of claims 7 to 15, wherein when the impeller is in its unconstrained configuration, each length of the helical elongated element measured along the longitudinal axis of the impeller is greater than 5 mm.

17. The device according to claim 16, wherein when the impeller is in its unconstrained configuration, each of the lengths of the helical elongated elements measured along the longitudinal axis of the impeller is less than 14 mm.

18. The device according to any one of claims 7 to 15, wherein when the impeller is in its unconstrained configuration, the span of the impeller in a direction perpendicular to the longitudinal axis of the impeller is greater than 8 mm.

19. The device according to claim 18, wherein the span of the impeller is greater than 10 mm.

20. The device according to claim 19, wherein the span of the impeller is less than 15 mm.

21. The device according to claim 18, wherein the span of the impeller is less than 15 mm.

22. The device according to claim 21, wherein the span of the impeller is less than 12 mm.

23. The apparatus according to any one of claims 7 to 14, wherein the plurality of helical elongated elements include two helical elongated elements that bend and proceed from the proximal end portion to the distal end portion.

24. The apparatus according to claim 23, wherein the radius of each of the two helical elongated elements is within 20% of each other.

25. The apparatus according to claim 23, wherein the radius of each of the two helical elongated elements is similar to each other.

26. The apparatus according to claim 23, wherein the pitch of each of the two helical elongated elements is within 20% of each other.

27. The apparatus according to claim 23, wherein the pitch of each of the two helical elongated elements is similar to each other.

28. The apparatus according to claim 23, wherein the longitudinal axes of each of the two helical elongated elements are parallel to each other and parallel to the longitudinal axis of the impeller.

29. The apparatus according to claim 23, wherein the material includes a continuous film of the material supported by the helical elongated elements.

30. The apparatus according to any one of claims 7 to 15, wherein each of the helical elongated elements defines at least one-eighth of a helical winding.

31. The apparatus according to claim 30, wherein each of the helical elongated elements defines less than half of a helical winding.

32. The apparatus according to any one of claims 7 to 15, wherein the helical elongated element defines its proximal end and distal end, and the helical elongated element is configured to support the material between the proximal end and the distal end of the helical elongated element, and the impeller does not include an additional support member for supporting the material between the proximal end and the distal end of the helical elongated element.

33. The apparatus according to claim 32, wherein the impeller is configured such that rotational movement is imparted from the proximal end portion of the impeller to the distal end portion of the impeller substantially only through the helical elongated element of the impeller.

34. The apparatus according to claim 32, wherein by not including an additional support member for supporting the material between the proximal end and the distal end of the helical elongated element, the impeller is configured to be radially compressible to a smaller diameter than if the impeller included an additional support member for supporting the material between the proximal end and the distal end of the helical elongated element.

35. The apparatus according to claim 32, wherein by not including an additional support member for supporting the material between the proximal end and the distal end of the helical elongated element, the impeller is configured to be more flexible than if the impeller included an additional support member for supporting the material between the proximal end and the distal end of the helical elongated element.

36. The apparatus according to claim 32, wherein by not including an additional support member for supporting the material between the proximal end and the distal end of the helical elongated element, the force required to axially elongate the impeller is smaller by a predetermined amount than would be required if the impeller included an additional support member for supporting the material between the proximal end and the distal end of the helical elongated element, and the impeller is configured accordingly.

37. The step of cutting the tube so as to define the structure having first and second end portions at the proximal and distal ends of the structure, wherein the end portions are connected to each other by a plurality of elongated elements. The step of axially compressing the structure, causing the elongated elements to expand radially and giving rise to the formation of helical elongated elements. Connecting the material to the helical elongated element such that the helical elongated element to which the material is connected defines at least one blade of the impeller A method comprising the step of manufacturing an impeller thereby.

38. The method according to claim 37, wherein the step of cutting the tube comprises the step of laser cutting the tube.

39. The method according to claim 37, wherein the step of manufacturing the impeller comprises the step of manufacturing a biocompatible impeller configured to be inserted into a target blood vessel.

40. The method according to claim 37, wherein the step of cutting the tube is a step of cutting the tube such that the cut tube defines a structure having first and second end portions at proximal and distal ends of the structure, the end portions being connected to each other by a plurality of strips.

41. The method according to claim 37, wherein the step of causing the elongated element to radially expand and form a helical elongated element causes at least one of the helical elongated elements to have a variable pitch, the at least one pitch of the elongated element varying along the length of the helical elongated element.

42. The method according to claim 37, wherein the step of cutting the tube such that the cut tube defines a structure having first and second end portions at proximal and distal ends of the structure comprises the step of cutting the tube such that the cut tube defines a structure having first and second rings at proximal and distal ends of the structure.

43. The method according to claim 37, wherein the step of cutting the tube is a step of forming a notch in at least one edge of the end portion, the notch being configured to facilitate connection of the material to the helical elongated element The method further comprising the step.

44. The method according to claim 37, wherein the method further comprises the step of joining a suture around the helically elongated element, the suture being configured to facilitate the connection of the material to the helically elongated element.

45. The method according to claim 37, wherein the step of cutting the tube is a step of cutting the tube such that the cut tube defines a structure having first and second end portions at a proximal end and a distal end of the structure, the end portions being connected to each other by three elongated elements, the step of causing the elongated elements to radially expand and form helically elongated elements includes the step of causing the elongated elements to form three helically elongated elements.

46. The method according to any one of claims 37 to 45, wherein the step of cutting the tube includes the step of cutting the tube such that the structure has a length greater than 15 mm measured along the longitudinal axis of the structure when there is no axial compression applied to the structure.

