Ventricular assist device

Abstract

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

Description

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

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority to the following:

[0004] U.S. Provisional Patent Application No. 62 / 796,138, filed by Tuval on January 24, 2019, entitled “Ventricular assist device”;

[0005] U.S. Provisional Patent Application No. 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 on July 5, 2019 by Tuval, entitled “Ventricular assist device”; and

[0007] Tuval, U.S. Provisional Patent Application No. 62 / 896,026, filed on September 5, 2019, and entitled “Ventricular assist device.”

[0008] This application is related to a U.S. application entitled “Distal tip element for aventricular assist device” filed on the same date as the present application, which claims priority to the above-mentioned 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. In particular, 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. Such assist devices are either designed to be permanently implanted or mounted on a catheter for temporary placement.

[0013] Embodiment Overview

[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 the proximal end of the tube is disposed within the aorta of the subject, and the distal end of the tube is disposed within the left ventricle of the subject. The impeller, the axial shaft, and the frame are disposed within a distal portion of the tube that is located within the left ventricle of the subject. 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, and during 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, and during operation of the impeller, blood flows from the tube into the ascending aorta via the blood outlet openings.

[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 being shaped 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. 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 so that when the distal tip element is inserted into the left ventricle so 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 disposed 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 disposed within the guidewire lumen proximal to the duckbill valve. Typically, the guidewire guide is shaped to define a hole therethrough, the diameter of the hole narrowing from the proximal end of the guidewire guide to the distal end of the guidewire guide, the shape of the guidewire guide being configured 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 measured around the circumference of the cylindrical portion of less than 2 mm (e.g., 1.4 mm-1.6 mm, or 1.6 mm-1.8 mm). 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 a non-radially constrained configuration of the impeller, the impeller is disposed within the cylindrical portion of the frame at a location where the impeller spans the greatest 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 so as to pump blood from the left ventricle to the aorta, and is configured to be stable relative to the frame such that during rotation of the impeller, a gap between an outer edge of the impeller and the liner is maintained and substantially constant. 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, the proximal radial support and the distal radial support are respectively disposed at the proximal and distal ends of the frame, 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 is rigid. For some applications, the impeller includes a bushing 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 the following area along the axial shaft, on which at least one bushing is configured to be slidable relative to the axial shaft, and the area is coated to substantially prevent impeller vibration by reducing the gap between at least one bushing and the impeller. For example, the area can 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-shaped formation. 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 to a position overlapping 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 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 to a position overlapping 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 that define 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 that defines at least one blood outlet opening. When the distal portion is disposed around at least a portion of the frame, the liner, the frame, and the distal portion of the elongated tube are heated via the mandrel. When the liner, the frame, and the 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 the distal portion of the elongated tube to the frame. For example, pressure may be applied by a silicone tube placed outside the distal portion of the elongated tube. For some applications, the liner and the elongated tube include a liner and an elongated tube 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. 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 forms 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 a blade 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 blade 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 steps 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 blade of the impeller. For example, a suture may 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 the radially outer edge of the coil, the coil being configured to enhance the 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 the radially outer edge of the sleeve, the sleeve being configured to enhance the bonding of the elastomeric material to the at least one helical elongated element. For some applications, 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 of the elastomeric material and the helical elongated element.

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

[0024] The scope of the invention includes the use of the apparatus and methods described herein in anatomical locations other than the left ventricle and the 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 of 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 disposed within a 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 through the tube to the aorta of the subject by pumping blood into the tube via at least one blood inlet opening defined by the tube and configured to be disposed within the left ventricle of the subject, 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 aorta of the subject; and

[0030] A distal tip element is configured to define a straight proximal portion and a curved distal portion, the straight proximal portion defining a longitudinal axis, the curved distal portion being 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 placed against an 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 so 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 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 so that the ridge ridges toward the septal wall, then 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 distal tip element is configured such that 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 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 in the descending aorta of the subject, the distal tip element itself is centered relative to the aortic valve of the subject. 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 disposed within the 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 faces 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, 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 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 entrance faces toward the distal end of the guide wire lumen and the narrow tip faces away from the distal end of the guide wire 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 of a subject, the left ventricular assist device comprising:

[0060] a tube configured to pass through an aortic valve of a 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 a non-radially constrained configuration of the impeller, 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 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 a situation where the impeller is not stable relative to the frame.

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

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

[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] An 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 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 overall 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 of a subject, the left ventricular assist device comprising:

[0080] a tube configured to pass through an aortic valve of a 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 being 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, which are disposed at the proximal end and the distal end of the frame, respectively;

[0083] an axial shaft extending 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 a non-radially constrained configuration of the impeller, 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 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 clearance 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 of a subject, the left ventricular assist device comprising:

[0091] a tube configured to pass through an aortic valve of a 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 being 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, which are disposed at the proximal end and the distal end of the frame, respectively;

[0094] an axial shaft extending 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 a non-radially constrained configuration of the impeller, 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 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 a situation where the impeller is not stable relative to the frame.

[0100] According to some applications of the present invention, a method is also provided, the method 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 at least one helical elongated element at least in part by axially compressing the structure; and

[0104] coupling the 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 step 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 also includes: placing a spring within the structure so 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 elongated element and forming at least one helical elongated element comprises: radially expanding two elongated elements and forming two helical elongated elements; and

[0110] Coupling the elastomeric material to 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 elongated element and forming at least one helical elongated element comprises: radially expanding three elongated elements and forming three or more helical elongated 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 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 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 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.

[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 a device for use with a delivery catheter, the device comprising:

[0121] A blood pump, comprising:

[0122] an impeller configured to pump blood through a body of a subject;

[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-shaped formation;

[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 frame's struts 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 paired struts branching from the joint are configured to pivot about the joint and move closer to each other to close.

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

[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 a proximal conical portion of the frame, and during at least some operation of the blood pump, at least a portion of the impeller is disposed within a 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 has a maximum span 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 between 1.4 mm and 1.6 mm measured around the circumference of the cylindrical portion.

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

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

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

[0138] placing a 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 around 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 to 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 measured around the circumference of the cylindrical portion that is less than 2 mm.

[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, placing 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 that is placed around the distal portion of the elongated tube from radially expanding, thereby causing the portion of the cylindrical portion of the frame that is placed around the distal portion of the elongated tube to be narrower than the portion of the cylindrical portion of the frame that is not placed 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 a support column;

[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 support column, 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 external covering material is connected from the outside of the frame to the internal connecting material, the external covering material is only arranged around a portion of the cylindrical portion of the frame, and the external covering material is configured to limit the radial expansion of the portion of the cylindrical portion of the frame surrounded by the external covering material, so that the portion of the distal portion of the cylindrical region of the frame surrounded by the external covering material is narrower than the portion of the cylindrical region of the frame that is not surrounded by the external covering material.

[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 toward 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 that is shaped to converge toward the impeller.

[0175] The present invention will be more fully understood from the following detailed description of embodiments of the present 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 to be placed 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 , Fig. 3I , Figure 3J and Figure 3K is a schematic diagram of an impeller or a 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] Fig. 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] Fig.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] Fig. 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, wherein the axial shaft and the bushing of the impeller are configured to prevent rotational movement of the bushing of the impeller relative to the axial shaft;

[0186] Fig. 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 gap 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] Fig. 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] Fig. 9 is a graph showing the change in the length of the drive cable of the ventricular assist device as the pressure gradient resisted by the impeller of the blood pump measured in the experiment conducted by the inventor of the present application changes;

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

[0191] Fig. 10D , Fig.10E and Fig.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] Fig.11A and Fig. 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] Fig. 11C Is used to promote Fig.11A and Fig. 11B A schematic diagram of a connection portion of an impeller crimped connection;

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

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

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

[0197] Fig.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 being configured to be inflated by a fluid for cleaning a drive cable of the device;

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

[0199] Fig.14A , Fig. 14B and Fig. 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] Fig.15A , Fig. 15B , Fig. 15C , Fig.15D and Fig.15E is a schematic diagram of a stator built into a tube of a ventricular assist device according to some applications of the present invention;

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

[0202] Fig. 16C and Fig.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] Fig.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] Fig.17A , Fig. 17B , Fig. 17C and Fig.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] Fig.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] Fig.19A , Fig.19B , Fig.19C , Fig.19D , Fig.19E , Fig.19F , Figure 19G and Fig.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 on the inside of a frame housing an impeller;

[0207] Fig. 20A , Fig. 20B and Fig. 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] Fig.21 is a schematic diagram of a ventricular assist device placed within the left ventricle of a subject according to some applications of the present invention, showing a cross-sectional view of the left ventricle;

[0209] Fig.22A , Fig. 22B , Fig. 22C and Fig.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] Fig.23A and Fig. 23B According to some applications of the present invention Fig.22D A schematic diagram of a ventricular assist device disposed within the left ventricle of a subject;

[0211] Fig.24A , Fig. 24B and Fig.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] Fig.25A , Fig.25B , Fig.25C , Fig.25D and Fig.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 curved when blood is pumped through the tube;

[0213] Fig.25F is a schematic diagram of a ventricular assist device according to some applications of the present invention, the ventricular assist device comprising 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] Fig.26A , Fig.26B , Fig.26C , Fig.26D , Fig.26E and Fig.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] Fig.27A , Fig.27B and Fig.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] Fig.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] Fig.28B and Fig.28C According to some applications of the present invention Fig.28A Schematic diagram of corresponding views of a duckbill valve;

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

[0219] Fig.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] Fig.30 is a schematic diagram of a ventricular assist device including two impellers according to some applications of the present invention;

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

[0222] Fig.32A , Fig.32B , Fig.32C , Fig.32D and Fig.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] Fig.33 is a schematic diagram of a venous 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 diagrams of a ventricular assist device 20 according to some applications of the present invention, the distal end of the ventricular assist device being configured to be positioned in a left ventricle 22 of a subject. Figure 1A shows an overview of a ventricular assist device system including a console 21 and a motor unit 23, Figure 1B showing 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 the proximal end 28 of the tube is disposed in the aorta 30 of the subject and the 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, the axial length of the tube being typically much greater than its diameter. The scope of the present invention includes using the apparatus and methods described herein in anatomical locations other than the left ventricle and the aorta. Therefore, 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 that is 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 disposed on the distal end of the device. Once the distal end of the device is disposed 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 end of treatment, the delivery catheter is advanced on 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, and during operation of the impeller, blood flows from the left ventricle into the tube via the blood inlet openings. For some applications, the proximal portion 106 of the tube defines one or more blood outlet openings 109, and during operation of the impeller, blood flows from the tube into the ascending aorta via the blood outlet openings.

[0229] For some applications, a console 21 (e.g., Figure 1A ) drives the impeller to rotate. For example, a computer processor can control the motor 74 (as shown in Figure 7 As shown), the motor 74 is arranged in the motor unit 23 (as shown 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 real physical article that communicates with the computer processor, having different magnetic polarities, charges, etc., depending on the memory technology used. 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 dedicated ventricular assist computer processor and / or a dedicated 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 ventricular assist device 20, for example, to cool various portions of the device and / or to flush debris from various portions of the device. 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 so 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) presents a generally circular, elliptical, or polygonal cross-sectional shape. By presenting 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 in a 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 state 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, such as a braided reinforcing structure such as a braided nitinol tube. Typically, the proximal portion of the tube is configured to be placed so 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 into the tube from the left ventricle 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 inwardly 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 reverse.

