ventricular assist device

Abstract

The present application relates to a ventricular assist device. An apparatus and method are described that include a left ventricular assist device (20) comprising a tube (24) configured to pass through an aortic valve of a subject, a distal portion of the tube being disposed within the subject's left ventricle. A frame (34) is disposed within the distal portion of the tube. A pump (50) disposed within the frame pumps blood through the tube. A distal tip element (107) defines a straight proximal portion (346) and a curved distal portion, the straight proximal portion defining a longitudinal axis (348), the curved distal portion being shaped to bend in a first direction relative to the longitudinal axis before passing through an inflection point and bending in a second direction relative to the longitudinal axis (348), such that the curved distal portion defines a ridge (351) on one side of the longitudinal axis (348). Other applications are also described.

Description

[0001] This application is a divisional application of the application with application date of January 23, 2020, application number 202080017728.9, and invention name “Ventricular Assist Device”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority from:

[0004] U.S. Provisional Patent Application 62 / 796,138, filed by Tuval on January 24, 2019, entitled “Ventricular assist device”;

[0005] U.S. Provisional Patent Application 62 / 851,716, filed by Tuval on May 23, 2019, entitled “Ventricular assist device”;

[0006] U.S. Provisional Patent Application No. 62 / 870,821, filed by Tuval on July 5, 2019, entitled “Ventricular assist device”; and

[0007] Tuval, U.S. Provisional Patent Application 62 / 896,026, entitled “Ventricular assist device,” filed on September 5, 2019.

[0008] This application is related to a U.S. provisional application filed on the same date as the present application and entitled “Distal tip element for a ventricular assist device”, which claims priority from the aforementioned U.S. provisional application.

[0009] All of these above-referenced applications are incorporated herein by reference in their entirety.

[0010] Field of the Invention Embodiments

[0011] Some applications of the present invention generally relate to medical devices. Specifically, some applications of the present invention relate to ventricular assist devices and methods of using the same. background

[0012] A ventricular assist device is a mechanical circulatory support device designed to assist and unload the heart chambers to maintain or increase cardiac output. These ventricular assist devices are used in patients with heart failure and in patients who are at risk of worsening heart function during percutaneous coronary intervention. Most commonly, a left ventricular assist device is placed in a defective heart to assist the left ventricle. In some cases, a right ventricular assist device is used to assist the right ventricle. These assist devices are either designed to be permanently implanted or mounted on a catheter for temporary placement.

[0013] Overview of the Examples

[0014] According to some applications of the present invention, a ventricular assist device includes an impeller disposed on an axial shaft, wherein a frame is disposed around the impeller. Typically, the ventricular assist device includes a tube that passes through the aortic valve of a subject, such that a proximal end of the tube is disposed within the subject's aorta and a distal end of the tube is disposed within the subject's left ventricle. The impeller, the axial shaft, and the frame are disposed within a distal portion of the tube that is located within the subject's left ventricle. Typically, the impeller is configured to pump blood from the left ventricle into the aorta by rotation. Typically, the tube defines one or more blood inlet openings at the distal end of the tube, through which blood flows from the left ventricle into the tube during operation of the impeller. For some applications, the proximal portion of the tube defines one or more blood outlet openings, through which blood flows from the tube into the ascending aorta during operation of the impeller.

[0015] For some applications, a ventricular assist device includes a distal tip element configured to define a straight proximal portion and a curved distal portion, the straight proximal portion defining a longitudinal axis, the curved distal portion shaped to curve in a first direction relative to the longitudinal axis of the straight proximal portion before passing through an inflection point and curving in a second direction relative to the longitudinal axis of the straight proximal portion, such that the curved distal portion defines a ridge on one side of the longitudinal axis of the straight proximal portion. Typically, the distal tip element has a question mark shape and / or a tennis racket shape.

[0016] For some applications, the distal tip element is configured to separate the blood inlet opening from the posterior wall of the subject's left ventricle when the distal tip element is placed against the apex of the subject's left ventricle. Typically, the distal tip element is configured to separate the blood inlet opening from the septal wall of the subject's left ventricle when the distal tip element contacts the apex of the subject's left ventricle. More typically, the distal tip element is configured such that when the distal tip element is inserted into the left ventricle such that the ridge ridges toward the septal wall, in response to the distal tip element being pushed against the apex of the subject's left ventricle, the blood inlet opening is pushed away from the septal wall and toward the free wall of the subject's left ventricle. For some applications, the blood inlet opening is pushed away from the septal wall and toward the free wall of the subject's left ventricle by pivoting the straight proximal portion of the distal tip element about the curved distal portion of the distal tip element.

[0017] For some applications, the duckbill valve is positioned within the distal-most 10 mm of the distal tip element. Typically, the duckbill valve defines a wide entrance and a narrow tip, the narrow tip defining a slit therethrough, the duckbill valve facing proximally such that the wide entrance faces the distal end of the distal tip element and such that the narrow tip faces away from the distal end of the distal tip element. For some applications, the ventricular assist device is configured for use with a guidewire, and the distal tip element defines a guidewire lumen. For some such applications, the ventricular assist device further includes a guidewire guide positioned within the guidewire lumen proximal to the duckbill valve. Typically, the guidewire guide is shaped to define a hole therethrough, the hole having a diameter that narrows from a proximal end of the guidewire guide to a distal end of the guidewire guide, the guidewire guide being shaped to guide the tip of the guidewire toward the slit at the narrow proximal end of the duckbill valve when the guidewire is inserted from the proximal end of the left ventricular assist device. For some applications, the duckbill valve is shaped to define a converging guide portion at a proximal end thereof that converges toward the slit, such that the guide portion is configured to guide the tip of the guide wire further toward the slit.

[0018] Typically, a frame disposed about the impeller defines a plurality of cells, and the frame is configured such that, in a non-radially constrained configuration of the frame, the frame includes a generally cylindrical portion. More typically, each cell within the cylindrical portion has a width less than 2 mm (e.g., 1.4 mm to 1.6 mm, or 1.6 mm to 1.8 mm) measured around the circumference of the cylindrical portion. For some applications, a liner lines at least the cylindrical portion of the frame, and the impeller is disposed within the frame such that, in the non-radially constrained configuration of the impeller, at a location where the impeller spans the greatest distance, the impeller is disposed within the cylindrical portion of the frame such that a gap between an outer edge of the impeller and the liner is less than 1 mm (e.g., less than 0.4 mm). Typically, the impeller is configured to rotate to pump blood from the left ventricle to the aorta, and is configured to be stable relative to the frame such that a gap between an outer edge of the impeller and the liner is maintained and substantially constant during rotation of the impeller. For some applications, the impeller is configured to reduce the risk of hemolysis by being stabilized relative to the frame, compared to a situation where the impeller is unstable relative to the frame.

[0019] For some applications, a proximal radial support and a distal radial support are disposed at the proximal and distal ends of the frame, respectively, and the axial shaft passes through the proximal radial support and the distal radial support. Typically, the impeller is stabilized relative to the frame by maintaining the impeller in a radially fixed position relative to the axial shaft and the axial shaft being rigid. For some applications, the impeller includes bushings disposed around the axial shaft, and at least one of the bushings is configured to be slidable relative to the axial shaft. For some applications, the impeller is stabilized relative to the frame by a region along the axial shaft where at least one bushing is configured to be slidable relative to the axial shaft, the region being coated to substantially prevent vibration of the impeller by reducing a gap between the at least one bushing and the impeller. For example, the region may be coated with a diamond-like carbon coating, a polytetrafluoroethylene coating, and / or a polymer sleeve.

[0020] For some applications, the frame defines struts having a structure such that as the frame transitions from the proximal end of the frame to the center of the frame, the struts pass through a junction where pairs of struts branch off from a single strut in a Y-shape. Typically, the structure of the struts of the frame is configured such that in response to the distal end of the delivery catheter and the frame being moved into an overlapping position relative to each other (e.g., by the distal end of the delivery catheter being advanced over the frame, or by the frame being retracted into the distal end of the delivery catheter), the frame is configured to assume its radially constrained configuration by becoming axially elongated, and is configured to cause the impeller to assume its radially constrained configuration by becoming axially elongated (e.g., by the pairs of struts branching off from each junction being configured to pivot about the junction and move closer to each other, thereby closing in response to the distal end of the delivery catheter and the frame being moved into an overlapping position relative to each other).

[0021] For some applications, a housing for an impeller of a blood pump is manufactured by performing the following steps: A liner is placed around a mandrel. A cylindrical portion of a frame is placed around the liner, the cylindrical portion of the frame including struts defining a generally cylindrical shape. A distal portion of an elongated tube is placed around at least a portion of the frame, the tube including a proximal portion defining at least one blood outlet opening. While the distal portion is positioned around at least a portion of the frame, the liner, frame, and distal portion of the elongated tube are heated via the mandrel. While the liner, frame, and distal portion of the elongated tube are heated, pressure is applied from outside the distal portion of the elongated tube to conform the distal portion of the elongated tube to the structure of the struts of the frame and to couple the liner and distal portion of the elongated tube to the frame. For example, the pressure can be applied via a silicone tube placed outside the distal portion of the elongated tube. For some applications, the liner and the elongated tube are made of different materials, and the material of the liner has a higher thermoforming temperature than the material of the elongated tube. For some such applications, the liner, frame, and distal portion of the elongated tube are heated to a temperature above the thermoforming temperature of the material from which the elongated tube is made and below the thermoforming temperature of the material from which the liner is made.

[0022] For some applications, an impeller is manufactured by forming a structure having a first bushing and a second bushing at a proximal end and a distal end of the structure, the first bushing and the second bushing being connected to each other by at least one elongated element. At least partially by axially compressing the structure, the at least one elongated element is radially expanded and formed into at least one helical elongated element. An elastomeric material is coupled to the at least one helical elongated element such that the at least one helical elongated element coupled with the elastomeric material defines blades of the impeller. Typically, the coupling is performed such that a layer of material is disposed about a radially outer edge of the at least one helical elongated element, the layer of material forming an effective edge of the blades of the impeller (i.e., an edge at which the blood pumping function of the impeller is substantially no longer effective). More typically, the method includes performing the step of enhancing the bonding of the elastomeric material to the at least one helical elongated element in a manner that does not result in protrusion from the effective edge of the blades of the impeller. For example, a suture can be placed within a groove defined by the at least one helical elongated element such that the suture does not protrude from the radially outer edge of the helical elongated element, the suture being configured to enhance the bonding of the elastomeric material to the at least one helical elongated element. Alternatively or additionally, a tightly wound coil is placed around the at least one helical elongated element such that the elastomeric material forms a substantially smooth layer along a radially outer edge of the coil, the coil being configured to enhance bonding of the elastomeric material to the at least one helical elongated element. Further alternatively or additionally, a sleeve is placed around the at least one helical elongated element such that the elastomeric material forms a substantially smooth layer along a radially outer edge of the sleeve, the sleeve being configured to enhance bonding of the elastomeric material to the at least one helical elongated element. For some applications, the at least one helical elongated element is provided with a rounded cross-section such that the elastomeric material forms a layer of substantially uniform thickness at the interface between the elastomeric material and the helical elongated element.

[0023] In general, in the specification and claims of this application, the term "proximal" and related terms, when used with respect to a device or a portion thereof, should be interpreted as meaning that when the device or a portion thereof is inserted into a subject, the end of the device or a portion thereof is generally closer to the location through which the device is inserted into the subject. The term "distal" and related terms, when used with respect to a device or a portion thereof, should be interpreted as meaning that when the device or a portion thereof is inserted into a subject, the end of the device or a portion thereof is generally further away from the location through which the device is inserted into the subject.

[0024] The scope of the present invention includes the use of the apparatus and methods described herein in anatomical locations other than the left ventricle and aorta.Thus, a ventricular assist device and / or portions thereof are sometimes referred to herein (in the specification and claims) as a blood pump.

[0025] Therefore, according to some applications of the present invention, there is provided an apparatus comprising:

[0026] A left ventricular assist device configured to assist left ventricular function in a subject, the left ventricular assist device comprising:

[0027] a tube configured such that a proximal portion of the tube passes through an aortic valve of the subject and a distal portion of the tube is positioned within the left ventricle of the subject;

[0028] a frame disposed within at least a distal portion of the tube;

[0029] a pump disposed within the frame and configured to pump blood from the left ventricle of the subject to the subject's aorta through the tube by pumping blood into the tube via at least one blood inlet opening defined by the tube and configured to be disposed within the subject's left ventricle, and pumping blood out of the tube via at least one blood outlet opening defined by the tube and configured to be disposed within the subject's aorta; and

[0030] A distal tip element is configured to define a straight proximal portion defining a longitudinal axis and a curved distal portion formed to bend in a first direction relative to the longitudinal axis of the straight proximal portion before passing through an inflection point and bending in a second direction relative to the longitudinal axis of the straight proximal portion, such that the curved distal portion defines a ridge on one side of the longitudinal axis of the straight proximal portion.

[0031] For some applications, the distal tip element is configured to separate the at least one blood inlet opening from a posterior wall of the subject's left ventricle when the distal tip element is positioned against the apex of the subject's left ventricle.

[0032] For some applications, the distal tip element has a question mark shape.For some applications, the distal tip element has a tennis racket shape.

[0033] For some applications, the curved distal portion of the distal tip element is shaped such that after passing the inflection point, the curved distal portion continues to bend such that the curved distal portion crosses back onto the longitudinal axis defined by the straight proximal portion. For some applications, the curved distal portion of the distal tip element is shaped such that after passing the inflection point, the curved distal portion does not cross back onto the longitudinal axis defined by the straight proximal portion.

[0034] For some applications, the blood pump includes an impeller disposed on an axial shaft, and the distal tip element includes an axial shaft receiving tube configured to receive the axial shaft of the blood pump, and a distal tip portion configured to define a curved distal portion of the distal tip element.

[0035] For some applications, the distal tip element is configured to separate the at least one blood inlet opening from the septal wall of the subject's left ventricle when the distal tip element contacts the apex of the subject's left ventricle. For some applications, the distal tip element is configured such that when the distal tip element is inserted into the left ventricle such that the ridge ridges toward the septal wall, the blood inlet opening is urged away from the septal wall and toward the free wall of the subject's left ventricle in response to the distal tip element being urged against the apex of the subject's left ventricle. For some applications, the distal tip element is configured such that in response to the distal tip element being urged against the apex of the subject's left ventricle, the blood inlet opening is urged away from the septal wall and toward the free wall of the subject's left ventricle by pivoting the straight proximal portion of the distal tip element about the curved distal portion of the distal tip element.

[0036] For some applications, the distal tip element is configured such that, when deployed within the descending aorta of the subject, the distal tip element itself is centered relative to the subject's aortic valve. For some applications, the curved distal portion is shaped to define an elongated straight portion after bending in a first direction and before the curved distal portion bends in a second direction, such that the elongated straight portion protrudes at an angle relative to a longitudinal axis of the proximal straight portion of the distal tip element.

[0037] For some applications, the duckbill valve is positioned within a distal-most 10 mm of the distal tip element. For some applications, the duckbill valve defines a wide inlet and a narrow tip defining a slit therethrough, the duckbill valve facing proximally such that the wide inlet faces the distal end of the distal tip element and the narrow tip faces away from the distal end of the distal tip element.

[0038] For some applications:

[0039] The left ventricular assist device is configured for use with a guidewire;

[0040] The distal tip element defines a guidewire lumen; and

[0041] The left ventricular assist device also includes a guide wire guide disposed within the guide wire lumen at a position proximal to the duckbill valve, the guide wire guide being shaped to define a hole therethrough having a diameter that narrows from a proximal end of the guide wire guide to a distal end of the guide wire guide, the shape of the guide wire guide being configured to guide the tip of the guide wire toward the slit at the narrow proximal end of the duckbill valve when the guide wire is inserted from the proximal end of the left ventricular assist device.

[0042] For some applications, the duckbill valve is shaped to define a converging guide portion at a proximal end thereof that converges toward the slit, such that the guide portion is configured to guide the tip of the guide wire further toward the slit.

[0043] According to some applications of the present invention, there is also provided an apparatus comprising:

[0044] A blood pump configured to be placed in a subject, the blood pump comprising:

[0045] impeller;

[0046] a frame configured to be disposed around the impeller;

[0047] a distal tip portion disposed distally relative to the frame; and

[0048] a duckbill valve that is fully disposed within the distal-most 10 mm of the distal tip portion,

[0049] The duckbill valve defines a wide inlet and a narrow tip defining a slit therethrough.

[0050] The duckbill valve faces proximally such that the wide inlet faces the distal end of the distal tip portion and the narrow tip faces away from the distal end of the distal tip portion.

[0051] According to some applications of the present invention, there is also provided an apparatus for use with a guide wire, the apparatus comprising:

[0052] a percutaneous medical device defining a guidewire lumen extending from a proximal end of the device to a distal end of the device;

[0053] a duckbill valve disposed within the distal portion of the guidewire lumen,

[0054] The duckbill valve defines a wide inlet and a narrow tip defining a slit therethrough.

[0055] The duckbill valve faces proximally such that the wide inlet faces toward the distal end of the guidewire lumen and the narrow tip faces away from the distal end of the guidewire lumen; and

[0056] A guide wire guide is disposed within the guide wire lumen at a position proximal to the duckbill valve, the guide wire guide being shaped to define a hole therethrough, the diameter of the hole narrowing from the proximal end of the guide wire guide to the distal end of the guide wire guide, the shape of the guide wire guide being configured to guide the tip of the guide wire toward the slit at the narrow proximal end of the duckbill valve when the guide wire is inserted from the proximal end of the percutaneous medical device.

[0057] For some applications, the duckbill valve is shaped to define a converging guide portion at a proximal end thereof that converges toward the slit, such that the guide portion is configured to guide the tip of the guide wire further toward the slit.

[0058] According to some applications of the present invention, there is also provided an apparatus comprising:

[0059] A left ventricular assist device configured to assist left ventricular function in a subject, the left ventricular assist device comprising:

[0060] a tube configured to pass through an aortic valve of the subject such that a proximal end of the tube is disposed within the aorta of the subject and a distal end of the tube is disposed within the left ventricle of the subject;

[0061] a frame disposed within at least a portion of the tube, the frame defining a plurality of cells, the frame being configured such that in a non-radially constrained configuration of the frame, the frame includes a generally cylindrical portion, each cell within the cylindrical portion having a width measured around a circumference of the cylindrical portion of less than 2 mm;

[0062] an inner liner lining at least a portion of the cylindrical portion of the frame; and

[0063] an impeller disposed within the frame such that, in its non-radially constrained configuration, at a location where the impeller spans the greatest, the impeller is disposed within the cylindrical portion of the frame such that the gap between the outer edge of the impeller and the inner liner is less than 1 mm,

[0064] The impeller is configured to:

[0065] Rotates to pump blood from the left ventricle to the aorta, and

[0066] Stable relative to the frame so that during rotation of the impeller, the gap between the outer edge of the impeller and the liner is maintained and is substantially constant.

[0067] For some applications, the impeller is configured to reduce the risk of hemolysis by being stabilized relative to the frame, compared to if the impeller were not stable relative to the frame.

[0068] For some applications, each cell within the cylindrical portion has a width measured around the circumference of the cylindrical portion of between 1.4 mm and 1.6 mm.

[0069] For some applications, each cell within the cylindrical portion has a width measured around the circumference of the cylindrical portion of between 1.6 mm and 1.8 mm.

[0070] For some applications, the impeller is configured such that the gap between the outer edge of the impeller and the liner is less than 0.4 mm.

[0071] For some applications:

[0072] The left ventricular assist device further includes an axial shaft and a proximal radial support and a distal radial support respectively disposed at the proximal end and the distal end of the frame, the axial shaft passing through the proximal radial support and the distal radial support;

[0073] The impeller is coupled to the axial shaft; and

[0074] The impeller is stabilized relative to the frame by holding the impeller in a radially fixed position relative to the axial shaft and the axial shaft being rigid.

[0075] For some applications, the impeller includes bushings disposed about the axial shaft, at least one of the bushings being configured to be slidable relative to the axial shaft, and the impeller is stabilized relative to the frame by a region along the axial shaft where the at least one bushing is configured to be slidable relative to the axial shaft, the region being coated to substantially prevent impeller vibration by reducing a clearance between the at least one bushing and the axial shaft.

[0076] For some applications, the impeller is stabilized relative to the frame by substantially preventing vibration of the frame relative to the axial shaft by having a ratio of the length of the cylindrical portion of the frame to the total length of the frame greater than 1:2.

[0077] For some applications, the ratio of the length of the cylindrical portion of the frame to the total length of the frame is greater than 2:3.

[0078] According to some applications of the present invention, there is also provided an apparatus comprising:

[0079] A left ventricular assist device configured to assist left ventricular function in a subject, the left ventricular assist device comprising:

[0080] a tube configured to pass through an aortic valve of the subject such that a proximal end of the tube is disposed within the aorta of the subject and a distal end of the tube is disposed within the left ventricle of the subject;

[0081] a frame disposed within at least a portion of the tube, the frame defining a plurality of cells, the frame configured such that in a non-radially constrained configuration of the frame, the frame includes a generally cylindrical portion;

[0082] a proximal radial support and a distal radial support disposed at the proximal end and the distal end of the frame, respectively;

[0083] an axial shaft passing through the proximal radial support and the distal radial support;

[0084] an inner liner lining at least a portion of the cylindrical portion of the frame; and

[0085] an impeller coupled to the axial shaft within the frame such that, in its non-radially constrained configuration, the impeller is disposed within the cylindrical portion of the frame at a location where the impeller spans the greatest distance, such that the gap between the outer edge of the impeller and the liner is less than 1 mm,

[0086] The impeller includes bushings disposed about the axial shaft, at least one of the bushings being configured to be slidable relative to the axial shaft, and

[0087] The impeller is stabilized relative to the frame by a region along the axial shaft where at least one bushing is configured to be slidable relative to the axial shaft, the region being coated to substantially prevent impeller vibration by reducing a gap between the at least one bushing and the impeller.

[0088] For some applications, at least one bushing is configured to be slidable relative to the axial shaft in an area along the axial shaft, the area being coated with a diamond-like carbon coating. For some applications, at least one bushing is configured to be slidable relative to the axial shaft in an area along the axial shaft, the area being coated with a polytetrafluoroethylene coating. For some applications, at least one bushing is configured to be slidable relative to the axial shaft in an area along the axial shaft, the area being coated with a polymer sleeve. For some applications, the impeller is configured to reduce the risk of hemolysis by being stabilized relative to the frame, compared to a situation where the impeller is unstable relative to the frame.

[0089] According to some applications of the present invention, there is also provided an apparatus comprising:

[0090] A left ventricular assist device configured to assist left ventricular function in a subject, the left ventricular assist device comprising:

[0091] a tube configured to pass through an aortic valve of the subject such that a proximal end of the tube is disposed within the aorta of the subject and a distal end of the tube is disposed within the left ventricle of the subject;

[0092] a frame disposed within at least a portion of the tube, the frame defining a plurality of cells, the frame configured such that in a non-radially constrained configuration of the frame, the frame includes a generally cylindrical portion;

[0093] a proximal radial support and a distal radial support disposed at the proximal end and the distal end of the frame, respectively;

[0094] an axial shaft passing through the proximal radial support and the distal radial support;

[0095] an inner liner lining at least a portion of the cylindrical portion of the frame; and

[0096] an impeller coupled to the axial shaft within the frame such that, in its non-radially constrained configuration, the impeller is disposed within the cylindrical portion of the frame at a location where the impeller spans the greatest distance, such that the gap between the outer edge of the impeller and the liner is less than 1 mm,

[0097] The impeller is stabilized relative to the frame in such a way that vibration of the frame relative to the axial shaft is substantially prevented by a ratio of the length of the cylindrical portion of the frame to the total length of the frame being greater than 1:2.

[0098] For some applications, the ratio of the length of the cylindrical portion of the frame to the total length of the frame is greater than 2:3.

[0099] For some applications, the impeller is configured to reduce the risk of hemolysis by being stabilized relative to the frame, compared to if the impeller were unstable relative to the frame.

[0100] According to some applications of the present invention, a method is further provided, comprising:

[0101] The impeller is manufactured in the following manner:

[0102] forming a structure having a first bushing and a second bushing at a proximal end and a distal end of the structure, the first bushing and the second bushing being connected to each other by at least one elongated member;

[0103] radially expanding the at least one elongated element and forming the at least one helical elongated element at least in part by axially compressing the structure; and

[0104] coupling an elastomeric material to the at least one helical elongated element such that the at least one helical elongated element to which the elastomeric material is coupled defines a blade of the impeller, the coupling being performed such that a layer of material is disposed about a radially outer edge of the at least one helical elongated element, the layer of material forming an effective edge of the blade of the impeller;

[0105] The method comprises the steps of performing a step of reinforcing the bonding of the elastomeric material to the at least one helical elongated element in a manner that does not result in protrusion from the effective edge of the blades of the impeller.

[0106] For some applications, manufacturing the impeller further includes placing a spring within the structure such that the spring extends from the first bushing to the second bushing, and coupling the elastomeric material to the at least one helical elongated element includes forming a film of the elastomeric material extending from the at least one helical elongated element to the spring.

[0107] For some applications:

[0108] Forming the structure includes: forming the structure having a first bushing and a second bushing at a proximal end and a distal end of the structure, the end portions being connected to each other by two elongated members;

[0109] Radially expanding at least one elongate element and forming at least one helical elongate element comprises: radially expanding two elongate elements and forming two helical elongate elements; and

[0110] Coupling the elastomeric material to the at least one helical elongated element includes coupling the elastomeric material to two helical elongated elements such that the two helical elongated elements to which the elastomeric material is coupled define blades of the impeller.

[0111] For some applications:

[0112] Forming the structure includes: forming the structure having a first bushing and a second bushing at a proximal end and a distal end of the structure, the end portions being connected to each other by three or more elongated members;

[0113] Radially expanding at least one elongate element and forming at least one helical elongate element comprises: radially expanding three elongate elements and forming three or more helical elongate elements; and

[0114] Coupling the elastomeric material to the at least one helical elongate element includes coupling the elastomeric material to three or more helical elongate elements such that each of the three or more helical elongate elements to which the elastomeric material is coupled defines a respective blade of the impeller.

[0115] For some applications, radially expanding the at least one elongated element and forming the at least one helical elongated element further includes twisting the structure.

[0116] For some applications, performing the step of enhancing the bonding of the elastomeric material to the at least one helical elongated element includes placing a suture within a groove defined by the at least one helical elongated element such that the suture does not protrude from a radially outer edge of the helical elongated element, the suture being configured to enhance the bonding of the elastomeric material to the at least one helical elongated element.

[0117] For some applications, performing the step of enhancing bonding of the elastomeric material to the at least one helical elongated element includes placing a tightly wound coil of wire around the at least one helical elongated element such that the elastomeric material forms a substantially smooth layer along a radially outer edge of the coil of wire, the coil of wire being configured to enhance bonding of the elastomeric material to the at least one helical elongated element.

[0118] For some applications, performing the step of enhancing bonding of the elastomeric material to the at least one helical elongated element includes placing a sleeve around the at least one helical elongated element such that the elastomeric material forms a substantially smooth layer along a radially outer edge of the sleeve, the sleeve being configured to enhance bonding of the elastomeric material to the at least one helical elongated element.

[0119] For some applications, performing the step of reinforcing the bonding of the elastomeric material to the at least one helical elongated member includes providing the at least one helical elongated member with a rounded cross-section such that the elastomeric material forms a layer of substantially uniform thickness at an interface between the elastomeric material and the helical elongated member.

[0120] According to some applications of the present invention, there is also provided an apparatus for use with a delivery catheter, the apparatus comprising:

[0121] A blood pump comprising:

[0122] an impeller configured to pump blood through the subject's body;

[0123] a frame, which is arranged around the impeller,

[0124] The impeller and the frame define a non-radially constrained configuration in which the impeller is configured to pump blood within a subject, and a radially constrained configuration in which the impeller and frame are inserted into and removed from the subject using a delivery catheter,

[0125] The frame defines struts having a structure such that as the frame transitions from a proximal end of the frame to a center of the frame, the struts pass through a junction where two struts branch off from a single strut in a Y-shape;

[0126] The structure of the struts of the frame is configured such that in response to the distal end of the delivery catheter and the frame being moved into an overlapping position relative to each other, the frame is configured to assume its radially constrained configuration by becoming axially elongated, and is configured to cause the impeller to assume its radially constrained configuration by becoming axially elongated.

[0127] For some applications, the structure of the struts of the frame is configured such that in response to the distal end of the delivery catheter and the frame being moved into an overlapping position relative to each other, the frame is configured to assume its radially constrained configuration by becoming axially elongated, and is configured to cause the impeller to assume its radially constrained configuration by becoming axially elongated, in such a way that the paired struts branching from the joint are configured to pivot about the joint and move closer to each other, thereby closing.

[0128] For some applications, the frame, in its radially unconstrained configuration, defines a proximal tapered portion, a distal tapered portion, and a cylindrical portion therebetween.

[0129] For some applications, the strut density of the frame is constant within the cylindrical portion of the frame.

[0130] For some applications, the density of the struts increases from the proximal tapered portion to the cylindrical portion, and from the distal tapered portion to the cylindrical portion.