47. The method according to claim 46, wherein the step of cutting the tube includes the step of cutting the tube such that the length of the structure measured along the longitudinal axis of the structure is less than 25 mm when there is no axial compression applied to the structure.

48. The method according to any one of claims 37 to 45, wherein the step of cutting the tube includes the step of cutting the tube such that each of the elongated elements has a length greater than 14 mm measured along the longitudinal axis of the structure when there is no axial compression applied to the structure.

49. The method according to claim 48, wherein the step of cutting the tube includes the step of cutting the tube such that the length of each of the elongated elements measured along the longitudinal axis of the structure is less than 22 mm when there is no axial compression applied to the structure.

50. The method according to any one of claims 37 to 45, wherein the step of axially compressing the structure comprises axially compressing the structure such that the structure defines a length greater than 8 mm as measured along the longitudinal axis of the structure.

51. The method according to claim 50, wherein the step of axially compressing the structure comprises axially compressing the structure such that the length measured along the longitudinal axis of the structure is less than 18 mm.

52. The method according to any one of claims 37 to 45, wherein the step of axially compressing the structure comprises axially compressing the structure such that each of the elongated elements defines a length greater than 5 mm as measured along the longitudinal axis of the structure.

53. The method according to claim 52, wherein the step of axially compressing the structure is the step of axially compressing the structure such that each of the lengths of the elongated elements measured along the longitudinal axis of the structure is less than 14 mm.

54. The method according to any one of claims 37 to 45, wherein the step of axially compressing the structure comprises axially compressing the structure such that the span of the structure in a direction perpendicular to the longitudinal axis of the structure is greater than 8 mm.

55. The method according to claim 54, wherein the step of axially compressing the structure comprises axially compressing the structure such that the span of the structure is greater than 10 mm.

56. The method according to claim 55, wherein the step of axially compressing the structure comprises axially compressing the structure such that the span of the structure is less than 15 mm.

57. The method according to claim 54, wherein the step of axially compressing the structure comprises axially compressing the structure such that the span of the structure is less than 15 mm.

58. The method according to claim 57, wherein the step of axially compressing the structure comprises axially compressing the structure such that the span of the structure becomes less than 12 mm.

59. The method according to any one of claims 37 to 44, wherein the step of connecting the material to the helical elongated element comprises immersing at least a portion of the structure into the material while the material is in its liquid state, and drying the material while the material is supported by the helical elongated element.

60. The method according to claim 59, wherein the step of drying the material comprises curing the material.

61. The method according to claim 59, wherein the step of cutting the tube is a step of cutting the tube so that the cut tube defines a structure having first and second end portions at the proximal and distal ends of the structure, the end portions being connected to each other by two elongated elements, and the step of causing the elongated elements to radially expand and form helical elongated elements comprises causing the elongated elements to form two helical elongated elements.

62. The method according to claim 61, wherein the step of drying the liquid material while the material is supported by the helical elongated elements is a step of causing the material to form a continuous film between the helical elongated elements, the continuous film being supported by the helical elongated elements.

63. The method according to any one of claims 37 to 44, wherein the step of cutting the tube is such that the cut tube has first and second A step of cutting the tube so as to define a structure having an end portion of 2, the end portion being connected to each other by two elongated elements, the step including causing the elongated elements to expand radially and form helical elongated elements, the method including causing the elongated elements to form two helical elongated elements.

64. The method according to claim 63, wherein the step of causing the elongated element to form the two helical elongated elements is a step of causing the elongated element to form two helical elongated elements, both of the two helical elongated elements originating from the first end portion and terminating at the second end portion, and the radii of the helical elongated elements being similar to each other.

65. The method according to claim 63, wherein the step of causing the elongated element to form the two helical elongated elements is a step of causing the elongated element to form two helical elongated elements, both of the two helical elongated elements originating from the first end portion and terminating at the second end portion, and the radii of the helical elongated elements being within 20 percent of each other.

66. The method according to claim 63, wherein the step of causing the elongated element to form the two helical elongated elements is a step of causing the elongated element to form two helical elongated elements, both of the two helical elongated elements originating from the first end portion and terminating at the second end portion, and the pitches of the helical elongated elements being similar to each other.

67. The method according to claim 63, wherein the step of causing the elongated element to form the two helical elongated elements is a step of causing the elongated element to form the two helical elongated elements, both of the two helical elongated elements originating from the first end portion and terminating at the second end portion, and the pitch of the helical elongated elements being within 20 percent of each other.

68. The method according to claim 63, wherein the step of causing the elongated element to form the two helical elongated elements is a step of causing the elongated element to form the two helical elongated elements, the longitudinal axes of both of the helical elongated elements being parallel to each other and parallel to the longitudinal axis of the impeller.

69. The method according to claim 63, wherein the step of causing the elongated element to form the two helical elongated elements is a step of causing the elongated element to form the two helical elongated elements, each of the helical elongated elements defining at least one-eighth of a turn of the helix.

70. The method according to claim 69, wherein the step of causing the elongated element to form the two helical elongated elements is a step of causing the elongated element to form the two helical elongated elements, each of the helical elongated elements defining less than half of a turn of the helix. Including, method.

71. The method according to any one of claims 37 to 45, wherein the step of cutting the tube is such that the cut tube defines a structure having first and second rings at the proximal and distal ends of the structure, and the first and second ends of each of the elongated elements are disposed at an angle to each other with respect to the periphery of the ring, the angle being greater than 50 degrees.