[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 thereof) such that the distal end of the tube defines a single axially facing blood inlet opening 108, such as Figure 1C 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 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 of Tuval, which is incorporated herein by reference. For such applications, the tube typically defines two to four lateral blood inlet openings.

[0234] Typically, 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, blood outlet opening 109 is defined by tube 24 such that the opening extends at least partially along the proximal tapered section of 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 along flow lines substantially parallel to the longitudinal axis of the tube 24 at the location of the blood outlet opening.

[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, so 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 1C, the ventricular assist device typically includes a distal tip element 107 that is disposed distally 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 thus the tube 24) assumes a generally circular, elliptical, or polygonal cross-sectional shape in the absence of any force being applied to the tube 24. By assuming its generally circular, elliptical, or polygonal cross-sectional shape, the frame is configured to hold 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 covered by a liner 39, as described below with reference to Figures 19A-19H As described below, for some applications, the impeller 50 performs axial reciprocating motion relative to the frame 34. Typically, during the motion of the impeller relative to the frame, the position of the portion of the impeller that defines the maximum span of the impeller is set within the cylindrical portion 38 of the frame 34. In some cases, if the cells of the cylindrical portion 38 of the frame 34 are too large, the tube 24 and / or the liner 39 are stretched between the edges of the cells so that the tube 24 and / or the liner 39 do not define a circular cross-section. For some applications, if this occurs in the area where the portion of the impeller that defines the maximum span of the impeller is set, this results in a non-constant gap between the edge of the impeller's blades and the tube 24 (and / or liner) at that location during the impeller's rotation cycle. For some applications, this may result in increased hemolysis compared to the case where there is a constant gap between the edge of the impeller's blades and the tube 24 (and / or liner) at that location during the impeller's rotation cycle.

[0239] Reference Figure 2A, at 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 arranged 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, for example, 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 joint 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 joints 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. Further, typically, the frame imparts 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 elongation from the delivery catheter (or other device configured to crimp the frame) to the frame, which in turn facilitates transferring the axial elongation to the impeller. This is because the paired 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 in an open state so that the impeller is placed in the frame via the distal end of the frame. Subsequently, the distal strut portion is closed around the outside of the distal support 118, as shown below with reference to Figure 5A-Figure 5B For some applications, the proximal end of the 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), for example, 25 mm-50 mm, or 30 mm-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), for example, 10 mm-25 mm, or 12 mm-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, for example, 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 a cylindrical portion 38 of a frame 34 of the ventricular assist device has a helical structure 55. For some applications, at least a portion of a cylindrical portion 38 of a frame 34 of the ventricular assist device has a helical structure 55 so that the 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 above ratio. For example, the ratio of the cylindrical portion of the frame to the total length of the frame can 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 if the cylindrical portion had a shorter relative length (assuming all else is the same). In turn, for some applications, this reduces vibration of the frame during rotation of the impeller. As described above, in order to reduce hemolysis, it is typically desirable to maintain a constant gap between the edge 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, the ventricular assist device including an expandable impeller housing 60. For some applications, rather than having a frame 34 surround 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 during a rotational cycle of the impeller, a constant gap exists between the edge of the blades of the impeller and the inner wall of the housing.

[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 connected. 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, such as to assume its deployed shape. Typically, the tube 24 extends proximally from the expandable impeller housing. For some applications, the tube 63 is along the tube 24 (e.g., the inner or outer surface of the tube), and the expandable housing is expanded via the tube. For some applications, the impeller housing is expanded by 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 flattened 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, such as Figure 2E As shown in the enlarged portion of FIG. 1 , as described 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, it is desirable that the cells be rounded in order to reduce strain at the joint. 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 elongated element 52, which is wound around a central axial spring 54, such that the helical structure defined by the helical elongated element is coaxial with the central axial spring. Typically, the impeller includes two or more helical elongated elements (e.g., three helical elongated 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 helical elongated element and the central axial spring support 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 sheet of Nitinol 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 respectively, wherein the material is supported between the helical elongated element and the spring.

[0249] Each helical elongate element defines a blade of a corresponding impeller together with a membrane extending from the helical elongate element to the spring, 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 film of a material (which is typically an elastomer, such as polyurethane, or silicone) and a helical elongated element (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 film of a 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 5000 show 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 in the grooves, as shown in enlarged view B. Typically, by embedding the suture in 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 elongated element 52 extend from a proximal bushing (i.e., sleeve support) 64 of the impeller such that the proximal ends of the spring 54 and the helical elongated element 52 are disposed at similar radial distances from the longitudinal axis of the impeller. Similarly, typically, the distal ends of the spring 54 and the helical elongated element 52 extend from a distal bushing 58 of the impeller such that the distal ends of the spring 54 and the helical elongated element 52 are disposed at similar radial distances from the longitudinal axis of the impeller. Typically, the spring 54 and the proximal bushing 64 and the distal bushing 58 of the impeller define an inner cavity 62 (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 lined 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 placed within the cylindrical portion of the frame and the tube 24 does not cover the cylindrical portion of the frame. However, the scope of the present 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 impeller 50 and liner 39, even at the location where the impeller spans the greatest. For some applications, it is desirable that the gap between the outer edge of the impeller blades and 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 frame 34 remain substantially constant throughout the rotation of the impeller within frame 34, for example, to reduce the risk of hemolysis.

[0254] For some applications, when both the impeller and the frame 34 are arranged in a non-radially constrained configuration, at the location where the impeller spans the largest, the gap G between the outer edge of the impeller and the liner 39 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-1 mm, or 0.1 mm-0.4 mm. For some applications, when the impeller is arranged in its non-radially constrained configuration, at the location where the outer diameter of the impeller is the largest, the outer diameter of the impeller 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-10 mm, or 8 mm-9 mm. For some applications, when the frame 34 is arranged in its non-radially constrained configuration, the inner diameter of the frame 34 (measured from the inner side of the 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, 7.5 mm-10.5 mm, or 8.5 mm-9.5 mm. For some applications, when the frame is arranged in its non-radially constrained configuration, the outer diameter of the 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, 8 mm-13 mm, or 9 mm-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 stable 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 even during rotation of the impeller, a relatively small gap (e.g., a gap as described above) is maintained between the outer edges of the blades of the impeller and the inner surface of the frame 34.

[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 a wire made of a different alloy or metal).

[0257] For some applications, the elongated element 67 holds the outer edge of the helical elongated element (which defines the outer edge of the blades of the impeller) within a given distance relative to the central axial spring. In this way, the elongated element is configured to prevent the outer edge of the impeller from being pushed radially outward due to the force applied to the impeller during the rotation of the impeller. The elongated element is thereby configured to maintain a gap between the outer edge of the blades of the impeller and the inner surface of the frame 34 during the 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., radially extending from the central axial spring 54 to the outer helical elongated element 52, and then returning from the helical elongated element to the central axial spring). For some applications, multiple elongated elements are formed by a single piece of rope or a single wire, wherein each elongated element extends from the spring to a corresponding helical elongated element and returns 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 a 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 the technique described in US 2016 / 0022890 of Schwammenthal. Typically, the spring 54 is inserted into the cutting and shaping tube so that the spring extends at least from the proximal bushing to the distal bushing along the length of the tube. For some applications, when the spring is in an axially compressed state, the spring is inserted into the cutting and shaping tube, and the spring is configured to remain in place relative to the tube by applying radial forces 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 a 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 tube, elongated element 67 as described above is placed, for example, in the following manner, extending 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 is penetrated so that (a) it is from mandrel to the first spiral elongated element in the spiral elongated element, (b) returns to mandrel from the first spiral elongated element in the spiral elongated element, (c) around mandrel, and to the second spiral elongated element in the spiral elongated element, (d) returns to mandrel from the second spiral elongated element in the spiral elongated element, etc. Once rope or line has been passed from mandrel to each spiral elongated element and passed back again, the ends of rope or line are just connected to each other, for example, by tying them to each other. For some applications, suture 53 (e.g., polyester suture) is wrapped around the spiral elongated element to facilitate bonding between the film of material (which is typically an elastomer, such as polyurethane, or silicone) and the spiral elongated element (which is typically a shape memory alloy, such as Nitinol) in subsequent stages of impeller manufacturing. 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 film 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 manufacturing.

[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 disposed through the lumen defined by the spring and the sleeve, although it should be noted that the mandrel is not inserted into the lumen. Figure 3A Typically, the material from which the membrane is made is silicone and / or polyurethane (and / or similar elastomers), and the assembled structure is immersed in the material while the material is in an uncured liquid state. Subsequently, the material is 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 that there is a continuous film of material extending between each helical elongate element and the spring, and also extending along the length of the spring so as to define a tube in which the spring is embedded. The portions of the film extending from each helical elongate element to the spring define the blades of the impeller. For applications where the impeller includes the elongate element 67, the elongate 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, the membrane 56 of the material (e.g., silicone and / or polyurethane) changes shape to coincide with the shape changes of the helical elongated element and the axial support spring (both of which support the membrane of the 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 combined. 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 constrained in the radial direction, 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, proximal bushing 64 of impeller 50 is coupled to axial shaft 92 such that the proximal bushing is fixed in axial position relative to the shaft and 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 (where the impeller is typically disposed in the non-radially constrained configuration during operation of the impeller).

[0264] Note that for illustration purposes, in some of the figures, impeller 50 is shown without the 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 the present application includes the use of an impeller having any 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 sutures 53. Sutures 53 are wound around helical elongated element 52 and are configured to facilitate bonding between the film 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).

[0266] As an alternative or in addition to suture 53, for some applications, coil 68 is wrapped around (or placed on) the helical elongated 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 elongated 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 and the material from which the membrane 56 is made, the material from which the elongated element is made typically having a relatively high stiffness (and typically Nitinol), and the material from which the membrane 56 is made typically being an elastomer having a relatively low stiffness. Thus, when the material is dry, 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 elongate member 52 before the elongate 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 element 52 is formed to have a rounded (eg, circular) cross-section, such as Figure 3F , which shows a cross-sectional view of an elongated element having a rounded cross-section. Figure 3F The left portion of FIG. 5 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 the 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, after the tube is cut, the elongated element typically has non-rounded edges. Therefore, for some applications, after the tube is cut, the edges of the elongated element are rounded, 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 spiral elongated element. For example, the spiral 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 spiral elongated element.

[0271] According to the above Figure 3A-Figure 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 the proximal and distal ends of the structure, the first bushing and the second bushing being connected to each other by at least one elongated element 52. The at least one elongated element is made to radially expand and form at least one helical elongated element at least in part by axially compressing the structure. 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 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. For example, the suture 53 can be placed in a groove defined by 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, a rounded cross-section is provided to at least one spiral elongated element 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 in contact 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 edge of the impeller blades does not protrude, as this would occupy a portion of the gap between the outer edges of the impeller blades (thus requiring a larger gap) without increasing the effectiveness of the impeller's blood pumping function.

