Ventricular assist device

Abstract

The present application relates to a ventricular assist device. An apparatus and method are described that include an impeller (50), the impeller including a proximal sleeve (64) and a distal sleeve (58). Two or more spiral elongated elements (52) extend from the proximal sleeve (64) to the distal sleeve (58), and an axial structure (54) is disposed inside the two or more spiral elongated elements (52) and along the axis around which the spiral elongated elements (52) are wound. The impeller (50) includes an impeller over-extension preventing element (72). The impeller over-extension preventing element is a single integrated structure that includes a ring (73) disposed around the axial structure (54) and a plurality of elongated elements (67), each elongated element (67) extending from the ring to a corresponding spiral elongated element (52) and coupled to the corresponding spiral elongated element (52) to prevent radial expansion of the impeller (50). Other applications are also described.

Description

[0001] This application is a divisional application of the application with application date of April 6, 2021, application number 202180006817.8, and invention name “Ventricular Assist Device”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority from the following applications:

[0004] U.S. Provisional Patent Application 63 / 006,122, filed by Tuval on April 7, 2020, entitled “Ventricular assist device”;

[0005] U.S. Provisional Patent Application 63 / 114,136, filed by Tuval on November 16, 2020, entitled “Ventricular assist device”; and

[0006] Tuval’s U.S. provisional patent application 63 / 129,983, titled “Ventricular assist device,” filed on December 23, 2020.

[0007] Each of the above-referenced U.S. provisional applications is incorporated herein by reference.

[0008] Field of Embodiments of the Invention

[0009] 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

[0010] Ventricular assist devices are mechanical circulatory support devices designed to assist and unload the heart chambers to maintain or increase cardiac output. They are used in patients with heart failure and in patients at risk of worsening heart function during percutaneous coronary intervention. Most commonly, left ventricular assist devices are used in defective hearts to assist the left ventricle. In some cases, right ventricular assist devices are used to assist the right ventricle. These assist devices are either designed to be permanently implanted or mounted on a catheter for temporary placement.

[0011] Overview of the Embodiments

[0012] According to some applications of the present invention, a blood pump includes an impeller. The impeller includes a proximal sleeve and a distal sleeve, and two or more spiral elongated elements (and typically three spiral elongated elements) extending from the proximal sleeve to the distal sleeve. An axial structure (e.g., a cylindrical axial structure, such as a spring) is disposed inside the two or more spiral elongated elements and along the axis around which the spiral elongated elements are wound. A film of material is supported between the spiral elongated elements and the axial structure, such that each of the spiral elongated elements with the film of material coupled thereto defines a corresponding blade of the impeller. An element to prevent over-extension of the impeller is disposed within the impeller. The element to prevent over-extension of the impeller is a single integrated structure comprising a ring and a plurality of elongated elements disposed around the axial structure. Each elongated element extends from the ring to a corresponding spiral elongated element and is coupled to the corresponding spiral elongated element to prevent radial expansion of the impeller. Typically, the elongated element is configured to not resist compression, and the elongated element is configured to prevent radial expansion of the impeller by applying a tensile force to the spiral elongated element.

[0013] For some applications, along at least a portion of the length of the impeller, the film of material forms a continuous U-shaped curved surface as it transitions from one impeller blade to an adjacent blade, wherein the U-shaped curvature of the film of material is substantially uninterrupted at the axial structure. For some applications, when viewed from the distal end of the impeller, the pressure side of each impeller blade (i.e., the side configured to push blood during operation of the impeller) is convex in a distal region of the impeller and concave in a proximal region of the impeller. Typically, the pressure side of each impeller blade transitions to be substantially radially oriented in the region of the elongated element within the impeller blade.