72. The method according to claim 71, wherein the step of cutting the tube is a step of cutting the tube such that the first and second ends of each of the elongated elements are disposed at an angle with respect to each other around the periphery of the ring, the angle being greater than 70 degrees.

73. The method according to claim 72, wherein the step of cutting the tube is a step of cutting the tube such that the first and second ends of each of the elongated elements are disposed at an angle with respect to each other around the periphery of the ring, the angle being greater than 90 degrees.

74. The method according to any one of claims 37 to 45, wherein the step of cutting the tube is a step of cutting the tube such that the cut tube defines a structure having first and second rings at the proximal and distal ends of the structure, and such that the first and second ends of each of the elongated elements are disposed at an angle with respect to each other around the periphery of the ring, the angle being less than 180 degrees.

75. The method according to claim 74, wherein the step of cutting the tube is a step of cutting the tube such that the first and second ends of each of the elongated elements are disposed at an angle with respect to each other around the periphery of the ring, the angle being less than 150 degrees.

76. The method according to claim 75, wherein the step of cutting the tube is a step of cutting the tube such that the first and second ends of each of the elongated elements are disposed at an angle with respect to each other around the periphery of the ring, the angle being less than 110 degrees.

77. The method according to any one of claims 37 to 45, wherein the step of connecting the material to the helical elongated element comprises connecting the material to the helical elongated element such that the material is supported by the helical elongated element between the proximal end and the distal end of the helical elongated element when there is no additional support member for supporting the material between the proximal end and the distal end of the helical elongated element.

78. The method according to claim 77, wherein the step of connecting the material to the helical elongated element when there is no additional support member for supporting the material between the proximal end and the distal end of the helical elongated element comprises configuring the impeller such that rotational movement is imparted from the proximal end portion to the distal end portion substantially only through the helical elongated element of the impeller.

79. The method according to claim 77, wherein when there is no additional support member for supporting the material between the proximal end and the distal end of the helical elongated element, the step of connecting the material to the helical elongated element comprises configuring the impeller to be radially compressible to a diameter smaller than if the impeller included an additional support member for supporting the material between the proximal end and the distal end of the helical elongated element.

80. The method according to claim 77, wherein when there is no additional support member for supporting the material between the proximal end and the distal end of the helical elongated element, the step of connecting the material to the helical elongated element comprises configuring the impeller to be more flexible than if the impeller included an additional support member for supporting the material between the proximal end and the distal end of the helical elongated element.

81. The method according to claim 77, wherein when there is no additional support member for supporting the material between the proximal end portion and the distal end portion of the helical elongated element, the step of connecting the material to the helical elongated element is such that the force required to axially elongate the impeller is less than a predetermined amount compared to what would be required if the impeller included an additional support member for supporting the material between the proximal end portion and the distal end portion of the helical elongated element, the method comprising the step of configuring the impeller.

82. In a radially expanded configuration, an impeller configured to pump fluid by rotating, A radially expandable cage disposed around the impeller, wherein in the radially expanded configuration of the impeller and the cage, the impeller is adapted to be separated from the inner surface of the cage, the cage; An engagement mechanism configured to engage the impeller with the cage, wherein in response to the cage being radially compressed, the engagement mechanism axially elongates the impeller and the impeller remains separated from the inner surface of the cage, the engagement mechanism; An apparatus comprising.

83. The apparatus according to claim 82, The cage and the impeller define an axially elongated configuration, and the cage is configured to accommodate the impeller inside the cage while the cage is in the axially elongated configuration, while the impeller is in the axially elongated configuration, The cage includes struts, and at least some of the struts include a wavy portion of the struts that is wavy at least when the cage is in the radially expanded configuration of the cage, The level of undulation of the wavy portion of the struts when the cage is in the radially expanded configuration is greater than the level of undulation of the wavy portion of the struts when the cage is in the axially elongated configuration, the apparatus.

84. The device according to claim 82, wherein the engagement mechanism is configured to allow rotation of the impeller while the cage is maintained in a position fixed in the rotational direction.

85. The device according to claim 82, wherein the engagement mechanism is configured to elongate the impeller in the axial direction by applying to the impeller a longitudinal movement caused by a longitudinal movement of the cage in response to the cage being compressed in the radial direction.

86. The device according to any one of claims 82 to 85, wherein the impeller includes a biocompatible impeller configured to be installed inside a blood vessel and to pump blood through the blood vessel by rotating, and the cage is configured to be disposed between the impeller and the inner wall portion of the blood vessel and to separate the impeller from the blood vessel wall portion.

87. The device according to claim 86, wherein the cage includes struts shaped to define cells, and the cage is configured to separate the impeller from the blood vessel wall portion even if the blood vessel wall portion protrudes through the cells of the cage.

88. The device according to any one of claims 82 to 85, wherein the impeller is connected to the cage such that the longitudinal axis of the impeller is aligned with the longitudinal axis of the cage, and the cage defines a central portion having a generally cylindrical shape, and an outer surface of the cage in the generally cylindrical portion of the cage is parallel to the longitudinal axis of the cage.

89. The device according to claim 88, wherein the impeller is configured to be installed inside a blood vessel and to pump blood through the blood vessel by rotating, and the cage is configured to be disposed between the impeller and the inner wall portion of the blood vessel and to separate the impeller from the inner wall portion of the blood vessel.

90. The device according to claim 89, wherein the cage is configured to expand radially inside the blood vessel, and the outer surface of the cage in the generally cylindrical portion of the cage engages the inner wall portion of the blood vessel, whereby the longitudinal axis of the cage is parallel to the local longitudinal axis of the blood vessel, and the cage is oriented within the blood vessel.