[0272] Now refer to Figure 3G and Figure 3H, these figures are schematic diagrams of an elongated element 67 extending between each spiral elongated element 52 and the spring 54 according to some applications of the present invention. For some applications, a corresponding annular elongated element 67 extends between each spiral 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 spiral elongated element (which defines the outer edge of the blades of the impeller) within a given distance relative to the central axial spring during rotation of the impeller, and thereby maintain a gap between the outer edge of the blades of the impeller 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 the 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 a longitudinal center of the spring 54, such as Figure 3G and Figure 3H Typically, the second end of the annular elongate element surrounds the tube at a longitudinal center position of the spring. Typically, this reduces the risk of tearing of the annular elongate element compared to a loop where the second end of the annular elongate element surrounds 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 in 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 illustrative drawings show two alternative ways in which the annular elongated element surrounds the body of the spiral elongated element. For some applications, the annular elongated element surrounds the outer surface of the spiral elongated element, as shown in enlarged view A. Alternatively, the spiral elongated element defines a groove 45 on its outer surface, and the annular elongated element surrounds the groove 45 (e.g., is embedded in the groove), as shown in enlarged view B. By embedding the annular elongated element in the groove, the annular elongated element typically does not increase the outer contour of the impeller, and the outer contour of the impeller is defined by the outer surface of the spiral elongated element.

[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 loop-shaped elongate member can pass to form a loop, such as Figure 3H As shown in the enlarged portion. Figure 3HEnlarged views A and B of show two optional ways in which the annular elongated element passes through the hole 71 to form a loop. For some applications, as shown in enlarged view A, the annular elongated element surrounds the outer surface of the spiral elongated element and the through hole 71. Alternatively, the spiral elongated element defines a groove 45 on its outer surface, and the annular elongated element surrounds the groove 45 and the through hole 71 (so as to be embedded in the groove), as shown in enlarged view B. By embedding the annular elongated element in the groove, the annular elongated element typically does not increase the outer contour of the impeller, and the outer contour of the impeller is defined by the outer surface of the spiral elongated element.

[0276] Now refer to Fig. 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 the longest. 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, such as between 45 degrees and 70 degrees. By comparison Figure 3J and Fig. 3I It can be observed that, assuming all else being equal, increasing the angle rho increases the effective maximum span length EML even if the total length of the impeller does not increase. Alternatively, 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 diagrams 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, in accordance with some applications of the present invention. During insertion of the impeller and frame into a subject via a catheter, the impeller and frame are typically configured in the radially constrained state, and during operation of the impeller within the left ventricle of the subject, the impeller and frame are configured in the non-radially constrained state. As described above, typically, tube 24 is disposed on at least a portion of the frame and extends proximally therefrom. However, for purposes of illustration, the impeller and frame are not configured in the radially constrained state. Figure 5A-Figure 5B The frame and the 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 catheter 143. Typically, in the radially constrained configuration of the impeller, the impeller has an overall 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-30 mm, or 20 mm-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-18 mm, or 10 mm-15 mm. Even more typically, when the impeller and frame 34 are arranged in a radially constrained configuration (e.g., Figure 5B As shown), the impeller has an outer diameter of less than 2 mm (e.g., less than 1.6 mm), and the frame has an outer diameter of less than 2.5 mm (e.g., 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 pushes the impeller to move in a direction opposite to the first direction. The purpose of the thrust bearing is to resist such 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 urged in the direction of arrow 206, and the thrust bearing resists this motion. Typically, these bearings are subject to significant levels of heating and wear due to the friction forces exerted on the bearings. Thrust bearings are typically subject to significant heating and wear due to the fact that the friction forces exerted on the thrust bearings are typically distributed over opposing surfaces that have less contact area between them 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 joint 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., a gap as described above) between the outer edge of the blades of the impeller 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 the distal direction along the axial shaft so that the impeller becomes axially elongated 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 disposed directly within any radial bearing or thrust bearing. Rather, bearings 116 and 118 act as radial bearings 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 only by one or more thrust bearings disposed outside the subject's body. For some applications, the mechanical element and / or the magnetic element are configured to maintain the impeller within a given axial position range. For example, a magnet (e.g., magnet 82, hereinafter referred to as magnet 82) disposed at the proximal end of the drive cable (e.g., outside the subject's body) Figure 7 ) can be configured to impart axial movement to the impeller, and / or to maintain the impeller within a given axial position range.

[0284] Now refer to Fig. 6A and Figure 6B , which are schematic diagrams of a ventricular assist device 20 at various stages of a motion cycle of an impeller 50 of the ventricular assist device 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 fixed) is driven to cause the impeller to reciprocate axially within frame 34 by moving the axial shaft in an axial reciprocating motion, as described below with reference to Figure 7 Further detailed description. Alternatively or additionally, the impeller and the axial shaft are configured to reciprocate axially within the frame 34 in response to a force acting on the impeller, without actively driving the axial shaft to move the axial shaft in an axial reciprocating manner. Typically, during the cardiac cycle of the subject, the pressure difference between the left ventricle and the aorta changes from about zero during the ventricular systole (hereinafter referred to as "systole") to a relatively large pressure difference (e.g., 50mmHg-70mmHg) during the ventricular diastole (hereinafter referred to as "diastole"). For some applications, due to the increase in the pressure difference against which the impeller pumps during the diastole (and because the drive cable 130 is stretchable), the impeller is pushed distally relative to the frame 34 during the diastole compared to the position of the impeller relative to the frame 34 during the systole. In turn, since the impeller is connected to the axial shaft, the axial shaft moves forward. During the systole, the impeller (and thus 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. Fig. 9 This passive axial reciprocating motion of the impeller will be described in further detail below. Fig. 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 that is in contact with the proximal support 116 and the distal support 118 is constantly changing. For some such applications, assuming all else is the same, in this manner, the frictional forces exerted on the axial shaft by the supports are dispersed over a larger area of ​​the axial shaft than if the axial shaft did not move relative to the supports, thereby reducing wear on the axial shaft. Alternatively or additionally, by moving in a 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-4 mm (e.g., 2 mm-3 mm) in length. 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, Fig. 6A indicating the impeller is in the most proximal position during the cardiac cycle (typically, the impeller is set to this position 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). Fig. 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 a position Id, which is at the distal end of the cylindrical segment of the 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, because 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, during the entire cardiac cycle, the segment of the impeller with the largest impeller span is disposed within the cylindrical portion of the frame 34. However, during at least a portion of the cardiac cycle, the proximal portion of the impeller is typically disposed within the proximal conical segment of the frame.

[0288] Refer again Fig. 6A and Figure 6B , and also refer to Figure 6C , Figure 6C is an enlarged schematic diagram 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 so that the distal tip portion is configured to not cause tissue damage to a subject even if the distal tip portion contacts 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 amides (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 guide wire, wherein the guide wire is disposed within lumen 122. For some applications, 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 the impeller and frame are held in their radially constrained configuration. For some applications, during insertion of the delivery catheter into the ventricle of a subject, distal tip element 107 extends distally from the delivery catheter. For some applications, at the proximal end of the distal tip element, the distal tip element has a flared portion 124 that acts as a stop and prevents the delivery catheter from being advanced beyond the flared portion.

[0290] It should be noted that Figure 6A-6C (and certain other figures) is shown as defining a complete loop, wherein the distal end of the distal tip portion (having 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 Fig.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 cavity 127, which is 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, which is configured to prevent the axial shaft from being advanced beyond the stop. For some applications, the stop includes a rigid component inserted (e.g., embedded) into the distal end of the shaft receiving tube. Alternatively, the stop includes a shoulder between the inner cavity 127 of the axial shaft receiving tube and the inner cavity 122 of the distal tip portion 120. Typically, such a shoulder exists because the inner cavity 122 of the tip portion 120 is narrower than the inner cavity 127. This is because lumen 127 is typically configured to accommodate an axial shaft, while lumen 122 is configured to accommodate a guidewire 10, and the axial shaft is typically wider than the guidewire 10 because the axial shaft itself is configured to accommodate the guidewire 10 within lumen 132 of the axial shaft (e.g., Fig. 10B and Fig. 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 50 and frame 34) during retraction of ventricular assist device 20 from the subject's ventricle. However, as the delivery catheter is advanced over impeller 50 and frame 34, stop 128 is configured to prevent the axial shaft from protruding into the tip portion. In some circumstances, 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, in such circumstances, the axial shaft could protrude into the tip portion. 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 axial reciprocating cycle of the impeller, the impeller is disposed relatively close to the distal tip portion. For example, during the entire axial reciprocating cycle of the impeller, the distance from the impeller to the distal tip portion may be within the farthest 50% of the tube 24, such as within the farthest 30% (or the farthest 20%).

[0294] Now refer to Fig.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, typically, the distal bushing 58 of the impeller is not fixedly coupled to the shaft. Also as described above, to reduce hemolysis, it is typically desirable to maintain a constant gap between the edge 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) coatings, 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, typically, vibration of the impeller is reduced compared to if the area of ​​the axial shaft is 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 in reference to Figures 11A-11C described), and techniques similar to those described above apply to the proximal sleeve.

[0295] Now refer to Fig. 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 distal bushing 58 of the impeller includes a protrusion 96 protruding 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, typically, the distal bushing 58 of the impeller is not fixedly coupled to the shaft. For some applications, when the impeller moves axially relative to the axial shaft, the protrusion 96 and the groove 97 are configured to prevent the distal end of the impeller from rotating relative to the axial shaft. Typically, at the proximal end of the groove 97, the groove 97 defines a stop 98. The stop is configured to prevent the distal bushing from sliding proximally beyond the stop by preventing the protrusion 96 from moving axially proximally 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 clearance between the edges of the impeller's blades and the tube 24 (and / or liner 39).

[0296] according to Figure 6A-6EWith reference to the above description (and the description of the other figures), the scope of the present invention includes one or more techniques for reducing hemolysis caused by the impeller pumping blood. Typically, a frame 34 disposed around 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 around 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 has the largest span, 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 so as 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 is not stabilized relative to the frame.

[0297] For some applications, the proximal radial support 116 and the distal radial support 118 are respectively disposed at the proximal and distal ends of the frame, and the axial shaft 92 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 is 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., the 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 in such a manner that on the region along the axial shaft, at least one bushing is configured to be slidable relative to the axial shaft, and the region is coated to substantially prevent the impeller from vibrating 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, 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.

[0298] Now refer to Fig. 6F and Figure 6G, which are schematic diagrams of ventricular assist devices 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 axial reciprocating motion. Typically, during the cardiac cycle of a subject, 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 pushed 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 produced 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. Fig. 6F shows the impeller 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 edge of the impeller's blades and tube 24 (and / or liner 39) is smaller during diastole than during systole. Because the clearance between the edge of the impeller's blades and tube 24 (and / or liner 39) is smaller, the pumping efficiency of the impeller during diastole is typically greater than the pumping efficiency of the impeller during systole. For some applications, it is desirable that the pumping efficiency during diastole is greater than the pumping efficiency during systole because the pressure gradient against which the impeller pumps increases during diastole relative to during systole, as described above.