[0131] For some applications, the impeller is configured to move relative to the frame during operation of the blood pump, and the range of movement of the impeller is such that during at least some operation of the blood pump, at least a portion of the impeller is disposed within the proximal tapered portion of the frame, and during at least some operation of the blood pump, at least a portion of the impeller is disposed within the cylindrical portion of the frame.

[0132] For some applications, the impeller is configured to be disposed within the cylindrical portion of the frame at a location where the impeller spans a maximum throughout operation of the blood pump.

[0133] For some applications, each cell within the cylindrical portion has a width less than 2 mm measured around the circumference of the cylindrical portion.

[0134] For some applications, each cell within the cylindrical portion has a width measured around the circumference of the cylindrical portion of between 1.4 mm and 1.6 mm.

[0135] For some applications, each cell within the cylindrical portion has a width measured around the circumference of the cylindrical portion of between 1.6 mm and 1.8 mm.

[0136] According to some applications of the present invention, a method is further provided, comprising:

[0137] The housing for the impeller of the blood pump is manufactured by the following steps:

[0138] Place the liner around the mandrel;

[0139] placing a cylindrical portion of a frame around the liner, the cylindrical portion of the frame including struts defining a generally cylindrical shape;

[0140] placing a distal portion of an elongated tube about at least a portion of the frame, the tube including a proximal portion defining at least one blood outlet opening;

[0141] heating the liner, the frame, and the distal portion of the elongated tube via the mandrel while the distal portion is disposed around at least a portion of the frame; and

[0142] While heating the liner, frame, and distal portion of the elongated tube, pressure is applied from outside the distal portion of the elongated tube to conform the distal portion of the elongated tube to the structure of the struts of the frame and couple the liner and distal portion of the elongated tube to the frame.

[0143] For some applications, the method further includes, after coupling the liner and the distal portion of the elongated tube to the frame, shaping the distal end of the frame to define a widened inlet.

[0144] For some applications, the method further includes, after coupling the liner and the distal portion of the elongated tube to the frame, shaping a portion of the frame to form a converging region such that the frame defines a narrowed region proximate a location within the frame configured to receive the impeller.

[0145] For some applications, positioning the distal portion of the elongated tube around at least a portion of the frame includes positioning the distal portion of the elongated tube around the entire cylindrical portion of the frame such that the distal portion of the elongated tube overlaps the entire liner.

[0146] For some applications:

[0147] The liner and the elongated tube include the liner and the elongated tube being made of different materials from each other, and the thermoforming temperature of the material making the liner is higher than the thermoforming temperature of the material making the elongated tube, and

[0148] Heating the liner, frame, and distal portion of the elongated tube includes heating the liner, frame, and distal portion of the elongated tube to a temperature above a thermoforming temperature of the material from which the elongated tube is made and below a thermoforming temperature of the material from which the liner is made.

[0149] For some applications, applying the pressure from outside the distal portion of the elongated tube includes applying the pressure from outside the distal portion of the elongated tube using an outer tube made of silicone.

[0150] For some applications, applying pressure from outside the distal portion of the elongated tube to couple the liner and the distal portion of the elongated tube to the frame includes coupling the liner to an inner surface of the cylindrical portion of the frame such that the liner forms a substantially cylindrical tube.

[0151] For some applications, the struts within the cylindrical portion of the frame are shaped to define cells, and each cell has a width less than 2 mm measured around the circumference of the cylindrical portion.

[0152] For some applications, positioning the distal portion of the elongated tube around at least a portion of the frame includes positioning the distal portion of the elongated tube around only a portion of the cylindrical portion of the frame such that the distal portion of the elongated tube does not overlap the entire liner.

[0153] For some applications, positioning the distal portion of the elongated tube around only a portion of the cylindrical portion of the frame includes preventing the portion of the cylindrical portion of the frame positioned around the distal portion of the elongated tube from radially expanding, thereby causing the portion of the cylindrical portion of the frame positioned around the distal portion of the elongated tube to be narrower than the portion of the cylindrical portion of the frame not positioned around the distal portion of the elongated tube.

[0154] According to some applications of the present invention, there is also provided an apparatus comprising:

[0155] A blood pump configured to be placed in a subject, the blood pump comprising:

[0156] impeller;

[0157] a frame configured to be disposed about the impeller, the frame comprising struts;

[0158] an inner liner, which is disposed within the frame;

[0159] an outer covering material that is joined from the outside of the frame to the inner joining material at discrete joining areas along the length of the frame,

[0160] Along the length of the frame, the density of the struts of the frame at the connection area is less than the density of the struts of the frame at other areas.

[0161] According to some applications of the present invention, there is also provided an apparatus comprising:

[0162] A blood pump configured to be placed in a subject, the blood pump comprising:

[0163] impeller;

[0164] a frame configured to be disposed about the impeller, the frame including a strut and a cylindrical portion of the frame shaped to define a cylindrical cross-section;

[0165] an inner liner, which is disposed within the frame;

[0166] An outer covering material is connected from the outside of the frame to the inner connecting material, the outer covering material is disposed only around a portion of the cylindrical portion of the frame, and the outer covering material is configured to limit radial expansion of the portion of the cylindrical portion of the frame around which the outer covering material is disposed, such that a portion of a distal portion of the cylindrical region of the frame around which the outer covering material is disposed is narrower than a portion of the cylindrical region of the frame not around which the outer covering material is disposed.

[0167] According to some applications of the present invention, there is also provided an apparatus comprising:

[0168] A blood pump configured to be placed in a subject, the blood pump comprising:

[0169] impeller;

[0170] a frame configured to be disposed about the impeller, the frame configured to define a cylindrical portion having a substantially cylindrical cross-section;

[0171] a cover material coupled to the cylindrical portion of the frame such that a distal end of the cylindrical portion of the frame defines a blood inlet opening, the impeller being configured to be disposed within 15 mm of the blood inlet opening throughout operation of the impeller,

[0172] A portion of the frame is shaped to reduce turbulence generated as blood flows from the blood inlet opening to the impeller.

[0173] For some applications, the portion of the frame includes a widened portion of the frame.

[0174] For some applications, the portion of the frame includes a portion of the frame shaped to converge toward the impeller.

[0175] The present invention will be more fully understood from the following detailed description of embodiments of the invention taken in conjunction with the accompanying drawings, in which: BRIEF DESCRIPTION OF THE DRAWINGS

[0176] Figure 1A 、 Figure 1B and Figure 1C is a schematic diagram of a ventricular assist device according to some applications of the present invention, the distal end of the ventricular assist device being configured for placement in the left ventricle of a subject;

[0177] Figure 2A 、 Figure 2B 、 Figure 2C 、 Figure 2D 、 Figure 2E and Figure 2F is a schematic diagram of a frame housing an impeller of a ventricular assist device according to some applications of the present invention;

[0178] Figure 3A 、 Figure 3B 、 Figure 3C 、 Figure 3D 、 Figure 3E 、 Figure 3F 、 Figure 3G 、 Figure 3H 、 Figure 3I 、 Figure 3J and Figure 3K is a schematic diagram of an impeller or portion thereof of a ventricular assist device according to some applications of the present invention;

[0179] Figure 4 is a schematic diagram of an impeller disposed within a frame of a ventricular assist device according to some applications of the present invention;

[0180] Figure 5A and Figure 5B is a schematic diagram of an impeller and a frame of a ventricular assist device in a non-radially constrained state and a radially constrained state, respectively, according to some applications of the present invention;

[0181] Figure 5C is a schematic diagram of a typical bearing assembly used in a prior art axial flow impeller-based blood pump;

[0182] Figure 6A and Figure 6Bis a schematic diagram of a ventricular assist device according to some applications of the present invention, with an impeller of the ventricular assist device at various stages of a motion cycle relative to a frame of the ventricular assist device;

[0183] Figure 6C is a schematic diagram of a distal tip element of a ventricular assist device according to some applications of the present invention, the distal tip element comprising an axial shaft receiving tube and a distal tip portion;

[0184] Figure 6D is a schematic diagram of an axial shaft of a ventricular assist device according to some applications of the present invention, the axial shaft being at least partially covered or coated to reduce a clearance between the axial shaft and a bushing of an impeller sliding on the axial shaft;

[0185] Figure 6E is a schematic diagram of an axial shaft of a ventricular assist device and a bushing of an impeller sliding on the axial shaft according to some applications of the present invention, the axial shaft and the bushing of the impeller being configured to prevent rotational movement of the bushing of the impeller relative to the axial shaft;

[0186] Figure 6F and Figure 6G is a schematic diagram of an impeller housing according to some applications of the present invention, the impeller housing being configured to provide a clearance between the impeller and the housing that varies during a cardiac cycle of a subject;

[0187] Figure 7 is a schematic diagram of a motor unit of a ventricular assist device according to some applications of the present invention;

[0188] Figure 8A and Figure 8B is a schematic diagram of a motor unit of a ventricular assist device according to some applications of the present invention;

[0189] Figure 9 is a graph showing changes in the length of a drive cable of a ventricular assist device as a function of the pressure gradient resisted by an impeller of a blood pump measured in experiments conducted by the inventors of the present application;

[0190] Figure 10A 、 Figure 10B and Figure 10C is a schematic diagram of a drive cable for a ventricular assist device according to some applications of the present invention;

[0191] Figure 10D 、 Figure 10E and Figure 10F is a schematic diagram of a drive cable and an axial shaft of a ventricular assist device according to some applications of the present invention;

[0192] Figure 11A and Figure 11Bis a schematic diagram of an impeller according to some applications of the present invention, the impeller being coupled to an axial shaft at a distal end of the impeller and not coupled to an axial shaft at a proximal end of the impeller;

[0193] Figure 11C Is used to promote Figure 11A and Figure 11B A schematic diagram of the impeller crimping connection portion;

[0194] Figure 12A is shown when the impeller is configured as Figure 11A A graph showing the relationship between the pressure gradient against which the impeller pumps and the pitch of the impeller;

[0195] Figure 12B is a graph showing pressure-flow curves for impellers having corresponding pitches according to some applications of the present invention;

[0196] Figure 13A 、 Figure 13B and Figure 13C is a schematic diagram of a process for cleaning a drive cable and / or radial support of a ventricular assist device according to some applications of the present invention;

[0197] Figure 13D is a schematic diagram of a ventricular assist device according to some applications of the present invention, the ventricular assist device including an expandable portion (e.g., a balloon) disposed about a distal tip portion thereof, the expandable portion configured to be inflated by a fluid for cleaning a drive cable of the device;

[0198] Figure 13E is a schematic diagram of techniques for reducing friction between a drive cable and an outer tube in which the drive cable rotates, and / or for reducing friction at radial supports of a ventricular assist device, according to some applications of the present invention;

[0199] Figure 14A 、 Figure 14B and Figure 14C is a schematic diagram of a stator according to some applications of the present invention, the stator being configured to be disposed within a tube of a ventricular assist device proximal to a frame in which an impeller of the ventricular assist device is disposed;

[0200] Figure 15A 、 Figure 15B 、 Figure 15C 、 Figure 15D and Figure 15E is a schematic diagram of a stator embedded in a tube of a ventricular assist device according to some applications of the present invention;

[0201] Figure 16A and Figure 16Bis a schematic diagram of a ventricular assist device including one or more ventricular blood pressure measurement tubes according to some applications of the present invention;

[0202] Figure 16C and Figure 16D is a schematic diagram of a ventricular assist device having an aortic blood pressure measurement channel within a delivery catheter according to some applications of the present invention;

[0203] Figure 16E is a schematic diagram of a ventricular assist device according to some applications of the present invention, the ventricular assist device including one or more sensors disposed on an outer surface of a tube of the device;

[0204] Figure 17A 、 Figure 17B 、 Figure 17C and Figure 17D is a schematic diagram of a ventricular assist device according to some applications of the present invention, the ventricular assist device including a pitot tube configured to measure blood flow through a tube of the device;

[0205] Figure 18 is a schematic diagram of a ventricular assist device including a coronary tube and / or line according to some applications of the present invention;

[0206] Figure 19A 、 Figure 19B 、 Figure 19C 、 Figure 19D 、 Figure 19E 、 Figure 19F 、 Figure 19G and Figure 19H is a schematic diagram of a ventricular assist device according to some applications of the present invention, the ventricular assist device including a liner positioned on the inside of a frame housing an impeller;

[0207] Figure 20A 、 Figure 20B and Figure 20C is a schematic diagram of a ventricular assist device according to some applications of the present invention, the ventricular assist device including an expandable portion (e.g., a balloon) disposed about a distal tip portion thereof;

[0208] Figure 21 is a schematic diagram of a ventricular assist device placed within the left ventricle of a subject, showing a cross-sectional view of the left ventricle, according to some applications of the present invention;

[0209] Figure 22A 、 Figure 22B 、 Figure 22C and Figure 22D is a schematic diagram of a distal tip element of a ventricular assist device according to some applications of the present invention, the distal tip element being at least partially curved to define a question mark shape or a tennis racket shape;

[0210] Figure 23A and Figure 23B According to some applications of the present invention Figure 22D A schematic diagram of a ventricular assist device positioned within the left ventricle of a subject;

[0211] Figure 24A 、 Figure 24B and Figure 24C is a schematic diagram of a distal tip element configured to center itself relative to an aortic valve of a subject according to some applications of the present invention;

[0212] Figure 25A 、 Figure 25B 、 Figure 25C 、 Figure 25D and Figure 25E is a schematic diagram of a ventricular assist device according to some applications of the present invention, the ventricular assist device including a tube configured to become tortuous as blood is pumped through the tube;

[0213] Figure 25F is a schematic diagram of a ventricular assist device according to some applications of the present invention, the ventricular assist device including a bending element made of a shape memory material and configured to provide a predetermined curvature to a portion of the ventricular assist device;

[0214] Figure 26A 、 Figure 26B 、 Figure 26C 、 Figure 26D 、 Figure 26E and Figure 26F is a schematic diagram of an at least partially curved distal tip element of a ventricular assist device according to some applications of the present invention;

[0215] Figure 27A 、 Figure 27B and Figure 27C is a schematic diagram of an atraumatic protrusion according to some applications of the present invention, the atraumatic protrusion comprising a closed ellipse or a closed circle and configured to extend distally from a distal tip element of a ventricular assist device;

[0216] Figure 28A is a schematic diagram of a duckbill valve and a guidewire guide disposed at the distal end of an atraumatic tip according to some applications of the present invention;

[0217] Figure 28B and Figure 28C According to some applications of the present invention Figure 28A Schematic diagram of corresponding views of a duckbill valve;

[0218] Figure 28D and Figure 28EAccording to some applications of the present invention Figure 28A Schematic diagrams of corresponding views of a guide wire guide;

[0219] Figure 29 is a schematic diagram of a delivery catheter according to some applications of the present invention, the delivery catheter including a sheath configured to facilitate reinsertion of a guidewire through a percutaneous puncture;

[0220] Figure 30 is a schematic diagram of a ventricular assist device including two impellers according to some applications of the present invention;

[0221] Figure 31 is a schematic diagram of a ventricular assist device including two impellers according to some applications of the present invention;

[0222] Figure 32A 、 Figure 32B 、 Figure 32C 、 Figure 32D and Figure 32E is a schematic diagram of a ventricular assist device configured to assist the function of the right heart of a subject according to some applications of the present invention; and

[0223] Figure 33 is a schematic diagram of an intravenous assist device according to some applications of the present invention. DETAILED DESCRIPTION

[0224] Now refer to Figure 1A 、 Figure 1B and Figure 1C , which are schematic illustrations of a ventricular assist device 20 according to some applications of the present invention, with a distal end of the ventricular assist device configured to be positioned in a left ventricle 22 of a subject. Figure 1A shows an overview of a ventricular assist device system comprising a console 21 and a motor unit 23, Figure 1B shows a ventricular assist device inserted into the left ventricle of a subject, and Figure 1C The pump portion 27 of the ventricular assist device is shown in more detail. The ventricular assist device includes a tube 24 that passes through the aortic valve 26 of the subject such that a proximal end 28 of the tube is disposed in the subject's aorta 30 and a distal end 32 of the tube is disposed within the left ventricle 22. Typically, the tube 24 (which is sometimes referred to herein as a "blood pump tube") is an elongated tube with an axial length that is typically much greater than its diameter. The scope of the invention includes using the apparatus and methods described herein in anatomical locations other than the left ventricle and aorta. Accordingly, the ventricular assist device and / or portions thereof are sometimes referred to herein (in the specification and claims) as a blood pump.

[0225] For some applications, the ventricular assist device is used to assist the function of the subject's left ventricle during percutaneous coronary intervention. In this case, the ventricular assist device is typically used for a period of up to 10 hours (e.g., up to 6 hours) during which there is a risk of developing hemodynamic instability (e.g., during or immediately after percutaneous coronary intervention). Alternatively or additionally, the ventricular assist device is used to assist the function of the subject's left ventricle for a longer period of time (e.g., for example, 2 days-20 days, e.g., 4 days-14 days) in a patient suffering from cardiogenic shock, which can include any low cardiac output state (e.g., acute myocardial infarction, myocarditis, cardiomyopathy, postpartum, etc.). For some applications, the ventricular assist device is used to assist the function of the subject's left ventricle for a longer period of time (e.g., weeks or months), for example, in "bridge to recovery" therapy. For some such applications, the ventricular assist device is permanently or semi-permanently implanted, and the impeller of the ventricular assist device is powered transcutaneously, for example, using an external antenna magnetically coupled to the impeller.

[0226] like Figure 1B , which illustrates the steps of deploying a ventricular assist device in the left ventricle, typically, the distal end of the ventricular assist device is guided to the left ventricle via a guide wire 10. During insertion of the distal end of the device into the left ventricle, a delivery catheter 143 is positioned over the distal end of the device. Once the distal end of the device is positioned in the left ventricle, the delivery catheter is typically retracted into the aorta and the guide wire is withdrawn from the subject's body. Typically, retraction of the delivery catheter causes the self-expanding component at the distal end of the device to assume a non-radially constrained configuration, as described in further detail below. Typically, the ventricular assist device is inserted into a subject to provide acute treatment to the subject. For some applications, in order to withdraw the left ventricular device from the subject at the conclusion of treatment, the delivery catheter is advanced over the distal end of the device, which causes the self-expanding component at the distal end of the device to assume a radially constrained configuration. Alternatively or additionally, the distal end of the device is retracted into the delivery catheter, which causes the self-expanding component at the distal end of the device to assume a radially constrained configuration.

[0227] For some applications (not shown), the ventricular assist device and / or delivery catheter 143 includes an ultrasound transducer at its distal end, and the ventricular assist device is advanced toward the subject's ventricle under ultrasound guidance.

[0228] Now refer to Figure 1C, which shows the pump portion 27 of the ventricular assist device 20 in more detail. Typically, the impeller 50 is disposed within the distal portion 102 of the tube 24 and is configured to pump blood from the left ventricle into the aorta by rotation. The tube typically defines one or more blood inlet openings 108 at the distal end of the tube. During operation of the impeller, blood flows from the left ventricle into the tube through the blood inlet openings. For some applications, the proximal portion 106 of the tube defines one or more blood outlet openings 109. During operation of the impeller, blood flows from the tube into the ascending aorta through the blood outlet openings.

[0229] For some applications, a console 21 (e.g., a computer processor 25) is typically included. Figure 1A For example, a computer processor may control motor 74 (as shown) to drive the impeller to rotate. Figure 7 As shown), the motor 74 is provided in the motor unit 23 (as Figure 1A ) and via a drive cable 130 (as Figure 7 ) drives the impeller to rotate. For some applications, the computer processor is configured to detect physiological parameters of the subject (e.g., left ventricular pressure, cardiac afterload, rate of change of left ventricular pressure, etc.) and control the rotation of the impeller in response thereto, as described in further detail below. Typically, the operations performed by the computer processor described herein convert the physical state of the memory into a different magnetic polarity, charge, etc., depending on the memory technology used, which is an actual physical article that communicates with the computer processor. The computer processor 25 is typically a hardware device programmed with computer program instructions to produce a special-purpose computer. For example, when programmed to perform the techniques described herein, the computer processor 25 typically acts as a special-purpose ventricular assist computer processor and / or a special-purpose blood pump computer processor.

[0230] For some applications, the cleaning system 29 (in Figure 1A ) drives fluid (e.g., glucose solution) through various portions of the ventricular assist device 20, for example, to cool the various portions of the device and / or to flush debris from the various portions of the device. The cleaning system 29 will be described in further detail below.

[0231] Typically, along the distal portion 102 of the tube 24, the frame 34 is disposed within the tube around the impeller 50. The frame is typically made of a shape memory alloy, such as Nitinol. For some applications, the shape memory alloy of the frame is shaped such that in the absence of any force being applied to the distal portion 102 of the tube 24, at least a portion of the frame (and therefore the distal portion 102 of the tube 24) assumes a generally circular, elliptical, or polygonal cross-sectional shape. By assuming the generally circular, elliptical, or polygonal cross-sectional shape of the frame, the frame is configured to maintain the distal portion of the tube in an open state. Typically, during operation of the ventricular assist device, the distal portion of the tube is configured to be placed within the subject such that the distal portion of the tube is at least partially disposed within the left ventricle.

[0232] For some applications, along the proximal portion 106 of the tube 24, the frame is not disposed within the tube, and thus the tube is not supported in the open position by the frame 34. The tube 24 is typically made of a collapsible material that is impermeable to blood. For example, the tube 24 may include polyurethane, polyester, and / or silicone. Alternatively or additionally, the tube may be made of polyethylene terephthalate (PET) and / or polyether block amide (e.g., ). For some applications (not shown), the tube is reinforced with a reinforcing structure, for example, a braided reinforcing structure such as a braided nitinol tube. Typically, the proximal portion of the tube is configured to be positioned such that it is at least partially disposed within the ascending aorta of the subject. For some applications, the proximal portion of the tube passes through the aortic valve of the subject, from the left ventricle of the subject, into the ascending aorta of the subject, such as Figure 1B As shown. As described above, the tube typically defines one or more blood inlet openings 108 at the distal end of the tube, and during the operation of the impeller, blood flows from the left ventricle into the tube via the blood inlet openings. For some applications, the proximal portion of the tube defines one or more blood outlet openings 109, and during the operation of the impeller, blood flows from the tube into the ascending aorta via the blood outlet openings 109. Typically, the tube defines a plurality of blood outlet openings 109, for example, between two blood outlet openings and eight blood outlet openings (for example, between two blood outlet openings and four blood outlet openings). During the operation of the impeller, the blood flow pressure through the tube typically keeps the proximal portion of the tube in an open state. For some applications, for example, in the event of an impeller failure, the proximal portion of the tube is configured to collapse inward in response to the pressure outside the proximal portion of the tube exceeding the pressure inside the proximal portion of the tube. In this way, the proximal portion of the tube acts as a safety valve, thereby preventing blood flow from the aorta from entering the left ventricle in the reverse direction.

[0233] Refer again Figure 1CFor some applications, the frame 34 is shaped such that the frame defines a proximal tapered portion 36, a central cylindrical portion 38, and a distal tapered portion 40. Typically, the proximal tapered portion is such that the narrow end of the cone is proximal relative to the wide end of the cone. More typically, the distal tapered portion is such that the narrow end of the cone is distal relative to the wide end of the cone. For some applications, the tube 24 extends to the end of the cylindrical portion 38 (or slightly proximal or distal thereto) such that the distal end of the tube defines a single axially-facing blood inlet opening 108, as shown. Figure 1C For some applications, within at least a portion of the frame 34, a liner 39 is positioned over the frame, as described below with reference to Figures 19A-19H As described. Depending on the respective application, the liner partially overlaps or completely overlaps the tube 24 on the portion of the frame lined by the liner. For such applications, the distal end of the liner defines a single axially facing blood inlet opening 108. For some applications (not shown), the tube 24 extends to the end of the distal tapered portion 40, and the tube defines one or more lateral blood inlet openings (not shown), for example, as described in US2019 / 0209758 to Tuval, which is incorporated herein by reference. For such applications, the tube typically defines two to four lateral blood inlet openings.

[0234] Typically, the tube 24 includes a tapered proximal portion 42 and a cylindrical central portion 44. The proximal tapered portion is typically such that the narrow end of the cone is proximal relative to the wide end of the cone. Typically, the blood outlet opening 109 is defined by the tube 24 such that the opening extends at least partially along the proximal tapered section of the tube 24. For some such applications, the blood outlet opening is teardrop shaped, such as Figure 1C Typically, the teardrop-shaped nature of the blood outlet opening, combined with the opening extending at least partially along the proximal tapered section of the tube 24, causes blood to flow out of the blood outlet opening at its location along flow lines that are substantially parallel to the longitudinal axis of the tube 24.

[0235] As described above, for some applications (not shown), the tube extends to the end of the distal tapered portion 40 of the frame 34. For such applications, the tube typically defines a distal tapered portion in which the narrow end of the cone is distal relative to the wide end of the cone. For some applications (not shown), the diameter of the tube 24 varies along the length of the central portion of the tube, such that the central portion of the tube has a frustoconical shape. For example, the central portion of the tube can widen from its proximal end to its distal end, or can narrow from its proximal end to its distal end. For some applications, at its proximal end, the central portion of the tube has a diameter between 5 mm and 7 mm, while at its distal end, the central portion of the tube has a diameter between 8 mm and 12 mm.

[0236] Refer again Figure 1CThe ventricular assist device typically includes a distal tip element 107 that is distally disposed relative to the frame 34 and includes an axial shaft receiving tube 126 and a distal tip portion 120, both of which will be described in further detail below.

[0237] Now refer to Figure 2A 、 Figure 2B 、 Figure 2C 、 Figure 2D 、 Figure 2E and Figure 2F , which are schematic diagrams of a frame 34 housing an impeller of a ventricular assist device 20 according to some applications of the present invention. As described above, the frame 34 is typically made of a shape memory alloy such as Nitinol, and the shape memory alloy of the frame is shaped so that the frame (and therefore the tube 24) assumes a generally circular, elliptical, or polygonal cross-sectional shape in the absence of any force applied to the tube 24. By assuming its generally circular, elliptical, or polygonal cross-sectional shape, the frame is configured to maintain the distal portion of the tube in an open state.

[0238] Typically, the frame is a stent-like frame in that it includes struts that in turn define cells. More typically, the frame is covered by tubes 24, and / or by a liner 39, as described below with reference to Figures 19A-19H As described below, for some applications, impeller 50 undergoes axial reciprocating motion relative to frame 34. Typically, during the motion of the impeller relative to the frame, the portion of the impeller defining the maximum span of the impeller is located within cylindrical portion 38 of frame 34. In some cases, if the cells of cylindrical portion 38 of frame 34 are too large, tube 24 and / or liner 39 may be stretched between the edges of the cells, causing tube 24 and / or liner 39 to not define a circular cross-section. For some applications, if this occurs in the region of the impeller defining the maximum span of the impeller, the gap between the edge of the impeller blade and tube 24 (and / or liner) at that location is not constant during the impeller's rotational cycle. For some applications, this may result in increased hemolysis compared to a situation where there was a constant gap between the edge of the impeller blade and tube 24 (and / or liner) at that location during the impeller's rotational cycle.

[0239] Reference Figure 2AAt least in part to account for the issues described in the previous paragraph, within the cylindrical portion 38 of the frame 34, the frame defines a large number of relatively small cells. Typically, when the frame is disposed in its non-radially constrained configuration, the maximum cell width CW of each cell within the cylindrical portion of the frame (i.e., the distance from the inner edge of the stent at the central junction on one side of the cell to the inner edge of the stent at the central junction on the other side of the cell, as measured around the circumference of the cylindrical portion 38) is less than 2 mm, e.g., between 1.4 mm and 1.6 mm, or between 1.6 mm and 1.8 mm. Because the cells are relatively small, the tube 24 (and / or liner) defines a substantially circular cross-section within the cylindrical portion of the frame.

[0240] Still refer to Figure 2A , and starting from the proximal end of the frame (on the left side of the figure), the frame typically defines the following portions: (a) a coupling portion 31 via which the frame is coupled to the proximal support 116 of the ventricular assist device (at Figure 4 ), (a) a proximal tapered portion 36, (c) a cylindrical portion 38, (d) a distal tapered portion 40, and (e) a distal strut junction 33. As shown, as the frame transitions from the proximal end of the frame to the center of the frame (e.g., as the frame passes through the coupling portion 31, through the proximal tapered portion 36, and transitions to the cylindrical portion 38), the struts 37 of the frame pass through junctions 35 where two struts branch off from a single strut in a Y-shape. As described in further detail below, the frame 34 is typically placed in a delivery catheter 143 in a radially constrained (i.e., crimped) configuration by the frame being axially elongated. Furthermore, the frame typically transfers its radial narrowing to the impeller, and the impeller becomes radially constrained by axially elongating within the frame. For some applications, the struts of the frame configured in the manner described above facilitate transferring axial extension from the delivery catheter (or other device configured to crimp the frame) to the frame, which in turn facilitates transferring the axial extension to the impeller. This is because the pair of struts branching from each joint 35 are configured to pivot about the joint and move closer to each other, thereby closing.