91. In a radially expanded configuration, an impeller configured to pump blood through a blood vessel by rotation, and a radially expandable cage disposed around the impeller placing inside the target blood vessel; radially expanding the cage and the impeller inside the blood vessel such that the impeller is separated from the inner wall portion of the blood vessel by the cage, wherein the impeller is engaged with the cage and, in response to the cage being radially compressed, the impeller is lengthened in the axial direction and remains separated from the inner wall portion of the blood vessel; operating a control unit to pump blood through the blood vessel by rotating the impeller A method comprising.

92. The method according to claim 91, wherein the blood vessel includes a renal vein, and operating the control unit to pump blood through the blood vessel includes operating the control unit to pump blood toward the vena cava of the subject away from the subject's kidney.

93. The method according to claim 91, wherein the method measures the pressure in the blood vessel of the subject at a first location in the blood vessel upstream of the impeller and at a second location in the blood vessel downstream of the impeller, and controls the rotation of the impeller in response to the pressure measured at the first and second locations, The method further comprising operating the control unit.

94. The method according to claim 91, wherein The step of installing the cage and the impeller inside the blood vessel includes the step of installing the cage and the impeller inside the blood vessel while the cage and the impeller are configured to be elongated in their axial directions, and while the cage in the state of being configured to be elongated in its axial direction houses the impeller inside the cage, and while the impeller is configured to be elongated in its axial direction. The cage includes a cage defining struts, and at least some of the struts include a portion of the strut that is wavy when at least the cage is configured to expand radially. The step of expanding the cage radially includes the step of expanding the cage radially such that the level of undulation of the wavy portion of the strut is greater than the level of undulation of the wavy portion of the strut when the cage is configured to be elongated in its axial direction.

95. The method according to claim 91, wherein the step of operating the control unit to rotate the impeller includes the step of operating the control unit to rotate the impeller while the cage is maintained in a position fixed in the rotational direction.

96. The method according to claim 91, wherein the cage includes struts shaped to define cells, and the step of expanding the cage radially includes the step of separating the blood vessel wall portion from the impeller by expanding the cage radially even if the blood vessel wall portion protrudes through the cells of the cage.

97. The method according to claim 91, The step of installing the impeller and the cage inside the blood vessel is the step of installing the impeller and the cage inside the blood vessel, and the step includes the impeller being connected to the cage such that the longitudinal axis of the impeller is aligned with the longitudinal axis of the cage. The cage includes a cage defining a central portion having a generally cylindrical shape, and an outer surface of the cage in the generally cylindrical portion of the cage is parallel to the longitudinal axis of the cage. The step of radially expanding the cage inside the blood vessel includes engaging the outer surface of the cage in the generally cylindrical portion of the cage with the inner wall portion of the blood vessel, whereby the cage is oriented in the blood vessel such that the longitudinal axis of the cage is parallel to the local longitudinal axis of the blood vessel. A method including the step of radially expanding the cage inside the blood vessel.

98. The method according to claim 91, the blood vessel has a predetermined diameter in the absence of the cage, the step of radially expanding the cage includes the step of expanding a portion of the blood vessel such that the diameter of the portion of the blood vessel is greater than the predetermined diameter, the step of radially expanding the impeller includes the step of radially expanding the impeller such that the span of the impeller is at least equal to the predetermined diameter. A method.

99. The method according to any one of claims 91 to 98, wherein the method measures the flow through the blood vessel, and responsive to the measured flow, controls the rotation of the impeller, further includes the step of operating the control unit.

100. The method according to claim 99, wherein the step of operating the control unit to measure the flow through the blood vessel is to operate the control unit to measure the blood flow via a thermal flow sensor disposed in the housing, the housing being configured such that the blood flow through the housing is in a direction substantially parallel to the local longitudinal axis of the blood vessel. A method including the step.

101. A radially expandable impeller configured to pump fluid by rotating in a radially expanded configuration, and a radially expandable cage disposed around the impeller, wherein in the radially expanded configuration of the impeller and the cage, the impeller is separated from the inner surface of the cage. A cage comprising an apparatus, the impeller is connected to the cage such that the longitudinal axis of the impeller is aligned with the longitudinal axis of the cage, The cage defines a central portion having a generally cylindrical shape, and an outer surface of the cage in the generally cylindrical portion of the cage is parallel to the longitudinal axis of the cage, apparatus.

102. The apparatus according to claim 101, wherein the cage and the impeller define a configuration elongated in its axial direction, and the cage is configured to accommodate the impeller inside the cage while the cage has a configuration elongated in its axial direction, while the impeller has a configuration elongated in its axial direction, the cage includes struts, and at least some of the struts include a portion of the struts that are wavy when at least the cage is in a configuration in which the cage is expanded in the radial direction of the cage, the level of the undulation of the wavy portion of the struts when the cage is in a configuration in which the cage is expanded in the radial direction is greater than the level of the undulation of the wavy portion of the struts when the cage is in a configuration in which the cage is elongated in its axial direction, apparatus.

103. The apparatus according to claim 101, wherein the impeller defines a proximal ring and a distal end at its proximal end and distal end, respectively, the cage defines a proximal ring and a distal ring at its proximal end and distal end, respectively, the impeller is installed on a first support element such that the proximal rings of the impeller and the cage are aligned with each other, and installed on a second support element such that the distal rings of the impeller and the cage are aligned with each other, connected to the cage such that the longitudinal axis of the impeller is aligned with the longitudinal axis of the cage, apparatus.