[0300] Despite Fig. 6E and Fig. 6F Although described, it is typically the case that the clearance between the edge of the impeller blades and the tube 24 (and / or liner 39) is constant throughout the axial movement cycle 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 the impeller 50 is also configured to control the reciprocating motion of the axial shaft. Typically, both types of motion are generated using the 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 configured to apply 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 shown by the double-headed arrow 79. Typically, due to the magnetic coupling of the motor to the drive cable, the motor applies reciprocating motion to the drive cable, which in turn applies the motion to the impeller. As described above and below, for some applications, the drive cable, impeller and / or axial shaft reciprocates axially in a passive manner, 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 connected 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 two drive magnets. The driven magnet 82 is arranged 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 passing 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, which 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 in a cylindrical housing 87. Typically, the pin 131 defines a guide wire lumen 133, which will be referred to below. Figure 10B-Figure 10C Described in further detail.

[0304] Note that Figure 7In the illustrated application, the drive magnet is disposed outside the driven magnet. However, the scope of the present application includes configurations that reverse the drive magnet and driven magnet (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 an axial overlap between the driven magnet and the drive magnet.

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

[0306] Typically, the magnet 82 and the pin 131 are held 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 thereby held in an 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 thereby 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 thereby 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 the impeller to a certain range of movement (by keeping 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 Fig. 8A and Figure 8B , these figures are schematic diagrams of motor units 23 according to some applications of the present invention. In general, as Fig. 8A and Figure 8B The motor unit 23 shown is similar to Figure 7 Motor units shown, unless otherwise specified, are Fig. 8A and Figure 8B The motor unit 23 shown comprises Figure 7 Components similar to the motor unit 23 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 manner. Typically, during the cardiac cycle of a subject, the pressure differential between the left ventricle and the aorta changes from approximately zero during systole to a relatively large pressure differential during diastole (e.g., 50 mmHg-70 mmHg). For some applications, due to the increased pressure differential against which the impeller pumps during diastole (and because the drive cable is stretchable), the impeller is pushed distally relative to the frame 34 during diastole, relative to the position of the impeller relative to the frame 34 during systole. In turn, because the impeller is 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 produced 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 Fig. 9 , which is a graph showing the length of a drive cable of a ventricular assist device as a function of the pressure gradient resisted by the impeller of the ventricular assist device (as measured in experiments performed 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 reproduce 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 pumping also changes. At the same time, the movement of the drive cable is imaged, and the change in drive cable length is determined via machine vision analysis of the image. Fig. 9 The graph shown in shows the measured variation of drive cable length as a function of pressure gradient. Fig. 9 The y-axis of the graph shown is 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 the elongation is negative (approximately -0.25 mm) at this pressure, 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 configuration is 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 Fig. 9 It can be seen in the portion of the curve shown that, after an initial shortening of the drive cable due to the effects described above, the subsequent situation is that the drive cable becomes longer and longer as the pressure gradient increases.

[0310] like Fig. 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 applied to the impeller (which indicates 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 controls axial reciprocating motion of the axial shaft in response thereto.

[0312] Refer again Figure 7 For some applications, ventricular assist device 20 includes sensor 84. For example, the sensor may include a Hall sensor disposed within motor unit 23, such as Figure 7 As shown. For some applications, the Hall sensor measures the change in the magnetic field generated by one of the magnets in order to measure the axial movement of the drive cable 130 and thereby 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. Since the inner magnet is longer than the outer magnet, the magnetic field lines emanating from the inner magnet are not transmitted 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 thereby causes the inner magnet to move axially. During operation, the motor 74 rotates, thereby generating an AC signal in the Hall sensor, which has 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 generates a low-frequency envelope in the signal measured by the Hall sensor, which typically has a frequency of 0.5 Hz-2 Hz. For some applications, the 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 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 (i.e., per unit change in the pressure differential between the left ventricle and the aorta) opposed by the impeller pumping is known. It is known that in most subjects, during systole, the left ventricular pressure is equal to the aortic pressure. Thus, for some applications, the aortic pressure of the subject is measured (e.g., using the calibrated pressure gauge hereinafter with reference to FIG. 1 ). 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 (with the pressure in the left ventricle being assumed to be equal to the pressure in the aorta).

[0314] For some applications, techniques generally similar to those described in the paragraph above are used, but rather than utilizing Hall sensor measurements, different parameters are measured in order to determine 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 a subject is measured (e.g., using the method described below with reference to FIG. 1 ). Figures 16A-16D The technique described above is performed, and a computer processor calculates 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 rotation rate at a given time, and (c) a predetermined relationship between the motor power consumption required to rotate the impeller at a given rotation rate and the pressure differential generated by the impeller. For some applications, the above technique is performed while maintaining the impeller rotation rate at a constant rate. Alternatively or additionally, the rotation rate of the impeller is varied, and the variation in the impeller rotation rate is taken into account in the above 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 is combined with 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, the ventricular pressure-volume loop is derived based on the determined ventricular pressure.

[0316] Now refer to Fig. 10A , Fig. 10B and Fig. 10C , which are schematic diagrams of a drive cable 130 of 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., Fig. 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 (such as Fig. 10B ), these wires 134 are arranged in a tightly coiled configuration to give the drive cable sufficient strength and flexibility so that a portion of the cable can remain within the aortic arch (corresponding to Fig. 10A The first outer tube 142 is a first outer tube 142 that is configured to move in an axially reciprocating manner while the cable is rotating. 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 reciprocating motion. 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, since 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 the thickness of the second outer tube is 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 Fig. 10AAs shown, during operation of the left ventricular device, the delivery catheter remains in the subject's aorta, and the 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 the delivery catheter 143 and the outer tube 142. Note that for illustration purposes, Fig. 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 so that the impeller and frame assume their radially constrained configuration. The catheter is then withdrawn from the subject.

[0318] Reference Fig. 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 the cable over the guide wire 10 (as described above) so that the guide wire is disposed within the lumen 132. Typically, the guide wire 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 guide wire passes through the guide wire lumen 122 (of the distal tip portion) and then enters the lumen 132 defined by the axial shaft at that point. The guide wire then continues to pass through the lumen 132 until the proximal end of the drive cable. From the proximal end of the drive cable, the guide wire passes through a guide wire lumen 133 defined by the pin 131, which is disposed outside the subject's body even after the distal end of the ventricular assist device 20 is inserted into the subject's left ventricle. Typically, when the distal end of the ventricular assist device is positioned inside the left ventricle of the subject, the guide wire is retracted from the subject by pulling the guide wire out of the proximal end of the guide wire 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 locked using a latch element 150 (eg Fig. 13B ) is coupled to a portion of the motor unit in which a 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 guide wire 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-1.2 mm, or 0.8 mm-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-0.7 mm or 0.4 mm-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-1.4 m, or 1.1 m-1.3 m. Typically, the diameters of guidewire lumens 122 and 133 are substantially similar to the diameter of lumen 132 .

[0320] Now refer to Fig. 10D , Fig.10E and Fig.10F , which are schematic diagrams of various steps of a technique for coupling a drive cable 130 to an axial shaft 92 using a butt weld outer sleeve 160 according to 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 so that the proximal end of the axial shaft 92 is visible at a given position of the window 162, such as at a midpoint across the width of the window, as shown in FIG. FIG. 10D to FIG. 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 disposed at a given position of the window 162 (e.g., at the midpoint across the width of the window) and typically contacts the proximal end of the axial shaft, as shown. Fig.10E and Fig.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 and then the axial shaft. It should also be noted that for illustration purposes, the drive cable is inserted in the Figure 10D-10F However, the drive cable typically comprises multiple coiled wires, e.g. Fig. 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 a midpoint across the width of the window. More typically, additional rings are welded on either side of the window 162, but at a location separated from the end 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 causes 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 for 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 drive cable 130 to axial shaft 92 (mutatis mutandis) are used to weld the proximal end of the drive cable to pin 131 (described above with reference to FIG. Figure 7 130 to axial shaft 92). For some applications, the drive cable includes portions having corresponding features (e.g., corresponding numbers of wires in a coiled wire set including multiple portions of the drive cable). For some such applications, techniques substantially similar to those described for welding the distal end of drive cable 130 to 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 are 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 above manner even without the helical groove.

[0325] Now refer to Fig.11A and Fig. 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 so 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 a proximal radial support 116 and a distal radial support 118. As described above, the proximal and distal ends of the frame 34 are rigidly coupled to the proximal and distal supports. 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, such that a relatively small gap (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 proximal bushing 64 of the impeller is configured to slide in a distal direction along the axial shaft such that the impeller becomes axially elongated 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 the proximal bushing sliding on the axial shaft while the distal bushing remains in an axially fixed position relative to the axial shaft.

[0326] Now refer to Fig. 11C , which is a schematic diagram of a first connecting portion 170A and a second connecting portion 170B according to some applications of the present invention, wherein the first connecting portion 170A and the second connecting portion 170B are independent of other components of the frame 34 to facilitate Figure 11A-11B The first portion 170A and the second portion 170B are configured to engage with 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 Fig.11A and Fig. 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. Subsequently, frame 34 is crimped. Typically, when the impeller and frame are positioned in the left ventricle of a subject, the first coupling portion and the second coupling portion are separated from each other so that the proximal end of the impeller can move relative to frame 34 and proximal support 116.

[0327] Now refer to Fig. 12A , which shows that when the impeller is Figure 11A-11BA graph showing the relationship between the pressure gradient against which the impeller pumps and the impeller pitch when configured as 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. Also refer to Fig. 12B , which is a graph showing pressure-flow curves for impellers with corresponding pitches as described herein. Curve C1 corresponds to an impeller with a relatively small pitch, C2 corresponds to an impeller with a medium pitch, and C3 corresponds to an impeller with a relatively large pitch. As shown, assuming all else is the same, the smaller the pitch of the impeller, the greater the gradient of the pressure-flow curve. In addition, assuming all else is the same, at relatively high pressure gradients, an impeller with a smaller pitch produces a greater flow than an impeller with a larger pitch, while at relatively low pressure gradients, an impeller with a larger pitch produces a greater flow than an impeller with a smaller pitch. According to Figure 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 (typically, where a smaller pitch produces a greater flow), the impeller has a smaller pitch, while at lower pressure gradients (typically, where a larger pitch produces a greater flow), the impeller has a larger pitch.

[0328] Reference Fig. 12B , and for an impeller typically configured in the context of this application (i.e., the proximal support is coupled to the axial shaft without Figure 11A-11B ), it is typically desirable that the impeller have the following features:

[0329] 1) At a rotation rate 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 rotation rate of less than 20,000 RPM (e.g., less than 19,000 RPM), the impeller provides a flow rate of 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 in diastole is within the above range, and the described flow rate needs 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 that the impeller 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-14 mm, 9 mm-13 mm, or 10 mm-12 mm. Typically, when the impeller has a pitch as described above, and at a rotation rate 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), such as 3.5 L / min-5 L / min, at a pressure gradient of greater than 50 mmHg (e.g., greater than 60 mmHg), such as 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 farther into the subject's body and is located upstream relative to the direction of antegrade blood flow) to the proximal end of the impeller (i.e., the end that is located downstream relative to the direction of antegrade blood flow) so that the pitch increases in the direction of blood flow. Typically, the blood flow velocity increases along the impeller, along the direction of blood flow. Therefore, the pitch increases along the direction of blood flow, thereby further accelerating the blood.