[0241] Still refer to Figure 2A For some applications, when the frame is coupled to the axial shaft 92 (at Figure 2D ), the distal strut joint 33 remains open so that the impeller is placed within the frame via the distal end of the frame. The distal strut portion is then closed around the outside of the distal support 118, as shown below with reference to Figure 5A-5B For some applications, the proximal end of distal tip element 107 ( Figure 1C ) maintains the distal strut portions in their closed configuration around the outside of the distal support 118.

[0242] Typically, when the frame 34 is disposed in its non-radially constrained configuration, the frame 34 has an overall length greater than 25 mm (e.g., greater than 30 mm) and / or less than 50 mm (e.g., less than 45 mm), e.g., 25 mm to 50 mm, or 30 mm to 45 mm. Typically, when the frame is disposed in its radially constrained configuration (within the delivery catheter 143), the length of the frame increases by between 2 mm and 5 mm. Typically, when the frame 34 is disposed in its non-radially constrained configuration, the cylindrical portion of the frame 34 has a length greater than 10 mm (e.g., greater than 12 mm) and / or less than 25 mm (e.g., less than 20 mm), e.g., 10 mm to 25 mm, or 12 mm to 20 mm. For some applications, the ratio of the length of the cylindrical portion of the frame to the overall length of the frame is greater than 1:4 and / or less than 1:2, e.g., between 1:4 and 1:2.

[0243] Now refer to Figure 2B , which is a schematic diagram of a pump portion of a ventricular assist device 20 according to some applications of the present invention, wherein at least a portion of cylindrical portion 38 of frame 34 of the ventricular assist device has a helical structure 55. For some applications, at least a portion of cylindrical portion 38 of frame 34 of the ventricular assist device has a helical structure 55 so that tube 24 (and / or liner) defines a substantially circular cross-section within the cylindrical portion of the frame, e.g., for the reasons provided above.

[0244] Now refer to Figure 2C , which is a schematic diagram of a frame 34 that transitions from its end to its maximum diameter (i.e., the cylindrical portion of the frame) over a relatively short distance D. Typically, this results in a ratio of the cylindrical portion of the frame to the total length of the frame that is greater than the ratios described above. For example, the ratio of the cylindrical portion of the frame to the total length of the frame may be greater than 1:2 or greater than 2:3. More typically, this results in the angle at which the frame widens within the tapered portion being greater than it would be if the cylindrical portion had a shorter relative length (assuming all else is equal). In turn, for some applications, this reduces vibration of the frame during rotation of the impeller. As described above, to reduce hemolysis, it is typically desirable to maintain a constant gap between the edges of the impeller's blades and the tube 24 (and / or liner 39). Therefore, it is typically desirable to reduce vibration of the frame relative to the impeller.

[0245] Now refer to Figure 2D, which is a schematic diagram of a pump portion of a ventricular assist device according to some applications of the present invention, including an expandable impeller housing 60. For some applications, rather than having a frame 34 surrounding the impeller, the expandable housing surrounds the impeller. For some applications, at least in the region of the housing surrounding the impeller, the frame is configured to define an internal circular cross-section such that a constant gap exists between the edges of the impeller blades and the inner wall of the housing during a rotational cycle of the impeller.

[0246] Typically, for Figure 2D In the illustrated application, the proximal support frame and the distal support frame 61 are disposed within an expandable impeller housing. The support frame is configured to act as a radial support relative to an axial shaft 92 (described below) to which the impeller 50 is coupled. For some applications, the impeller housing is made of a flexible and expandable material. Typically, the impeller housing is inserted into the left ventricle in a deflated state and expands once disposed within the left ventricle, e.g., to assume its deployed shape. Typically, a tube 24 extends proximally from the expandable impeller housing. For some applications, a tube 63 is disposed along the tube 24 (e.g., an inner or outer surface of the tube), and the expandable housing is expanded via the tube. For some applications, the impeller housing is expanded with saline and / or a different solution (e.g., a glucose solution). For some applications, the expandable impeller housing defines one or more blood inlet openings 108.

[0247] Now refer to Figure 2E and Figure 2F , which are schematic diagrams of a flat outline of a frame 34 according to some applications of the present invention, the frame being generally configured as Figure 2A Typically, the frame 34 is laser cut from a tube of a shape memory alloy such as Nitinol. Figure 2E and Figure 2F The outline shown in , depicts (for illustrative purposes) how the frame of the device would appear if, before shaping the frame, longitudinal cuts were made along its length at given circumferential locations in the frame and then the frame was laid flat on a surface. For some applications, within the cylindrical portion 38 of the frame, cells are cut by directing the laser along the peripheral contours of the cells, e.g. Figure 2E As shown in the enlarged portion of FIG. As mentioned above, typically within the cylindrical portion, the cells are relatively small, which means that a relatively large number of cells are cut within the circumference of the frame. Due to the size of the laser used to cut the cells, it may be challenging to pass the laser around the entire perimeter of the cell. However, near the joint, in order to reduce the strain at the joint, it is desirable that the cells be rounded. Therefore, for some applications, approximately Figure 2FThe cylindrical portion of the frame is shown cut. That is, at the joints 35, the laser cuts a rounded edge 41. However, between the joints, the laser cuts a single slit 43, rather than cutting around the perimeter of the cell.

[0248] Now refer to Figure 3A-3C , which are schematic diagrams of impellers 50 or portions thereof according to some applications of the present invention. Typically, the impeller includes at least one outer helical elongate element 52 wound around a central axial spring 54 such that the helical structure defined by the helical elongate element is coaxial with the central axial spring. Typically, the impeller includes two or more helical elongate elements (e.g., three helical elongate elements, such as Figure 3A-3C For some applications, the helical elongated element and the central axial spring are made of a shape memory material, such as a shape memory alloy such as Nitinol. Typically, each of the helical elongated element and the central axial spring supports a membrane 56 of material (e.g., an elastomer such as polyurethane, and / or silicone) between them. For some applications, the membrane of material includes a Nitinol sheet embedded therein, such as to strengthen the membrane of material. For illustrative purposes, the impeller is Figure 3A The material is shown without. Figure 3B and Figure 3C A view of an impeller is shown where the material is supported between the helical elongated element and the spring.

[0249] Each helical elongate element, together with a membrane extending from the helical elongate element to the spring, defines a blade of a corresponding impeller, wherein the helical elongate element defines the outer edge of the blade and the axial spring defines the axis of the impeller. Typically, the membrane of material extends along and covers the spring. For some applications, suture 53 (e.g., polyester suture, such as Figure 3B and Figure 3C 22890 to Schwammenthal, which is incorporated herein by reference. Typically, the suture is configured to facilitate bonding between a membrane of material (which is typically an elastomer, such as polyurethane or silicone) and a spring (which is typically a shape memory alloy, such as nitinol). For some applications, a suture (e.g., a polyester suture, not shown) is wrapped around spring 54. Typically, the suture is configured to facilitate bonding between a membrane of material (which is typically an elastomer, such as polyurethane or silicone) and a spring (which is typically a shape memory alloy, such as nitinol).

[0250] Figure 3CEnlarged views A and B of illustrative figures illustrate two alternative ways in which the suture is tethered around the helical elongated member 52. For some applications, the suture is tethered around the outer surface of the helical elongated member, as shown in enlarged view A. Alternatively, the helical elongated members define grooves 45 on their outer surfaces, and the suture is embedded within the grooves, as shown in enlarged view B. Typically, by embedding the suture within the grooves, the suture does not increase the outer profile of the impeller, and the outer profile of the impeller is defined by the outer surface of the helical elongated member.

[0251] Typically, the proximal ends of the spring 54 and the helical elongate element 52 extend from the impeller's proximal bushing (i.e., sleeve support) 64 such that the proximal ends of the spring 54 and the helical elongate element 52 are disposed at similar radial distances from the impeller's longitudinal axis. Similarly, typically, the distal ends of the spring 54 and the helical elongate element 52 extend from the impeller's distal bushing 58 such that the distal ends of the spring 54 and the helical elongate element 52 are disposed at similar radial distances from the impeller's longitudinal axis. Typically, the spring 54 and the impeller's proximal and distal bushings 64, 58 define an internal cavity 62 therethrough (e.g., Figure 3C shown).

[0252] Now refer to Figure 4 , which is a schematic diagram of an impeller 50 disposed within a frame 34 of a ventricular assist device 20 according to some applications of the present invention. For some applications, within at least a portion of the frame 34, a liner 39 is disposed on the frame, as described below with reference to Figures 19A-19H According to the respective application, the liner partially or completely overlaps the tube 24 on the portion of the frame lined by the liner. Figure 4 In the application shown, the liner is positioned within the cylindrical portion of the frame and the tube 24 does not cover the cylindrical portion of the frame. However, the scope of this application includes reference to Figure 4 The apparatus and methods described herein are used with reference to Figures 19A-19H Any application described.

[0253] like Figure 4 As shown, typically, there is a gap G between the outer edge of the impeller 50 and the inner liner 39, even at the location where the impeller spans the greatest distance. For some applications, it is desirable that the gap between the outer edge of the impeller blades and the inner liner 39 be relatively small so that the impeller effectively pumps blood from the subject's left ventricle into the subject's aorta. However, it is also desirable that the gap between the outer edge of the impeller blades and the inner surface of the frame 34 remain substantially constant throughout the rotation of the impeller within the frame 34, for example, to reduce the risk of hemolysis.

[0254] For some applications, when both the impeller and frame 34 are arranged in a non-radially constrained configuration, the gap G between the outer edge of the impeller and the liner 39 at the location where the impeller spans the largest is greater than 0.05 mm (e.g., greater than 0.1 mm) and / or less than 1 mm (e.g., less than 0.4 mm), for example, 0.05 mm to 1 mm, or 0.1 mm to 0.4 mm. For some applications, when the impeller is arranged in its non-radially constrained configuration, the outer diameter of the impeller at the location where the outer diameter of the impeller is the largest is greater than 7 mm (e.g., greater than 8 mm) and / or less than 10 mm (e.g., less than 9 mm), for example, 7 mm to 10 mm, or 8 mm to 9 mm. For some applications, when frame 34 is positioned in its non-radially constrained configuration, the inner diameter of frame 34 (measured from the inner side of liner 39 on one side of the frame to the inner side of the liner on the opposite side of the frame) is greater than 7.5 mm (e.g., greater than 8.5 mm) and / or less than 10.5 mm (e.g., less than 9.5 mm), for example, between 7.5 mm and 10.5 mm, or between 8.5 mm and 9.5 mm. For some applications, when frame 34 is positioned in its non-radially constrained configuration, the outer diameter of frame 34 is greater than 8 mm (e.g., greater than 9 mm), and / or less than 13 mm (e.g., less than 12 mm), for example, between 8 mm and 13 mm, or between 9 mm and 12 mm.

[0255] Typically, the axial shaft 92 passes through the axis of the impeller 50 via the inner cavity 62 of the impeller. More typically, the axial shaft is rigid, such as a rigid tube. For some applications, the proximal bushing 64 of the impeller is coupled to the shaft such that the axial position of the proximal bushing relative to the shaft is fixed and the distal bushing 58 of the impeller is slidable relative to the shaft. The axial shaft itself is radially stabilized via proximal radial supports 116 and distal radial supports 118. In turn, the axial shaft, by passing through the inner cavity 62 defined by the impeller, radially stabilizes the impeller relative to the inner surface of the frame 34 so that a relatively small gap (e.g., the gap described above) is maintained between the outer edges of the impeller's blades and the inner surface of the frame 34 even during rotation of the impeller.

[0256] Refer again Figure 3A-3CFor some applications, the impeller includes a plurality of elongated elements 67 extending radially from the central axial spring 54 to the outer helical elongated element 52. The elongated elements are typically flexible but substantially inextensible along the axis defined by the elongated elements. More typically, each elongated element is configured to not apply a force to the helical elongated element unless a force acts on the impeller to cause the helical elongated element to move radially outward, so that (in the absence of the elongated elements) the spacing between the helical elongated element and the central axial spring is greater than the length of the elongated element. For example, the elongated element may include a rope (e.g., polyester, and / or another polymer or natural material containing fibers) and / or a wire (e.g., nitinol wire, and / or wire made from a different alloy or metal).

[0257] For some applications, the elongated element 67 holds the spiral elongated element (which defines the outer edges of the impeller's blades) within a given distance relative to the central axial spring. In this way, the elongated element is configured to prevent the outer edges of the impeller from being pushed radially outward due to forces exerted on the impeller during rotation of the impeller. The elongated element is thereby configured to maintain a gap between the outer edges of the impeller's blades and the inner surface of the frame 34 during rotation of the impeller. Typically, more than one (e.g., more than two) and / or less than eight (e.g., less than four) elongated elements 67 are used in the impeller, wherein each elongated element is typically folded in half (i.e., extending radially from the central axial spring 54 to the outer spiral elongated element 52, and then returning from the spiral elongated element to the central axial spring). For some applications, multiple elongated elements are formed from a single piece of rope or wire, wherein each elongated element extends from the spring to a corresponding spiral elongated element and back to the spring, as described in further detail below.

[0258] For some applications, the impeller is manufactured in the following manner. The proximal bushing 64, the distal bushing 58 and the spiral elongated element 52 are cut from a tube of shape memory material (e.g., Nitinol). The cutting of the tube and the shaping of the shape memory material are typically performed in the following manner so that the spiral elongated element is defined by the shape memory material, for example, using a technique substantially similar to that described in US2016 / 0022890 of Schwammenthal. Typically, the spring 54 is inserted into the cutting and shaping tube so that the spring extends along the length of the tube at least from the proximal bushing to the distal bushing. For some applications, the spring is inserted into the cutting and shaping tube when the spring is in an axially compressed state, and the spring is configured to remain in place relative to the tube by applying a radial force on the proximal bushing and the distal bushing. Alternatively or additionally, multiple portions of the spring are welded to the proximal bushing and the distal bushing. For some applications, the spring is cut from a tube of shape memory material (e.g., Nitinol). For some such applications, the spring is configured such that when the spring is disposed in a non-radially constrained configuration (where the spring is typically disposed during operation of the impeller), there is substantially no gap between a coil of the spring and its adjacent coils.

[0259] For some applications, after spring 54 is inserted into cutting and shaping pipe, elongated element 67 as above is placed into, for example, in the following manner, extends between spring and one or more spiral elongated elements. Mandrel (for example, polyetheretherketone (PEEK) and / or polytetrafluoroethylene (PTFE) mandrel) is inserted through the inner cavity defined by spring and bushing.Then, rope or line are penetrated, make its (a) from mandrel to the first spiral elongated element in spiral elongated element, (b) return to mandrel from the first spiral elongated element in spiral elongated element, (c) around mandrel, and to the second spiral elongated element in spiral elongated element, (d) return to mandrel from the second spiral elongated element in spiral elongated element, or the like.Once rope or line have been passed to each spiral elongated element from mandrel and are passed back again, the end of rope or line just couples to each other, for example, by tying them together to each other. For some applications, suture 53 (e.g., polyester suture) is wrapped around the helical elongated element to facilitate bonding between the membrane of material (which is typically an elastomer, such as polyurethane or silicone) and the helical elongated element (which is typically a shape memory alloy, such as Nitinol) in subsequent stages of impeller fabrication. For some applications, suture (e.g., polyester suture, not shown) is wrapped around spring 54. Typically, the suture is configured to facilitate bonding between the membrane of material (which is typically an elastomer, such as polyurethane or silicone) and the spring (which is typically a shape memory alloy, such as Nitinol) in subsequent stages of impeller fabrication.

[0260] Typically, at this stage, the Figure 3A The structure 59 is shown. The structure includes a cutting and shaping tube that defines the proximal and distal sleeves, the helical elongated element, and the spring (and optionally the elongated element and suture). The structure is immersed in the material defining the membrane 56. For some applications, the assembled structure is immersed in the material with the mandrel positioned to pass through the lumen defined by the spring and sleeve, although it should be noted that the mandrel is not inserted into the lumen. Figure 3A Typically, the membrane is made of silicone and / or polyurethane (and / or similar elastomers), and the assembled structure is immersed in the material while it is in an uncured liquid state. The material is then cured, so that it solidifies, for example, by drying it. Once the material has dried, the mandrel is typically removed from the inner cavity defined by the bushing and spring.

[0261] Typically, the result of the above process is a continuous film of material extending between each helical elongated element and the spring, and also extending along the length of the spring to define a tube within which the spring is embedded. The portions of the film extending from each helical elongated element to the spring define the blades of the impeller. For applications where the impeller includes elongated element 67, the elongated element is typically embedded within these portions of the film.

[0262] Typically, the impeller 50 is inserted into the left ventricle via a catheter while the impeller 50 is in a radially constrained configuration. In the radially constrained configuration, both the helical elongated element 52 and the central axial spring 54 become axially elongated and radially constrained. Typically, a membrane 56 of material (e.g., silicone and / or polyurethane) changes shape to conform to the shape changes of the helical elongated element and the axial support spring (both of which support the membrane of material). Typically, the use of a spring to support the inner edge of the membrane allows the membrane to change shape without the membrane breaking or collapsing because the spring provides a large surface area to which the inner edge of the membrane is bound. For some applications, the use of a spring to support the inner edge of the membrane reduces the diameter of the impeller that may be radially constrained, compared to, for example, using a rigid shaft to support the inner edge of the membrane, because the diameter of the spring itself can be reduced by axially extending the spring.

[0263] As described above, for some applications, the proximal bushing 64 of the impeller 50 is coupled to the axial shaft 92 such that the proximal bushing is fixed in axial position relative to the shaft, while the distal bushing 58 of the impeller is slidable relative to the shaft. For some applications, when the impeller is radially restrained for insertion into a ventricle or for removal from a subject, the impeller is axially extended by sliding the distal bushing distally along the axial shaft. Figure 3A-3C As shown, after being released into the subject, the impeller assumes its non-radially constrained configuration (wherein the impeller is typically disposed in the non-radially constrained configuration during operation of the impeller).

[0264] Note that for illustrative purposes, in some of the figures, the impeller 50 is shown without the impeller 50 as shown in FIG. Figure 3A-3C All features of the impeller shown and described herein. For example, some figures show an impeller that does not include sutures 53 and / or elongated elements 67. The scope of this application includes the use of an impeller having any of the features of the impeller shown and described herein in conjunction with any of the devices and methods described herein. Figure 3A-3C An impeller having any of the characteristics shown and described.

[0265] Now refer to Figure 3D 、 Figure 3E and Figure 3F , these figures are schematic diagrams of impellers 50 or portions thereof according to some applications of the present invention. As described above, for some applications, impeller 50 includes suture 53. Suture 53 is wound around helical elongated member 52 and is configured to facilitate bonding between the membrane of material (which is typically an elastomer, such as polyurethane or silicone) and the helical elongated member (which is typically a shape memory alloy, such as Nitinol).

[0266] As an alternative to or in addition to suture 53, for some applications, coil 68 is wrapped around (or placed on) the helical elongate member, such as Figure 3D For example, a tightly wound coil (e.g., a tightly wound Nitinol coil) can be wrapped around (or placed around) each of the helical elongated elements. Typically, the coil facilitates bonding between the film of material and the helical elongated element by increasing the surface area of ​​the material to bond at the interface between the material and the helical elongated element. For some applications, structure 59 is modularly formed (e.g., as described below with reference to Figure 3F For some such applications, a coil is placed around each elongate member 52 (eg, by sliding the entire coil over the elongate member in a single motion) before the elongate member is coupled to the proximal and distal bushings of the impeller.

[0267] As a further alternative or in addition to suture 53, for some applications, a sleeve 69 is placed around the helical elongate member, such as Figure 3EAs shown. For example, such a sleeve can be made of a polymer, such as polyester. Typically, the sleeve promotes bonding between the film of material and the spiral elongated element by increasing the surface area of ​​the material to which it bonds at the interface between the material and the spiral elongated element. For some applications, the sleeve acts as an intermediary between the material from which the elongated element is made, which typically has a relatively high stiffness (and is typically Nitinol), and the material from which the membrane 56 is made, which is typically an elastomer with a relatively low stiffness. Thus, when the material dries, the sleeve enhances the strength of the connection between the material and the spiral elongated element. For some applications, a sleeve 69 is applied to structure 59. For some such applications, a longitudinal slit is formed in the sleeve to allow the sleeve to be placed around the spiral elongated element 52. After being placed around the spiral elongated element 52, the slit is closed (e.g., closed by suturing or adhering the slit). For some applications, structure 59 is formed modularly (e.g., as described below with reference to Figure 3F For some such applications, a sleeve is placed around the elongated member 52 before the elongated member is coupled to the proximal and distal bushings of the impeller.

[0268] As yet another alternative or in addition to suture 53, for some applications, elongated member 52 is formed to have a rounded (e.g., circular) cross-section, such as Figure 3F , which shows a cross-sectional view of an elongated element with a rounded cross-section. Figure 3F The left portion of FIG shows a cross-sectional view of an elongated member 52, wherein the material of a membrane 56 is coupled to the elongated member for the case where the elongated member has a non-rounded cross-section (e.g., a square or rectangular cross-section). As shown, it is sometimes the case that the material (e.g., silicone and / or polyurethane) from which the membrane is made forms a thinner layer at the corners of an elongated member having a non-rounded cross-section. In contrast, as shown in FIG. Figure 3F As shown in the left portion of , when the elongated element has a rounded cross-section, the material typically forms a layer of substantially uniform thickness at the interface with the elongated element. Therefore, for some applications, the elongated element has a rounded cross-section.

[0269] For some applications, the proximal and distal bushings 64 and 58 and the elongated element 52 are cut from an alloy tube, such as described above. For such applications, the elongated element typically has non-rounded edges after the tube is cut. Therefore, for some applications, the edges of the elongated element are rounded after the tube is cut, for example, using grinding, sandblasting, tumbling, etching, plasma, surface charging, and / or by adding rounded edges to the elongated element. Alternatively, the proximal and distal bushings and the elongated element can be formed in a modular manner and can subsequently be coupled to one another (e.g., via welding and / or swaging). For some such applications, the elongated element coupled to the proximal and distal bushings has a rounded cross-section. As described above with reference to Figure 3E As mentioned, for some applications, bushing 69 is placed over the elongate member before the elongate member is coupled to the proximal bushing and / or before the elongate member is coupled to the distal bushing.

[0270] For some applications, alternative or additional techniques are used to promote bonding between the film of material and the helical elongated element. For example, the helical elongated element may be treated with a surface treatment (e.g., grinding, sandblasting, tumbling, etching, plasma, surface charging, etc.) to roughen the outer surface of the helical elongated element.

[0271] According to the above Figures 3A-3FAs described above, for some applications of the present invention, an impeller 50 is manufactured as follows: a structure is formed having a first bushing 64 and a second bushing 58 at a proximal end and a distal end of the structure, the first bushing and the second bushing being connected to each other by at least one elongated member 52. The at least one elongated member is caused to radially expand and form at least one helical elongated member by axially compressing the structure at least in part. An elastomeric material is coupled to the at least one helical elongated member such that the at least one helical elongated member to which the elastomeric material is coupled defines blades of the impeller. Typically, the coupling is performed such that a layer of material is disposed about a radially outer edge of the at least one helical elongated member, the layer of material forming an effective edge of the blades of the impeller (i.e., an edge at which the blood pumping function of the impeller is substantially no longer effective). More typically, the method includes performing the step of reinforcing the elastomeric material in conjunction with the at least one helical elongated member in a manner that does not result in protrusion from the effective edge of the blades of the impeller. For example, the suture 53 can be placed within a groove defined by the at least one spiral elongated element such that the suture does not protrude from the radially outer edge of the spiral elongated element, the suture being configured to enhance the bonding of the elastomeric material to the at least one spiral elongated element. Alternatively or additionally, a tightly wound coil 68 can be placed around the at least one spiral elongated element such that the elastomeric material forms a substantially smooth layer along the radially outer edge of the coil, the coil being configured to enhance the bonding of the elastomeric material to the at least one spiral elongated element. Further alternatively or additionally, a sleeve 69 can be placed around the at least one spiral elongated element such that the elastomeric material forms a substantially smooth layer along the radially outer edge of the sleeve, the sleeve being configured to enhance the bonding of the elastomeric material to the at least one spiral elongated element. For some applications, at least one spiral elongated element is provided with a rounded cross-section such that the elastomeric material forms a layer of substantially uniform thickness at the interface between the elastomeric material and the spiral elongated element. As described above, it is typically desired that the outer edges of the blades of the impeller are aligned with the liner 39 (e.g., Figure 4 The gap G between the outer edges of the impeller blades (shown) is relatively small. Therefore, it is desirable that the effective edges of the impeller blades do not protrude, as this would occupy a portion of the gap between the outer edges of the impeller blades (thereby requiring a larger gap) without increasing the effectiveness of the impeller's blood pumping function.

[0272] Now refer to Figure 3G and Figure 3H, which are schematic illustrations of an elongated element 67 extending between each helical elongated element 52 and the spring 54, according to some applications of the invention. For some applications, a corresponding annular elongated element 67 extends between each helical elongated element and the spring. Typically, the annular elongated element is a closed loop having a predetermined length and being (substantially) inextensible. The length of the annular elongated element is typically predetermined so as to maintain the helical elongated element (which defines the outer edges of the impeller's blades) within a given distance relative to the central axial spring during rotation of the impeller, and thereby maintain a gap between the outer edges of the impeller's blades and the inner surface of the frame 34, as described above. For some applications, such as Figure 3G and Figure 3H As shown in the enlarged portion of , the impeller is formed by wrapping the first end of an annular elongated element around each spiral elongated element. Subsequently, the spring 54 is inserted through the proximal bushing 64 and the distal bushing 58 and through the second end of the annular spiral elongated element.

[0273] For some applications, the spring 54 is shaped to define a tube 70 (ie, without a coil) at its longitudinal center, as shown. Figure 3G and Figure 3H Typically, the second end of the annular elongate element wraps around the tube at a longitudinally central location of the spring. Typically, this reduces the risk of tearing of the annular elongate element compared to wrapping the second end of the annular elongate element around the spring. For some applications (not shown), the tube defines a groove therein, and the second end of the annular elongate element is configured to be retained within the groove.

[0274] For some applications, the annular elongate member surrounds the body of the helical elongate member, e.g. Figure 3G As shown in the enlarged portion. Figure 3G Enlarged views A and B of FIGURE 1 illustrate two alternative ways in which the annular elongated member surrounds the body of the spiral elongated member. For some applications, the annular elongated member surrounds the outer surface of the spiral elongated member, as shown in enlarged view A. Alternatively, the spiral elongated member defines a groove 45 on its outer surface, and the annular elongated member surrounds the groove 45 (e.g., is embedded within the groove), as shown in enlarged view B. By embedding the annular elongated member within the groove, the annular elongated member typically does not increase the outer profile of the impeller, and the outer profile of the impeller is defined by the outer surface of the spiral elongated member.

[0275] For some applications, the helical elongate member is shaped to define two holes 71 that are disposed very close to each other and through which the looped elongate member can be looped, e.g. Figure 3H As shown in the enlarged portion. Figure 3HEnlarged views A and B of FIG. 10 illustrate two alternative ways in which the annular elongated member is looped through hole 71. For some applications, as shown in enlarged view A, the annular elongated member surrounds the outer surface of the spiral elongated member and through hole 71. Alternatively, the spiral elongated member defines a groove 45 on its outer surface, and the annular elongated member surrounds the groove 45 and through hole 71 (so as to be embedded in the groove), as shown in enlarged view B. By embedding the annular elongated member in the groove, the annular elongated member typically does not increase the outer profile of the impeller, and the outer profile of the impeller is defined by the outer surface of the spiral elongated member.

[0276] Now refer to Figure 3I 、 Figure 3J and Figure 3K For some applications, structure 59 is configured to provide a relatively long effective maximum span length EML, which is defined as the axial length along which the impeller spans its maximum. Typically, increasing the effective maximum span length EML of the impeller increases the efficiency of the impeller (i.e., the flow rate generated by the impeller at a given rotational rate). For some applications, the leading edges of the impeller blades form an angle rho greater than 45 degrees with respect to the longitudinal axis of the impeller, for example, between 45 degrees and 70 degrees. By comparison Figure 3J and Figure 3I It can be observed that, assuming all else is equal, increasing the angle rho increases the effective maximum span length EML even if the total length of the impeller does not increase. Alternatively, as Figure 3K As shown, the effective maximum span length EML of the impeller is increased by making the impeller longer.

[0277] Now refer to Figure 5A and Figure 5B , which are schematic illustrations of an impeller 50 and frame 34 of a ventricular assist device 20 in a non-radially constrained state and a radially constrained state, respectively, according to some applications of the present invention. The impeller and frame are typically configured in the radially constrained state during insertion of the impeller and frame into a subject via a catheter, and in the non-radially constrained state during operation of the impeller within the left ventricle of the subject. As described above, the tube 24 is typically disposed on at least a portion of the frame and extends proximally therefrom. However, for illustrative purposes, the tube 24 is not disposed in the radially constrained state. Figure 5A-5B The frame and impeller are shown without the tubes 24 .