[0014] For some applications, the impeller is manufactured by forming a structure having a first bushing and a second bushing at a proximal end and a distal end of the structure, the first bushing and the second bushing being connected to each other by at least one elongated element. At least partially by axially compressing the structure, the at least one elongated element is radially expanded and formed into at least one helical elongated element. The at least one helical elongated element is coated with a coupling agent, the coupling agent being configured to enhance the bond between the helical elongated element and the elastomeric layer. The coated helical elongated element is then coated with the elastomeric layer. Subsequently, an elastomeric film is coupled to the at least one helical elongated element such that the at least one helical elongated element with the elastomeric film coupled thereto defines the blades of the impeller. For example, the helical elongated element can be immersed in an elastomeric material and the elastomeric layer is made of the elastomeric material. For some applications, the elastomeric film comprises an elastomeric material having an ultimate elongation greater than 300%, a melt flow index of at least 4, and / or an ultimate tensile strength greater than 6000 psi.

[0015] For some applications, the impeller is driven to rotate by one or more drive magnets (the drive magnets are coupled to a motor) that drive one or more driven magnets to rotate, and the driven magnets are coupled to the impeller via a drive cable. According to some applications of the present invention, a magnetic phase difference between one or more driven magnets and one or more drive magnets is measured, and a physiological parameter of the subject is determined at least in part in response to the measured magnetic phase difference. For example, based at least in part on a change in the phase difference, a computer processor can determine the difference between the subject's left ventricular pressure and the subject's aortic pressure, the subject's left ventricular pressure, an event in the subject's cardiac cycle, the subject's cardiac afterload, and / or different physiological parameters. For some applications, the physiological parameter is determined based on a phase difference measurement result combined with one or more additional measurement results (e.g., a flux amplitude measurement result, the power consumed by the motor, and / or the current consumed by the motor). Typically, such measurements are combined in a mathematical model, such as a linear regression model, and / or a spatial state model.

[0016] For some applications of the present invention, during operation of a ventricular assist device acting as a blood pump, a subject's arterial pulsation is measured, and parameters are derived from the subject's arterial pulsation. Typically, as the impeller rotation rate increases, the flow rate generated by the blood pump increases. Typically, the flow generated by the blood pump is non-pulsatile because the blood pump is a continuous-flow blood pump rather than a pulsatile blood pump. Therefore, typically, as the impeller rotation rate increases and the flow rate generated by the blood pump increases, the subject's arterial pulsation decreases. For some applications, the subject's arterial pulsation is measured as the impeller rotation rate changes. Based on these measurements, a relationship between the arterial pulsation and the impeller rotation rate and / or the pump flow rate is derived. For some applications, the subject's natural cardiac output is derived based on this relationship. For some such applications, the relationship between the subject's arterial pulsation and the pump flow rate is extrapolated to determine what the pump flow rate would be when the subject's arterial pulsation reaches zero. It is assumed that, at this value, the blood pump is replacing the heart's natural function, and that the flow rate generated by the pump at this value provides an approximation of the subject's natural cardiac output.

[0017] Therefore, according to some applications of the present invention, there is provided a device comprising:

[0018] A blood pump configured to be placed within a subject, the blood pump comprising:

[0019] Impeller, impeller includes:

[0020] a proximal bushing and a distal bushing;

[0021] two or more helical elongate members, the helical elongate members extending from the proximal hub to the distal hub;

[0022] an axial structure disposed inside the two or more helical elongated elements and along the axis about which the helical elongated elements are wound; and

[0023] a film of material supported between the helical elongate member and the axial structure such that each of the helical elongate members with the film of material coupled thereto defines a respective blade of the impeller; and

[0024] The impeller over-extension preventing element is a single integrated structure comprising a ring and a plurality of elongated elements, the ring being arranged around the axial structure,

[0025] Each elongate element extends from the ring to and is coupled to a corresponding helical elongate element to prevent radial expansion of the impeller.

[0026] In some applications, the impeller includes three spiral elongated elements such that the three spiral elongated elements with the film of material coupled thereto define three blades of the impeller, and a respective elongated element extends from the ring to each of the three spiral elongated elements such that a respective elongated element is present within each of the three blades of the impeller.