[0333] Now refer to Fig.13A , Fig. 13B and Fig. 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, during rotation of the drive cable, both the first outer tube and the second outer tube remain stationary. For some applications, the cleaning system 29 (e.g., Figure 1A ) via inlet port 86 and outlet port 88 (at Figure 7 , Fig. 8A , Figure 8B , Fig. 13B and Fig. 13C ) to control the flow of a cleaning fluid (e.g., a fluid containing glucose or dextrose). 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 92 and the proximal support 116 and / or the distal support 118.

[0334] Reference Fig.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, such as Fig.13A 148. 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 the interface (and / or reducing friction at the interface), such as Fig.13A 149. 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 (ref. Fig. 10B ), the drive cable typically includes a plurality of 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 in the lumen 132, the cleaning fluid flows in the proximal and distal directions, such as Fig.13A As shown by arrow 151. Fig.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. Fig.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, such as Fig.13A As shown by arrow 151. Now refer to Fig. 13B Typically, at the proximal end of ventricular assist device 20, the purge fluid flows out of the proximal end of lumen 132 in the direction of arrow 156 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 out of outlet port 88 in the direction of arrow 158. Typically, the purging 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 Fig. 13C For some applications, the ventricular assist device includes an additional purge fluid inlet port 89, which is typically used to pump a 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 via the channel, as described in further detail below. For some applications, rather than continuously pumping purge fluid into channel 224, fluid is pumped into the channel periodically 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 Fig.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 includes an expandable portion 153 (e.g., a balloon) on its distal tip that is configured to be expanded by a fluid used to clean the drive cable of the device. As described above, with reference to Fig.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 according to the present invention, such as Fig.13D (and e.g. Fig.16A , Fig. 16B , Fig.16E , Fig.17D , Fig.30 and Fig.31 ) is generally as described in US2019 / 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 Fig.13D The configuration of the frame 34 shown is generally as described in US2019 / 0209758 of 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 the distal tip portion and / or configuration of the frame 34 described herein.

[0341] Reference Fig.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, such as by passing through an aperture defined by the tube 140. For some such applications, a thermally conductive element is disposed within the first outer tube and / or the second outer tube to dissipate heat away from areas where a large amount of heat is generated by frictional forces.

[0342] For some applications, the fluid has a relatively high viscosity, such as greater than 100 mPa.s (e.g., greater than 500 mPa.s), such as a viscosity between 100 mPa.s and 1000 mPa.s, so that the fluid remains substantially in place during operation of the ventricular assist device. For example, petroleum jelly 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 Fig.14A , Fig. 14B and Fig. 14C , these figures are schematic diagrams of stators 250 according to some applications of the present invention, which are configured to be disposed within tube 24 of ventricular assist device 20, proximal to frame 34 and impeller 50. For some applications, the stator is composed of a frame 252 coupled to 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. ) is made. Typically, when the device 20 is in a non-radially constrained configuration, the stator is shaped to define a plurality of curved protrusions 256 (e.g., more than 2 and / or less than 8 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 Fig.15A , Fig. 15B , Fig. 15C , Fig.15D and Fig.15E , these figures are schematic diagrams of a stator 260 defined by a tube 24 of a 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 disposed proximally relative to the frame 34 and the impeller 50, and is configured to reduce a rotational flow component of 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 around the outer tube 142 within the tube 24, such as Fig.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, such as Fig. 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, such as Fig. 15C Alternatively, Fig.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 function as stators 260. For some applications, as shown, the spiral tubes are wound around each other. Typically, Fig.15A , Fig. 15B , Fig. 15C , Fig.15D and Fig.15E Each of the examples of stators 260 shown in 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 Fig.16A and Fig. 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 a 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 the 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 to the opening 214 at the distal end of the tube, and the pressure sensor 216 is arranged toward the proximal end of the tube, such as outside the subject. For some applications, the computer processor 25 ( Figure 1A ) receives an indication of a 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 measuring tubes 220, such as Fig.16A and Fig. 16B As shown. For some applications, based on the blood pressure measured in each left ventricular blood pressure measurement tube, the computer processor 25 determines whether the opening of one of the two or more ventricular blood pressure measurement tubes is blocked. For example, this may occur 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 left ventricular pressure of the subject based on the blood pressure measured in another of the two or more ventricular blood pressure measurement tubes.

[0349] Reference Fig.16AAs described above, for some applications, the drive cable 130 extends from a motor outside the subject's body to the axial shaft 92 on which the impeller 50 is disposed. Typically, the drive cable is disposed within the 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, the 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 outer surface of the outer tube 142 outside the subject's body to the subject's aorta, so 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 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 outer tube 142, such as Fig.16A and Fig. 16B 214 . For some applications, within outer tube 142, the blood pressure measuring tube has an elliptical cross-section (as shown). Typically, this increases the cross-sectional area of ​​the tube relative to a case where the cross-section is circular. Typically, within the distal portion of each ventricular blood pressure measuring tube 220 (which extends to opening 214), the tube has a circular cross-section. For some applications, the diameter of the distal portion of the tube is greater than 0.2 mm, and / or less than 0.5 mm (e.g., 0.2 mm-0.5 mm).

[0351] like Fig.16A and Fig. 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, a 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 Fig. 16C and Fig.16D , these figures are schematic diagrams of ventricular assist devices 20 according to some applications of the present invention, the device having an aortic blood pressure measurement channel 224 within a delivery catheter 143. 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, Fig. 10AA gap is shown between the outside of the outer tube 142 and the inside of the delivery catheter 143, which can be used as the aforementioned passage. Note that for illustration purposes, Fig. 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 disposed within the aorta of the subject and the proximal end of the delivery catheter is disposed outside the subject. Thus, by sensing the pressure in 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 Fig. 13C As shown) sense the aortic pressure. As described above, refer to Fig. 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 the aortic blood pressure can still be detected through the channel in the manner described above.

[0353] For some applications, a spacer tube 240 is placed 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 may 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, the spacer tube is not disposed between the delivery catheter and the outer tube near the hole 242, such as Fig. 16C Thus, near the hole 242, a channel 224 is defined between the delivery catheter and the outer tube 142, so that the aortic blood pressure of the subject is detected via the channel 224 in the manner described above. Alternatively, near the hole 242, a spacer tube is disposed between the delivery catheter and the outer tube, but the spacer tube defines a channel 224 extending from the hole to the proximal end of the delivery catheter, as shown. Fig.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 Fig.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 tube 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 the tip of the wire that is electrically connected to 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 sensor. 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 an 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 a current between a distal-most electrode and a proximal-most electrode, the distal-most electrode being typically configured to be disposed near the apex of the heart and the proximal-most electrode being typically configured to be disposed 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 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 rotation 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 the conductance measurement 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 the conductance measurement 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 the left ventricular pressure, which is itself an important clinical parameter. Note that the first derivative of the left ventricular pressure is typically not affected by changes in the aortic pressure because the aortic pressure curve is relatively flat as the left ventricular pressure curve undergoes clinically important changes.

[0357] Now refer to Fig.17A , Fig. 17B , Fig. 17C and Fig.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 Fig.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 Fig. 17B As shown, the stagnation pressure interface is arranged close enough inside the funnel-shaped flow obstacle 226 so that the flow obstacle itself serves to remove the turbulent component in the flow before the blood reaches the stagnation pressure interface. For some applications, the stagnation pressure interface includes a short tube 233, which protrudes from the outer tube 142 inside the funnel-shaped flow obstacle 226, so that the opening of the short tube 233 faces the direction of the axial blood flow through the tube 24, as shown in FIG. Fig. 17C As shown. The outer tube 142 also defines an opening 219, which 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 body of the subject.

[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 Fig.17D For some applications, region 230 of tube 24 where pitot tube 225 is disposed 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 an 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 Fig.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, the 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 the 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 a ventricular blood pressure measurement tube 220 as 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 Fig.19A , Fig.19B , Fig.19C , Fig.19D , Fig.19E , Fig.19F , Figure 19G and Fig.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 that houses an impeller 50. For illustrative purposes, Figure 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 disposed 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 the impeller pumping the blood compared to blood being pumped between the impeller and the struts of the frame 34. For some applications, the liner includes polyurethane, polyester and / or silicone. Alternatively or additionally, the liner includes polyethylene terephthalate (PET) and / or polyether block amide

[0369] Typically, the liner is disposed on at least the inner surface of the cylindrical portion of the frame 34 (e.g., the cylindrical portion is disposed on the inner surface of the frame 34). 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. Fig.19A For some applications, there is only a partial overlap between the tube 24 and the liner 39, e.g. Fig.19B For example, the tube 24 may overlap the liner along less than 50% (e.g., less than 25%) of the length of the liner. For some such applications, during insertion of the ventricular assist device 20 into the subject, the impeller is advanced distally within the frame 34 such that the impeller is not disposed 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 Fig.19A and Fig.19B In the illustrated application, the liner 39 is shaped to form a smooth surface over the overlap region between the liner 39 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). Fig.19A Typically, at the overlap region between the liner 39 and the tube 24, the tube and liner are coupled to each other, for example, via vacuum, via adhesive, and / or using a thermoforming process, for example 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, while 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, such as Fig.19A For some applications, the combination of the frame, liner, and the portion of the tube 24 disposed around the frame is then shaped into the desired shape and size using shaping techniques known in the art.

[0372] According to the above description, 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 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. When the distal portion is arranged around at least a portion of the frame, the liner, the frame, and the distal portion of the elongated tube are heated via the mandrel. When the liner, the frame, and the distal portion of the elongated tube are heated, pressure is applied from the outside of the distal portion of the elongated tube to make the distal portion of the elongated tube conform to the strut structure of the frame and to make the liner and the distal portion of the elongated tube become coupled to the frame. For example, pressure can be applied by a silicone tube placed outside the distal portion of the elongated tube. For some applications, the liner and the elongated tube include a liner and an elongated tube 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. 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 Fig.19C For some applications, the tube 24 does not overlap the liner 39, but the tabs 322 extend from the tube 24 through the struts of the frame 34 to the liner 39 and are used to sealingly couple the tube to the liner (e.g., by adhering to the liner). Alternatively or additionally (not shown), the tabs 322 extend from the liner to the tube 24 and are used 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. Fig.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 widens the blood inlet opening 108 (which is typically defined by the liner at the distal end of the cylindrical portion of the frame) relative to the remainder of the cylindrical portion of the frame. Typically, the impeller is disposed very close to the blood inlet opening throughout the operation of the impeller (and during axial reciprocation), wherein the distal end of the impeller is typically disposed 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. 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 Fig.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 the distal portion 332 of the cylindrical portion 38 of the frame converges from the distal end of the cylindrical portion of the frame and toward the impeller (e.g., defines a portion of the frame that is narrower than the remainder of the cylindrical portion of the frame near the impeller (e.g., near the distal end of the impeller)). 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 Fig.19F For some applications, the combination of the frame, the liner, and the portion of the tube 24 disposed around the frame is shaped so that reference is made to Fig.19D and Fig.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 Fig.19DAs described above, typically, the impeller is disposed very close to the blood inlet opening throughout the operation (and axial reciprocation) of the impeller, wherein the distal end of the impeller is typically disposed 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. 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.