104. The apparatus according to any one of claims 101 to 103, wherein the apparatus further comprises an engagement mechanism configured to engage the impeller with the cage, and in response to the cage being radially compressed, the engagement mechanism elongates the impeller in the axial direction such that the impeller remains separated from the inner surface of the cage.

105. The apparatus according to claim 104, wherein the engagement mechanism is configured to allow rotation of the impeller while the cage is maintained in a position fixed in the rotational direction.

106. The apparatus according to claim 104, wherein the engagement mechanism is configured to elongate the impeller in the axial direction by applying to the impeller a longitudinal movement caused by a longitudinal movement of the cage in response to the cage being radially compressed.

107. The apparatus according to claim 104, wherein the impeller is a biocompatible impeller configured to be installed inside a blood vessel and to pump blood through the blood vessel by rotation, and the cage is configured to be disposed between the impeller and the inner wall portion of the blood vessel and to separate the blood vessel wall portion from the impeller.

108. The apparatus according to claim 107, wherein the cage includes struts shaped to define cells, and the cage is configured to separate the blood vessel wall portion from the impeller even if the blood vessel wall portion protrudes through the cells of the cage.

109. The apparatus according to any one of claims 101 to 103, wherein the impeller is a biocompatible impeller configured to be installed inside a blood vessel and to pump blood through the blood vessel by rotation, and the cage is configured to be disposed between the impeller and the inner wall portion of the blood vessel and to separate the blood vessel wall portion from the impeller.

110. The device according to claim 109, wherein the cage is configured to expand radially inside the blood vessel, and an outer surface of the cage in the generally cylindrical portion of the cage engages the inner wall portion of the blood vessel, whereby the cage is oriented within the blood vessel such that the longitudinal axis of the cage is parallel to the local longitudinal axis of the blood vessel.

111. In a radially expanded configuration, an impeller configured to pump blood through the blood vessel by rotation, A radially expandable cage disposed around the impeller, wherein the impeller is connected to the cage such that the longitudinal axis of the impeller is aligned with the longitudinal axis of the cage, and the cage has a generally cylindrical shape Defining a central portion thereof, and an outer surface of the cage in the generally cylindrical portion of the cage is parallel to the longitudinal axis of the cage, the radially expandable cage Installing inside the blood vessel of the subject; The impeller is separated from the inner wall portion of the blood vessel by the cage, and An outer surface of the cage in the generally cylindrical portion of the cage engages the inner wall portion of the blood vessel, whereby the cage is oriented within the blood vessel such that the longitudinal axis of the cage is parallel to the local longitudinal axis of the blood vessel, Radially expanding the cage and the impeller inside the blood vessel; Operating a control unit to pump blood through the blood vessel by rotating the impeller A method comprising:

112. The method according to claim 111, wherein the blood vessel includes a renal vein, and the step of operating the control unit to pump blood through the blood vessel includes operating the control unit to pump blood toward the vena cava of the subject away from the subject's kidney.

113. The method according to claim 111, wherein the method At a first location in the blood vessel upstream of the impeller and at a second location in the blood vessel downstream of the impeller, to measure the pressure in the target blood vessel, and Responsive to the pressure measured at the first and second locations, to control the rotation of the impeller, The method further comprising the step of operating the control unit.

114. The method according to claim 111, The step of installing the cage and the impeller inside the blood vessel includes the step of installing the cage and the impeller inside the blood vessel while the cage and the impeller are elongated in their axial direction, and while the cage in its axially elongated configuration houses the impeller inside the cage, and while the impeller is elongated in its axial direction. The cage includes a cage defining struts, at least some of the struts including a portion of the strut that is wavy when at least the cage is in a configuration in which it is expanded radially of the cage. The step of expanding the cage radially includes the step of expanding the cage radially such that the level of undulation of the wavy portion of the strut is greater than the level of undulation of the wavy portion of the strut when the cage is in a configuration in which it is elongated in its axial direction.

115. The method according to claim 111, wherein the cage includes struts shaped to define cells, and the step of expanding the cage radially includes the step of separating the impeller from the blood vessel wall by expanding the cage radially even if the blood vessel wall protrudes through the cells of the cage.

116. The method according to claim 111, The blood vessel has a predetermined diameter in the absence of the cage, The step of expanding the cage radially includes the step of expanding a portion of the blood vessel such that the diameter of the portion of the blood vessel is greater than the predetermined diameter, The step of expanding the impeller radially includes the step of expanding the impeller radially such that the span of the impeller is at least equal to the predetermined diameter.

117. The method according to any one of Claims 111 to 116, wherein the step of installing the impeller and the cage inside the blood vessel is a step of installing the impeller and the cage inside the blood vessel, the impeller is engaged with the cage, and in response to the cage being compressed in the radial direction, the impeller is lengthened in the axial direction, and the impeller remains separated from the inner wall portion of the blood vessel. The method includes the step of.

118. The method according to Claim 117, wherein the step of operating the control unit to rotate the impeller includes operating the control unit to rotate the impeller while the cage is maintained at a fixed position in the rotational direction. The method of.

119. The method according to any one of Claims 111 to 116, wherein the method is To measure the flow through the blood vessel, and Responsive to the measured flow, to control the rotation of the impeller, The method further includes the step of operating the control unit.