[0278] like Figure 5BAs shown, the frame and impeller are typically held in a radially constrained configuration by the delivery conduit 143. Typically, in the radially constrained configuration of the impeller, the impeller has a total length greater than 15 mm (e.g., greater than 20 mm) and / or less than 30 mm (e.g., less than 25 mm), for example, 15 mm to 30 mm, or 20 mm to 25 mm. More typically, in the non-radially constrained configuration of the impeller, the impeller has a length greater than 8 mm (e.g., greater than 10 mm) and / or less than 18 mm (e.g., less than 15 mm), for example, 8 mm to 18 mm, or 10 mm to 15 mm. Even more typically, when the impeller and frame 34 are arranged in a radially constrained configuration (e.g., Figure 5B ), the impeller has an outer diameter of less than 2 mm (eg, less than 1.6 mm), and the frame has an outer diameter of less than 2.5 mm (eg, less than 2.1 mm).

[0279] Also refer to Figure 5C , which shows a typical bearing assembly used in a prior art axial flow impeller based blood pump. Figure 5C The purpose of the illustration is to serve as a reference point for some applications of the invention described herein. Figure 5C As shown, the bearing assembly typically includes a radial bearing (indicated by ellipse 200) and a thrust bearing (indicated by circle 202). The radial bearing is configured to reduce radial movement of the impeller by maintaining the axis of the impeller at a given radial position. In response to the impeller pumping blood in a first direction, a force acting on the impeller typically urges the impeller to move in a direction opposite to the first direction. The purpose of the thrust bearing is to resist this movement of the impeller and maintain the axial position of the impeller. Figure 5C In the example shown, in response to the impeller pumping blood in the direction of arrow 204, the impeller is pushed in the direction of arrow 206, and the thrust bearing resists this motion. Typically, these bearings are subject to significant heating and wear due to the frictional forces exerted on the bearings. Thrust bearings are typically subject to significant heating and wear due to the fact that the frictional forces exerted on the thrust bearings are typically distributed across opposing surfaces, which have a smaller contact area than is the case for radial bearings.

[0280] As described above, typically, the axial shaft 92 passes through the axis of the impeller 50 via the inner cavity 62 of the impeller. Typically, the proximal bushing 64 of the impeller is coupled to the shaft via a coupling element 65 so that the axial position of the proximal bushing relative to the shaft is fixed and the distal bushing 58 of the impeller can slide relative to the shaft. The axial shaft itself is radially stabilized via the proximal radial support 116 and the distal radial support 118.

[0281] Typically, the coupling portion 31 of the frame 34 is coupled to the proximal radial support 116, for example, via a snap-fit ​​coupling and / or via welding. Typically, at the distal end of the frame 34, the distal strut engagement portion 33 is placed into a groove defined by the outer surface of the distal radial support 118, the groove being shaped to conform to the shape of the distal strut portion. The proximal end of the distal tip element 107 (which defines the distal tip portion 120) typically retains the distal strut portion in its closed configuration around the outside of the distal radial support 118, as shown. For some applications, the device includes a distal extension 121 extending distally from the distal radial support. Typically, the extension is configured to reinforce the area of ​​the distal tip element into which the distal end of the shaft 92 is moved (e.g., the axial shaft receiving tube 126 or a portion thereof described below).

[0282] As described above, the axial shaft 92 is radially stabilized via the proximal radial support 116 and the distal radial support 118. In turn, the axial shaft radially stabilizes the impeller relative to the inner surface of the frame 34 by passing through the inner cavity 62 defined by the impeller, so that during rotation of the impeller, even a relatively small gap (e.g., such as the gap described above) between the outer edges of the impeller's blades and the inner surface of the frame 34 is maintained, as described above. For some applications, the axial shaft 92 is made of stainless steel, and the proximal support 116 and / or the distal support 118 are made of hardened steel. Typically, when the impeller and frame are crimped (i.e., radially constrained) for insertion into a subject, the distal bushing 58 of the impeller is configured to slide in a distal direction along the axial shaft, causing the impeller to become axially extended, while the proximal bushing remains in an axially fixed position relative to the axial shaft. More typically, the impeller changes from its radially constrained configuration to its non-radially constrained configuration, and vice versa, by sliding the distal bushing on the axial shaft while the proximal bushing remains in an axially fixed position relative to the axial shaft. For some applications, the impeller's distal bushing 58 is coupled to the shaft via a coupling element 65 such that the axial position of the distal bushing relative to the shaft is fixed and the impeller's proximal bushing 64 is slidable relative to the shaft. Figures 11A-11C Describe the application.

[0283] Typically, the impeller itself is not directly disposed within any radial or thrust bearings. Instead, supports 116 and 118 act as radial supports relative to the axial shaft. Typically, pump portion 27 (and ventricular assist device 20 more generally) does not include any thrust bearings configured to be disposed within the subject and configured to resist thrust generated by rotation of the impeller. For some applications, one or more thrust bearings are disposed outside the subject (e.g., within motor unit 23, such as Figure 1A 、 Figure 7 and Figure 8A-8B), and the resistance to the thrust generated by the rotation of the impeller is provided solely by one or more thrust bearings disposed outside the subject's body. For some applications, mechanical and / or magnetic elements are configured to maintain the impeller within a given axial position range. For example, a magnet (e.g., magnet 82, hereinafter referred to as Figure 7 ) can be configured to impart axial motion to the impeller, and / or to maintain the impeller within a given range of axial positions.

[0284] Now refer to Figure 6A and Figure 6B , which are schematic diagrams of a ventricular assist device 20 showing an impeller 50 of the ventricular assist device at various stages of a motion cycle relative to a frame 34 of the ventricular assist device, according to some applications of the present invention. For some applications, as the impeller rotates to pump blood through tube 24, an axial shaft 92 (to which the impeller is secured) is driven to cause the impeller to reciprocate axially within the frame 34 by moving the axial shaft in an axial reciprocating motion, as described below with reference to Figure 7 As further described in detail. Alternatively or additionally, the impeller and axial shaft are configured to reciprocate axially within the frame 34 in response to forces acting on the impeller, without requiring the axial shaft to be actively driven to cause the axial shaft to move in an axially reciprocating manner. Typically, during a subject's cardiac cycle, the pressure differential between the left ventricle and the aorta varies from approximately zero during ventricular contraction (hereinafter referred to as "systole") to a relatively large pressure differential (e.g., 50 mmHg-70 mmHg) during ventricular relaxation (hereinafter referred to as "diastole"). For some applications, due to the increased pressure differential against which the impeller pumps during diastole (and because the drive cable 130 is stretchable), the impeller is pushed distally relative to the frame 34 during diastole compared to its position relative to the frame 34 during systole. Furthermore, because the impeller is connected to the axial shaft, the axial shaft moves forward. During systole, the impeller (and, therefore, the axial shaft) moves back to their systolic position. In this way, the axial reciprocating motion of the impeller and the axial shaft is generated in a passive manner, i.e., the axial shaft and the impeller do not need to be actively driven to cause them to undergo such motion. Figure 9 This passive axial reciprocating motion of the impeller will be described in further detail below. Figure 6A shows the impeller and axial shaft disposed in their typical systolic position, and Figure 6B The impeller and axial shaft are shown disposed in their typical diastolic positions.

[0285] For some applications, by moving in an axial reciprocating motion, the portion of the axial shaft in contact with the proximal and distal supports 116, 118 is continuously varied. For some such applications, assuming all else is equal, in this manner, the frictional forces exerted on the axial shaft by the supports are distributed over a larger area of ​​the axial shaft than if the axial shaft were not moved relative to the supports, thereby reducing wear on the axial shaft. Alternatively or additionally, by moving in an axial reciprocating motion relative to the supports, the axial shaft clears any residue, such as blood residue, from the interface between the axial shaft and the supports.

[0286] For some applications, when the frame 34 and impeller 50 are in their non-radially constrained configuration (e.g., when the frame and impeller are deployed within the left ventricle), the length of the frame exceeds the length of the impeller by at least 2 mm (e.g., at least 4 mm, or at least 8 mm). Typically, the proximal support 116 and the distal support 118 are each 2 mm to 4 mm in length (e.g., 2 mm to 3 mm). More typically, the impeller and the axial shaft are configured to reciprocate axially within the frame along at least the length of each of the proximal and distal supports, or at least along twice the length of each of these supports. Thus, during the reciprocating axial movement of the axial shaft, the axial shaft is wiped clean on either side of each of the supports.

[0287] For some applications, the range of impeller motion is as follows Figure 6A-6B As shown, Figure 6A Indicates the impeller is in a proximal-most arrangement during the cardiac cycle (typically, the impeller is set to this arrangement during systole), and Figure 6B Indicates the most distal arrangement of the impeller during the cardiac cycle (typically, the impeller is set to this arrangement during diastole). Figure 6A As shown, for some applications, at the most proximal position of the impeller, the proximal end of the impeller is disposed at a position Ip that is within the proximal conical section of the frame 34. Figure 6B As shown, for some applications, at the most distal position of the impeller, the distal end of the impeller is disposed at position Id, which is at the distal end of the cylindrical segment of frame 34. For the purposes of this application, the entire segment of the frame from Ip to Id can be considered to house the impeller, as this entire segment of the frame typically houses at least a portion of the impeller during at least a portion of the cardiac cycle. Typically, throughout the entire cardiac cycle, the segment of the impeller with the largest impeller span is disposed within the cylindrical portion of frame 34. However, during at least a portion of the cardiac cycle, the proximal portion of the impeller is typically disposed within the proximal tapered segment of the frame.

[0288] Refer again Figure 6A and Figure 6B , and also refer to Figure 6C , Figure 6C is an enlarged schematic illustration of a distal tip element 107 according to some applications of the present invention, the distal tip element 107 including an axial shaft receiving tube 126 and a distal tip portion 120 of a ventricular assist device 20. Typically, the distal tip element 107 is a single integrated element including both the axial shaft receiving tube 126 and the distal tip portion 120. For some applications, the distal tip element 107 is configured to be soft such that the distal tip portion is configured to not cause tissue damage to a subject even if the distal tip portion comes into contact with tissue (e.g., tissue of the left ventricle). For example, the distal tip element 107 can be made of silicone, polyethylene terephthalate (PET), and / or polyether block amide (e.g., ). For some applications, the distal tip portion defines a lumen 122 therethrough. For some such applications, during insertion of a ventricular assist device into the left ventricle, the guide wire 10 ( Figure 1B ) is first inserted into the left ventricle according to, for example, known techniques. The distal tip portion of the ventricular assist device is then guided to the left ventricle by advancing the distal tip portion over a guidewire disposed within lumen 122. For some applications, a duckbill valve 390 (or a different type of hemostatic valve) is disposed at the distal end of lumen 122 of distal tip portion 120, as described in further detail below.

[0289] Typically, during insertion of the ventricular assist device into a ventricle of a subject, delivery catheter 143 is placed over impeller 50 and frame 34 and holds the impeller and frame in their radially constrained configuration. For some applications, distal tip element 107 extends distally from the delivery catheter during insertion of the delivery catheter into the ventricle of the subject. For some applications, distal tip element 107 has a flared portion 124 at its proximal end that acts as a stop and prevents the delivery catheter from being advanced beyond the flared portion.

[0290] It should be noted that Figures 6A-6C (and some other figures) are shown as defining a complete loop, wherein the distal end of the distal tip portion (with the duckbill valve 390 disposed therein) spans a more proximal portion of the distal tip portion. Typically, the distal tip portion remains partially straightened due to having a guide wire inserted therethrough (during insertion of a ventricular assist device into the left ventricle), even after the guide wire is removed from the distal tip portion. Typically, the partial straightening of the distal tip portion is such that when the distal tip portion is disposed within the left ventricle, in the absence of external forces acting on the distal tip portion, the distal tip portion does not define a complete loop, e.g., as Figure 1B and Figure 23AOther aspects of the shape of the distal tip portion will be described in further detail below.

[0291] Refer again Figure 6C For some applications, an axial shaft receiving tube 126 extends proximally from the distal tip portion 120 of the distal tip element 107. As described above, typically, during operation of the impeller 50, the axial shaft undergoes axial reciprocating motion. The axial shaft receiving tube 126 defines an inner lumen 127 configured to receive the axial shaft when the axial shaft extends beyond the distal support 118. For some applications, the shaft receiving tube defines a stop 128 at its distal end, the stop being configured to prevent the axial shaft from being advanced beyond the stop. For some applications, the stop comprises a rigid member inserted (e.g., embedded) into the distal end of the shaft receiving tube. Alternatively, the stop comprises a shoulder between the inner lumen 127 of the axial shaft receiving tube and the inner lumen 122 of the distal tip portion 120. Typically, such a shoulder is present because the inner lumen 122 of the tip portion 120 is narrower than the inner lumen 127. This is because lumen 127 is typically configured to receive an axial shaft, while lumen 122 is configured to receive a guidewire 10, and the axial shaft is typically wider than the guidewire 10 because the axial shaft itself is configured to receive the guidewire 10 within lumen 132 of the axial shaft (e.g., Figure 10B and Figure 10C shown).

[0292] Typically, during normal operation of the impeller, the axial shaft does not extend to the stop 128, even when the drive cable 130 ( Figure 7 1 and 2. The axial shaft 128 is also configured to prevent the axial shaft from protruding into the tip portion when the delivery catheter 50 and frame 34 are advanced during retraction of the ventricular assist device 20 from the subject's ventricle. In some instances, there is a risk of the drive cable snapping during advancement of the delivery catheter over the frame and impeller. In the absence of stop 128, the axial shaft could protrude into the tip portion in such circumstances. Stop 128 prevents this from occurring, even in the event of a drive cable snapping.

[0293] Typically, during operation of the ventricular assist device and throughout the entire axial reciprocating cycle of the impeller, the impeller is positioned relatively close to the distal tip portion. For example, the distance from the impeller to the distal tip portion may be within a maximum of 50%, such as a maximum of 30% (or a maximum of 20%) of the tube 24 throughout the entire axial reciprocating cycle of the impeller.

[0294] Now refer to Figure 6D, which is a schematic diagram of an impeller 50 and an axial shaft 92 of a ventricular assist device 20 according to some applications of the present invention, a region of the axial shaft being coated with a coating or covering material 95. As described above, the distal bushing 58 of the impeller is typically not fixedly coupled to the shaft. Also as described above, to reduce hemolysis, it is typically desirable to maintain a constant gap between the edges of the blades of the impeller and the tube 24 (and / or liner 39). Thus, it is typically desirable to reduce vibration of the impeller. For some applications, the impeller is stabilized relative to the frame along a region of the axial shaft by reducing the gap between at least one bushing and the impeller (e.g., by substantially filling the gap) in such a manner that the distal bushing is configured to slide relative to the axial shaft that is coated to substantially prevent vibration of the impeller. For example, the region of the axial shaft may be coated with polytetrafluoroethylene (e.g., ) and / or diamond-like carbon (DLC) coating, or may be covered with a sleeve (typically a polymer, such as polyester). By substantially filling the gap between the inner surface of the distal bushing 58 and the outer surface of the axial shaft 92, vibration of the impeller is typically reduced compared to if the area of ​​the axial shaft were not coated. For some applications, whether or not the axial shaft is coated, the gap between the distal bushing and the axial shaft is less than 40 microns, such as less than 30 microns. For some applications, the proximal bushing of the impeller is configured to slide relative to the axial shaft (e.g., as described with reference to FIG. Figures 11A-11C described), and techniques similar to those described above apply to the proximal sleeve.

[0295] Now refer to Figure 6E , which is a schematic diagram of an impeller 50 and an axial shaft 92 of a ventricular assist device 20 according to some applications of the present invention, the impeller's distal bushing 58 includes a protrusion 96 projecting from its inner surface, which is configured to slide within a groove 97 defined by the outer surface of the axial shaft. As described above, the impeller's distal bushing 58 is typically not fixedly coupled to the shaft. For some applications, when the impeller is axially moved relative to the axial shaft, the protrusion 96 and groove 97 are configured to prevent the distal end of the impeller from rotating relative to the axial shaft. Typically, groove 97 defines a stop 98 at its proximal end. The stop is configured to prevent the distal bushing from sliding proximally beyond the stop by preventing proximal axial movement of the protrusion 96 beyond the stop. Typically, by preventing the distal bushing from sliding proximally beyond the stop, a minimum length of the impeller is maintained. This in turn typically prevents the span of the impeller from increasing beyond a given maximum span, which maintains a clearance between the edges of the impeller's blades and the tube 24 (and / or liner 39).

[0296] according to Figures 6A-6E

[0014] As described above (and in conjunction with the description of the other figures), the scope of the present invention includes one or more techniques for reducing hemolysis caused by the pumping of blood by an impeller. Typically, a frame 34 disposed about the impeller defines a plurality of cells, and the frame is configured such that, in a non-radially constrained configuration of the frame, the frame includes a generally cylindrical portion 38. More typically, each cell within the cylindrical portion has a cell width CW measured about the circumference of the cylindrical portion that is less than 2 mm (e.g., 1.4 mm-1.6 mm, or 1.6 mm-1.8 mm). For some applications, a liner 39 lines at least the cylindrical portion of the frame, and the impeller is disposed within the frame such that, in the non-radially constrained configuration of the impeller, at a location where the impeller spans the greatest distance, the impeller is disposed within the cylindrical portion of the frame such that a gap G between an outer edge of the impeller and the liner is less than 1 mm (e.g., less than 0.4 mm). Typically, the impeller is configured to rotate to pump blood from the left ventricle to the aorta and is stabilized relative to the frame such that a gap between an outer edge of the impeller and the inner liner is maintained and substantially constant during rotation of the impeller. Typically, the impeller is configured to reduce the risk of hemolysis by being stabilized relative to the frame such that a gap between an outer edge of the impeller and the inner liner is maintained and substantially constant during rotation of the impeller, compared to if the impeller were not stabilized relative to the frame.

[0297] For some applications, proximal and distal radial supports 116 and 118 are disposed at the proximal and distal ends of the frame, respectively, and the axial shaft 92 passes through the proximal and distal radial supports. Typically, the impeller is stabilized relative to the frame by maintaining the impeller in a radially fixed position relative to the axial shaft and the axial shaft being rigid. For some applications, the gap between each axial support and the axial shaft is less than 15 microns, for example, between 2 microns and 13 microns. For some applications, the impeller includes bushings 64, 58 disposed around the axial shaft, and at least one of these bushings (e.g., distal bushing 58) is configured to be slidable relative to the axial shaft. For some applications, the impeller is stabilized relative to the frame along the following region of the axial shaft by having at least one bushing configured to be slidable relative to the axial shaft in the region along the axial shaft, the region being coated to substantially prevent impeller vibration by reducing the gap between at least one bushing and the impeller. For example, the region may be coated with a diamond-like carbon coating, a polytetrafluoroethylene coating, and / or a polymer sleeve.For some applications, regardless of whether the axial shaft is coated, the gap between the distal bushing and the axial shaft is less than 40 microns, such as less than 30 microns.

[0298] Now refer to Figure 6F and Figure 6G, which are schematic diagrams of a ventricular assist device 20 according to some applications of the present invention, with cylindrical portion 38 of frame 34 tapering from a proximal end of the cylindrical portion to a distal end of the cylindrical portion. As described above, for some applications, impeller 50 and axial shaft 92 are configured to reciprocate axially within frame 34 in response to forces acting on the impeller, without actively driving the axial shaft to move in an axially reciprocating motion. Typically, during a subject's cardiac cycle, the pressure differential between the left ventricle and the aorta varies from approximately zero during systole to a relatively large pressure differential (e.g., 50 mmHg-70 mmHg) during diastole. For some applications, due to the increased pressure differential against which the impeller pumps during diastole (and because drive cable 130 is stretchable), the impeller is urged distally relative to frame 34 during diastole compared to its position relative to frame 34 during systole. In turn, due to the impeller being connected to the axial shaft, the axial shaft moves forward. During systole, the impeller (and thus the axial shaft) moves back to its systolic position. In this way, the axial reciprocating motion of the impeller and the axial shaft is generated in a passive manner, i.e., the axial shaft and the impeller do not need to be actively driven to cause them to undergo such motion. Figure 6F The impeller is shown in its typical systolic position, and Figure 6G The impeller is shown disposed in its typical diastolic position.

[0299] For some applications, because the cylindrical portion of frame 34 tapers from the proximal end to the distal end of the cylindrical portion, the clearance between the edges of the impeller blades and tube 24 (and / or liner 39) is smaller during diastole than during systole. Due to the smaller clearance between the edges of the impeller blades and tube 24 (and / or liner 39), the pumping efficiency of the impeller is typically greater during diastole than during systole. For some applications, it is desirable to have a greater pumping efficiency during diastole than during systole because the impeller pumps against an increased pressure gradient during diastole relative to during systole, as described above.

[0300] Despite the Figure 6E and Figure 6F While described, it is typically the case that the clearance between the edges of the impeller blades and the tube 24 (and / or liner 39) is constant throughout the cycle of axial motion of the impeller.

[0301] Now refer to Figure 7 , which is a schematic diagram of an exploded view of a motor unit 23 of a ventricular assist device 20 according to some applications of the present invention. For some applications, the console 21 ( Figure 1A) that controls the rotation of impeller 50 is also configured to control the reciprocating motion of the axial shaft. Typically, both types of motion are generated using motor unit 23. The scope of the present invention includes controlling reciprocating motion of any frequency. For some applications, an indication of the subject's cardiac cycle is detected (e.g., by detecting the subject's ECG), and the reciprocating motion of the axial shaft is synchronized with the subject's cardiac cycle.

[0302] Typically, the motor unit 23 includes a motor 74 that is configured to impart rotational motion to the impeller 50 via a drive cable 130. As described in further detail below, the motor is typically magnetically coupled to the drive cable. For some applications, an axial motion driver 76 is configured to drive the motor to move in an axial reciprocating motion, as indicated by the double-headed arrow 79. Typically, due to the magnetic coupling of the motor to the drive cable, the motor imparts reciprocating motion to the drive cable, which in turn imparts the motion to the impeller. As described above and below, for some applications, the drive cable, impeller, and / or axial shaft are passively reciprocated axially, for example, due to periodic changes in the pressure gradient against which the impeller pumps blood. Typically, for such applications, the motor unit 23 does not include an axial motion driver 76.

[0303] For some applications, the magnetic coupling between the motor and the drive cable is Figure 7 As shown. Figure 7 As shown, a set of drive magnets 77 are coupled to the motor via a drive magnet housing 78. For some applications, the drive magnet housing includes a ring 81 (e.g., a steel ring) and the drive magnets are adhered to the inner surface of the ring. For some applications, as shown, a spacer 85 is adhered to the inner surface of the ring 81 between the two drive magnets. The driven magnet 82 is disposed between the drive magnets so that there is an axial overlap between the drive magnet and the driven magnet. The driven magnet is coupled to a pin 131 that extends beyond the distal end of the driven magnet 82, wherein the pin is coupled to the proximal end of the drive cable 130. For example, the driven magnet can be cylindrical and define a hole therethrough, and the pin 131 can be adhered to the inner surface of the driven magnet that defines the hole. For some applications, the driven magnet is cylindrical and the magnet includes a north pole and a south pole that are separated from each other along the length of the cylinder along a line 83 that bisects the cylinder, as shown. For some applications, the driven magnet is housed within a cylindrical housing 87. Typically, the pin 131 defines a guidewire lumen 133, which will be referred to below. Figure 10B-10C Described in further detail.

[0304] Note that in Figure 7In the illustrated application, the drive magnet is disposed outside the driven magnet. However, the scope of the present application includes configurations in which the drive and driven magnets are reversed (mutatis mutandis). For example, the proximal end of the drive cable may be coupled to two or more driven magnets that are disposed around the drive magnet such that there is axial overlap between the driven and drive magnets.

[0305] As mentioned above, typically, the cleaning system 29 (e.g. Figure 1A 8 (shown in FIG2 ) is used with a ventricular assist device 20. Typically, motor unit 23 includes an inlet port 86 and an outlet port 88 for use with a purge system. For some applications, a purge fluid is continuously or periodically pumped into the ventricular assist device via inlet port 86 and out of the ventricular assist device via outlet port 88. Other aspects of the purge system are described below.

[0306] Typically, the magnet 82 and the pin 131 are maintained in an axially fixed position within the motor unit 23. Typically, the proximal end of the drive cable is coupled to the pin 131 and is thereby maintained in the axially fixed position by the pin. Typically, the drive cable 130 extends from the pin 131 to the axial shaft 92 and thereby at least partially fixes the axial position of the axial shaft and, in turn, the impeller 50. For some applications, the drive cable is somewhat stretchable. For example, the drive cable may be made of a stretchable coiled wire. The drive cable typically allows the axial shaft (and, in turn, the impeller) to assume a range of axial positions (by the drive cable becoming more or less stretched), but limits the axial movement of the axial shaft and impeller to a certain range of motion (by maintaining the proximal end of the drive cable in an axially fixed position and the stretchability of the drive cable being limited).

[0307] Now refer to Figure 8A and Figure 8B , these figures are schematic diagrams of motor units 23 according to some applications of the present invention. In general, as Figure 8A and Figure 8B The motor unit 23 shown is similar to Figure 7 Motor units shown, unless otherwise stated, are Figure 8A and Figure 8B The motor unit 23 shown comprises Figure 7 Components similar to the motor unit 23 shown are shown. For some applications, the motor unit includes a heat sink 90 configured to dissipate heat generated by the motor. Alternatively or additionally, the motor unit includes a vent 93 configured to help dissipate heat generated by the motor. For some applications, the motor unit includes vibration dampers 94 and 96 configured to dampen vibrations of the motor unit caused by rotational movement and / or axial reciprocating movement of components of the ventricular assist device.

[0308] As described above, for some applications, the impeller 50 and the axial shaft 92 are configured to reciprocate axially within the frame 34 in response to forces acting on the impeller, without actively driving the axial shaft to move in an axial reciprocating motion. Typically, during a subject's cardiac cycle, the pressure differential between the left ventricle and the aorta varies from approximately zero during systole to a relatively large pressure differential (e.g., 50 mmHg-70 mmHg) during diastole. For some applications, because the pressure differential against which the impeller pumps increases during diastole (and because the drive cable is stretchable), the impeller is urged distally relative to the frame 34 during diastole, relative to its position relative to the frame 34 during systole. Furthermore, because the impeller is connected to the axial shaft, the axial shaft moves forward. During systole, the impeller (and, therefore, the axial shaft) returns to its systolic position. In this way, the axial reciprocating motion of the impeller and the axial shaft is generated in a passive manner, ie, the axial shaft and the impeller do not need to be actively driven in order for them to undergo such motion.

[0309] Now refer to Figure 9 , which is a graph showing how the length of a drive cable of a ventricular assist device varies with changes in the pressure gradient resisted by the impeller of the ventricular assist device (as measured in experiments conducted by the inventors of the present application). The impeller and drive cable described herein are used to pump a glycerol-based solution through a chamber, wherein the chamber is configured to replicate the left ventricle and aorta, and the solution has properties similar to blood (e.g., density and viscosity). As the volume of fluid disposed within the chamber pumped by the impeller increases, the pressure gradient resisted by the impeller also changes. Simultaneously, the movement of the drive cable is imaged, and the change in drive cable length is determined via machine vision analysis of the image. Figure 9 The graph shown in shows the measured drive cable length as a function of pressure gradient. Figure 9 The y-axis of the graph shown is the length of the drive cable when the impeller is stationary, with an elongation of 0 mm representing the length of the drive cable. Note that the graph begins at a pressure gradient value of 65 mmHg, and that at this pressure the elongation is negative (approximately -0.25 mm), i.e., the drive cable is shortened relative to the length of the drive cable before the impeller begins to rotate. This is because the drive cable is configured such that when the impeller first begins pumping, the drive cable is shortened (compared to the length of the drive cable before the impeller starts) due to the unwinding of the coils within the drive cable. As shown in Figure 9 As can be seen in the portion of the curve shown, after an initial shortening of the drive cable due to the effects described above, the drive cable subsequently becomes increasingly longer as the pressure gradient increases.

[0310] like Figure 9As shown and described above, typically, the impeller reciprocates relative to frame 34 in response to changes in the pressure against which the impeller pumps blood (e.g., the pressure differential between the left ventricle and the aorta). In turn, the movement of the impeller causes drive cable 130 to become more or less stretched.

[0311] For some applications, during operation of the ventricular assist device, console 21 ( Figure 1A ) is configured to measure an indication of pressure exerted on the impeller (indicative of a pressure differential between the left ventricle and the aorta) by measuring tension in drive cable 130 and / or an indication of axial movement of the drive cable. For some applications, based on the measured indications, the computer processor detects events in the subject's cardiac cycle, determines the subject's left ventricular pressure, and / or determines the subject's cardiac afterload. For some applications, the computer processor controls rotation of the impeller and / or, in response thereto, controls axial reciprocating motion of the axial shaft.

[0312] Refer again Figure 7 For some applications, ventricular assist device 20 includes sensor 84. For example, the sensor may include a Hall effect sensor disposed within motor unit 23, such as Figure 7 As shown. For some applications, the Hall sensor measures changes in the magnetic field generated by one of the magnets to measure the axial movement of the drive cable 130 and, in turn, determine the pressure resisted by the impeller pumping. For example, the inner driven magnet 82 can be longer in the axial direction than the outer drive magnet 77. Because the inner magnet is longer than the outer magnet, the magnetic field lines emanating from the inner magnet are not transferred to the outer magnet, and the magnetic flux generated by these field lines, measured by the Hall sensor, changes due to the drive cable and, in turn, causes the inner magnet to move axially. During operation, the motor 74 rotates, thereby generating an AC signal in the Hall sensor having a frequency typically between 200 Hz and 800 Hz. Typically, when the tension in the drive cable changes due to the subject's cardiac cycle, this produces a low-frequency envelope in the signal measured by the Hall sensor, typically having a frequency of 0.5 Hz to 2 Hz. For some applications, a computer processor measures the low-frequency envelope and derives the subject's cardiac cycle from the measured envelope. Note that typically the axial motion of the magnet is substantially less than the axial motion of the impeller because the full range of motion of the impeller is not transmitted along the length of the drive cable. However, it is typically the case that the axial reciprocating motion of the impeller causes measurable reciprocating motion of the magnet.