[0378] Reference Fig.19H , for some applications, to facilitate coupling of the liner 39 to the frame 34, an outer covering material is coupled (e.g., using an adhesive, vacuum, and / or thermoforming process) from the outer frame 34 to the liner at certain discrete coupling regions 326 along the length of the frame. Note that in FIG. 19 , for purposes of illustration, 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 34. Alternatively or additionally, at one or more of the attachment regions, additional exterior covering material 328 is placed around frame 34. For example, the additional attachment material may be made of a material similar to that used for liner 39 and / or tube 24. For some applications, at the attachment regions, frame 34 has a strut density (i.e., the ratio of the surface area occupied by the struts to the area of ​​the open spaces between the struts) that is lower than the strut density of the frame at other locations along the length of the frame. 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 covering 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 Fig. 20A , Fig. 20B and Fig. 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 Fig. 20A , Fig. 20B and Fig. 20C In each of the respective expanded states. For some applications (as shown), the expandable portion 331 is in the same manner as described above with reference to Fig.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, the inflation lumen for inflating the expandable portion is configured to pass through outer tube 142 and then along the outer surface of tube 24 and to the expandable portion of 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., Figure 20A-20C ) and is configured to act as a dilator during insertion of a ventricular assist device through a puncture in a subject's body, as described above. In this manner, 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 subject's body, expandable portion 331 is maintained in a deflated state, as described above. Fig. 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. Fig. 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 Fig. 20B The state shown is more fully expanded (e.g., fully expanded). Typically, when the expandable portion is more fully expanded, the expandable portion separates one or more blood inlet openings 108 from the internal structure of the left ventricle in three dimensions. In this way, the expandable portion separates one or more blood inlet openings 108 from the intraventricular septum, chordae tendineae, papillary muscles, and / or the apex of the left ventricle. 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 hemostatic valve (e.g., duckbill valve 390) is disposed within lumen 122 of distal tip portion 120. For some applications, the hemostatic valve prevents blood from flowing into lumen 122 and / or lumen 132. Typically, the hemostatic valve prevents the flow of cleaning fluid out of the distal end of lumen 122 so that the cleaning fluid flows toward the interface between axial shaft 92 and distal support 118, as described above.

[0384] Now refer to Fig.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 purposes of illustration, Fig.21 The aortic valve 26 is shown overlaid on a cross-section of the left ventricle, although the aortic valve is located in a different plane than the plane of the main cross-sectional view. Figure 22A-22D , which are schematic diagrams 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 similar to a question mark, and also referring to Fig.23A and Fig. 23B , which are views of a 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 ventricular assist device is guided by a guidewire, over which the ventricular assist device is inserted toward the apex 342 of the left ventricle. The walls of the left ventricle can be considered to be composed of the septal wall 338 (which separates the left ventricle from the right ventricle 340), the posterior wall 336 (the papillary muscles 341 protrude from the posterior wall 336, and the mitral valve device is disposed above the posterior wall 336), and the free wall 334, each of which occupies approximately one-third of the circumference of the left ventricle (e.g., Fig.21 Typically, it is undesirable for the distal tip element (or any other portion of the ventricular assist device) to contact the septal wall because of 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 ventricular assist device) 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 ventricular assist device. Therefore, the ventricular assist device is typically guided toward the apex in such a manner that if and when the distal tip element contacts the inner wall of the left ventricle, the ventricular assist device contacts the free wall 334, as shown. Fig.21 and Figure 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 Figure 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), when deployed within the left ventricle of a subject, the curvature of the distal tip portion is less than Figure 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. Figure 22C-Figure 22D The distal tip of Fig.23A is shown within the left ventricle of a subject, and the distal tip portion does not form a complete ring.

[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 Figure 22A-22B As shown, within the plane of the paper, the distal tip element first bends toward the top of the paper, then bends toward the bottom of the paper, and as shown in FIG. Figure 22C-Figure 22D As shown, within the plane of the paper, the distal tip element first bends toward the bottom of the paper and then bends toward the top of the paper. Typically, when formed as Figure 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 straight 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 ridge shape that is substantially similar to a semi-ellipse.

[0388] like Figure 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 onto the longitudinal axis 348 . Fig.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 there is a large gap between the distal end of the distal tip element and the proximal end of the curved portion. Fig. 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 (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 so 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 Fig.22A and Fig. 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 provided as described below with reference to Figure 28A-28C For example, Fig.22A Shows the use of Figure 28A-28C Alternatively, a different duckbill valve may be used, such as Fig. 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 Figure 28A-Figure 28E For some applications, the guide wire guide 392 is disposed within the distal tip portion 120 at a location proximal to the duckbill valve (e.g., Fig.22A As shown in Figure 22A-22D As shown, typically, the distal segment of the distal portion is widened to accommodate a duckbill valve and / or a guide wire guide. For some applications, due to the widening of the distal portion, the distal tip of the distal tip portion (through which the guide wire is inserted into the distal tip portion) has no sharp edges. 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 Fig.23A and Fig. 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, the distal tip element 107 is inserted into the left ventricle such that the ridge 351 ridges toward the septal wall 338. When arranged in this configuration, in response to the 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 in the direction of the free wall 334 and away from the septal wall 338 (at Fig. 23B 346 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 is curved in a single direction of curvature) that is oriented such that the pigtail curve is 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 Fig.24A , Fig. 24B , Fig.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. Fig.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. Fig. 24BAs shown, the distal tip element is configured so that when released 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 through 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 released within the left ventricle. Fig.24C An alternative or additional way to configure the distal tip element to provide the above functionality is that the radius of the protrusion 351 of the distal tip element is large enough to center the distal tip element relative to the aortic valve. For example, the radius of the protrusion of the distal tip element can be greater than 15 mm (e.g., greater than 17 mm).

[0394] Reference Figure 21-24C Throughout the Figures, note 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 Fig.25A , which is a schematic diagram of a ventricular assist device 20 according to some applications of the present invention, the tube 24 of the device being configured to become curved as blood is pumped through the tube. Fig.25B , which is in the absence of other components of a ventricular assist device according to some applications of the present invention Fig.25A Schematic diagram of the tube 24. Fig.25C , which is disposed within the aorta 30 and the left ventricle 22 of a subject according to some applications of the present invention. Figure 25A-25B Schematic diagram of a ventricular assist device 20. Note that Fig.25C The views of the aorta and left ventricle shown are different from e.g. Figure 1B View shown. Figure 1B and similar figures are schematic illustrations, provided for purposes of illustration, and do not necessarily accurately depict the scale and orientation of the ventricular assist relative to the anatomy. Note also that Fig.25C The views of the aorta and left ventricle shown are different from e.g. Fig.23A and Fig. 23B View shown. Fig.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 state 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 operation of the impeller. 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 operation of the impeller. During operation of the impeller, the blood flow 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, the tube is curved when the blood flow pressure through the tube maintains the proximal portion of the tube in an open state. Typically, the curvature is such that when the proximal end of the tube is disposed within the aorta, at least a portion of the tube is disposed 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 disposed within the aorta, at least a portion of the tube is disposed 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 a subvalvular portion of the mitral valve (e.g., chordae tendineae 404 and / or papillary muscles 341), such as Fig.25C shown.

[0398] Typically, the tube 24 is preformed using blow molding in a curved mold, or is preformed using a forming mold after a blow molding process or an impregnation process. Typically, the distal portion of the tube (wherein the frame 34, the impeller 50 and the axial shaft 92 are provided) is maintained in a straight and open configuration by the frame 34. The portion of the tube that is located proximal to the frame 34 and is disposed in the left ventricle is typically shaped to limit the above-mentioned curvature. For some applications, the curvature makes 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 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-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 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. Fig.25B A dashed circle is shown in , with the dashed line spanning its diameter to indicate how the radius of curvature R is measured.

[0399] Note that, as referenced Figure 25A-Figure 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, such as Fig.25A and Fig.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 element disposed within the tube) causing the tube to bend. Alternatively, the outer tube 140 and / or 142 (which is disposed around the drive cable) is shaped to define a curve, and the outer tube causes the drive cable and tube 24 to assume a curved shape. For some applications, both the outer tube 140 and / or 142 and the tube 24 are shaped to define a curved shape.

[0400] Note that Figure 25A-Figure 25C The tube 24 shown is generally as described above with reference to Figure 2A The invention is configured as 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 reference Figure 25A-Figure 25C The described curved configurations of the tubes are combined with other general configurations of the tubes (eg, as described above).

[0401] Now refer to Figure 25D-Figure 25E, which are schematic diagrams 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. Fig.25D and Fig.25E , for illustrative purposes, tube 24 is shown without other components of the ventricular assist device (eg, impeller 50, frame 34, etc.). Fig.25E is disposed within the aorta 30 and the left ventricle 22 of a subject according to some applications of the present invention, Fig.25D Schematic diagram of a ventricular assist device 20 . Fig.25E The view of the left ventricle shown is similar to Fig.25C For some applications, inlet opening 108 and / or outlet opening 109 are arranged in a non-axisymmetric configuration around tube 24. Typically, tube 24 defines the position of the inlet opening and / or outlet opening so that tube 24 becomes curved and / or maintains the curvature of tube 24, as shown in FIG. Figure 25A-Figure 25C As described. For example, as shown, the blood inlet hole can be disposed on one side of the tube 24 located at the inner side of the bend of the tube (or on the inner side 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 the area (as shown by arrow 310). Alternatively or additionally, the blood outlet opening 109 can be disposed on one side of the tube 24 located at the inner side of the bend of the tube (or on the inner side 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 Figure 25A-Figure 25C Typically, 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), such as Fig.25E Typically, the curvature is such that when the proximal end of the tube is disposed in the aorta, at least a portion of the tube is disposed in 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 disposed in the aorta, at least a portion of the tube is disposed in 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 Fig.25F , which is a schematic diagram of a ventricular assist device 20 according to some applications of the present invention, the ventricular assist device includes a bending element 410 configured to provide a predetermined curvature to a tube 24. For some applications, as the tube 24 itself is shaped to define a bend (e.g., as shown in FIG. Figure 25A-Figure 25E As an alternative or in addition to the 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" known in the art (i.e., a Nitinol tube having microengineered features along its length). 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 element is shaped to have a substantially similar Figure 25A-Figure 25E Regarding the curvature described in relation to 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), for example, 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 on the inner side of the bend defines a radius of curvature greater than 10 mm, for example, greater than 20 mm, and / or less than 200 mm (e.g., 100 mm), for example, 10 mm-200 mm, or 20 mm-100 mm. As described with reference to Figure 25A-Figure 25C Typically, as Fig.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 disposed within the aorta, at least a portion of the tube is disposed 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 disposed within the aorta, at least a portion of the tube is disposed 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 Figure 25A-Figure 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 Figure 23A-23B The curvature of the tube shown is less than Figure 25A-Figure 25F The curvature of the tube shown is due to Figure 23A-23B Different views of the device are shown. Figure 23A-23B In the view shown, the curvature is typically not as good as Figure 25A-Figure 25F The view shown is obvious.

[0406] Now refer to Fig.26A , Fig.26B , Fig.26C , Fig.26D , Fig.26E and Fig.26F , these figures are schematic diagrams of a distal tip element 107 of a ventricular assist device 20 according to respective applications of the present invention, the distal tip element being at least partially curved. Figure 26B-Figure 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 via 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 Figure 26A-26F One of the shapes shown.