[0027] In some applications, the elongated element is configured not to resist compression, and the elongated element is configured to prevent radial expansion of the impeller by applying a tensile force to the helical elongated element.

[0028] In some applications, the film of material forms a continuous U-shaped curved surface along at least a portion of the length of the impeller as the film of material transitions from one impeller blade to an adjacent blade, wherein the U-shaped curvature of the film of material is substantially uninterrupted at the axial structure.

[0029] In some applications, when viewed from the distal end of the impeller, a pressure side of each blade of the impeller (the pressure side configured to push blood during operation of the impeller) is convex in a distal region of the impeller and concave in a proximal region of the impeller. In some applications, the pressure side of each blade of the impeller transitions to be substantially radially oriented in the region of the elongated element within the impeller blade.

[0030] In some applications, the helical elongated element is coated with a coupling agent configured to enhance bonding between the helical elongated element and the film of material. In some applications, the film of material comprises an elastomeric material, and the coupling agent comprises at least two functional groups configured to bond to the helical elongated element and the elastomeric material, respectively. In some applications, the coupling agent comprises a silane compound.

[0031] In some applications, the device further comprises an elastomeric layer disposed between the film of material and the coupling agent. In some applications, the elastomeric layer is configured to round the helical elongated element. In some applications, the film of material is made of an elastomer. In some applications, the elastomer comprises a polycarbonate-based thermoplastic polyurethane.

[0032] In some applications, the axial structure comprises a spring. In some applications, the spring comprises a tube at an intermediate position along the length of the spring, and the ring is disposed around the tube.

[0033] Therefore, according to some applications of the present invention, there is provided a method comprising:

[0034] The impeller is manufactured by the following steps:

[0035] 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;

[0036] radially expanding the at least one elongated member and forming the at least one helical elongated member at least in part by axially compressing the structure;

[0037] coating the at least one helical elongate member with a coupling agent configured to enhance a bond between the helical elongate member and the elastomeric layer;

[0038] coating the coated helical elongated member with an elastomeric layer; and

[0039] Subsequently, the elastomeric film is coupled to the at least one helical elongated element such that the at least one helical elongated element with the elastomeric film coupled thereto defines blades of the impeller.

[0040] In some applications, coupling the elastomeric membrane to the at least one helical elongated element such that the at least one helical elongated element with the elastomeric membrane coupled thereto defines blades of the impeller includes dipping the helical elongated element in an elastomeric material from which the elastomeric membrane is made.

[0041] In some applications, the elastomeric film comprises an elastic material having an ultimate elongation exceeding 300%. In some applications, the elastomeric film comprises an elastic material having a melt flow index of at least 4. In some applications, the elastomeric film comprises an elastic material having an ultimate tensile strength greater than 6000 psi.

[0042] In some applications, coating at least one helical elongated element with a coupling agent includes coating at least one helical elongated element with a silane compound comprising a first functional group configured to bond to the helical elongated element and a second functional group configured to bond to the elastomeric layer.

[0043] In some applications, the elastomeric layer is made of a given elastomeric material, and the elastomeric film is made of a given elastomeric material. In some applications, the elastomeric layer is made of a first elastomeric material, and the elastomeric film is made of a second elastomeric material different from the first elastomeric material.

[0044] In some applications, coating the coated helical elongate element with the elastomeric layer comprises spraying an elastomer onto the coated helical elongate element. In some applications, coating the coated helical elongate element with the elastomeric layer comprises at least partially rounding the coated helical elongate element.

[0045] In some applications, coating the coated helical elongate element with the elastomeric layer includes coating the coated helical elongate element with the elastomeric layer within a given time period of coating at least one helical elongate element with the coupling agent. In some applications, coating the coated helical elongate element with the elastomeric layer also includes spraying additional elastomeric material onto the coated helical elongate element after coating the coated helical elongate element with the elastomeric layer within a given time period of coating at least one helical elongate element with the coupling agent.