[0313] For some applications, the Hall sensor measurements are initially calibrated so that the change in magnetic flux per unit change in pressure opposed by the impeller pumping (i.e., per unit change in the pressure differential between the left ventricle and the aorta) is known. It is known that in most subjects, during systole, the left ventricular pressure is equal to the aortic pressure. Therefore, for some applications, the aortic pressure of the subject is measured (e.g., using the calibrated pressure gauge below). Figures 16A-16D The subject's left ventricular pressure at a given time is then calculated by a computer processor based on (a) the measured aortic pressure and (b) the difference between the magnetic flux measured by the Hall sensor at that time and the magnetic flux measured by the Hall sensor during systole (assuming that the pressure in the left ventricle is equal to the pressure in the aorta).

[0314] For some applications, generally similar techniques to those described in the paragraph above are used, but rather than utilizing Hall sensor measurements, different parameters are measured in order to determine the left ventricular blood pressure at a given time. For example, typically there is a relationship between the amount of power required to drive the impeller to rotate at a given rotational rate and the pressure differential created by the impeller. Note that a portion of the pressure differential created by the impeller is used to overcome the pressure gradient against which the impeller is pumping, and a portion of the pressure differential created by the impeller is used to actively pump blood from the left ventricle to the aorta by creating a positive pressure differential between the left ventricle and the aorta. Furthermore, the relationship between the above components typically changes over the course of the cardiac cycle. For some applications, calibration measurements are performed so that the relationship between (a) the motor power consumption required to rotate the impeller at a given rotational rate and (b) the pressure differential created by the impeller is known. For some applications, the aortic pressure of the subject is measured (e.g., using the method described below with reference to FIG. Figures 16A-16D The technique is performed using a computer processor to calculate the left ventricular pressure of the subject at a given time based on (a) the measured aortic pressure, (b) the motor power consumption required to rotate the impeller at a given rotational rate at a given time, and (c) a predetermined relationship between the motor power consumption required to rotate the impeller at a given rotational rate and the pressure differential generated by the impeller. For some applications, the technique is performed while maintaining the impeller rotational rate at a constant rate. Alternatively or additionally, the impeller rotational rate is varied, and the variation in the impeller rotational rate is accounted for in the calculation.

[0315] Typically, tube 24 has a known cross-sectional area (when the tube is in an open state due to blood flowing through the tube). For some applications, the flow rate through tube 24 generated by the impeller is determined based on the determined pressure differential generated by the impeller and the known cross-sectional area of ​​the tube. For some applications, this flow calculation incorporates calibration parameters to account for factors such as flow resistance, which are specific to the ventricular assist device (or type of ventricular assist device) for which the calculation is performed. For some applications, a ventricular pressure-volume loop is derived based on the determined ventricular pressure.

[0316] Now refer to Figure 10A 、 Figure 10B and Figure 10C , which are schematic diagrams of a drive cable 130 for a ventricular assist device 20 according to some applications of the present invention. Typically, as described above, the rotational motion of the impeller (applied via the axial shaft) and the axial reciprocating motion of the axial shaft are transmitted to the axial shaft via the drive cable. Typically, the drive cable extends from the motor unit 23 (which is typically disposed outside the subject's body) to the proximal end of the axial shaft 92 (e.g., Figure 10C , which shows the connection between the distal end of the drive cable and the proximal end of the axial shaft). For some applications, the drive cable includes multiple wires 134 (e.g., Figure 10B These wires 134 are arranged in a tightly coiled configuration to impart sufficient strength and flexibility to the drive cable so that a portion of the cable can remain within the aortic arch (corresponding to Figure 10A Typically, the drive cable is disposed within a first outer tube 140 that is configured to remain stationary while the drive cable undergoes rotation and / or axial reciprocation. The first outer tube is configured to effectively act as a support along the length of the drive cable. Typically, the first outer tube is made of a polymer (e.g., polyetheretherketone) that is configured to be highly fatigue-resistant even under the friction generated by the relative motion between the drive cable and the first outer tube. However, because such polymers are typically relatively hard, only a thin layer of polymer is typically used in the first outer tube. For some applications, the first outer tube is disposed within a second outer tube 142 that is made of a material having greater flexibility than the first outer tube (e.g., nylon and / or polyether block amide) and having a thickness greater than the thickness of the first outer tube.

[0317] Typically, during insertion of the impeller and cage into the left ventricle, the impeller 50 and frame 34 are held in a radially constrained configuration by the delivery catheter 143. As described above, to position the impeller and frame in a non-radially constrained configuration, the delivery catheter is retracted. For some applications, such as Figure 10AAs shown, during operation of the left ventricular device, the delivery catheter remains in the subject's aorta, and outer tube 142 is disposed inside the delivery catheter. For some applications, during operation of the left ventricular device, a passage 224 is defined between delivery catheter 143 and outer tube 142. Note that for illustration purposes, Figure 10A The channels shown are not to scale. Channel 224 will be described in further detail below. To retract the left ventricular device from the subject, the delivery catheter is advanced over the impeller and frame, causing the impeller and frame to assume their radially constrained configuration. The catheter is then withdrawn from the subject.

[0318] Reference Figure 10C (which shows a cross-sectional view of the drive cable 130 and the axial shaft 92), typically, the axial shaft and the drive cable define a continuous lumen 132 therethrough. For some applications, the left ventricular device is guided to the aorta and left ventricle by placing the axial shaft and cable over the guidewire 10 (as described above) such that the guidewire is disposed within the lumen 132. Typically, the guidewire is inserted through a duckbill valve 390 (or other hemostatic valve) disposed at the distal end of the distal tip portion of the distal tip element 107. The guidewire passes through the guidewire lumen 122 (of the distal tip portion) and then into the lumen 132 defined by the axial shaft at that point. The guidewire then continues through the lumen 132 until it reaches the proximal end of the drive cable. From the proximal end of the drive cable, the guidewire passes through a guidewire lumen 133 defined by the pin 131, which is disposed external to the subject even after the distal end of the ventricular assist device 20 is inserted into the left ventricle of the subject. Typically, when the distal end of the ventricular assist device is positioned inside the left ventricle of the subject, the guidewire is retracted from the subject by pulling the guidewire out of the proximal end of the guidewire lumen 133. Subsequently, the axial position of the driven magnet 82 (with the pin 131 disposed therein) is fixed so as to be disposed between the driving magnets 77, as shown in FIG. Figure 7 For example, a portion of the motor unit 23 in which the driven magnet is disposed may be secured using a latch element 150 (e.g. Figure 13B ) is coupled to a portion of the motor unit in which the drive magnet 77 is disposed.

[0319] For some applications, by using the lumen 132 of the axial shaft and cable in the manner described above, it is not necessary to provide an additional guidewire guide for use during insertion of the left ventricular assist device 20. For some applications, the axial shaft and cable each have an outer diameter greater than 0.6 mm (e.g., greater than 0.8 mm) and / or less than 1.2 mm (e.g., less than 1 mm), for example, 0.6 mm to 1.2 mm, or 0.8 mm to 1 mm. For some applications, the diameter of the lumen 132 defined by the shaft and cable is greater than 0.3 mm (e.g., greater than 0.4 mm) and / or less than 0.7 mm (e.g., less than 0.6 mm), for example, 0.3 mm to 0.7 mm or 0.4 mm to 0.6 mm. For some applications, the drive cable 130 has a total length greater than 1 m (e.g., greater than 1.1 m) and / or less than 1.4 m (e.g., less than 1.3 m), for example, 1 m to 1.4 m, or 1.1 m to 1.3 m. Typically, the diameters of guidewire lumen 122 and guidewire lumen 133 are substantially similar to the diameter of lumen 132 .

[0320] Now refer to Figure 10D 、 Figure 10E and Figure 10F , which are schematic diagrams of various steps in a technique for coupling a drive cable 130 to an axial shaft 92 using a butt-weld outer sleeve 160 in accordance with some applications of the present invention. Typically, the butt-weld outer sleeve defines a window 162 and a helical groove 164. For some applications, the axial shaft is inserted into the first end of the butt-weld outer sleeve such that the proximal end of the axial shaft 92 is visible at a given location in the window 162, such as at a midpoint across the width of the window, as shown in FIG. Figures 10D to 10E Subsequently, the drive cable 130 is inserted into the other end of the butt-welded outer sleeve until the distal end of the drive cable is also positioned at a given position in the window 162 (e.g., at a midpoint across the width of the window) and typically contacts the proximal end of the axial shaft, as shown. Figure 10E and Figure 10F The transition is shown.

[0321] Note that the order in which the axial shaft and the drive cable are inserted into the butt weld outer sleeve 160 can be reversed from the order shown. That is, the drive cable can be inserted first, followed by the axial shaft. It should also be noted that for illustration purposes, the drive cable is inserted in the Figures 10D-10F However, the drive cable typically comprises multiple coiled wires, e.g. Figure 10B shown.

[0322] Typically, once both the axial shaft and the drive cable have been inserted into the butt-weld outer sleeve 160, a plurality of welding rings 166 are welded into the butt-weld outer sleeve. Typically, one ring is welded at a given location of the window 162, for example, at the midpoint across the width of the window. More typically, additional rings are welded on either side of the window 162, but at positions spaced apart from the ends of the butt-weld outer sleeve. In this way, the additional welding rings weld the butt-weld outer sleeve to the axial shaft and the drive cable without welding the additional welding rings directly to the outer surface of the axial shaft and the outer surface of the drive cable. For some applications, this method results in less strain on the welding rings than welding the additional welding rings at the ends of the butt-weld outer sleeve so that the additional welding rings are directly welded to the outer surface of the axial shaft and the outer surface of the drive cable. Typically, the welding rings are welded to such a depth that the butt-weld outer sleeve is welded to the axial shaft and the drive cable without reducing the diameter of the guide wire lumen 132. As shown, typically, the drive cable is inserted into the butt weld outer sleeve so that the helical groove is disposed around the drive cable. Typically, the helical groove provides flexibility to the portion of the butt weld outer sleeve disposed over the drive cable 130.

[0323] For some applications, techniques generally similar to those described for welding the distal end of the drive cable 130 to the axial shaft 92 are used, mutatis mutandis, to weld the proximal end of the drive cable to the pin 131 (described above with reference to FIG. Figure 7 92 ). For some applications, the drive cable includes portions having corresponding characteristics (e.g., a corresponding number of wires in a coiled set comprising multiple portions of the drive cable). For some such applications, techniques substantially similar to those described for welding the distal end of the drive cable 130 to the axial shaft 92 are used, mutatis mutandis, to weld the various portions of the drive cable to one another.

[0324] For some applications, certain features of the butt-weld outer sleeve 160 and the techniques used therewith can be implemented in the absence of other features. For example, the butt-weld outer sleeve can include a window, and the weld ring can be welded in the manner described above even in the absence of the helical groove.

[0325] Now refer to Figure 11A and Figure 11B, these figures are schematic diagrams of an impeller 50 according to some applications of the present invention, the impeller being coupled to an axial shaft 92 at the distal end of the impeller and not coupled to the axial shaft at the proximal end of the impeller. As described above, typically, the axial shaft 92 passes through the axis of the impeller 50 via the inner cavity 62 of the impeller. For some applications, the distal bushing 58 of the impeller is coupled to the shaft via a coupling element 65 such that the axial position of the distal bushing relative to the axial shaft is fixed and the proximal bushing 64 of the impeller is slidable relative to the axial shaft. The axial shaft itself is radially stabilized via proximal and distal radial supports 116, 118. As described above, the proximal and distal ends of the frame 34 are rigidly coupled to the proximal and distal supports. Furthermore, the axial shaft, by passing through the internal cavity 62 defined by the impeller, radially stabilizes the impeller relative to the inner surface of the frame 34, such that a relatively small clearance (e.g., such as that described above) is maintained between the outer edges of the impeller's blades and the inner surface of the frame 34 even during rotation of the impeller, as described above. For such applications, typically, when the impeller and frame are crimped (i.e., radially constrained) for insertion into a subject, the impeller's proximal bushing 64 is configured to slide distally along the axial shaft, causing the impeller to become axially extended while the distal bushing remains in an axially fixed position relative to the axial shaft. More generally, the impeller changes from its radially constrained configuration to its non-radially constrained configuration, and vice versa, by sliding the proximal bushing on the axial shaft while the distal bushing remains in an axially fixed position relative to the axial shaft.

[0326] Now refer to Figure 11C , which is a schematic diagram of a first coupling portion 170A and a second coupling portion 170B according to some applications of the present invention, which facilitates coupling independently of other components of the frame 34. Figures 11A-11B The first portion 170A and the second portion 170B are configured to engage each other. The first portion is disposed on the impeller, while the second portion is coupled to the frame 34 and / or the proximal support 116. Referring again to Figure 11A and Figure 11B For some applications, the impeller is radially constrained by engaging portions 170A and 170B with each other and axially extending the impeller to constrain the impeller radially prior to crimping frame 34. Frame 34 is then crimped. Typically, when the impeller and frame are positioned in the left ventricle of a subject, the first and second coupling portions are separated from each other, allowing the proximal end of the impeller to move relative to frame 34 and proximal support 116.

[0327] Now refer to Figure 12A , which shows that when the impeller is Figures 11A-11BA graph showing the relationship between the pressure gradient against which the impeller pumps and the impeller pitch for the configuration shown. As shown, since the proximal end of the impeller is slidable, as the pressure gradient against which the impeller pumps increases, the pitch of the impeller decreases because the impeller blades are axially compressed by the pressure against which the impeller pumps. Figure 12B , which is a graph showing pressure-flow curves for impellers having corresponding pitches as described herein. Curve C1 corresponds to an impeller having a relatively small pitch, C2 corresponds to an impeller having a medium pitch, and C3 corresponds to an impeller having a relatively large pitch. As shown, assuming all else is equal, the smaller the pitch of the impeller, the greater the gradient of the pressure-flow curve. Furthermore, assuming all else is equal, at relatively high pressure gradients, the impeller with the smaller pitch produces a greater flow than the impeller with the larger pitch, while at relatively low pressure gradients, the impeller with the larger pitch produces a greater flow than the impeller with the smaller pitch. According to Figures 12A-12B For some applications, because the impeller is coupled to the axial shaft at its distal end and is slidable relative to the axial shaft at its proximal end, the pitch of the impeller decreases as the pressure gradient against which the impeller is pumping increases. Thus, at higher pressure gradients (where a smaller pitch typically produces a higher flow rate), the impeller has a smaller pitch, while at lower pressure gradients (where a larger pitch typically produces a higher flow rate), the impeller has a larger pitch.

[0328] Reference Figure 12B and for an impeller typically configured in the context of this application (i.e., with the proximal support coupled to the axial shaft and not Figures 11A-11B ), it is typically desirable for the impeller to have the following features:

[0329] 1) At a rotational speed of less than 20,000 RPM (e.g., less than 19,000 RPM), the impeller provides positive flow or at least zero flow when pumping against a pressure gradient of 100 mmHg-120 mmHg. Thus, even though there may be abnormally high back pressure from the aorta to the left ventricle, no blood flows in this direction.

[0330] 2) At a rotational speed of less than 20,000 RPM (e.g., less than 19,000 RPM), the impeller provides a flow rate greater than 3.5 L / min (e.g., greater than 4.5 L / min), e.g., 3.5 L / min-5 L / min, when pumping against a pressure gradient greater than 50 mmHg (e.g., greater than 60 mmHg), e.g., 50 mmHg-70 mmHg. Under normal physiological conditions, the pressure gradient between the left ventricle and the aorta during diastole is within the above range, and the described flow rates need to be provided even during diastole.

[0331] As shown by the curves shown in 12B, to provide the first feature, an impeller with a smaller pitch (corresponding to curve C1) is preferred, but to provide the second feature, an impeller with a larger pitch (corresponding to curve C3) is preferred. With this background in mind, the inventors of the present application have discovered that, in order to optimally satisfy the first and second features, it is typically desirable for the impeller to have a pitch such that, when the impeller is in its non-radially constrained configuration, the helical elongated elements of the impeller (and therefore the blades of the impeller) undergo a complete rotation of 360 degrees (or will undergo a complete rotation if they are long enough) over an axial length of greater than 8 mm (e.g., greater than 9 mm) and / or less than 14 mm (e.g., less than 13 mm), such as 8 mm to 14 mm, 9 mm to 13 mm, or 10 mm to 12 mm. Typically, when the impeller has a pitch as described above, and at a rotational speed of less than 20,000 RPM (e.g., less than 19,000 RPM), the impeller provides zero flow or positive flow at a pressure gradient of greater than 100 mmHg (e.g., greater than 110 mmHg), and provides a flow rate of greater than 3 L / min (e.g., greater than 4.5 L / min), e.g., 3.5 L / min-5 L / min, at a pressure gradient of greater than 50 mmHg (e.g., greater than 60 mmHg), e.g., 50 mmHg-70 mmHg. Typically, when the impeller is in its non-radially constrained configuration, the impeller is configured to provide the aforementioned flow rates with an impeller having a maximum diameter greater than 7 mm (e.g., greater than 8 mm).

[0332] For some applications, at least when the impeller is in a non-radially constrained configuration, the pitch of the helical elongated element 52 of the impeller (and therefore the blades of the impeller) varies along the length of the helical elongated element. Typically, for such applications, the pitch increases from the distal end of the impeller (i.e., the end that is inserted further into the subject and that is upstream relative to the direction of antegrade blood flow) to the proximal end of the impeller (i.e., the end that is downstream relative to the direction of antegrade blood flow) such that the pitch increases in the direction of blood flow. Typically, blood flow velocity increases along the impeller, in the direction of blood flow. Therefore, the pitch increases along the direction of blood flow, thereby further accelerating the blood.

[0333] Now refer to Figure 13A 、 Figure 13B and Figure 13C , these figures are schematic diagrams of a process for cleaning a drive cable 130 of a ventricular assist device 20 according to some applications of the present invention. For some applications, as described above, proximal to the proximal support 116, the axial shaft 92 and the cable 130 are surrounded by a first outer tube 140 and a second outer tube 142. Typically, both the first outer tube and the second outer tube remain stationary during rotation of the drive cable. For some applications, the cleaning system 29 (e.g., Figure 1A shown) via inlet port 86 and outlet port 88 (at Figure 7 、 Figure 8A 、 Figure 8B 、 Figure 13B and Figure 13C ) controls the flow of a purge fluid (e.g., a fluid containing glucose or dextrose) through the drive cable 130. The fluid is configured to remove air from the space between the drive cable and the outer tube and / or reduce friction between the drive cable 130 (which rotates) and the outer tube 140 (which remains stationary during drive cable rotation), and / or reduce friction between the axial shaft 92 and the proximal support 116 and / or the distal support 118.

[0334] Reference Figure 13A For some applications, a cleaning fluid is pumped between the first outer tube and the second outer tube, and an opening 146 is provided in the first outer tube near the proximal support. For some applications, the cleaning fluid flows between the first outer tube 140 and the drive cable 130 via the opening 146, as shown in FIG. Figure 13A 14. In this manner, the interface between the drive cable 130 (which rotates) and the outer tube 140 (which remains stationary during the rotation of the drive cable) is cleaned. For some applications, some cleaning fluid additionally flows to the interface between the axial shaft and the proximal support 116, thereby cleaning that interface (and / or reducing friction at that interface), as shown in FIG. Figure 13A 14. The cleaning fluid flow arrows 149 in FIG. 14. Typically, the flow of cleaning fluid in the direction of arrow 149 also prevents blood from flowing into the interface between the axial shaft and the proximal support.

[0335] As mentioned above (refer to Figure 10B ), the drive cable typically includes multiple coiled wires. For some applications, the cleaning fluid enters the lumen 132 defined by the drive cable through the gaps in the coiled wires. Once the cleaning fluid is disposed within the lumen 132, the cleaning fluid flows in the proximal and distal directions, such as Figure 13A As shown by arrow 151. Figure 13A As shown by arrow 152, the cleaning fluid flowing in the distal direction typically flows out of the distal end of the lumen 132 and flows toward the lumen 122 defined by the distal tip portion. At the end of the distal tip portion, the cleaning fluid is typically prevented from flowing out of the distal tip portion by a duckbill valve 390. Therefore, some of the cleaning fluid typically flows toward the interface between the axial shaft and the distal support 118, thereby cleaning the interface (and / or reducing friction at the interface), as shown in FIG. Figure 13A 154. Typically, the flow of cleaning fluid in the direction of arrow 154 also prevents blood from flowing into the interface between the axial shaft and the distal support.

[0336] As described above, once the cleaning fluid is disposed within lumen 132, the cleaning fluid flows in both the proximal and distal directions, as shown in FIG. Figure 13A As shown by arrow 151. Now refer to Figure 13B Typically, at the proximal end of ventricular assist device 20, the purge fluid flows in the direction of arrow 156 out of the proximal end of lumen 132 and then out of the proximal end of lumen 133 defined by pin 131. For some applications, the purge fluid then flows in the direction of arrow 157 and around the driven magnet to reduce frictional forces experienced by the driven magnet. For some applications, the purge fluid then flows in the direction of arrow 158 out of outlet port 88. Typically, the purge fluid is then disposed of. Alternatively, the purge fluid is pumped back into the device via inlet port 86.

[0337] With reference to the above description of the cleaning process typically used with the ventricular assist device 20, it should be noted that the guide wire lumens 122, 132 and 133 (which, as described above, were previously used to facilitate insertion of the device over the guide wire 10) are typically used as flow paths for the cleaning fluid during use of the ventricular assist device.

[0338] Now refer to Figure 13C For some applications, the ventricular assist device includes an additional purge fluid inlet port 89, which is typically used to pump purge fluid into a channel 224 between the delivery catheter 143 and the outer tube 142. For some applications, the purge fluid is pumped into the channel at a sufficiently low pressure that aortic blood pressure can still be detected through the channel, as described in further detail below. For some applications, rather than continuously pumping purge fluid into channel 224, fluid is periodically pumped into the channel to flush the channel. For some applications, port 89 and channel 224 are used for aortic pressure sensing, as described in further detail below.

[0339] Now refer to Figure 13D , which is a schematic diagram of a ventricular assist device 20 according to some applications of the present invention, the ventricular assist device 20 including an expandable portion 153 (e.g., a balloon) on its distal tip that is configured to be inflated by a fluid used to clean the drive cable of the device. As described above, with reference to Figure 13AFor some applications, a cleaning fluid is pumped through a lumen 132 defined by the drive cable 130 and the axial shaft 92 such that at least some of the fluid flows all the way to the distal end of the axial shaft. Typically, for such applications, the cleaning fluid continues to flow into the lumen 122 of the distal tip portion 120. For some applications, an expandable portion 153 is disposed about the distal tip portion, and an opening 155 is present between the lumen 122 and the interior of the expandable portion. The expandable portion is expanded by the cleaning fluid entering the interior of the expandable portion through the opening 155. For some applications, the expansion of the expandable portion is controlled by controlling the pressure at which the cleaning fluid is pumped into the ventricular assist device 20.

[0340] Note that some applications of the present invention, such as Figure 13D (and e.g. Figure 16A 、 Figure 16B 、 Figure 16E 、 Figure 17D 、 Figure 30 and Figure 31 ) is substantially as described in US 2019 / 0209758 to Tuval, which is incorporated herein by reference. The scope of the present invention includes combining the apparatus and methods described with respect to any of the figures with any shape of distal tip element described herein. It should also be noted that according to some applications of the present invention, such as Figure 13D The configuration of the frame 34 shown is generally as described in US 2019 / 0209758 to Tuval, which is incorporated herein by reference. The scope of the present invention includes combining the instruments and methods described with respect to any of the figures with any shape of the distal tip portion and / or configuration of the frame 34 described herein.

[0341] Reference Figure 13EFor some applications, as an alternative to pumping a purge fluid through the ventricular assist device throughout operation of the ventricular assist device, fluid 147 is initially released into the space between the drive cable 130 (which rotates) and the outer tube 140 (which remains stationary during rotation of the drive cable), such that the fluid fills the space between the drive cable and the outer tube 140 and the lumen 132. The fluid is then typically maintained in place between the drive cable and the outer tube 140 and within the lumen 132 throughout operation of the ventricular assist device. The fluid is configured to remove air from the space between the drive cable and the outer tube and / or reduce friction between the drive cable 130 (which rotates) and the outer tube 140 (which remains stationary during rotation of the drive cable), and / or reduce friction between the axial shaft and the proximal support 116 and / or the distal support 118. For some applications, the fluid is also configured to fill the space between the tube 140 and the tube 142, for example, by passing through an aperture defined by the tube 140. For some such applications, thermally conductive elements are disposed within the first outer tube and / or the second outer tube to dissipate heat away from areas where significant heat is generated by frictional forces.

[0342] For some applications, the fluid has a relatively high viscosity, e.g., greater than 100 mPa.s (e.g., greater than 500 mPa.s), e.g., a viscosity between 100 mPa.s and 1000 mPa.s, such that the fluid remains substantially in place during operation of the ventricular assist device. For example, petrolatum and / or ultrasound coupling gel can be used as the fluid. For some applications, in order to pump the fluid toward the distal end of the ventricular assist device, the fluid is initially heated to temporarily reduce its viscosity.

[0343] Now refer to Figure 14A 、 Figure 14B and Figure 14C , these figures are schematic diagrams of a stator 250 according to some applications of the present invention, the stator 250 being configured to be disposed within the tube 24 of the ventricular assist device 20, proximal to the frame 34 and the impeller 50. For some applications, the stator is comprised of a frame 252 coupled to the outer tube 142 and a flexible material 254 (e.g., polyurethane, polyester, silicone, polyethylene terephthalate (PET) and / or polyether block amide) coupled to the frame. ). Typically, when the device 20 is in the non-radially constrained configuration, the stator is shaped to define a plurality of curved protrusions 256 (e.g., more than two and / or fewer than eight curved protrusions) extending radially from the outer tube 142. The curvature of the curved protrusions is typically opposite to the direction of rotation of the impeller. The stator is typically configured to reduce the rotational flow component of the blood flow before the blood flows from the outlet opening 109 of the tube 24. For some applications, the protrusions of the stator 250 are not curved.

[0344] Typically, during insertion of tube 24 into the left ventricle, the curved protrusions of the stator are radially constrained by the delivery catheter 143. When released from the delivery catheter, the curved protrusions are configured to automatically assume their curved configuration.

[0345] Now refer to Figure 15A 、 Figure 15B 、 Figure 15C 、 Figure 15D and Figure 15E , these figures are schematic diagrams of a stator 260 defined by the tube 24 of the ventricular assist device 20 according to some applications of the present invention. Typically, the stator 260 is defined by a portion of the tube 24 that is disposed proximally relative to the frame 34 and the impeller 50 and is configured to reduce the rotational flow component of the blood flow before the blood flows from the outlet opening 109 of the tube 24. For some applications, the stator 260 is comprised of one or more curved bands 262 that curve within the tube 24 around the outer tube 142, as shown. Figure 15A Alternatively or additionally, the stator 260 includes a portion 266 of the tube 24 that is twisted so that the tube wall itself defines folds that reduce the rotational flow component of the blood flow before the blood flows from the outlet opening 109 of the tube 24, as shown. Figure 15B shown.

[0346] For some applications, along a portion of tube 24 between the proximal end of frame 34 and outlet opening 109, the tube is divided into a plurality of compartments 267 by a plurality of curved ribbons 262 such that the compartments define a wound helix along the length of the portion of the tube, e.g. Figure 15C Alternatively, as Figure 15D As shown, along a portion of the tube 24 between the proximal end of the frame 34 and the outlet opening 109, the tube is divided into a plurality of compartments 269 by a plurality of strips 264 parallel to the longitudinal axis of the tube 24. For some applications, within a portion of the tube 24 between the proximal end of the frame 34 and the outlet opening 109, the tube 24 includes a plurality of spiral tubes 268 configured to serve as stators 260. For some applications, as shown, the spiral tubes are wound around each other. Typically, Figure 15A 、 Figure 15B 、 Figure 15C 、 Figure 15D and Figure 15E Each example of the stator 260 shown in FIG. 2 is configured to reduce a rotational flow component of blood flow before the blood flows from the outlet opening 109 of the tube 24 .