[0407] Typically, the distal tip element 107 is configured such that in its unconstrained configuration (i.e., without any forces acting on the distal tip portion), the distal tip element is at least partially bent. For some applications, the distal tip element is bent 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-180 degrees, 120 degrees-180 degrees, or 120 degrees-160 degrees, for example. Fig.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 Fig.26B As shown. 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 degrees-160 degrees or 140 degrees-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 degrees-140 degrees or 120 degrees-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 Fig.26C and Fig.26D For some applications, within a given plane, the distal tip element has a proximal straight portion 346 defining a longitudinal axis 348, bends in a first direction away from the longitudinal axis 348, and then bends in an opposite direction relative to the longitudinal axis 348. For example, Fig.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. Fig.26D As shown, within the plane of the page, the distal tip element first bends toward the right side of the page, and then bends toward the left side of the page. Fig.26D The example shown in is roughly similar to Fig.22A In addition to the examples shown in Fig.26D 22). The tip is configured such that the distal portion of the tip where it intersects the longitudinal axis 348 is shorter than in FIG. 22).

[0410] Note that Fig.26C When shaped as shown, the distal tip element 107 typically defines a first turning point 347 and a second turning point 349, wherein the first turning point 347 is disposed on a first side of the longitudinal axis 348 of the proximal straight portion 346 of the distal tip portion 120 (e.g., to the left of the longitudinal axis, such as Fig.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, on the right side of the longitudinal axis, as shown in FIG. 1 ). Fig.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 semi-circle. 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 Fig.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 straight 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 shape 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 a 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 Fig.26C ), and / or by bending in at least two directions (e.g., as Fig.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 when the distal tip element is bent in a single direction.

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

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

[0416] Note that for all curved distal tip elements described herein (e.g., see Figure 21-24C and Figure 26A-26F ), typically, the curvature of the distal tip portion is all within a single plane. Referring to the shape of the distal tip portion described herein (e.g., referring 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 Fig.27A , Fig.27B and Fig.27C , which 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. Figure 27A-27CThe protrusion 350 is shown without the distal tip element 107. 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 ventricle of the subject via a guide wire. Along a proximal portion of the atraumatic protrusion 350, the atraumatic protrusion defines a guide wire lumen 352. The closed circle or ellipse of the atraumatic protrusion typically defines holes 354 on its sidewalls, and the guide wire passes through these holes. During insertion of the ventricular assist device into the ventricle of the subject, 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 vasculature of the subject.

[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 a wall of the left ventricle.

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

[0420] Now refer to Fig.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. Fig.28B and Fig.28C , which are schematic diagrams of the proximal narrow end 420 of the duckbill valve 390 and the distal wide end 422 of the duckbill valve 390 according to some applications of the present invention. Fig.28D and Fig.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 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 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 duckbill valve 390 and guidewire guide 392 in the tip of any percutaneous device and is not limited to using duckbill valve 390 and guidewire guide 392 in 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 such that 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 Figure 13A-13C The duckbill valve faces the proximal end to prevent fluid from flowing out of the distal end of the distal portion, allowing fluid to flow back toward the distal support 118, as described above. Typically, blood will not flow into the guide wire lumen 122 because the pressure inside the guide wire lumen 122 is greater than the blood pressure outside the lumen, in the left ventricle.

[0423] Typically, the ventricular assist device is inserted via a guide wire (e.g., guide wire 10, such as Figure 1B 1 (shown) is advanced into the left ventricle. A guide wire is typically inserted into the guide wire lumen 122 of the distal tip portion 120 via the distal end of the distal tip portion. Typically, insertion of the guide wire 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 guide wire 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 positioned 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 in operation, it may be desirable to utilize an existing percutaneous puncture and insert a guidewire via guidewire lumen 122 prior to retracting ventricular assist device 20, rather than retracting the ventricular assist device and having to reinsert the guidewire via a 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 narrowing in diameter 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 the 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, the converging guide portions converging toward the slit 434, such that the guide portion is configured to further guide the tip of the guidewire toward the slit 434.

[0426] The scope of the present invention includes the use of duckbill valve 390 and guidewire guide 392 in a guidewire lumen of any percutaneous device and is not limited to the use of duckbill valve 390 and guidewire guide 392 in 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 Fig.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 through a percutaneous puncture. Typically, the sheath includes a covering (e.g., polyurethane, polyester, silicone, polyethylene terephthalate (PET) and / or polyether block amide A covering) is disposed 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. Figure 28A-Figure 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 sheath 440 has been retracted from the percutaneous puncture. Subsequently, the guide wire is inserted through the existing percutaneous puncture by advancing through sheath 440 (i.e., between the covering and the outer surface of 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, sheath 440 is disposed around a portion of outer tube 142 along a distal segment of the length of the outer tube, and the function of the sheath is substantially 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 via an existing percutaneous puncture and is not limited to use with the delivery catheter 143 of a ventricular assist device 20.

[0429] Now refer to Fig.30 and Fig.31 , these figures are schematic diagrams of a ventricular assist device 20 including two impellers 50 according to some applications of the present invention. Fig.30As shown, for some applications, the first impeller and the second impeller are arranged parallel to each other, and each impeller is driven by a respective 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 overlapping each other. For some applications, the proximal impeller pumps blood via a parallel tube 24A 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 Fig.30 Thus, typically only tube 24 (and not parallel tube 24A) passes through the aortic valve.

[0430] like Fig.31 As shown, for some applications, the first impeller and the second impeller are arranged in series with each other, and each impeller is driven by a single drive cable 130. Typically, the first impeller in the impeller 50 and its corresponding frame 34 are arranged distally of 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 overlapping 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 position configured to be located downstream of the aortic valve (the position of the aortic valve is in Fig.30 Thus, typically only tube 24 (and not parallel tube 24A) passes through the aortic valve.

[0431] Note that by having one impeller pumping through parallel tubes 24A while a 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 this may result in inefficiencies in the proximal impeller pumping blood if the proximal impeller is used to pump blood that has already been pumped by the distal impeller. It should also be noted that doubling the number of impellers will typically double the amount of hemolysis produced by the ventricular assist device 20, assuming all else is equal. Conversely, increasing the rotation rate of a single impeller and / or increasing the length of the impeller may result in a disproportionate increase in the amount of hemolysis produced by the impeller.

[0432] About reference Figure 1A-Figure 31 All aspects of the ventricular assist device 20 described herein 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 so that the device (with necessary modifications) passes through the pulmonary valve of the subject, and the technology described herein is 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 a pump that is 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, apparatus 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) is 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) can be placed in a blood vessel and can be used to pump blood through the blood 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 invention includes the use of the apparatus and methods described herein at 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 Fig.32A , Fig.32B , Fig.32C , Fig.32D and Fig.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 substantially similar to the components described above with reference to ventricular assist device 20, the same reference numerals as used above are used. Typically, these components are substantially as described above, except for the differences described below.

[0435] Fig.32EDevice 360 ​​in non-radial constrained configuration is shown in a manner without subject anatomical structure. As shown, typically, in order to assist the right heart function of the subject, impeller 50 and frame 34 are arranged at the proximal end of tube 24. Similarly, (multiple) blood inlet openings are arranged at the proximal end of the tube. Impeller is configured to pump blood through tube 24 to the blood outlet opening 109 arranged at the distal end of tube 24 in the distal direction. For some applications, balloon 362 is arranged at the distal end of the device. Balloon 362 is configured to help introduce the distal end of the device into the pulmonary artery 364, in a manner that the balloon migrates to the pulmonary artery with the blood flow of the subject. 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 tube 24.

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

[0437] Note that Figure 32B-Figure 32D In the configuration shown, the heart assist device will reduce the preload on the right heart (by pumping blood from the right atrium or vena cava), but will increase the afterload (by pumping blood into the pulmonary artery). Fig.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 Fig.33 , which is a schematic diagram of a venous assist system 380 according to some applications of the present invention. For components of device 380 that are substantially similar to components described above with reference to ventricular assist device 20, the same reference numerals as used above are used. Typically, these components are substantially as described above, except for the differences described below. For some applications, venous assist device 380 includes impeller 50 and frame 34, which are substantially as described above. For some applications, venous assist device does not include tube 24, e.g., as Fig.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 may be inserted into a vein 382 (e.g., iliac vein or femoral vein) of a leg of a subject suffering from ischemia in the leg and may assist in pumping blood through the vein.

[0440] For some applications, the scope of the present 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 an end of the drive cable and an end of the rigid tube are disposed at given positions within the butt-weld outer sleeve, the ends are visible through a window defined by the butt-weld outer sleeve, and the drive cable is placed 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

[0445] A weld ring is formed around the butt-welded outer sleeve.

[0446] For some applications, forming a weld ring around the butt weld outer sleeve includes: forming a weld ring separated from the edge of the butt weld outer sleeve, so that the weld ring welds the butt weld outer sleeve to the rigid tube and the drive cable without directly welding the weld ring 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 certain depth so 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, connecting the drive cable to the rigid tube includes: connecting the drive cable to an axial shaft configured to support an impeller. For some applications, connecting the drive cable to the rigid tube includes: connecting the drive cable to a pin configured to couple to a magnet, and the magnet is configured to be driven to rotate by a motor. Reference above Figure 10D-10E Some examples of such applications are described.

[0447] An apparatus comprising:

[0448] a drive cable comprising a plurality of coiled wires;

[0449] a rigid tube configured to be coupled to the drive cable; and

[0450] A butt-weld outer sleeve configured to facilitate butt-welding of a drive cable to a rigid tube, the butt-weld outer sleeve defining:

[0451] a window configured to provide visibility of the ends of the drive cable and the ends of the rigid tube when the ends are disposed at a given position within the butt-welded outer casing, thereby facilitating placement of the ends of the drive cable and the ends of the rigid tube at a given position within the butt-welded outer casing; and

[0452] A helical groove is located in a portion of the butt weld outer sleeve that is configured to be disposed over the drive cable and provides flexibility to the portion of the butt weld outer sleeve that is configured to be disposed over the drive cable.

[0453] 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.

[0454] A method comprising:

[0455] A first portion and a second portion of a drive cable comprising a plurality of coiled wires are coupled to each other by:

[0456] placing the end of the first portion and the end of the second portion of the drive cable at a given position inside the butt-welded outer sleeve,

[0457] When the end of the first portion and the end of the second portion of the drive cable are disposed at a given position within the butt-weld outer sleeve, these ends are visible through a window defined by the butt-weld outer sleeve, and

[0458] 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

[0459] A weld ring is formed around the butt-welded outer sleeve.

[0460] Referenced above Figure 10D-10E Some examples of such applications are described.

[0461] A method comprising:

[0462] The rigid tube is coupled to a drive cable comprising a plurality of coiled wires by:

[0463] Place the end of the drive cable and the end of the rigid tube at a given position inside the butt-welded outer casing,

[0464] When the ends of the drive cable and the ends of the rigid tube are arranged at given positions inside the butt-weld outer sleeve, these ends are visible through the windows defined by the butt-weld outer sleeve, and welding rings are formed around the butt-weld outer sleeve, which are separated from the edges of the butt-weld outer sleeve, so that the welding 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 outer surface of the drive cable.