120. The method according to Claim 119, wherein the step of operating the control unit to measure the flow through the blood vessel is a step of operating the control unit to measure the blood flow through a thermal flow sensor disposed in the housing, the housing being configured such that the blood flow through the housing is substantially parallel to the local longitudinal axis of the blood vessel. The method includes the step of.

121. In a radially expanded configuration, a radially expandable impeller configured to pump fluid by rotating, and A radially expandable cage disposed around the impeller, wherein in the radially expanded configuration of the impeller and the cage, the impeller is separated from the inner surface of the cage. Cage and An apparatus comprising The cage and the impeller define a configuration elongated in its axial direction, and the cage is configured to accommodate the impeller inside the cage while having a configuration elongated in its axial direction. On the other hand, the impeller has a configuration elongated in its axial direction, The cage includes struts, and at least some of the struts include a wavy portion of the struts that is wavy when at least the cage is in a configuration expanded in the radial direction of the cage. An apparatus, wherein a level of undulation of the wavy portion of the strut when the cage is in a configuration expanded in the radial direction is greater than a level of undulation of the wavy portion of the strut when the cage is in a configuration elongated in its axial direction.

122. The apparatus according to claim 121, wherein for each of the struts including the wavy portion, the strut has a first length of the strut when the cage is in a configuration elongated in its axial direction the shortest distance from the end in the longitudinal direction of the strut to the end in the second longitudinal direction of the strut, and the shortest distance from the end in the first longitudinal direction of the strut to the end in the second longitudinal direction of the strut when the cage is in a configuration expanded in the radial direction is configured such that a ratio thereof is greater than 1.05:

1.

123. The apparatus according to claim 122, wherein the ratio is less than 1.4:

1.

124. The apparatus according to claim 122, wherein the ratio is greater than 1.15:

1.

125. The apparatus according to claim 124, wherein the ratio is greater than 1.2:

1.

126. The apparatus according to claim 121, further comprising an engagement mechanism configured to engage the impeller with the cage, wherein in response to the cage being elongated in the axial direction, the impeller is elongated in the axial direction and the impeller remains separated from the inner surface of the cage.

127. The apparatus according to claim 126, wherein the engagement mechanism is configured to allow rotation of the impeller while the cage is maintained in a position fixed in the rotational direction.

128. The apparatus according to claim 126, wherein the engagement mechanism is configured to elongate the impeller in the axial direction by applying to the impeller a longitudinal movement caused by a longitudinal movement of the cage in response to the cage being elongated in the axial direction.

129. The apparatus according to any one of claims 126, wherein the cage and the impeller are biocompatible and are configured to be inserted into a blood vessel while the impeller is disposed inside the cage and while the cage and the impeller are in their axially elongated configuration, the impeller being configured to radially expand inside the blood vessel and to pump blood through the blood vessel by rotating, the cage being configured to radially expand inside the blood vessel and to be disposed between the impeller and the inner wall portion of the blood vessel to separate the inner wall portion of the blood vessel from the impeller.

130. The apparatus according to claim 129, wherein the struts of the cage are shaped to define cells, and the cage is configured to separate the blood vessel wall from the impeller even if the blood vessel wall protrudes through the cells of the cage.

131. The apparatus according to claim 121, wherein the impeller is connected to the cage such that the longitudinal axis of the impeller is aligned with the longitudinal axis of the cage, the cage defining a central portion thereof having a generally cylindrical shape, the outer surface of the cage in the generally cylindrical portion of the cage being parallel to the longitudinal axis of the cage.

132. The apparatus according to claim 131, wherein the impeller is biocompatible, the imp eller being configured to be installed inside a blood vessel and to pump blood through the blood vessel by rotating, the cage being configured to be disposed between the impeller and the inner wall portion of the blood vessel and to separate the inner wall portion of the blood vessel from the impeller.

133. The apparatus according to claim 132, wherein the cage is configured to expand radially inside the blood vessel, and the outer surface of the cage in the generally cylindrical portion of the cage engages the inner wall portion of the blood vessel, whereby the longitudinal axis of the cage is parallel to the local longitudinal axis of the blood vessel, and the cage is oriented within the blood vessel.

134. In a radially expanded configuration, an impeller configured to pump blood through a blood vessel by rotation, and A radially expandable cage disposed around the impeller, the cage defining struts Installing inside the blood vessel of interest, While the cage and the impeller are configured to be elongated in their axial directions, and while the cage is configured to be elongated in its axial direction, while accommodating the impeller inside the cage, and while the impeller is configured to be elongated in its axial direction, the installing step is performed. Radially expanding the cage and the impeller inside the blood vessel such that the cage and the impeller are configured to expand radially, and such that the impeller is separated from the inner wall portion of the blood vessel by the cage. Operating a control unit to pump blood through the blood vessel by rotating the impeller. The cage includes struts, and at least some of the struts include a portion of the struts that are wavy, at least when the cage is configured to be expanded radially. The step of radially expanding the cage includes radially expanding the cage such that the level of undulation of the wavy portion of the struts is greater than the level of undulation of the wavy portion of the struts when the cage is configured to be elongated in its axial direction. A method comprising.

135. The method according to claim 134, wherein the blood vessel includes a renal vein, and the step of operating the control unit to pump blood through the blood vessel includes operating the control unit to pump blood toward the vena cava of the subject away from the kidney of the subject.

136. The method according to claim 134, wherein the method measures the pressure in the blood vessel of the subject at a first location in the blood vessel upstream of the impeller and at a second location in the blood vessel downstream of the impeller, and operates the control unit to control the rotation of the impeller in response to the pressure measured at the first and second locations. The method further includes the step of operating the control unit.