[0347] Now refer to Figure 16A and Figure 16B, these figures are schematic diagrams of a ventricular assist device 20 according to some applications of the present invention, the ventricular assist device including one or more ventricular blood pressure measuring tubes 220. As described above, the ventricular assist device typically includes a tube 24 that passes through the aortic valve of the subject such that the proximal end of the tube is disposed within the subject's aorta and the distal end of the tube is disposed within the subject's left ventricle. Typically, a blood pump (which typically includes an impeller 50) is disposed within the tube 24, within the subject's left ventricle, and is configured to pump blood from the left ventricle into the subject's aorta through the tube 24. For some applications, the ventricular blood pressure measuring tube 220 is configured to extend at least to an outer surface 212 of the tube 24 such that an opening 214 at the distal end of the blood pressure measuring tube is in direct fluid communication with the subject's blood flow outside the tube 24. Typically, the opening 214 is configured to be within the subject's left ventricle, proximal to the blood pump (e.g., proximal to the impeller 50). The pressure sensor 216 (at Figure 1A Typically, the pressure sensor measures the blood pressure of the subject outside of tube 24 (i.e., the left ventricular blood pressure) by measuring the blood pressure in the left ventricular blood pressure measuring tube. Typically, the blood pressure measuring tube 220 extends from outside the subject's body to an opening 214 at the distal end of the tube, and the pressure sensor 216 is positioned toward the proximal end of the tube, e.g., outside the subject's body. For some applications, the computer processor 25 ( Figure 1A ) receives an indication of the measured blood pressure and controls the pumping of blood by the impeller in response to the measured blood pressure.

[0348] For some applications, the ventricular assist device includes two or more such ventricular blood pressure measurement tubes 220, such as Figure 16A and Figure 16B For some applications, computer processor 25 determines whether the opening of one of the two or more ventricular blood pressure measurement tubes is blocked based on the blood pressure measured within each left ventricular blood pressure measurement tube. This may occur, for example, due to the opening contacting the intraventricular septal wall and / or a different ventricular portion. Typically, in response to determining that the opening of one of the two or more ventricular blood pressure measurement tubes is blocked, the computer processor determines the subject's left ventricular pressure based on the blood pressure measured within another of the two or more ventricular blood pressure measurement tubes.

[0349] Reference Figure 16AAs described above, for some applications, a drive cable 130 extends from a motor outside the subject's body to an axial shaft 92 on which the impeller 50 is disposed. Typically, the drive cable is disposed within an outer tube 142. For some applications, the drive cable is disposed within the first outer tube 140 and the second outer tube 142, as described above. For some applications, aortic blood pressure is measured using at least one aortic blood pressure measurement tube 222, which defines an opening 219 in the outer tube 142 at its distal end. The aortic blood pressure measurement tube is configured to extend from the outside of the subject's body to the outer surface of the outer tube 142 within the subject's aorta, such that the opening at the distal end of the aortic blood pressure measurement tube is in direct fluid communication with the subject's aortic blood flow. The blood pressure sensor 216 is configured to measure the subject's aortic blood pressure by measuring the blood pressure within the aortic blood pressure measurement tube.

[0350] For some applications, one or more ventricular blood pressure measuring tubes 220 and / or one or more aortic blood pressure measuring tubes 222 are disposed within the outer tube 142, surrounding the drive cable. For some applications, portions of the one or more blood pressure measuring tubes are defined by the wall of the outer tube 142, such as Figure 16A and Figure 16B , as shown in cross-section. For some applications, within outer tube 142, the blood pressure measurement tubes have an elliptical cross-section (as shown). Typically, this increases the cross-sectional area of ​​the tubes relative to a circular cross-section. Typically, within the distal portion of each ventricular blood pressure measurement tube 220 (which extends to opening 214), the tubes have a circular cross-section. For some applications, the diameter of the distal portion of the tubes is greater than 0.2 mm and / or less than 0.5 mm (e.g., 0.2 mm to 0.5 mm).

[0351] like Figure 16A and Figure 16B As shown, for some applications, outer tube 142 defines a groove 215 in a portion of the outer surface of the outer tube that is configured to be disposed within tube 24. Typically, during insertion of a ventricular assist device into a subject, the portion of ventricular blood pressure measuring tube 220 that extends from within tube 24 to at least the outer surface of tube 24 is configured to be disposed within the groove such that the portion of the ventricular blood pressure measuring tube does not protrude from the outer surface of the outer tube.

[0352] Now refer to Figure 16C and Figure 16D , these figures are schematic diagrams of a ventricular assist device 20 having an aortic blood pressure measurement channel 224 within a delivery catheter 143 according to some applications of the present invention. For some applications, during operation of the ventricular assist device, channel 224 is defined between the delivery catheter 143 and the outer tube 142, extending from the distal end of the delivery catheter to the proximal end of the delivery catheter. For example, Figure 10AThe gap between the outside of the outer tube 142 and the inside of the delivery catheter 143 is shown, which can be used as the aforementioned passage. Note that for illustration purposes, Figure 10A The proportions of the channels shown are not to scale. Typically, during operation of the ventricular assist device, the distal end of the delivery catheter is positioned within the aorta of the subject and the proximal end of the delivery catheter is positioned outside the subject's body. Thus, by sensing the pressure within the channel between the delivery catheter 143 and the outer tube 142, the blood pressure sensor 216 (which is located in the Figure 1A For some applications, the pressure sensor is connected to the aortic pressure sensor via port 89 (such as Figure 13C As shown) sense the aortic pressure. As mentioned above, refer to Figure 13C , a purge fluid is typically pumped into the channel between the delivery catheter 143 and the outer tube 142. For some applications, the purge fluid is pumped into the channel at a sufficiently low pressure that aortic blood pressure can still be detected through the channel in the manner described above.

[0353] For some applications, a spacer tube 240 is positioned between the outer tube 142 and the delivery catheter 143 along at least a distal portion of the delivery catheter 143 to fill a gap between the outer tube and the delivery catheter. For some applications, the spacer tube is configured to prevent debris, emboli, and / or other material from flowing out of the distal end of the delivery catheter where they could flow into the carotid artery 241. For some applications, the delivery catheter defines a side hole 242 exposed to aortic blood flow. For some such applications, a spacer tube is not positioned between the delivery catheter and the outer tube near the hole 242, e.g., Figure 16C Thus, a passage 224 is defined between the delivery catheter and the outer tube 142 near the aperture 242, such that the subject's aortic blood pressure is detected via the passage 224 in the manner described above. Alternatively, a spacer tube is disposed between the delivery catheter and the outer tube near the aperture 242, but the spacer tube defines a passage 224 extending from the aperture to the proximal end of the delivery catheter, as shown. Figure 16D Typically, the subject's aortic blood pressure is detected via channel 224 in the manner described above (eg, via port 89).

[0354] Now refer to Figure 16E, which is a schematic diagram of a ventricular assist device 20 according to some applications of the present invention, the device including one or more blood pressure measurement sensors 270 disposed on the outer surface of tube 24. For some applications, techniques substantially similar to those described with reference to ventricular blood pressure measurement tube 220 are performed using wires 272 that extend along blood pump tubing 24 (and the wires typically extend from outside the subject's body) to the outer surface of tube 24. Blood pressure measurement sensor 270 is disposed at a tip of the wire that is in electrical communication with the subject's blood flow outside tube 24. The subject's blood pressure outside tube 24 (e.g., the subject's ventricular blood pressure and / or the subject's aortic blood pressure) is measured by detecting electrical parameters using the sensors. For some applications, wire 272 and / or sensor 270 are printed on the outer surface of tube 24.

[0355] For some applications, sensor 270 is configured to perform conductivity measurements. For some applications, the conductivity sensor is disposed within tube 24 (rather than on the outer surface of tube 24), but is configured to sense conductivity using a frequency that is not substantially attenuated by tube 24. For some applications, an additional conductivity sensor is disposed on the left ventricular assist device, for example, on distal tip element 107. For some such applications, computer processor 25 ( Figure 1A ) applies an electric current between a distal-most electrode and a proximal-most electrode, the distal-most electrode being typically configured to be positioned near the apex of the heart and the proximal-most electrode being typically configured to be positioned above the aortic valve. The conductance of the current between each pair of electrodes is then measured by a computer processor. For some applications, the application of the electric current and the conductance measurement are performed using techniques substantially similar to those described in an article by Cassidy et al., entitled “The Conductance Volume Catheter Technique for Measurement of Left Ventricular Volume in Young Piglets” (Pediatric Research, Vol. 31, No. 1, 1992, pp. 85-90). For some applications, the computer processor is configured to derive a real-time left ventricular pressure-volume loop of the subject based on the conductance measurement. For some applications, the computer processor controls the rotational rate of the impeller in response to the derived pressure-volume loop.

[0356] For some applications, the subject's ventricular blood pressure is derived from a conductance measurement. For some such applications, the subject's aortic blood pressure is measured (e.g., as described above). The subject's left ventricular pressure is derived by measuring conductance measurements during the subject's cardiac cycle and determining the difference between the left ventricular pressure and the aortic pressure at any given point in the cardiac cycle based on conductance measurements previously calibrated with the left ventricular / aortic pressure gradient. For some applications, the computer processor is configured to calculate the first derivative of the left ventricular pressure measurement. Typically, this change represents the rate of change of pressure within the left ventricle, which is itself an important clinical parameter. Note that the first derivative of left ventricular pressure is typically not affected by changes in aortic pressure because the aortic pressure curve is relatively flat as the left ventricular pressure curve undergoes clinically important changes.

[0357] Now refer to Figure 17A 、 Figure 17B 、 Figure 17C and Figure 17D , which are schematic diagrams of outer tube 142 of ventricular assist device 20 including a Pitot tube 225 configured to measure blood flow through tube 24 of the device, according to some applications of the present invention. Figures 17A-17D The portion of outer tube 142 shown is typically disposed within tube 24. For some applications, flow obstruction 226 (which is typically funnel-shaped) is configured to create a stagnation region near stagnation pressure port 227. For some applications, such as Figure 17A As shown, a flow straightener 228 is added to the outer surface of the tube 142 to remove any turbulent components in the flow (which do not contribute to the axial flow rate). Alternatively, as shown Figure 17B As shown, the stagnation pressure interface is positioned sufficiently close to the funnel-shaped flow obstruction 226 so that the flow obstruction itself serves to remove turbulent components from the flow before the blood reaches the stagnation pressure interface. For some applications, the stagnation pressure interface includes a short tube 233 that protrudes from the outer tube 142 within the funnel-shaped flow obstruction 226 so that the opening of the short tube 233 faces the direction of axial blood flow through the tube 24, as shown in FIG. Figure 17C The outer tube 142 also defines an opening 219 that serves as a static pressure port 229. The pressure within the stagnation pressure port 227 and the static pressure port 229 is measured using a pressure sensor, for example, as described above with reference to Figures 16A-16D The pressure sensor is arranged outside the subject's body.

[0358] In some applications, the flow rate through tube 24 is calculated based on the pressure measurement. For example, the flow rate through tube 24 can be calculated using the following equation:

[0359]

[0360] in:

[0361] Q is the flow rate through tube 24,

[0362] C is a calibration constant determined empirically and taking into account factors such as impeller speed and the geometry of pressure ports 227 and 229,

[0363] A is the cross-sectional area of ​​tube 24 (excluding the area occupied by outer tube 142),

[0364] ΔP is the difference between the stagnation pressure (measured via pressure port 227) and the static pressure (measured via pressure port 229),

[0365] ρ is the fluid density of blood.

[0366] Reference Figure 17D For some applications, a region 230 of tube 24 where pitot tube 225 is located is narrowed relative to the remainder of the cylindrical portion of tube 24. For some applications, the narrowing in this region facilitates more accurate measurements using the pitot tube. For some applications, narrow region 230 of tube 24 is configured to be placed within the aortic valve of a subject. Typically, the narrowing of the tube at region 230 is configured to facilitate placement of region 230 at the aortic valve. For some applications, tube 24 includes narrow region 230 even in the absence of pitot tube 225 to facilitate placement of this region of the tube at the aortic valve in the manner described above.

[0367] Now refer to Figure 18, which is a schematic diagram of a ventricular assist device 20 according to some applications of the present invention, the ventricular assist device including a coronary tube and / or wire 304. For some applications, one or more tubes and / or wires extend along the exterior or interior of a proximal portion of tube 24. The tubes and / or wires are shaped such that, in a non-radially constrained configuration of the tubes and / or wires, distal ends of the tubes and / or wires extend radially from the outer surface of tube 24. The tubes and / or wires are positioned to extend radially along tube 24 from an axial position such that when the distal ends of the tubes and / or wires are positioned at a coronary artery 306 of the subject, the pump portion 27 of the device is properly positioned within the left ventricle 22 of the subject. For some applications, medical personnel deploying ventricular assist device 20 ensure that the pump portion 27 of the device is properly positioned within the left ventricle 22 of the subject by inserting the distal ends of the tubes and / or wires into the coronary artery 306. For some applications, a tube is used in the above-described embodiments, and the tube extends proximally to the proximal end of the ventricular assist device (e.g., via outer tubes 140, 142 and / or via delivery catheter 143). For some such applications, one or more coronary arteries are operated on via the tube. Alternatively or additionally, a contrast agent is injected via the tube to help image the current position of the device. For some applications, a substantially similar technique is performed using the ventricular blood pressure measurement tube 220 described above. For example, a contrast agent can be injected via the blood pressure measurement tube to help image the current position of the device.

[0368] Now refer to Figure 19A 、 Figure 19B 、 Figure 19C 、 Figure 19D 、 Figure 19E 、 Figure 19F 、 Figure 19G and Figure 19H , these figures are schematic diagrams of a ventricular assist device 20 according to some applications of the present invention, the device including a liner 39 lining the interior of a frame 34 housing an impeller 50. For illustrative purposes, Figures 19A-19E , the liner 39 and tube 24 on the side of the device facing out of the page are shown as transparent. For some applications, the liner 39 is positioned within the frame 34 to provide a smooth inner surface through which blood pumped by the impeller passes. Typically, by providing a smooth surface, the covering material reduces hemolysis caused by blood pumped by the impeller as compared to blood pumped between the impeller and the struts of the frame 34. For some applications, the liner comprises polyurethane, polyester and / or silicone. Alternatively or additionally, the liner comprises polyethylene terephthalate (PET) and / or polyether block amide

[0369] Typically, the liner is provided on at least the inner surface of the cylindrical portion of the frame 34 (e.g., the cylindrical portion is Figure 2A-2CFor some applications, the tube 24 also covers the cylindrical portion 38 of the frame 34, e.g., around the outside of the frame, so that the tube 24 and the liner 39 overlap over at least 50% of the length of the liner, e.g., over the entire length of the cylindrical portion of the frame 34, e.g., as shown in FIG. Figure 19A For some applications, there is only a partial overlap between the tube 24 and the liner 39, e.g. Figure 19B For example, the tube 24 may overlap the liner along less than 50% (e.g., less than 25%) of the liner's length. For some such applications, during insertion of the ventricular assist device 20 into a subject, the impeller is advanced distally within the frame 34 such that the impeller is not positioned within the overlap region between the tube and the liner, such that there is no longitudinal position where the impeller, tube 24, frame 34, and liner 39 all overlap one another.

[0370] Typically, for Figure 19A and Figure 19B In the illustrated application, the liner 39 is shaped to form a smooth surface over the overlap region between the liner and the tube 24 (e.g., to reduce hemolysis, as described above), and the tube 24 is shaped to conform to the struts of the frame 34 (e.g., as described above). Figure 19A Typically, at the overlap region between the liner 39 and the tube 24, the tube and liner are coupled to one another, such as via vacuum, via adhesive, and / or using a thermoforming process, such as described below.

[0371] For some applications, the liner 39 and the tube 24 are made of different materials. For example, the liner can be made of polyurethane and the tube can be made of polyether block amide. Typically, the material from which the liner is made has a higher thermoforming temperature than the material from which the tube is made. For some applications where the liner and tube overlap along at least a portion of the frame 34 (e.g., along a cylindrical portion of the frame 34), the tube and liner are bonded to each other and / or to the frame in the following manner. Initially, the liner is placed on a mandrel. Subsequently, the frame is placed over the liner. Next, the tube 24 is placed around the outside of the frame. For some applications, in order to mold the tube 24 to conform to the struts of the frame 34 without causing deformation of the liner, the frame is heated to a temperature that is higher than the thermoforming temperature of the tube 24 but lower than the thermoforming temperature of the liner 39. Typically, the frame is heated from the inside of the frame using a mandrel. Typically, when the frame is heated to the above-mentioned temperature, the outer tube (which is typically made of silicone) applies pressure to the tube 24, causing the tube 24 to be pushed radially inward so that the tube conforms to the shape of the struts of the frame, as Figure 19A For some applications, the combination of the frame, liner, and the portion of the tube 24 disposed about the frame is then formed into the desired shape and size using forming techniques known in the art.

[0372] As described above, the scope of the present invention includes a method for manufacturing a housing for an impeller of a blood pump, the method comprising performing the following steps: A liner is positioned around a mandrel. A cylindrical portion of a frame is positioned around the liner, the cylindrical portion of the frame including struts defining a generally cylindrical shape. A distal portion of an elongated tube is positioned around at least a portion of the frame, the tube including a proximal portion defining at least one blood outlet opening. While the distal portion is positioned around at least a portion of the frame, the liner, frame, and distal portion of the elongated tube are heated via the mandrel. While heating the liner, frame, and distal portion of the elongated tube, pressure is applied from the exterior of the distal portion of the elongated tube to cause the distal portion of the elongated tube to conform to the strut structure of the frame and to cause the liner and distal portion of the elongated tube to become coupled to the frame. For example, the pressure can be applied via a silicone tube positioned outside the distal portion of the elongated tube. For some applications, the liner and the elongated tube are made of different materials, and the material of the liner is thermoformed at a higher temperature than the material of the elongated tube. For some such applications, the liner, frame, and distal portion of the elongated tube are heated to a temperature above the thermoforming temperature of the material from which the elongated tube is made and below the thermoforming temperature of the material from which the liner is made.

[0373] Reference Figure 19C For some applications, tube 24 does not overlap liner 39, but tabs 322 extend from tube 24 through the struts of frame 34 to liner 39 and serve to sealingly couple the tube to the liner (e.g., by adhering to the liner). Alternatively or additionally (not shown), tabs 322 extend from the liner to tube 24 and serve to sealingly couple the tube to the inner material (e.g., by adhering to the tube).

[0374] As described above, for some applications, the combination of the frame, liner, and the portion of the tube 24 disposed about the frame is shaped to the desired shape and size using shaping techniques known in the art. Figure 19DFor some applications, the combination of the frame, the liner, and the portion of the tube 24 disposed about the frame is shaped such that the distal portion 330 of the cylindrical portion 38 of the frame is widened relative to the remainder of the cylindrical portion of the frame. Typically, the widening of the frame causes the blood inlet opening 108 (which is typically defined by the liner at the distal end of the cylindrical portion of the frame) to be widened relative to the remainder of the cylindrical portion of the frame. Typically, the impeller is disposed very close to the blood inlet opening throughout operation of the impeller (and during axial reciprocation), with the distal end of the impeller typically being disposed within 15 mm of the blood inlet opening throughout operation of the impeller. For some applications, having the widened blood inlet opening very close to the impeller reduces turbulence generated as blood flows into the blood inlet opening. The reduction in turbulence typically increases blood flow and / or reduces hemolysis generated by the impeller compared to a non-widened blood inlet opening defined by the frame.

[0375] Reference Figure 19E For some applications, the combination of the frame, the liner, and the portion of the tube 24 disposed about the frame is shaped such that a distal portion 332 of the frame's cylindrical portion 38 converges from the distal end of the frame's cylindrical portion and toward the impeller (e.g., defines a portion of the frame that is narrower than the remainder of the frame's cylindrical portion near the impeller (e.g., near the impeller's distal end)). For some applications, converging a portion of the frame toward the impeller reduces turbulence generated when blood flows from the blood inlet opening toward the impeller. The reduction in turbulence typically increases blood flow and / or reduces hemolysis generated by the impeller compared to a frame that does not define a converging portion.

[0376] Reference Figure 19F For some applications, the combination of the frame, the liner, and the portion of the tube 24 disposed about the frame are shaped so that reference is made to Figure 19D and Figure 19E The features described are combined. That is, the first distal portion 330 of the cylindrical portion of the frame widens relative to the remainder of the cylindrical portion 38 of the frame, while the second portion 332 of the cylindrical portion of the frame converges towards the impeller.

[0377] Reference Figure 19G , for some applications, the tube 24 does not extend to the distal end of the cylindrical portion 38 of the frame 34. For some such applications, along the portion of the frame over which the tube extends, the tube is configured to limit radial expansion of the frame. Along the distal portion of the cylindrical portion of the frame (over which the tube does not extend), expansion of the frame is not limited by the tube 24. Thus, the distal portion of the cylindrical portion of the frame is wider relative to the portion of the cylindrical portion of the frame proximal to the distal portion (over which the tube 24 extends). For some applications, this causes the blood inlet opening 108 to be wider than if the tube 24 extended along the entire length of the cylindrical portion of the frame. As described with reference to Figure 19DAs described above, the impeller is typically positioned very close to the blood inlet opening throughout the operation (and axial reciprocating motion) of the impeller, with the distal end of the impeller typically being positioned within 15 mm of the blood inlet opening throughout the operation of the impeller. For some applications, having a widened blood inlet opening very close to the impeller reduces turbulence generated as blood flows into the blood inlet opening. This reduction in turbulence typically increases blood flow and / or reduces hemolysis generated by the impeller, compared to a non-widened blood inlet opening defined by the frame.

[0378] Reference Figure 19H For some applications, to facilitate coupling of the liner 39 to the frame 34, an outer covering material is coupled (e.g., using adhesives, vacuum, and / or thermoforming processes) from the outer frame 34 to the inner liner at certain discrete coupling regions 326 along the length of the frame. Note that in FIG. 19 , for illustrative purposes, the catheter 24 and frame 34 are shown without other components of the ventricular assist device (e.g., the impeller and axial shaft). For some applications, at at least one of these coupling regions, the tube 24 includes an outer covering material, such as Figure 19G 39 and / or the tube 24. Alternatively or additionally, at one or more of the coupling regions, additional outer covering material 328 is placed around the frame 34. For example, the additional coupling material can be made of a material similar to that used for the liner 39 and / or tube 24. For some applications, at the coupling regions, the frame 34 has a lower strut density (i.e., the ratio of the surface area occupied by the struts to the area of ​​the open spaces between the struts) than the frame has at other locations along its length. For example, as Figure 19G As shown, along the cylindrical portion 38 of the frame, at the coupling region where the frame has straight axial struts 329 (and conversely at other regions within the cylindrical portion of the frame), the frame defines zigzag struts with a ratio of two zigzag struts for each straight strut. Typically, the reduced strut density at the coupling region allows the outer cover material to be directly coupled to the inner liner over a greater surface area than if the frame did not have the reduced strut density at the coupling region.

[0379] Now refer to Figure 20A 、 Figure 20B and Figure 20C , which are schematic diagrams of a ventricular assist device 20 according to some applications of the present invention, the ventricular assist device 20 includes an expandable portion 331 (e.g., a balloon) that is Figure 20A 、 Figure 20B and Figure 20C For some applications (as shown), the expandable portion 331 is in a corresponding expanded state. Figure 13DThe expandable portion 153 shown is expanded in a manner generally similar to that described above. That is, the expandable portion is expanded by a cleaning fluid that enters the interior of the expandable portion through opening 155. For some applications, the expansion of the expandable portion is controlled by controlling the pressure at which the cleaning fluid is pumped into the ventricular assist device 20. Alternatively or additionally, an inflation lumen for inflating the expandable portion is configured to pass through outer tube 142 and subsequently along the outer surface of tube 24 and to the expandable portion at the distal tip portion.

[0380] For some applications, the expandable portion is configured to be in a corresponding expanded state during various stages of ventricular assist device deployment. For some applications, distal tip portion 120 has a radially converging shape (e.g., Figures 20A-20C ) and is configured to act as a dilator during insertion of the ventricular assist device through a puncture in the body of a subject, as described above. In this manner, the delivery catheter 143 and components of the ventricular assist device disposed within the delivery catheter can be inserted into the puncture without the need for pre-dilation of the puncture and without the need for a separate guide device to facilitate insertion of the delivery catheter through the puncture. Typically, during insertion of the distal tip portion through the puncture in the body of a subject, the expandable portion 331 is maintained in a deflated state, as Figure 20A shown.

[0381] For some applications, after the distal tip portion is inserted through a puncture in the subject's body, the distal tip portion is used to guide the delivery catheter along a tortuous anatomical structure (e.g., an aortic arch). For some applications, during this stage of the procedure, the expandable portion is partially inflated to prevent the distal tip portion from causing damage to the subject's vasculature. Figure 20B Shown in a partially expanded state.

[0382] For some applications, when ventricular assist device 20 is deployed such that the distal tip portion is within the left ventricle of the subject, expandable portion 331 is larger than the expandable portion at Figure 20B 1. The state shown is more fully expanded (e.g., fully expanded). Typically, when the expandable portion is more fully expanded, the expandable portion three-dimensionally separates the one or more blood inlet openings 108 from the internal structures of the left ventricle. In this way, the expandable portion separates the one or more blood inlet openings 108 from the intraventricular septum, chordae tendineae, papillary muscles, and / or the left ventricular apex. For some applications, the expandable portion is shaped so as to direct blood from the left ventricle into the one or more blood inlet openings.

[0383] Typically, a hemostasis valve (e.g., duckbill valve 390) is disposed within lumen 122 of distal tip portion 120. For some applications, the hemostasis valve prevents blood from flowing into lumen 122 and / or lumen 132. Typically, the hemostasis valve prevents the flow of rinsing fluid from the distal end of lumen 122, thereby directing the flow of rinsing fluid toward the interface between axial shaft 92 and distal support 118, as described above.

[0384] Now refer to Figure 21 , which is a schematic diagram of a ventricular assist device 20 placed within a left ventricle 22 of a subject (showing a cross-sectional view of the left ventricle) in accordance with some applications of the present invention. For illustrative purposes, Figure 21 The aortic valve 26 is shown overlaid on a cross-section of the left ventricle, although the aortic valve lies in a different plane than that of the main cross-sectional view. Figures 22A-22D , which are schematic illustrations of a distal tip element 107 of a ventricular assist device according to some applications of the present invention, the distal tip element 107 being at least partially curved to define a curvature resembling a question mark, and also referring to Figure 23A and Figure 23B , which are diagrams of a device disposed within the left ventricle of a subject, according to some applications of the present invention. Figure 22C-Figure 22D Schematic diagram of a ventricular assist device.

[0385] For some applications, the VAD is guided over a guidewire, which is used to insert the VAD toward the apex 342 of the left ventricle. The walls of the left ventricle can be considered to consist of the septal wall 338 (which separates the left ventricle from the right ventricle 340), the posterior wall 336 (from which the papillary muscles 341 protrude, and over which the mitral valve device is positioned), and the free wall 334, each of which occupies approximately one-third of the circumference of the left ventricle (e.g., the septal wall 338 separates the left ventricle from the right ventricle 340), the posterior wall 336 (from which the papillary muscles 341 protrude, and over which the mitral valve device is positioned), and the free wall 334. Figure 21 Typically, it is undesirable for the distal tip element (or any other portion of the VAD) to contact the septal wall due to the risk of causing arrhythmias. More typically, it is desirable to maintain a distance between the distal tip element (and any other portion of the VAD) and the posterior wall so as not to interfere with the mitral valve device and to prevent the mitral valve device from interfering with the function of the VAD. Thus, the VAD is typically directed toward the apex in such a manner that if and when the distal tip element contacts the left ventricular inner wall, the VAD contacts the free wall 334, as shown. Figure 21 and Figures 23A-23B shown.

[0386] Typically, as described above, the ventricular assist device is introduced into the subject's ventricle over a guidewire. Distal tip portion 120 defines a guidewire lumen 122 such that the distal tip portion is maintained in a straight configuration during introduction of the ventricular assist device into the subject's ventricle. For some applications, the distal tip portion is configured to assume its curved shape when the guidewire is removed. Note that Figures 22A-22D The shape of the distal tip portion 120 when initially formed is shown. Typically, due to the insertion of a guidewire through the guidewire lumen 122 (thereby temporarily straightening the distal tip portion), the curvature of the distal tip portion when deployed within the left ventricle of a subject is less than Figures 22A-22D For example, Figure 22C-Figure 22D The curvature of the distal tip portion is shown such that the curved portion of the distal tip portion forms a complete loop. However, Figure 22C-Figure 22D The distal tip of Figure 23A is shown within the left ventricle of a subject, and the distal tip portion does not form a complete loop.

[0387] As described above, the distal tip portion 120 typically forms a portion of the distal tip element 107, which also includes the axial shaft receiving tube 126. Typically, the distal tip element 107 is configured such that in its unconstrained configuration (i.e., in the absence of any forces acting on the distal tip portion), the distal tip element is at least partially bent. For some applications, within a given plane, the distal tip element 107 has a proximal straight portion 346 (at least a portion of which typically includes the axial shaft receiving tube 126). The proximal straight portion of the distal tip element 107 defines a longitudinal axis 348. The curved portion of the distal tip element 107 curves away from the longitudinal axis 348 in a first direction and then passes through an inflection point and bends in an opposite direction relative to the longitudinal axis 348. For example, as Figures 22A-22B As shown, within the plane of the paper, the distal tip element bends first toward the top of the paper and then toward the bottom of the paper, and as shown Figure 22C-Figure 22D As shown, in the plane of the paper, the distal tip element bends first toward the bottom of the paper and then toward the top of the paper. Typically, when formed as Figures 22A-22D As shown, the distal tip element defines an overall curvature similar to a question mark or a tennis racket, with the distal tip element defining a ridge 351 on one side of the longitudinal axis of the straight proximal portion of the distal tip element. For some applications, the ridge is generally shaped as a semi-ellipse. Note that in this context, the term "semi-ellipse" includes a semi-circle. It should also be noted that in some cases, the tip does not define a precise semi-ellipse, but rather a ridged shape that substantially resembles a semi-ellipse.