[0465] For some applications, forming a weld ring around the butt weld outer sleeve includes: forming the weld ring to a certain depth so 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 so that a spiral groove defined by a portion of the butt weld outer sleeve is disposed above the drive cable. For some applications, connecting the drive cable to the rigid tube includes: connecting the drive cable to an axial shaft configured to support an impeller. For some applications, connecting the drive cable to the rigid tube includes: connecting 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.

[0466] An apparatus comprising:

[0467] A blood pump configured to be placed in a subject, the blood pump comprising:

[0468] impeller;

[0469] a frame configured to be disposed around the impeller;

[0470] an axial shaft on which the impeller is disposed;

[0471] a proximal radial support and a distal radial support configured to radially stabilize the axial shaft during rotation of the impeller;

[0472] an atraumatic distal tip portion disposed distally relative to the impeller, the atraumatic distal tip portion including an expandable portion; and

[0473] 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.

[0474] Referenced above Fig.13D Some examples of such applications are described.

[0475] An apparatus comprising:

[0476] A blood pump configured to be placed in a subject, the blood pump comprising:

[0477] a tube defining at least one blood inlet opening and at least one blood outlet opening;

[0478] an impeller configured to pump the subject's blood into the blood inlet opening, through the tube, and out the blood outlet opening;

[0479] 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 placed within a left ventricle of a subject when the impeller pumps blood of the subject;

[0480] an expandable portion disposed about the distal tip portion, the expandable portion being configured to define:

[0481] 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,

[0482] b) a first expanded state, wherein the expandable portion is configured to prevent the distal tip portion from causing damage to the vasculature of the subject during advancement of the distal tip portion through the vasculature of the subject, and

[0483] 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 disposed within the left ventricle of the subject, the expandable portion in its second expanded state is configured to three-dimensionally separate the one or more blood inlet openings from the internal structure of the left ventricle of the subject.

[0484] Referenced above Figure 20A-20C Some examples of such applications are described.

[0485] An apparatus comprising:

[0486] A left ventricular assist device configured to assist left ventricular function of a subject, the left ventricular assist device comprising:

[0487] 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 disposed within a left ventricle of the subject;

[0488] 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,

[0489] 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;

[0490] 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 during the pumping of the blood through the tube:

[0491] The proximal portion of the tube remains open, and

[0492] At least a portion of the tube becomes curved such that the tube curves away from the posterior wall of the left ventricle.

[0493] 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. Figure 25A-Figure 25F Some examples of such applications are described.

[0494] An apparatus comprising:

[0495] A left ventricular assist device configured to assist left ventricular function of a subject, the left ventricular assist device comprising:

[0496] 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 disposed within a left ventricle of the subject;

[0497] 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,

[0498] 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;

[0499] 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 in an open state during pumping of blood through the tube;

[0500] as well as

[0501] A bending element is disposed proximally within the tube relative to the frame, the bending element being configured to cause at least a portion of the tube to bend such that the tube bends away from the posterior wall of the left ventricle.

[0502] For some applications, the bending element is configured to cause at least a portion of the tube to become curved such that the tube bends away from the septal wall of the left ventricle. Figure 25A-Figure 25FSome examples of such applications are described.

[0503] An apparatus comprising:

[0504] A left ventricular assist device configured to assist left ventricular function of a subject, the left ventricular assist device comprising:

[0505] 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 disposed within a left ventricle of the subject;

[0506] a frame disposed within at least a distal portion of the tube,

[0507] a pump disposed within the frame and configured to pump blood from the left ventricle of the subject to the aorta of the subject 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 left ventricle of the subject, and by pumping blood out of the tube through a set of one or more blood outlet openings defined by the tube and disposed within the aorta of the subject;

[0508] Wherein at least one opening in the set of openings in the tube is arranged in a non-axisymmetric configuration relative to the tube, so 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, so that the tube bends away from the posterior wall of the left ventricle.

[0509] 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. Figure 25A-Figure 25F Some examples of such applications are described.

[0510] An apparatus comprising:

[0511] An impeller, the impeller comprising:

[0512] an impeller frame including a proximal portion and a distal portion and at least one helical elongated element wound from the proximal portion to the distal portion;

[0513] 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

[0514] A coil is wound around the at least one helical elongated member, the coil being configured to facilitate coupling of material to the at least one helical elongated member.

[0515] A method comprising:

[0516] The impeller is manufactured in the following manner:

[0517] 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;

[0518] winding a coil around at least one elongated member;

[0519] By axially compressing the structure, the at least one elongated element is radially expanded and forms at least one helical elongated element; and

[0520] 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,

[0521] The coil is configured to facilitate coupling of material to the helical elongate element.

[0522] Referenced above Figure 3A-3K Some examples of such applications are described.

[0523] An apparatus comprising:

[0524] An impeller, the impeller comprising:

[0525] an impeller frame including a proximal portion and a distal portion and at least one helical elongated element wound from the proximal portion to the distal portion;

[0526] 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

[0527] A sleeve is disposed about the at least one helical elongated member, the sleeve being configured to facilitate coupling of material to the at least one helical elongated member.

[0528] A method comprising:

[0529] The impeller is manufactured in the following manner:

[0530] 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;

[0531] placing a sleeve around at least one elongated member;

[0532] By axially compressing the structure, the at least one elongated element is radially expanded and forms at least one helical elongated element; and

[0533] 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,

[0534] The sleeve is configured to facilitate coupling of material to the helical elongate member.

[0535] Referenced above Figure 3A-3K Some examples of such applications are described.

[0536] An apparatus comprising:

[0537] An impeller, the impeller comprising:

[0538] an impeller frame including 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

[0539] 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

[0540] 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.

[0541] A method comprising:

[0542] The impeller is manufactured in the following manner:

[0543] 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;

[0544] By axially compressing the structure, the at least one elongated element is radially expanded and forms at least one helical elongated element; and

[0545] 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,

[0546] 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.

[0547] Referenced above Figure 3A-3K Some examples of such applications are described.

[0548] A method comprising:

[0549] The impeller is manufactured in the following manner:

[0550] 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;

[0551] by axially compressing the structure, radially expanding the at least one elongated element and forming at least one helical elongated element;

[0552] 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;

[0553] 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;

[0554] coupling a material to at least one helical elongate element and a spring such that a film of material is supported between the helical elongate element and the spring, the film of material defining blades of the impeller,

[0555] The annular elongate element is configured to hold the helical elongate element within a given distance from the spring.

[0556] Referenced above Figure 3A-3K Some examples of such applications are described.

[0557] An apparatus comprising:

[0558] A left ventricular blood pump, the left ventricular blood pump comprising:

[0559] impeller;

[0560] 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

[0561] A computer processor is configured to measure the motor power consumption required to rotate the impeller at a given rotation rate and determine the subject's left ventricular blood pressure responsive at least in part thereto.

[0562] Referenced above Fig. 9 Some examples of such applications are described.

[0563] An apparatus comprising:

[0564] A left ventricular assist device configured to assist left ventricular function of a subject, the left ventricular assist device comprising:

[0565] 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 disposed 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 disposed within the left ventricle and the at least one blood outlet opening being configured to be disposed within the aorta of the subject;

[0566] 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;

[0567] a drive cable configured to extend from the impeller to outside the subject's body;

[0568] one or more outer tubes within which the drive cables are configured to rotate;

[0569] a motor disposed outside the subject's body and configured to drive the impeller to rotate via a drive cable; and

[0570] A stator configured to reduce a rotational flow component of blood flow through a blood pump tube before the blood flows out of at least one outlet opening, the stator comprising:

[0571] a frame coupled to one or more outer tubes within the blood pump tube; and

[0572] 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.

[0573] For some applications, the framework is a self-extensible framework. Figure 14A-Figure 14C Some examples of such applications are described.

[0574] An apparatus comprising:

[0575] A left ventricular assist device configured to assist left ventricular function of a subject, th...

Claims

1. A method comprising: The rigid tube is coupled to a drive cable comprising a plurality of coiled wires by: placing the end of the drive cable and the end of the rigid tube at a given position inside the butt-welded outer casing, When the end of the drive cable and the end of the rigid tube are disposed at the given position within the butt-weld outer sleeve, the end of the drive cable and the end of the rigid tube are visible through a window defined by the butt-weld outer sleeve, and The drive cable is placed within the butt-weld outer sleeve such that a helical groove defined by a portion of the butt-weld outer sleeve is disposed above the drive cable; as well as A weld ring is formed around the butt-welded outer sleeve.

2. The method of claim 1 , wherein forming a weld ring around the butt-welded outer sleeve comprises: A welding ring is formed spaced apart from an edge of the butt-weld outer sleeve so that the welding ring welds the butt-weld outer sleeve to the rigid tube and the drive cable without directly welding the welding ring to the outer surface of the rigid tube and the outer surface of the drive cable.

3. The method of claim 1 , wherein forming a weld ring around the butt-welded outer sleeve comprises: The weld ring is formed 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 an inner cavity defined by the rigid tube and the drive cable.

4. The method of claim 1 , wherein forming a weld ring around the butt-weld outer sleeve comprises: At least one welding ring is formed at the given position within the butt-welded outer sleeve where the end portion of the drive cable and the end portion of the rigid tube are placed.

5. The method of claim 1 , wherein coupling the rigid tube to the drive cable comprises: The drive cable is coupled to an axial shaft configured to support an impeller.

6. The method of claim 1 , wherein coupling the rigid tube to the drive cable comprises: The drive cable is coupled to a pin configured to couple to a magnet configured to be rotated by a motor.

7. An apparatus comprising: a drive cable comprising a plurality of coiled wires; a rigid tube configured to be coupled to the drive cable; and a butt-weld outer sleeve configured to facilitate butt-welding the drive cable to the rigid tube, the butt-weld outer sleeve defining: a window configured to facilitate placement of the end of the drive cable and the end of the rigid tube at a given position within the butt-weld outer sleeve by providing visibility of the end of the drive cable and the end of the rigid tube when the end of the drive cable and the end of the rigid tube are disposed at the given position within the butt-weld outer sleeve; and A helical groove is located in a portion of the butt weld outer sleeve, the helical groove being configured to be disposed over the drive cable and providing flexibility to the portion of the butt weld outer sleeve configured to be disposed over the drive cable.

8. An apparatus according to claim 7, wherein the butt-weld outer sleeve is butt-welded to the drive cable and the rigid tube by a welding ring separated from an edge of the butt-weld outer sleeve, so that the welding ring welds the butt-weld outer sleeve to the rigid tube and the drive cable without directly welding the welding ring to the outer surface of the rigid tube and the outer surface of the drive cable.

9. An apparatus according to claim 7, wherein the butt-welded outer sleeve is butt-welded to the drive cable and the rigid tube by forming a welding ring to a certain depth, so that the butt-welded 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.

10. The apparatus according to claim 7, wherein the butt-welded outer sleeve is butt-welded to the drive cable and the rigid tube by at least one welding ring, and the at least one welding ring is formed at the given position inside the butt-welded outer sleeve where the end of the drive cable and the end of the rigid tube are placed.

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