137. The method according to claim 134, wherein the struts of the cage include struts shaped to define cells, and the step of radially expanding the cage includes separating the impeller from the blood vessel wall by radially expanding the cage, even if the blood vessel wall protrudes through the cells of the cage. The method includes the step of separating the impeller from the blood vessel wall by radially expanding the cage.

138. The method according to claim 134, wherein the blood vessel has a predetermined diameter in the absence of the cage, the step of radially expanding the cage includes expanding a portion of the blood vessel such that the diameter of the portion of the blood vessel is greater than the predetermined diameter, and the step of radially expanding the impeller includes radially expanding the impeller such that the span of the impeller is at least equal to the predetermined diameter.

139. The method according to any one of claims 134 to 138, wherein the step of radially expanding the cage, for each of the struts including the corrugated portion, the shortest distance from the first longitudinal end of the strut to the second longitudinal end of the strut when the cage is in a configuration elongated in its axial direction, and the shortest distance from the first longitudinal end of the strut to the second longitudinal end of the strut when the cage is in a configuration radially expanded, and the ratio is greater than 1.05:1, and the method includes the step of radially expanding the cage.

140. The method according to claim 139, wherein the step of radially expanding the cage comprises radially expanding the cage such that, for each of the struts including the wavy portion, the ratio is less than 1.4:

1.

141. The method according to claim 139, wherein the step of radially expanding the cage comprises radially expanding the cage such that, for each of the struts including the wavy portion, the ratio is greater than 1.15:

1.

142. The method according to claim 141, wherein the step of radially expanding the cage comprises radially expanding the cage such that, for each of the struts including the wavy portion, the ratio is greater than 1.2:

1.

143. The method according to any one of claims 134 to 138, wherein the step of installing the impeller and the cage inside the blood vessel is a step of installing the impeller and the cage inside the blood vessel, wherein the impeller is engaged with the cage, and in response to the cage being radially compressed, the impeller is lengthened in the axial direction and remains separated from the inner wall portion of the blood vessel.

144. The method according to claim 143, wherein the step of operating the control unit to rotate the impeller comprises operating the control unit to rotate the impeller while the cage is maintained in a fixed position in the rotational direction.

145. The method according to any one of claims 134 to 138, wherein the method measures the flow through the blood vessel, and responsive to the measured flow, controls the rotation of the impeller, further comprising the step of operating the control unit.

146. The method according to claim 145, wherein the control for measuring the flow through the blood vessel The step of operating the unit is the step of operating the control unit to measure blood flow through a thermal flow sensor disposed within the housing, wherein the housing is configured such that blood flow through the housing is in a direction substantially parallel to the local longitudinal axis of the blood vessel. The method includes this step.

147. Installing a radially expandable structure inside the target blood vessel, wherein the blood vessel has a predetermined diameter in the absence of the radially expandable structure, and Expanding a portion of the blood vessel such that the diameter of the portion of the blood vessel becomes larger than the predetermined diameter by expanding the radially expandable structure inside the portion of the blood vessel, and Installing an impeller inside the portion of the blood vessel, wherein the impeller includes impeller blades and the span of the impeller blades is at least equal to the predetermined diameter, and Operating the control unit to pump blood through the blood vessel by rotating the impeller with respect to the blood vessel, and A method including these steps.

148. The method according to claim 147, wherein the step of expanding the radially expandable structure includes expanding a radially expandable cage disposed around the impeller such that the impeller is separated from the inner wall of the blood vessel by the cage.

149. The method according to claim 147, wherein the blood vessel includes a renal vein, and the step of operating the control unit to pump blood through the blood vessel includes operating the control unit to pump blood toward the vena cava of the subject away from the subject's kidney.

150. The method according to claim 147, wherein the method further includes Measuring the pressure in the blood vessel of the subject at a first location in the blood vessel upstream of the impeller and at a second location in the blood vessel downstream of the impeller, and Operating the control unit to control the rotation of the impeller in response to the pressure measured at the first and second locations. A method further including this step.

151. The method according to any one of claims 147 to 150, wherein the method comprises: operating the control unit to measure the flow through the blood vessel, and operating the control unit to control the rotation of the impeller in response to the measured flow, further comprising the step of operating the control unit.

152. The method according to claim 151, wherein the step of operating the control unit to measure the flow through the blood vessel comprises operating the control unit to measure the blood flow via a thermal flow sensor disposed within the housing, the housing being configured such that the blood flow through the housing is in a direction substantially parallel to the local longitudinal axis of the blood vessel.

153. The method according to any one of claims 147 to 150, wherein the step of expanding the portion of the blood vessel comprises expanding the radially expandable structure inside the portion of the blood vessel such that the diameter of the portion of the blood vessel becomes greater than 105% of the predetermined diameter.

154. The method according to claim 153, wherein the step of expanding the portion of the blood vessel comprises expanding the radially expandable structure inside the portion of the blood vessel such that the diameter of the portion of the blood vessel becomes greater than 115% of the predetermined diameter.

155. The method according to claim 153, wherein the step of expanding the portion of the blood vessel comprises expanding the radially expandable structure inside the portion of the blood vessel such that the diameter of the portion of the blood vessel becomes less than 125% of the predetermined diameter.