[0388] like Figures 22A-22BAs shown, for some applications, after passing the inflection point, the distal tip element continues to bend such that the distal tip element crosses back over the longitudinal axis 348 . Figure 22A An example is shown in which the end of the distal tip element has not yet crossed back onto the longitudinal axis again, and a larger gap exists between the distal end of the distal tip element and the proximal end of the curved portion. Figure 22B An example is shown in which the end of the distal tip element crosses back onto the longitudinal axis again, and there is a small gap between the distal end of the distal tip element and the proximal end of the curved portion. Figure 22C-Figure 22D As shown in FIG34 (these figures are a cross-sectional view and an isometric view, respectively, of the same shaped distal tip element), for some applications, after passing the inflection point, the tip does not bend such that the distal tip element crosses back onto the longitudinal axis 348. Instead, all of the curvature of the curved portion of the distal tip element occurs on one side of the longitudinal axis 348.

[0389] Reference Figure 22A and Figure 22C Typically, a hemostatic valve (e.g., duckbill valve 390) is disposed within the distal segment of distal tip portion 120 and is configured to prevent blood from flowing into lumen 122. For some applications, duckbill valve 390 is described below with reference to Figures 28A-28C For example, Figure 22A Shows the use of Figures 28A-28C Alternatively, a different duckbill valve may be used, such as Figure 22C Typically, the duckbill valve has a maximum width of less than 3 mm, such as less than 2 mm. Typically, the entire duckbill valve is disposed within a distal segment of the distal tip portion, which is disposed within the distal-most 10 mm of the distal tip portion, such as within the distal-most 5 mm of the distal tip portion. For some applications, the duckbill valve faces proximally (i.e., such that the wide inlet of the valve faces the distal end of the distal tip portion and the narrow tip of the valve faces away from the distal end of the distal tip portion 120), as described below with reference to Figures 28A-28E For some applications, the guide wire guide 392 is positioned within the distal tip portion 120 proximal to the duckbill valve (e.g., Figure 22A As shown). Figures 22A-22D As shown, the distal segment of the distal portion is typically widened to accommodate a duckbill valve and / or a guidewire guide. For some applications, due to the widening of the distal portion, the distal tip of the distal tip portion (through which the guidewire is inserted into the distal tip portion) does not have a sharp edge. More specifically, the edge has a width greater than 1 mm. Typically, the absence of a sharp edge at the distal tip of the distal tip portion helps prevent the distal tip of the distal tip portion from causing damage to structures within the left ventricle.

[0390] Typically, when deployed within the left ventricle of a subject, the curvature of the curved portion of distal tip element 107 is configured to provide an atraumatic tip to ventricular assist device 20. More typically, the distal tip element is configured to separate inlet opening 108 of the ventricular assist device from the wall of the left ventricle.

[0391] Now refer to Figure 23A and Figure 23B , first note that these figures show a cross-sectional view of left ventricle 22, with septal wall 338 disposed on the left side of the page and free wall 334 disposed on the right side of the page. In this view, left atrium 359 and left atrial appendage 358 are visible above the left ventricle, and right ventricle 340 is visible to the left of the left ventricle. For some applications, distal tip element 107 is configured to separate the blood inlet opening from the posterior wall of the subject's left ventricle when the distal tip element is placed against the apex of the subject's left ventricle. Typically, the distal tip element is configured to separate the blood inlet opening from the septal wall of the subject's left ventricle when the distal tip element contacts the apex of the subject's left ventricle.

[0392] Typically, distal tip element 107 is inserted into the left ventricle such that ridge 351 bulges toward septal wall 338. When arranged in this configuration, in response to distal tip element 107 being pushed toward the apex (e.g., due to advancement of the device by the physician or in response to movement of the left ventricle), the blood inlet opening is typically pushed toward free wall 334 and away from septal wall 338 (at Figure 23B Typically, this is due to the proximal straight portion 346 pivoting about the question mark-shaped curved portion, as shown. In contrast, other shaped tips, if arranged in a similar orientation, may result in the blood inlet opening being pushed toward the septum wall. For example, if the distal tip element has a pigtail tip (where the tip curves along a single direction of curvature) that is oriented such that the pigtail curve is located on the free wall side of the longitudinal axis of the straight portion of the distal tip element, pushing the tip distally will typically result in the blood inlet opening being pushed toward the septum wall due to the tightening of the pigtail curve loop.

[0393] Now refer to Figure 24A 、 Figure 24B 、 Figure 24C , which are schematic illustrations of a distal tip element 107 configured to center itself relative to the aortic valve 26, according to some applications of the present invention. Figure 24A As shown, for some applications, the curved distal portion is shaped such that, after being bent in a first direction and before being bent in a second direction, the curved distal portion defines an elongated straight portion 353. Figure 24BAs shown, the distal tip element is configured such that when deployed within the subject's aorta, the distal tip element centers itself relative to the aortic valve 26. Thus, the distal tip portion can be used to guide the ventricular assist device across the aortic valve in an atraumatic manner. This may be desirable, for example, in the event that the ventricular assist device is mistakenly retracted from the left ventricle through the aortic valve after the distal tip element is deployed within the left ventricle. Figure 24C Alternatively or additionally, the distal tip element may be configured to provide the aforementioned functionality by having a radius of the protrusion 351 of the distal tip element that is sufficiently large to center the distal tip element relative to the aortic valve. For example, the radius of the protrusion of the distal tip element may be greater than 15 mm (e.g., greater than 17 mm).

[0394] Reference Figure 21-24C , it is noted that the scope of the present invention includes the use of a question mark or tennis racket shaped distal tip element in combination with any ventricular assist device, even without other features and / or portions of the distal tip element 107 (e.g., the axial shaft receiving tube 126).

[0395] Now refer to Figure 25A , which is a schematic diagram of a ventricular assist device 20 according to some applications of the present invention, wherein the tube 24 of the device is configured to become curved as blood is pumped through the tube. Figure 25B , which is in accordance with some applications of the present invention in the absence of other components of a ventricular assist device Figure 25A Schematic diagram of the tube 24. Figure 25C , which is disposed within the aorta 30 and left ventricle 22 of a subject according to some applications of the present invention. Figures 25A-25B Schematic diagram of a ventricular assist device 20. Note that Figure 25C The views of the aorta and left ventricle shown are different from e.g. Figure 1B The view shown. Figure 1B and similar figures are schematic illustrations, provided for illustrative purposes, and do not necessarily accurately depict the scale and orientation of the ventricular assist relative to the anatomy. Note also that Figure 25C The views of the aorta and left ventricle shown are different from e.g. Figure 23A and Figure 23B The view shown. Figure 25C A cross-sectional view of the left ventricle is shown, with the posterior wall 336 disposed on the left side of the page and the free wall 334 disposed on the right side of the page.

[0396] As described above, for some applications, along the proximal portion of the tube 24, the frame 34 is not disposed within the tube, and thus the tube is not supported in an open position by the frame 34. The tube 24 is typically made of a collapsible material that is impermeable to blood. For example, the tube 24 may include polyurethane, polyester, and / or silicone. Alternatively or additionally, the tube may be made of polyethylene terephthalate (PET) and / or polyether block amide. Typically, the proximal portion of the tube is configured to be placed such that it is at least partially disposed within the ascending aorta of the subject. For some applications, the proximal portion of the tube passes through the aortic valve of the subject, from the left ventricle of the subject into the ascending aorta of the subject, such as Figure 1B As described above, the tube typically defines one or more blood inlet openings 108 at the distal end of the tube through which blood flows from the left ventricle into the tube during impeller operation. For some applications, the proximal portion of the tube defines one or more blood outlet openings 109 through which blood flows from the tube into the ascending aorta during impeller operation. During impeller operation, blood pressure through the tube typically maintains the proximal portion of the tube in an open state.

[0397] For some applications, the tube 24 is preformed so that during operation of the impeller, when the pressure of blood flow through the tube holds the proximal portion of the tube in an open state, the tube is curved. Typically, the curvature is such that when the proximal end of the tube is positioned within the aorta, at least a portion of the tube is positioned within the left ventricle and curves away from the posterior wall of the left ventricle, toward the apex of the left ventricle, and / or toward the free wall. Furthermore, typically, the curvature is such that when the proximal end of the tube is positioned within the aorta, at least a portion of the tube is positioned within the left ventricle and curves away from the septal wall of the left ventricle, toward the apex of the left ventricle, and / or toward the free wall. For some applications, the curvature of the tube is such that separation is maintained between the blood inlet opening 108 and the posterior wall 336 of the left ventricle, the mitral valve leaflets 402, and / or the subvalvular portion of the mitral valve (e.g., the chordae tendineae 404 and / or the papillary muscles 341), as described herein. Figure 25C shown.

[0398] Typically, the tube 24 is preformed using blow molding in a curved mold, or preformed using a forming mold after the blow molding process or the dipping process. Typically, the distal portion of the tube (wherein the frame 34, the impeller 50, and the axial shaft 92 are disposed) is maintained in a straight and open configuration by the frame 34. The portion of the tube located proximal to the frame 34 and disposed within the left ventricle is typically shaped to define the above-mentioned curvature. For some applications, the curvature is such that the angle gamma between the longitudinal axis of the tube at the proximal end of the tube and the longitudinal axis of the tube at the distal end of the tube is greater than 90 degrees (e.g., greater than 120 degrees, or greater than 140 degrees), and / or less than 180 degrees (e.g., less than 160 degrees, or less than 150 degrees), for example, 90 degrees to 180 degrees, 90 degrees to 160 degrees, 120 degrees to 160 degrees, or 140 degrees to 150 degrees. For some applications, the curvature of the tube is such that the surface of the tube located inside the bend defines a radius of curvature R that is greater than 10 mm, such as greater than 20 mm, and / or less than 200 mm (e.g., 100 mm), such as 10 mm-200 mm, or 20 mm-100 mm. Figure 25B A dashed circle is shown in , with the dashed line spanning its diameter in order to indicate how the radius of curvature R is measured.

[0399] Note that, as referenced Figures 25A-25C As described, the tube 24 is configured such that (a) in the absence of blood flowing through the tube, the tube typically collapses in response to the pressure outside the tube exceeding the pressure inside the tube, and (b) when blood flows through the tube at a sufficient rate such that the pressure inside the tube exceeds the pressure outside the tube, the tube assumes its pre-formed curved configuration. It should also be noted that when the tube 24 assumes its curved configuration, the tube typically causes the portion of the drive cable 130 disposed within the curved portion of the tube to also become curved, as shown in FIG. Figure 25A and Figure 25C That is, it is the pre-shaping of the tube itself that typically causes the tube and drive cable to bend, rather than the drive cable (or a different component disposed within the tube) causing the tube to bend. Alternatively, outer tubes 140 and / or 142 (which are disposed around the drive cable) are shaped to define a curve, and the outer tubes cause the drive cable and tube 24 to assume the curved shape. For some applications, both outer tubes 140 and / or 142 and tube 24 are shaped to define a curved shape.

[0400] Note that Figures 25A-25C The tube 24 shown is generally as described above with reference to Figure 2A The invention is not limited to the configuration described above (i.e., having a tapered distal portion 46 and a plurality of blood inlet openings 108). However, the scope of the invention includes the use of Figures 25A-25C The described curved configurations of tubes are combined with other general configurations of tubes (eg, as described above).

[0401] Now refer to Figure 25D-Figure 25E, these figures are schematic diagrams of a ventricular assist device 20 having a tube 24 configured to become curved as blood is pumped through the tube, according to some applications of the present invention. Figure 25D and Figure 25E , tube 24 is shown without other components of the ventricular assist device (eg, impeller 50, frame 34, etc.) for illustrative purposes. Figure 25E is disposed within the aorta 30 and left ventricle 22 of a subject according to some applications of the present invention, Figure 25D Schematic diagram of a ventricular assist device 20. Figure 25E The view of the left ventricle shown is similar to Figure 25C For some applications, the inlet opening 108 and / or the outlet opening 109 are arranged in a non-axisymmetric configuration about the tube 24. Typically, the tube 24 defines the position of the inlet opening and / or the outlet opening so that the tube 24 becomes curved and / or maintains the curvature of the tube 24, as shown in FIG. Figures 25A-25C As described. For example, as shown, the blood inlet hole can be provided on one side of the tube 24 located inside the bend of the tube (or on the inside of the desired bend of the tube). As blood flows into the blood inlet opening, this reduces the pressure in the area above the blood inlet opening, and the distal end of the tube 24 is pulled toward this area (as shown by arrow 310). Alternatively or additionally, the blood outlet opening 109 can be provided on one side of the tube 24 located inside the bend of the tube (or on the inside of the desired bend of the tube). As blood flows out of the blood outlet opening, the blood impacts the aortic wall, which causes the proximal end of the tube 24 to be pushed in the opposite direction, i.e., the direction of arrow 312.

[0402] As reference Figures 25A-25C Typically, the curvature of the tube maintains separation between the blood inlet opening 108 and the posterior wall 336 of the left ventricle, the mitral valve leaflets 402, and / or the subvalvular portion of the mitral valve (e.g., the chordae tendineae 404 and / or the papillary muscles 341), as described above. Figure 25E Typically, the curvature is such that when the proximal end of the tube is positioned within the aorta, at least a portion of the tube is positioned within the left ventricle and curves away from the posterior wall of the left ventricle, toward the apex of the left ventricle, and / or toward the free wall. More typically, the curvature is such that when the proximal end of the tube is positioned within the aorta, at least a portion of the tube is positioned within the left ventricle and curves away from the septal wall of the left ventricle, toward the apex of the left ventricle, and / or toward the free wall.

[0403] Now refer to Figure 25F , which is a schematic diagram of a ventricular assist device 20 according to some applications of the present invention, the ventricular assist device including a bending element 410 configured to provide a predetermined curvature to the tube 24. For some applications, as the tube 24 itself is shaped to define a bend (e.g., as shown in FIG. Figures 25A-25E As an alternative or in addition to the embodiments described above, the ventricular assist device includes a bending element 410. Typically, the bending element is made of a shape memory material (e.g., a shape memory alloy such as Nitinol). For some applications, the bending element is formed from a Nitinol tube that is cut to define holes or slits so that the tube can be preformed into a desired curved shape. For example, the Nitinol element can be a Nitinol "hypotube" (i.e., a Nitinol tube having microengineered features along its length) as is known in the art. Typically, the bending element 410 is disposed around the drive cable 130 along a longitudinal segment of the drive cable that is proximal to (e.g., directly proximal to) the proximal radial support 116. For some applications, the bending element is used in place of the outer tube 142 along this longitudinal segment of the drive cable.

[0404] For some applications, the flexure is shaped to have a substantially similar Figures 25A-25E Regarding the curvature described for tube 24. For some applications, the curvature is such that the angle ohm between the longitudinal axis of the bending element at the proximal end of the bending element and the longitudinal axis of the bending element at the distal end of the bending element is greater than 90 degrees (e.g., greater than 120 degrees, or greater than 140 degrees), and / or less than 180 degrees (e.g., less than 160 degrees, or less than 150 degrees), such as 90 degrees - 180 degrees, 90 degrees - 160 degrees, 120 degrees - 160 degrees, or 140 degrees - 150 degrees. For some applications, the curvature of the tube is such that the surface of the bending element located inside the bend defines a radius of curvature greater than 10 mm, such as greater than 20 mm, and / or less than 200 mm (e.g., 100 mm), such as 10 mm - 200 mm, or 20 mm - 100 mm. As described with reference to Figures 25A-25C Typically, as Figure 25C As shown, the curvature of the tube maintains separation between the blood inlet opening 108 and the posterior wall 336 of the left ventricle, the mitral valve leaflets 402, and / or the subvalvular portion of the mitral valve (e.g., the chordae tendineae 404 and / or the papillary muscles 341). Typically, the curvature is such that when the proximal end of the tube is positioned within the aorta, at least a portion of the tube is positioned within the left ventricle and curves away from the posterior wall of the left ventricle, toward the apex of the left ventricle, and / or toward the free wall. Further, more typically, the curvature is such that when the proximal end of the tube is positioned within the aorta, at least a portion of the tube is positioned within the left ventricle and curves away from the septal wall of the left ventricle, toward the apex of the left ventricle, and / or toward the free wall.

[0405] Reference Figures 25A-25F Note that for some applications, tube 24 adopts a curved shape as outer tube 142 is anchored to the aorta and distal tip portion 120 becomes anchored to the left ventricular inner wall (e.g., the free wall near the apex), as described above. Note also that Figures 23A-23B The curvature of the tube shown is less than Figures 25A-25F The curvature of the tube is shown because Figures 23A-23B Different views of the device are shown. Figures 23A-23B In the view shown, the curvature is typically not as good as Figures 25A-25F The view shown is obvious.

[0406] Now refer to Figure 26A 、 Figure 26B 、 Figure 26C 、 Figure 26D 、 Figure 26E and Figure 26F , these figures are schematic diagrams of distal tip elements 107 of ventricular assist devices 20 according to respective applications of the present invention, the distal tip elements being at least partially curved. Figures 26B-26F , distal tip element 107 is shown without the distal end of frame 34. Typically, as described above, the ventricular assist device is introduced into the ventricle of the subject over a guidewire. Distal tip portion 120 defines a guidewire lumen 122 such that the distal tip portion maintains a straight configuration during introduction of the ventricular assist device into the ventricle of the subject. For some applications, when the guidewire is removed, the distal tip portion is configured to present a Figures 26A-26F One of the shapes shown.

[0407] Typically, the distal tip element 107 is configured such that in its unconstrained configuration (i.e., in the absence of any forces acting on the distal tip portion), the distal tip element is at least partially curved. For some applications, the distal tip element is curved around an angle greater than 90 degrees (e.g., greater than 120 degrees) and less than 180 degrees (e.g., less than 160 degrees), such as 90 degrees to 180 degrees, 120 degrees to 180 degrees, or 120 degrees to 160 degrees, for example, as Figure 26A shown.

[0408] For some applications, the distal tip element defines a first proximal curvature 343 and defines a second distal curvature 344, such as Figure 26B For some applications, the first bend defines an angle theta (θ) greater than 130 degrees (e.g., greater than 140 degrees) and / or less than 160 degrees (e.g., less than 150 degrees), such as 130-160 degrees or 140-150 degrees. For some applications, the second bend defines an angle alpha (α) greater than 110 degrees (e.g., greater than 120 degrees) and / or less than 140 degrees (e.g., less than 130 degrees), such as 110-140 degrees or 120-130 degrees. Typically, the stiffness of the curved portions 343, 344 of the distal tip element 107 is less than the stiffness of the proximal straight portion 346 of the distal tip element disposed proximal to the two curved portions. For some applications, the stiffness of the second curved portion 344 is less than the stiffness of the first proximal curved portion 343.

[0409] Reference Figure 26C and Figure 26D For some applications, within a given plane, the distal tip element has a proximal straight portion 346 defining a longitudinal axis 348, curves in a first direction away from the longitudinal axis 348, and then curves in an opposite direction relative to the longitudinal axis 348. For example, Figure 26C As shown, within the plane of the page, the distal tip element first bends toward the left side of the page, then toward the right side of the page, and then again toward the left side of the page. Figure 26D As shown, in the plane of the page, the distal tip element bends first to the right side of the page and then to the left side of the page. Figure 26D The example shown in is roughly similar to Figure 22A In addition to the examples shown in Figure 26D 22). The portion of the tip disposed distal to the intersection of the tip and the longitudinal axis 348 is shorter than in FIG. 22).

[0410] Note that when Figure 26C When shaped as shown, the distal tip element 107 typically defines a first turning point 347 and a second turning point 349, with the first turning point 347 being disposed on a first side of a longitudinal axis 348 of a proximal straight portion 346 of the distal tip portion 120 (e.g., to the left of the longitudinal axis, as shown). Figure 26C ), the second turning point 349 is disposed on the opposite side of the longitudinal axis 348 of the proximal straight portion 346 of the distal tip portion 120 (eg, to the right of the longitudinal axis, as shown). Figure 26C 348 ). For some applications, the distal tip portion is thus shaped to define two ridges on either side of the longitudinal axis 348. Typically, as shown, the distal ridge 412 is larger (e.g., wider) than the proximal ridge 411. For some applications, the ridges are generally shaped as semi-ovals. Typically, as shown, the distal semi-oval defines a larger radius than the proximal semi-oval. Note that in this context, the term "semi-oval" includes a semicircle. It should also be noted that in some cases, the tip does not define two precise semi-ovals, but rather a ridge shape that is substantially similar to a semi-oval.

[0411] Typically, when Figure 26D When shaped as shown, the distal tip element defines an overall curvature similar to a question mark, with the tip portion defining a ridge 351 on one side of the longitudinal axis of the straight proximal portion of the distal tip portion. For some applications, the ridge is generally shaped as a semi-ellipse. It should be noted that in this context, the term "semi-ellipse" includes a semi-circle. It should also be noted that in some cases, the tip does not define a precise semi-ellipse, but rather a ridge that is substantially similar to a semi-ellipse.

[0412] Typically, when deployed within the left ventricle of a subject, the curvature of portions of distal tip element 107 is configured to provide atraumatic properties to tip portion 120. More typically, distal tip portion 120 is configured to separate inlet opening 108 of the ventricular assist device from the wall of the left ventricle.

[0413] For some applications, the turning point may be defined by bending in at least three directions, for example, on either side of the longitudinal axis 348 (e.g., as shown in FIG. Figure 26C ), and / or by bending in at least two directions (e.g., as Figure 26D ), the distal tip element is configured to absorb forces exerted on the distal tip portion by the wall of the left ventricle to a greater extent than if the distal tip element were bent in a single direction.

[0414] For some applications, distal tip element 107 defines multiple bends, each bend defining a different radius of curvature, and / or the bends are in respective directions, e.g., Figure 26E and Figure 26F shown.

[0415] As described above, for some applications, a duckbill valve 390 is disposed within the distal section of the distal tip portion 120. The duckbill valve is referred to below with reference to Figures 28A-28C shown and described in further detail.

[0416] Note that for all curved distal tip elements described herein (e.g., Figure 21-24C and Figures 26A-26F ), typically, the curvature of the distal tip portion is all within a single plane. With reference to the shape of the distal tip portion described herein (e.g., with reference to Figure 21-24C ), the scope of the present invention includes the use of a question mark or tennis racket shaped distal tip portion in combination with any ventricular assist device, even without other features and / or portions of the distal tip element 107 (e.g., the axial shaft receiving tube 126).

[0417] Now refer to Figure 27A 、 Figure 27B and Figure 27C , these figures are schematic diagrams of atraumatic protrusions 350 according to respective applications of the present invention, which are configured to extend from the distal end of the distal tip element 107 of the ventricular assist device 20. Figures 27A-27C107. For some applications, the atraumatic protrusion comprises a closed ellipse or a closed circle. Typically, as described above, the ventricular assist device is introduced into the subject's ventricle over a guidewire. Along a proximal portion of the atraumatic protrusion 350, the atraumatic protrusion defines a guidewire lumen 352. The closed circle or ellipse of the atraumatic protrusion typically defines holes 354 in its sidewalls, and the guidewire passes through these holes. During insertion of the ventricular assist device into the subject's ventricle, the circle or ellipse is typically axially elongated by retaining the proximal portion of the circle or ellipse within a delivery catheter. More typically, the distal portion of the axially elongated circle or ellipse protrudes from the distal tip of the delivery catheter and serves as the atraumatic tip of the delivery catheter as the catheter is passed through the subject's vasculature.

[0418] Typically, when deployed within the left ventricle of a subject, protrusion 350 is configured to provide an atraumatic tip to distal tip element 107. More typically, the protrusion is configured to separate inlet opening 108 of the ventricular assist device from the wall of the left ventricle.

[0419] Figure 27A 、 Figure 27B and Figure 27C The corresponding shapes of the protrusion 350 are shown when the protrusion is in a non-radially constrained configuration. Typically, the protrusion 350 is configured to assume these shapes when the protrusion is deployed within the left ventricle of a subject.

[0420] Now refer to Figure 28A , which is a schematic diagram of a duckbill valve 390 and a guidewire guide 392 disposed at the distal end of the distal tip portion 120 of a ventricular assist device according to some applications of the present invention. Figure 28B and Figure 28C , which are schematic diagrams of the proximal narrow end 420 and the distal wide end 422 of the duckbill valve 390 according to some applications of the present invention. Figure 28D and Figure 28E , which are schematic illustrations of a proximal end 424 of a guidewire guide 392 and a distal end 426 of a guidewire guide 392, according to some applications of the present invention.

[0421] It should be noted that although the duckbill valve 390 and guidewire guide 392 are shown at the distal end of a given example of distal tip element 107, the scope of the present invention includes combining the duckbill valve 390 and guidewire guide 392 with any other example of distal tip element described herein. Furthermore, the scope of the present invention includes using the duckbill valve 390 and guidewire guide 392 within the tip of any percutaneous device and is not limited to use with the duckbill valve 390 and guidewire guide 392 within a ventricular assist device.

[0422] As described above, the duckbill valve 390 typically has a maximum width of less than 3 mm, such as less than 2 mm. Typically, the entire duckbill valve is disposed within a distal segment of the distal tip portion, which is disposed within the distal-most 10 mm of the distal tip portion, such as within the distal-most 5 mm of the distal tip portion. More typically, as shown, the duckbill valve faces proximally (i.e., such that the wide inlet of the duckbill valve faces the distal end of the distal tip portion and the narrow tip of the duckbill valve faces away from the distal end of the distal tip portion 120). This is because the pressure of the fluid typically pumped into the distal tip portion (e.g., as described above with reference to Figures 13A-13C The duckbill valve faces the proximal end to prevent fluid from flowing out of the distal end of the distal portion, causing fluid to flow back toward the distal support 118, as described above. Typically, blood will not flow into the guidewire lumen 122 because the pressure within the guidewire lumen 122 is greater than the blood pressure outside the lumen, in the left ventricle.

[0423] Typically, the ventricular assist device is placed over a guide wire (e.g., guide wire 10, such as Figure 1B 1 and 2. The guidewire is typically inserted into the guidewire lumen 122 of the distal tip portion 120 via the distal end of the distal tip portion. Typically, insertion of the guidewire through the distal end of the distal tip portion is relatively simple because the distal wide end 422 of the duckbill valve 390 guides the guidewire through the duckbill valve.

[0424] For some applications, it may be desirable to insert another guidewire from the proximal end of the ventricular assist device to the distal end of the distal tip portion while the ventricular assist device is deployed within the subject. For example, if further surgery is to be performed on the subject's left ventricle after the left ventricular assist device is operational, it may be desirable to utilize an existing percutaneous puncture and insert a guidewire through guidewire lumen 122 prior to retracting ventricular assist device 20, rather than retracting the ventricular assist device and having to reinsert the guidewire via the percutaneous puncture.

[0425] Typically, to facilitate insertion of a guidewire from the proximal end of the ventricular assist device through the guidewire lumen 122, the ventricular assist device includes a guidewire guide 392. The guidewire guide 392 is configured to facilitate insertion of a guidewire through the narrow proximal end 420 of the duckbill valve 390. The guidewire guide is shaped to define a hole 432 therethrough, the hole having a diameter that narrows from the proximal end 424 of the guidewire guide to the distal end 426 of the guidewire guide. The shape of the guidewire guide is configured to guide the tip of the guidewire toward a slit 434 at the narrow proximal end of the duckbill valve. For some applications, the duckbill valve is further shaped to define a converging guide portion 430 at its proximal end that converges toward the slit 434, such that the guide portion is configured to guide the tip of the guidewire further toward the slit 434.

[0426] The scope of the present invention includes the use of duckbill valve 390 and guidewire guide 392 within a guidewire lumen of any percutaneous device and is not limited to the use of duckbill valve 390 and guidewire guide 392 within a ventricular assist device. Typically, duckbill valve 390 and guidewire guide 392 facilitate the insertion of a guidewire from the proximal end of the device to the distal end of the device through the guidewire lumen.

[0427] Now refer to Figure 29 , which is a schematic diagram of a delivery catheter according to some applications of the present invention, the delivery catheter including a sheath 440 configured to facilitate reinsertion of a guide wire via percutaneous puncture. Typically, the sheath comprises a covering (e.g., polyurethane, polyester, silicone, polyethylene terephthalate (PET) and / or polyether block amide) A covering is provided around at least a portion of the circumference of the delivery catheter 143 along a distal segment of the delivery catheter length (e.g., along a length greater than 10 mm and / or less than 100 mm, such as 10 mm-100 mm), as shown. Figures 28A-28E As described, for some applications, when the ventricular assist device is positioned within the subject, it is desirable to insert another guide wire through an existing percutaneous puncture, rather than retracting the ventricular assist device and then having to reinsert the guide wire through the percutaneous puncture. For some applications, the ventricular assist device and delivery catheter are retracted until the proximal end of the sheath 440 has been retracted from the percutaneous puncture. The guide wire is then inserted through the existing percutaneous puncture by advancing through the sheath 440 (i.e., between the covering and the outer surface of the delivery catheter 143). The ventricular assist device and delivery catheter can then be removed from the percutaneous puncture, leaving the guide wire in place. For some applications, the sheath 440 is positioned around a portion of the outer tube 142 along a distal segment of the length of the outer tube, and the function of the sheath is generally as described above.