[0046] According to some applications of the present invention, there is further provided a device comprising:

[0047] A ventricular assist device, the ventricular assist device comprising:

[0048] an impeller configured to be placed within the left ventricle of a subject;

[0049] motor;

[0050] at least one drive magnet coupled to the motor and configured to be rotated by the motor;

[0051] at least one driven magnet magnetically coupled to the driving magnet and configured to be rotated by the driving magnet;

[0052] a drive cable extending from the driven magnet and configured to transfer rotational motion from the driven magnet to the impeller;

[0053] a set of sensors configured to detect a magnetic phase difference between the driven magnet and the driving magnet; and

[0054] A computer processor is configured to receive the detected magnetic phase difference and determine a physiological parameter of the subject responsive at least in part to the detected magnetic phase difference.

[0055] In some applications, the set of sensors is further configured to measure a magnetic flux amplitude signal, and the computer processor is configured to determine a physiological parameter of the subject based at least in part on a combination of the magnetic flux amplitude signal and the detected magnetic phase difference.

[0056] In some applications, the computer processor is configured to determine a pressure differential between the subject's left ventricle and the subject's aorta responsive at least in part to a magnetic phase difference between the driven magnet and the driving magnet. In some applications, the computer processor is configured to determine the subject's left ventricular pressure responsive at least in part to a magnetic phase difference between the driven magnet and the driving magnet. In some applications, the computer processor is configured to determine an event in the subject's cardiac cycle responsive at least in part to a magnetic phase difference between the driven magnet and the driving magnet.

[0057] In some applications, the set of sensors includes a first magnetometer configured to measure a magnetic phase of a driven magnet and a second magnetometer configured to measure a magnetic phase of the driven magnet. In some applications, the second magnetometer is configured to measure the magnetic phase of the driven magnet by measuring a magnetic phase of a motor.

[0058] In some applications, the computer processor is configured to receive a signal indicative of a current draw of the motor, and is configured to determine a physiological parameter of the subject based at least in part on a combination of the current draw of the motor and the detected magnetic phase difference. In some applications, the set of sensors is further configured to measure a magnetic flux amplitude signal, and the computer processor is configured to determine the physiological parameter of the subject based at least in part on a combination of the current draw of the motor, the magnetic flux amplitude signal, and the detected magnetic phase difference.

[0059] According to some applications of the present invention, there is further provided a device comprising:

[0060] a ventricular assist device comprising an impeller configured to be placed within a left ventricle of a subject and configured to pump blood from the left ventricle of the subject to an aorta of the subject;

[0061] a blood pressure sensor configured to measure aortic pressure of the subject;

[0062] A computer processor configured to:

[0063] deriving an arterial pulsatility of the subject based on the measured aortic pressure; and

[0064] The subject's natural cardiac output is estimated based at least in part on the arterial pulsation.

[0065] According to some applications of the present invention, there is further provided a device comprising:

[0066] A left ventricular assist device configured to assist left ventricular function of a subject, the left ventricular assist device comprising:

[0067] impeller;

[0068] a frame, which is arranged around the impeller,

[0069] A rigid axial shaft extends from a proximal end of the frame to a distal end of the frame, the impeller is coupled to the rigid axial shaft, and the rigid axial shaft includes a proximal portion and a distal portion coupled to each other via a joint, the proximal portion and the distal portion being configured to bend relative to each other via the joint.

[0070] For some applications, the frame has a length exceeding 25 mm.

[0071] According to some applications of the present invention, there is further provided a device comprising:

[0072] An impeller, comprising:

[0073] a proximal bushing and a distal bushing;

[0074] a plurality of helical elongated elements;

[0075] an axial structure disposed inside the helical elongate element and along the axis about which the helical elongate element is wound; and

[0076] a membrane of elastomeric material supported between the helical elongated element and the axial structure such that each helical elongated element with the membrane of elastomeric material coupled thereto defines a respective blade of the impeller,

[0077] The elastomeric film forms a continuous U-shaped curvature along at least a portion of the length of the impeller as the film transitions from one impeller blade to an adjacent blade, wherein the U-shaped curvature of the elastomeric film is substantially uninterrupted at the axial structure.