156. A blood pump configured to pump blood through a blood vessel of a subject, the blood pump comprising: an elongate element, and an impeller disposed at a distal end of the elongate element, the impeller being configured to pump blood through the blood vessel by rotating, a blood pump. A thermal flow sensor configured to measure the flow of the pumped blood, the thermal flow sensor including an upstream temperature sensor, a heating element, and a downstream temperature sensor that are continuously disposed along a portion of the length of the elongated element. An apparatus including The elongated element includes a housing configured to store the thermal flow sensor, and the housing is configured such that blood flow through the housing is in a direction substantially parallel to the local longitudinal axis of the blood vessel. **Claim 157** The apparatus according to claim 156, wherein the housing includes a portion of the outer surface of the elongated element shaped to define a recess therein, and the upstream temperature sensor, the heating element, and the downstream temperature sensor are continuously disposed along the recess. **Claim 158** The apparatus according to claim 157, wherein a ratio of a length of the recess to a width of the recess is greater than 4:

1. **Claim 159** The apparatus according to claim 157, wherein the apparatus further includes a cover connected to the elongated element and disposed to cover the thermal sensor. **Claim 160** The apparatus according to claim 156, wherein the housing includes a housing disposed on an outer surface of the elongated element, and the upstream temperature sensor, the heating element, and the downstream temperature sensor are continuously disposed along an inner side of the housing. **Claim 161** The apparatus according to claim 160, wherein the housing includes a compressible tube disposed on the outer surface of the elongated element. **Claim 162** The apparatus according to claim 160, wherein a ratio of a length of the housing to a width of the housing is greater than 4:

1. **Claim 163** The apparatus according to claim 160, wherein a ratio of a length of the housing to a height of the housing is greater than 4:

1. **Claim 164** A step of installing a blood pump into a target blood vessel, the blood pump including an elongated element, and An impeller disposed at a distal end of the elongated element including a step; Operating the control unit to measure the flow of the pumped blood using a thermal flow sensor, the thermal flow sensor including an upstream temperature sensor, a heating element, and a downstream temperature sensor continuously disposed along a portion of the length of the elongated element; The elongated element includes a housing configured to house the thermal flow sensor, and the housing is configured such that blood flow through the housing is substantially parallel to the local longitudinal axis of the blood vessel; Operating the control unit to pump blood through the blood vessel by rotating the impeller at least partially in response to the measured flow; A method including.

165. The method according to claim 164, wherein the step of installing the elongated element including the housing into the blood vessel is a step of installing the elongated element into the blood vessel, a portion of the outer surface of the elongated element being shaped to define a recess therein, the upstream temperature sensor, the heating element, and the downstream temperature sensor being continuously disposed along the recess.

166. The method according to claim 165, wherein the step of installing the elongated element into the blood vessel is a step of installing the elongated element into the blood vessel, and the ratio of the length to the width of the recess defined by the portion of the outer surface of the elongated element is greater than 4:

1.

167. The method according to claim 165, wherein the step of installing the elongated element into the blood vessel is a step of installing the elongated element into the blood vessel, and the elongated element includes a cover connected thereto, the cover being disposed to cover the thermal sensor.

168. The method according to claim 164, wherein the step of placing the elongated element into the blood vessel is a step of placing the elongated element into the blood vessel, wherein the housing is disposed on the outer surface of the elongated element, and the upstream temperature sensor, the heating element, and the downstream temperature sensor are continuously disposed along the inside of the housing.

169. The method according to claim 168, wherein the step of placing the elongated element into the blood vessel is a step of placing the elongated element into the blood vessel, wherein the housing includes a compressible tube disposed on the outer surface of the elongated element. The method including the step.

170. The method according to claim 168, wherein the step of placing the elongated element into the blood vessel is a step of placing the elongated element into the blood vessel, wherein the ratio of the length of the housing to the width of the housing is greater than 4:

1.

171. The method according to claim 168, wherein the step of placing the elongated element into the blood vessel is a step of placing the elongated element into the blood vessel, wherein the ratio of the length of the housing to the height of the housing is greater than 4:

1.

172. A pump configured to pump a fluid, the pump comprising: an elongated element, and an impeller disposed at a distal end of the elongated element, the impeller being configured to pump the fluid by rotating. The pump including the impeller, and a thermal flow sensor configured to measure the flow of the pumped fluid, the thermal flow sensor including an upstream temperature sensor, a heating element, and a downstream temperature sensor that are continuously disposed along a portion of the length of the elongated element. The device including the thermal flow sensor. The elongated element includes a housing, the housing being configured to store the thermal flow sensor, the housing being configured such that the flow of the fluid through the housing is in a direction substantially parallel to the local longitudinal axis of the elongated element, apparatus.

173. The apparatus according to claim 172, wherein the housing includes a portion of the outer surface of the elongated element shaped to define a recess therein, the upstream temperature sensor, the heating element, and the downstream temperature sensor being arranged continuously along the recess, apparatus.

174. The apparatus according to claim 173, wherein the ratio of the length of the recess to the width of the recess is greater than 4:1, apparatus.

175. The apparatus according to claim 173, wherein the apparatus further includes a cover, the cover being connected to the elongated element and arranged to cover the thermal sensor, apparatus.

176. The apparatus according to claim 172, wherein the housing includes a housing arranged on the outer surface of the elongated element, the upstream temperature sensor, the heating element, and the downstream temperature sensor being arranged continuously along the inside of the housing, apparatus.

177. The apparatus according to claim 176, wherein the housing includes a compressible tube arranged on the outer surface of the elongated element, apparatus.

178. The apparatus according to claim 176, wherein the ratio of the length of the housing to the width of the housing is greater than 4:1, apparatus.

179. The apparatus according to claim 176, wherein the ratio of the length of the housing to the height of the housing is greater than 4:1, apparatus.

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