[0428] The scope of the present invention includes the use of sheath 440 on any type of percutaneous catheter to facilitate reinsertion of a guidewire through an existing percutaneous puncture and is not limited to use with the delivery catheter 143 of the ventricular assist device 20.

[0429] Now refer to Figure 30 and Figure 31 , these figures are schematic diagrams of a ventricular assist device 20 including two impellers 50 according to some applications of the present invention. Figure 30As shown, for some applications, the first and second impellers are arranged parallel to each other, each impeller being driven by a respective drive cable 130. Typically, the first impeller in the impellers 50 and its corresponding frame 34 are arranged distally of the second impeller in the impellers 50 and its corresponding frame 34, so that when the impellers and frames are arranged in a radially constrained configuration within the delivery catheter 143, they are not in a configuration that overlaps with each other. For some applications, the proximal impeller pumps blood via a parallel tube 24A that is parallel to the tube 24, wherein the fluid flow from the parallel tube 24A flows into the tube 24 at a position configured to be located downstream of the aortic valve 26 (the position of the aortic valve 26 is at Figure 30 Thus, typically only tube 24 (and not parallel tube 24A) passes through the aortic valve.

[0430] like Figure 31 As shown, for some applications, the first impeller and the second impeller are arranged in series with each other, with each impeller being driven by a single drive cable 130. Typically, the first impeller in the impeller 50 and its corresponding frame 34 are arranged distal to the second impeller in the impeller 50 and its corresponding frame 34, so that when the impellers and frames are arranged in a radially constrained configuration within the delivery catheter 143, they are not in a configuration that overlaps with each other. More typically, the impellers pump blood into corresponding blood inlet openings 108, and initially one impeller pumps blood through tube 24 while the second impeller pumps blood through parallel tube 24A of tube 24. Typically, the fluid flow from parallel tube 24A flows into tube 24 at a location that is configured to be located downstream of the aortic valve (the location of the aortic valve is in the Figure 30 Thus, typically only tube 24 (and not parallel tube 24A) passes through the aortic valve.

[0431] Note that by having one impeller pump through parallel tubes 24A while the second impeller pumps blood via tube 24, it is not the case that the proximal impeller is pumping blood that has already been pumped by the distal impeller. The inventors have discovered that if the proximal impeller is used to pump blood that has already been pumped by the distal impeller, this may result in inefficiencies in the proximal impeller's pumping of blood. It should also be noted that, assuming all else is equal, doubling the number of impellers will typically double the amount of hemolysis generated by ventricular assist device 20. Conversely, increasing the rotational speed of a single impeller and / or increasing the length of the impeller may result in a disproportionate increase in the amount of hemolysis generated by the impeller.

[0432] About reference Figure 1A-Figure 31 All aspects of the ventricular assist device 20 described should be noted that although Figure 1A and Figure 1BA ventricular assist device 20 is shown in the left ventricle of a subject, but for some applications, the device 20 is placed in the right ventricle of the subject, such that the device (with necessary modifications) passes through the subject's pulmonary valve, and the techniques described herein are applied. For some applications, components of the device 20 are applicable to different types of blood pumps. For example, aspects of the present invention may be applicable to pumps used to pump blood from the vena cava and / or right atrium into the right ventricle, from the vena cava and / or right atrium into the pulmonary artery, and / or from the renal vein into the vena cava. These aspects may include features of the tube 24 (e.g., the curvature of the tube), the impeller 50, features of the pump portion 27, the drive cable 130, devices and methods for measuring blood pressure, etc. Alternatively or additionally, the device 20 and / or a portion thereof (e.g., the impeller 50, even without the tube 24) may be placed in a different part of the subject's body to assist in pumping blood from that part. For example, the device 20 and / or a portion thereof (e.g., the impeller 50, even without the tube 24) may be placed in a blood vessel and may be used to pump blood through the vessel. For some applications, device 20 and / or portions thereof (e.g., impeller 50, even without tube 24) are configured (mutatis mutandis) for placement within the subclavian vein or jugular vein, at the junction of the vein with the lymphatic vessels, and for increasing the flow of lymphatic fluid from the lymphatic vessels into the vein. Because the scope of the present invention includes the use of the apparatus and methods described herein in anatomical locations other than the left ventricle and aorta, ventricular assist devices and / or portions thereof are sometimes referred to herein (in the specification and claims) as blood pumps.

[0433] Refer to the following Figure 32A-Figure 33 Some examples of devices that include components of ventricular assist device 20 but are used in different anatomical locations are described.

[0434] Now refer to Figure 32A 、 Figure 32B 、 Figure 32C 、 Figure 32D and Figure 32E , these figures are schematic diagrams of a cardiac assist device 360 ​​configured to assist the function of the right heart of a subject, according to some applications of the present invention. For components of device 360 ​​that are generally similar to those described above with reference to ventricular assist device 20, the same reference numerals are used as above. Typically, these components are generally as described above, except for the differences described below.

[0435] Figure 32EThe device 360 ​​in a non-radially constrained configuration is shown in a manner without the subject's anatomical structure. As shown, typically, in order to assist the subject's right heart function, the impeller 50 and the frame 34 are arranged at the proximal end of the tube 24. Similarly, (multiple) blood inlet openings are arranged at the proximal end of the tube. The impeller is configured to pump blood along the distal direction through the tube 24 to the blood outlet opening 109 arranged at the distal end of the tube 24. For some applications, a balloon 362 is arranged at the distal end of the device. The balloon 362 is configured to help the distal end of the device be introduced into the pulmonary artery 364 in such a way that the balloon migrates to the pulmonary artery along with the subject's blood flow. Typically, (multiple) blood outlet openings are configured to be arranged in the pulmonary artery so that the impeller pumps blood into the pulmonary artery via the tube 24.

[0436] like Figure 32A As shown, for some applications, blood inlet opening(s) 108 are positioned within a right ventricle 366 of the subject such that the impeller pumps blood from the right ventricle via tube 24 into pulmonary artery 364. Alternatively, blood inlet opening(s) 108 are positioned within a right atrium 368 of the subject such that the impeller pumps blood from the right atrium via tube 24 into pulmonary artery 364, as shown. Figure 32B As shown. Further alternatively, the blood inlet opening(s) 108 are positioned within the subject's superior vena cava 370 such that the impeller pumps blood from the superior vena cava via the tube 24 into the pulmonary artery 364, as shown. Figure 32C As shown. Further alternatively, the blood inlet opening(s) 108 are positioned within the inferior vena cava 372 of the subject such that the impeller pumps blood from the inferior vena cava via the tube 24 into the pulmonary artery 364, as shown. Figure 32D shown.

[0437] Note that in Figures 32B-32D In the configuration shown, the heart assist device will reduce the preload on the right side of the heart (by pumping blood from the right atrium or vena cava), but will increase the afterload (by pumping blood into the pulmonary artery). Figure 32A In the configuration shown, the heart assist device effectively does not increase afterload because the volume of blood pumped into the pulmonary artery by the impeller is the same as the volume of blood pumped out of the right ventricle.

[0438] Now refer to Figure 33 , which is a schematic diagram of an intravenous assist system 380 according to some applications of the present invention. For components of device 380 that are generally similar to those described above with reference to ventricular assist device 20, the same reference numerals as used above are used. Typically, these components are generally as described above, except for the differences described below. For some applications, intravenous assist device 380 includes impeller 50 and frame 34, which are generally as described above. For some applications, intravenous assist device does not include tube 24, e.g., Figure 33shown.

[0439] For some applications, venous assist device 380 is inserted into a vein of a subject to assist in pumping blood through the vein. For example, venous assist device 380 can be inserted into a vein 382 (e.g., the iliac vein or femoral vein) of a leg of a subject experiencing ischemia and can assist in pumping blood through the vein.

[0440] For some applications, the scope of this application includes any of the following apparatus and methods in combination with any other apparatus and methods described herein:

[0441] A method comprising:

[0442] The rigid tube is coupled to a drive cable comprising a plurality of coiled wires by:

[0443] Place the end of the drive cable and the end of the rigid tube at a given position inside the butt-welded outer casing,

[0444] When the ends of the drive cable and the rigid tube are disposed at given positions within the butt-weld outer sleeve, these ends are visible through the window defined by the butt-weld outer sleeve, and

[0445] placing a drive cable within the butt-weld outer sleeve such that a helical groove defined by a portion of the butt-weld outer sleeve is disposed over the drive cable; and

[0446] A weld ring is formed around the butt-welded outer sleeve.

[0447] For some applications, forming a weld ring around the butt-weld outer sleeve includes forming a weld ring separated from an edge of the butt-weld outer sleeve such that the weld ring welds the butt-weld outer sleeve to the rigid tube and the drive cable without welding the weld ring directly to the outer surface of the rigid tube and the outer surface of the drive cable. For some applications, forming a weld ring around the butt-weld outer sleeve includes forming the weld ring to a depth such that the butt-weld outer sleeve is welded to the rigid tube and the drive cable without reducing the diameter of the inner cavity defined by the rigid tube and the drive cable. For some applications, forming a weld ring around the butt-weld outer sleeve includes forming at least one weld ring at a given position within the butt-weld outer sleeve where the end of the drive cable and the end of the rigid tube are placed. For some applications, coupling the drive cable to the rigid tube includes coupling the drive cable to an axial shaft configured to support an impeller. For some applications, coupling the drive cable to the rigid tube includes coupling the drive cable to a pin configured to couple to a magnet, which is configured to be driven to rotate by a motor. Reference above Figure 10D-10E Some examples of such applications are described.

[0448] An apparatus comprising:

[0449] a drive cable comprising a plurality of coiled wires;

[0450] a rigid tube configured to be coupled to the drive cable; and

[0451] A butt-weld outer sleeve configured to facilitate butt welding of a drive cable to a rigid tube, the butt-weld outer sleeve defining:

[0452] a window configured to provide visibility to the ends of the drive cable and the rigid tube when the ends are positioned at a given position within the butt-weld outer casing, thereby facilitating placement of the ends of the drive cable and the rigid tube at the given position within the butt-weld outer casing; and

[0453] A helical groove is located in a portion of the butt weld outer sleeve that is configured to be positioned over the drive cable and provides flexibility to the portion of the butt weld outer sleeve that is configured to be positioned over the drive cable.

[0454] For some applications, the apparatus includes an impeller, and the rigid tube includes an axial shaft configured to support the impeller. For some applications, the apparatus includes a motor and a magnet configured to be rotated by the motor, and the rigid tube includes a pin configured to couple to the magnet. Figure 10D-10E Some examples of such applications are described.

[0455] A method comprising:

[0456] A first portion and a second portion of a drive cable comprising a plurality of coiled wires are coupled to each other by:

[0457] The end of the first portion and the end of the second portion of the drive cable are placed at given positions inside the butt-welded outer sleeve,

[0458] When the end of the first portion and the end of the second portion of the drive cable are disposed at given positions within the butt-weld outer sleeve, these ends are visible through the window defined by the butt-weld outer sleeve, and

[0459] placing at least one of the portions of the drive cable within the butt-weld outer sleeve such that a helical groove defined by a portion of the butt-weld outer sleeve is disposed over the at least one of the portions of the drive cable; and

[0460] A weld ring is formed around the butt-welded outer sleeve.

[0461] Referenced above Figure 10D-10E Some examples of such applications are described.

[0462] A method comprising:

[0463] The rigid tube is coupled to a drive cable comprising a plurality of coiled wires by:

[0464] Place the end of the drive cable and the end of the rigid tube at a given position inside the butt-welded outer casing,

[0465] When the ends of the drive cable and the rigid tube are disposed at given positions within the butt-weld outer sleeve, these ends are visible through the window defined by the butt-weld outer sleeve, and

[0466] Weld rings are formed around the butt weld outer sleeve and are spaced apart from the edges of the butt weld outer sleeve so that the weld rings weld the butt weld outer sleeve to the rigid tube and the drive cable without directly welding to the outer surface of the rigid tube and the drive cable.

[0467] For some applications, forming a weld ring around the butt weld outer sleeve includes forming the weld ring to a depth such that the butt weld outer sleeve is welded to the rigid tube and the drive cable without reducing the diameter of the inner cavity defined by the rigid tube and the drive cable. For some applications, forming a weld ring around the butt weld outer sleeve includes forming at least one weld ring at a given position within the butt weld outer sleeve where the end of the drive cable and the end of the rigid tube are placed. For some applications, placing the end of the drive cable and the end of the rigid tube at a given position within the butt weld outer sleeve includes placing the drive cable within the butt weld outer sleeve such that a spiral groove defined by a portion of the butt weld outer sleeve is disposed above the drive cable. For some applications, coupling the drive cable to the rigid tube includes coupling the drive cable to an axial shaft configured to support an impeller. For some applications, coupling the drive cable to the rigid tube includes coupling the drive cable to a pin configured to couple to a magnet, which is configured to be driven to rotate by a motor. Reference above Figure 10D-10E Some examples of such applications are described.

[0468] An apparatus comprising:

[0469] A blood pump configured to be placed in a subject, the blood pump comprising:

[0470] impeller;

[0471] a frame configured to be disposed around the impeller;

[0472] an axial shaft on which the impeller is mounted;

[0473] a proximal radial support and a distal radial support configured to radially stabilize the axial shaft during rotation of the impeller;

[0474] an atraumatic distal tip portion disposed distally relative to the impeller, the atraumatic distal tip portion including an expandable portion; and

[0475] A cleaning fluid is configured to be pumped toward the distal tip portion to (a) clean the distal support and (b) expand the expandable portion of the distal tip portion.

[0476] Referenced above Figure 13D Some examples of such applications are described.

[0477] An apparatus comprising:

[0478] A blood pump configured to be placed in a subject, the blood pump comprising:

[0479] a tube defining at least one blood inlet opening and at least one blood outlet opening;

[0480] an impeller configured to pump the subject's blood into the blood inlet opening, through the tube, and out the blood outlet opening;

[0481] a distal tip portion disposed distally relative to the blood inlet opening, the distal tip portion defining a radially converging shape and configured to be positioned within the left ventricle of the subject when the impeller pumps the subject's blood;

[0482] an expandable portion disposed about the distal tip portion, the expandable portion being configured to define:

[0483] a) a deflated state, when the expandable portion is in its deflated state, the distal tip portion is configured to act as a dilator during insertion of the blood pump via a puncture in the skin of a subject,

[0484] b) a first expanded state, wherein the expandable portion is configured to prevent the distal tip portion from causing damage to the subject's vasculature during advancement of the distal tip portion through the subject's vasculature, and

[0485] c) a second expanded state, wherein the expandable portion is more fully expanded than in the first expanded state, and when the distal tip portion is positioned within the left ventricle of the subject, the expandable portion is configured in its second expanded state to three-dimensionally separate the one or more blood inlet openings from the internal structure of the left ventricle of the subject.

[0486] Referenced above Figures 20A-20C Some examples of such applications are described.

[0487] An apparatus comprising:

[0488] A left ventricular assist device configured to assist left ventricular function in a subject, the left ventricular assist device comprising:

[0489] a tube configured such that a proximal portion of the tube passes through an aortic valve of the subject and a distal portion of the tube is positioned within the left ventricle of the subject;

[0490] a frame disposed within the distal portion of the tube, the frame being configured to maintain the distal portion of the tube in an open state,

[0491] the frame is not disposed within the proximal portion of the tube, and the proximal portion of the tube is thus configured to collapse inwardly in response to a pressure outside the proximal portion of the tube exceeding a pressure within the proximal portion of the tube;

[0492] A pump disposed within the frame and configured to pump blood from the subject's left ventricle to the subject's aorta through the tube, such that during the pumping of the blood through the tube:

[0493] The proximal portion of the tube remains open, and

[0494] At least a portion of the tube becomes curved such that the tube curves away from the posterior wall of the left ventricle.

[0495] For some applications, the pump is configured to pump blood from the left ventricle of the subject to the subject's aorta through the tube, such that during pumping of blood through the tube, at least a portion of the tube becomes curved such that the tube curves away from the septal wall of the left ventricle. Figures 25A-25F Some examples of such applications are described.

[0496] An apparatus comprising:

[0497] A left ventricular assist device configured to assist left ventricular function in a subject, the left ventricular assist device comprising:

[0498] a tube configured such that a proximal portion of the tube passes through an aortic valve of the subject and a distal portion of the tube is positioned within the left ventricle of the subject;

[0499] a frame disposed within the distal portion of the tube, the frame being configured to maintain the distal portion of the tube in an open state,

[0500] the frame is not disposed within the proximal portion of the tube, and the proximal portion of the tube is thus configured to collapse inwardly in response to a pressure outside the proximal portion of the tube exceeding a pressure within the proximal portion of the tube;

[0501] a pump disposed within the frame and configured to pump blood from the left ventricle of the subject to the subject's aorta through the tube, such that a proximal portion of the tube remains open during pumping of blood through the tube;

[0502] as well as

[0503] A bending element is disposed proximally within the tube relative to the frame, the bending element being configured to bend at least a portion of the tube such that the tube bends away from the posterior wall of the left ventricle.

[0504] For some applications, the bending element is configured to cause at least a portion of the tube to bend such that the tube bends away from the septal wall of the left ventricle. Figures 25A-25F Some examples of such applications are described.

[0505] An apparatus comprising:

[0506] A left ventricular assist device configured to assist left ventricular function in a subject, the left ventricular assist device comprising:

[0507] a tube configured such that a proximal portion of the tube passes through an aortic valve of the subject and a distal portion of the tube is positioned within the left ventricle of the subject;

[0508] a frame disposed within at least a distal portion of the tube,

[0509] a pump disposed within the frame and configured to pump blood from the left ventricle of the subject to the subject's aorta through the tube by pumping blood into the tube through a set of one or more blood inlet openings defined by the tube and disposed within the subject's left ventricle, and pumping blood out of the tube through a set of one or more blood outlet openings defined by the tube and disposed within the subject's aorta;

[0510] wherein at least one opening in the set of openings in the tube is arranged in a non-axisymmetric configuration relative to the tube such that pumping blood through the at least one opening in the set of openings causes at least a portion of the tube to become curved such that the tube curves away from the posterior wall of the left ventricle.

[0511] For some applications, at least one opening in the set of openings in the tube is arranged in a non-axisymmetric configuration relative to the tube such that pumping blood through the at least one opening in the set of openings causes at least a portion of the tube to become curved such that the tube curves away from the septal wall of the left ventricle. Figures 25A-25F Some examples of such applications are described.

[0512] An apparatus comprising:

[0513] An impeller, comprising:

[0514] an impeller frame comprising a proximal portion and a distal portion and at least one helical elongated member wound from the proximal portion to the distal portion;

[0515] material coupled to at least one helical elongated element such that the at least one helical elongated element to which the material is coupled defines blades of the impeller; and

[0516] A coil is wound around the at least one helical elongated member, the coil being configured to facilitate coupling material to the at least one helical elongated member.

[0517] A method comprising:

[0518] The impeller is manufactured in the following manner:

[0519] forming a structure having a first end portion and a second end portion at a proximal end and a distal end of the structure, the end portions being connected to each other by at least one elongated member;

[0520] winding a coil around at least one elongated member;

[0521] axially compressing the structure, radially expanding the at least one elongated element and forming the at least one helical elongated element; and

[0522] coupling the material to the at least one helical elongated element such that the at least one helical elongated element to which the material is coupled defines blades of the impeller,

[0523] The coil is configured to facilitate coupling of material to the helical elongate member.

[0524] Referenced above Figure 3A-3K Some examples of such applications are described.

[0525] An apparatus comprising:

[0526] An impeller, comprising:

[0527] an impeller frame comprising a proximal portion and a distal portion and at least one helical elongated member wound from the proximal portion to the distal portion;

[0528] material coupled to at least one helical elongated element such that the at least one helical elongated element to which the material is coupled defines blades of the impeller; and

[0529] A sleeve is disposed about the at least one helical elongated member, the sleeve being configured to facilitate coupling material to the at least one helical elongated member.

[0530] A method comprising:

[0531] The impeller is manufactured in the following manner:

[0532] forming a structure having a first end portion and a second end portion at a proximal end and a distal end of the structure, the end portions being connected to each other by at least one elongated member;

[0533] placing a sleeve around at least one elongated member;

[0534] axially compressing the structure, radially expanding the at least one elongated element and forming the at least one helical elongated element; and

[0535] coupling the material to the at least one helical elongated element such that the at least one helical elongated element to which the material is coupled defines blades of the impeller,

[0536] The sleeve is configured to facilitate coupling of material to the helical elongate member.

[0537] Referenced above Figure 3A-3K Some examples of such applications are described.

[0538] An apparatus comprising:

[0539] An impeller, comprising:

[0540] an impeller frame comprising a proximal portion and a distal portion and at least one helical elongated element wound from the proximal portion to the distal portion, the helical elongated element having a rounded cross-section; and

[0541] material coupled to at least one helical elongated element such that the at least one helical elongated element to which the material is coupled defines blades of the impeller; and

[0542] The roundness of the helical elongate element is configured such that the material forms a layer of substantially uniform thickness at the interface of the material and the helical elongate element.

[0543] A method comprising:

[0544] The impeller is manufactured in the following manner:

[0545] forming a structure having a first end portion and a second end portion at a proximal end and a distal end of the structure, the end portions being connected to each other by at least one elongated member having a rounded cross-section;

[0546] axially compressing the structure, radially expanding the at least one elongated element and forming the at least one helical elongated element; and

[0547] coupling the material to the at least one helical elongated element such that the at least one helical elongated element to which the material is coupled defines blades of the impeller,

[0548] The roundness of the helical elongate element is configured such that the material forms a layer of substantially uniform thickness at the interface between the material and the helical elongate element.

[0549] Referenced above Figure 3A-3K Some examples of such applications are described.

[0550] A method comprising:

[0551] The impeller is manufactured in the following manner:

[0552] forming a structure having a first end portion and a second end portion at a proximal end and a distal end of the structure, the end portions being connected to each other by at least one elongated member;

[0553] by axially compressing the structure, causing the at least one elongated element to radially expand and form at least one helical elongated element;

[0554] looping a first end of a looped elongate member around the helical elongate member, the looped elongate member having a predetermined length and being substantially inextensible;

[0555] inserting the spring along an axis defined by the first end portion and the second end portion such that the second end of the annular elongated member loops around the spring;

[0556] coupling a material to at least one helical elongated element and a spring such that a film of material is supported between the helical elongated element and the spring, the film of material defining blades of the impeller,

[0557] The annular elongate element is configured to retain the helical elongate element within a given distance from the spring.

[0558] Referenced above Figure 3A-3K Some examples of such applications are described.

[0559] An apparatus comprising:

[0560] A left ventricular blood pump, the left ventricular blood pump comprising:

[0561] impeller;

[0562] a motor configured to drive the impeller to pump blood from the subject's left ventricle to the subject's aorta by rotating the impeller; and

[0563] A computer processor is configured to measure motor power consumption required to rotate the impeller at a given rotational rate and determine the subject's left ventricular blood pressure responsive thereto, at least in part.

[0564] Referenced above Figure 9 Some examples of such applications are described.

[0565] An apparatus comprising:

[0566] A left ventricular assist device configured to assist left ventricular function in a subject, the left ventricular assist device comprising:

[0567] a blood pump tube configured such that a proximal portion of the tube passes through an aortic valve of the subject and a distal portion of the tube is positioned within the left ventricle of the subject, the tube defining at least one blood inlet opening and at least one blood outlet opening, the at least one blood inlet opening being configured to be positioned within the left ventricle and the at least one blood outlet opening being configured to be positioned within the aorta of the subject;

[0568] an impeller configured to pump blood from the left ventricle of the subject through the tube to the aorta of the subject by pumping blood into the tube through one or more blood inlet openings defined by the tube and disposed within the left ventricle of the subject, and by pumping blood out of the tube through one or more blood outlet openings defined by the tube and disposed within the aorta of the subject;

[0569] a drive cable configured to extend from the impeller to outside the subject's body;

[0570] one or more outer tubes within which the drive cables are configured to rotate;

[0571] a motor disposed outside the subject's body and configured to rotate the impeller via a drive cable; and

[0572] a stator configured to reduce a rotational flow component of blood flow through the blood pump tubing before the blood flows out of the at least one outlet opening, the stator comprising:

[0573] a frame coupled to one or more outer tubes within the blood pump tubing; and

[0574] A flexible material is coupled to the frame such that in a non-radially constrained configuration of the stator, the stator defines a plurality of curved protrusions extending radially from the one or more outer tubes.

[0575] For some applications, the framework is a self-extensible framework. Figures 14A-14C Some examples of such applications are described.

[0576] An apparatus comprising:

[0577] A left ventricular assist device configured to assist left ventricular function in a subject, the left ventricular assist device comprising:

[0578] a blood pump tube configured such that a proximal portion of the tube passes through an aortic valve of the subject and a distal portion of the tube is positioned within the left ventricle of the subject, the tube defining at least one blood inlet opening and at least one blood outlet opening, the at least one blood inlet opening being configured to be positioned within the left ventricle and the at least one blood outlet opening being configured to be positioned within the aorta of the subject;

[0579] an impeller configured to pump blood from the left ventricle of the subject through the tube to the aorta of the subject by pumping blood into the tube through one or more blood inlet open...

Claims

1. A method comprising: The housing (60) of the impeller (50) for the blood pump is manufactured by the following steps: placing a liner (39) around the mandrel; placing a cylindrical portion (38) of a frame (34) around the liner (39), the cylindrical portion of the frame including struts defining a generally cylindrical shape; placing a distal portion of an elongated tube (24) around at least a portion of the frame (34), the elongated tube (24) including a proximal portion defining at least one blood outlet opening (109); heating the liner (39), the frame (34), and the distal portion of the elongated tube (24) via the mandrel while the distal portion of the elongated tube (24) is disposed around the at least a portion of the frame (34); and While heating the liner (39), the frame (34) and the distal portion of the elongated tube (24), pressure is applied from outside the distal portion of the elongated tube (24) to conform the distal portion of the elongated tube (24) to the structure of the struts of the frame (34) and to couple the liner (39) and the distal portion of the elongated tube (24) to the frame (34).

2. The method according to claim 1, further comprising: After coupling the liner (39) and the distal portion of the elongated tube (24) to the frame (34), the distal end of the frame (34) is shaped to define a widened inlet.

3. The method according to claim 1, further comprising: After coupling the liner (39) and the distal portion of the elongated tube (24) to the frame (34), a portion (332) of the frame (34) is shaped to form a converging region such that the frame (34) defines a narrowing region within the frame (34) proximate a location configured to accommodate the impeller (50).

4. The method according to claim 1, wherein: The liner (39) and the elongated tube (24) include the liner (39) and the elongated tube (24) being made of different materials, and the thermoforming temperature of the material for making the liner (39) is higher than the thermoforming temperature of the material for making the elongated tube (24); and Heating the liner (39), the frame (34) and the distal portion of the elongated tube (24) includes heating the liner (39), the frame (34) and the distal portion of the elongated tube (24) to a temperature that is higher than the thermoforming temperature of the material from which the elongated tube (24) is made and lower than the thermoforming temperature of the material from which the liner (39) is made.

5. The method according to claim 1, wherein Applying pressure from outside the distal portion of the elongated tube (24) includes applying pressure from outside the distal portion of the elongated tube (24) using an outer tube made of silicone.

6. The method according to claim 1, wherein Placing the distal portion of the elongated tube (24) around at least a portion of the frame (34) includes placing the distal portion of the elongated tube (24) around the entire cylindrical portion (38) of the frame (34) such that the distal portion of the elongated tube (24) overlaps the entire liner (39).

7. The method according to any one of claims 1 to 6, wherein Applying pressure from outside the distal portion of the elongated tube (24) to couple the liner (39) and the distal portion of the elongated tube (24) to the frame (34) includes coupling the liner (39) to the inner surface of the cylindrical portion of the frame (34) so ​​that the liner (39) forms a substantially cylindrical tube.

8. The method according to claim 7, wherein: The struts within the cylindrical portion (38) of the frame (34) are shaped to define cells, and each of the cells has a width (CW) measured around the circumference of the cylindrical portion (38) of less than 2 mm.

9. The method according to any one of claims 1 to 5, wherein Placing the distal portion of the elongated tube (24) around at least a portion of the frame (34) includes placing the distal portion of the elongated tube (24) around only a portion of the cylindrical portion (38) of the frame (34) such that the distal portion of the elongated tube (24) does not overlap the entire liner (39).

10. The method according to claim 9, wherein: Placing the distal portion of the elongated tube (24) around only a portion of the cylindrical portion (38) of the frame (34) includes preventing the portion of the cylindrical portion of the frame (34) that is positioned around the distal portion of the elongated tube (24) from radially expanding, thereby making the portion of the cylindrical portion of the frame (34) that is positioned around the distal portion of the elongated tube (24) narrower than the portion of the cylindrical portion of the frame (34) that is not positioned around the elongated tube (24).

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