[0078] In some applications, the axial structure comprises a cylindrical axial structure. In some applications, the cylindrical axial structure comprises a spring.

[0079] According to some applications of the present invention, a method is also provided, comprising:

[0080] inserting a ventricular assist device through an arteriotomy and into the vascular system of the subject via an introducer sheath, the ventricular assist device comprising a delivery catheter, a drive cable, and an outer tube surrounding the drive cable;

[0081] removing the introducer sheath while the ventricular assist device remains within the subject's vascular system; and

[0082] A sterile sleeve positioned between the outer tube and the delivery catheter is used to maintain the sterility of the arteriotomy while allowing movement of the outer tube relative to the delivery catheter.

[0083] According to some applications of the present invention, there is further provided a device comprising:

[0084] A blood pump comprising:

[0085] Axial shaft;

[0086] an impeller disposed on the axial shaft;

[0087] a motor unit including a motor configured to drive the impeller by rotating the impeller in a given rotational direction to pump blood from a distal end of the impeller to a proximal end of the impeller;

[0088] a drive cable configured to extend from the motor unit to the axial shaft, the drive cable configured to transmit rotational motion from the motor to the impeller by rotation,

[0089] At least a portion of the drive cable comprises two or more layers, each layer comprising a plurality of wires,

[0090] the plurality of wires of each of the two or more layers are arranged in a coiled configuration such that, in response to rotation of the drive cable in a given rotational direction, the wires of each layer at least partially unwind, causing axial shortening of that portion of the drive cable, and

[0091] The drive cable is kept in a pre-tensioned state, so that even when the impeller is at rest, the drive cable is stretched relative to its rest state.

[0092] According to some applications of the present invention, there is further provided a device comprising:

[0093] A blood pump comprising:

[0094] Axial shaft;

[0095] an impeller disposed on the axial shaft;

[0096] a motor unit including a motor configured to drive the impeller to pump blood from a distal end of the impeller to a proximal end of the impeller by rotating the impeller in a counterclockwise direction when viewed from the proximal end of the impeller to the distal end of the impeller;

[0097] a drive cable configured to extend from the motor unit to the axial shaft, the drive cable configured to transmit rotational motion from the motor to the impeller by rotation,

[0098] At least a portion of the drive cable comprises two or more layers, each layer comprising a plurality of wires,

[0099] The plurality of wires of each of the two or more layers are arranged in a left-handed coiled configuration.

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

[0101] A blood pump comprising:

[0102] Axial shaft;

[0103] an impeller disposed on the axial shaft;

[0104] a motor unit including a motor configured to drive the impeller to pump blood from a distal end of the impeller to a proximal end of the impeller by rotating the impeller in a clockwise direction when viewed from the proximal end of the impeller to the distal end of the impeller;

[0105] a drive cable configured to extend from the motor unit to the axial shaft, the drive cable configured to transmit rotational motion from the motor to the impeller by rotation,

[0106] At least a portion of the drive cable comprises two or more layers, each layer comprising a plurality of wires,

[0107] The plurality of wires of each of the two or more layers are arranged in a right-handed coiled configuration.

[0108] According to some applications of the present invention, there is further provided a device comprising:

[0109] A blood pump comprising:

[0110] Axial shaft;

[0111] an impeller disposed on the axial shaft;

[0112] a motor unit including a motor configured to drive the impeller so as to pump blood from a distal end of the impeller to a proximal end of the impeller by rotating the impeller in a given rotational direction;

[0113] a drive cable configured to extend from the motor unit to the axial shaft, the drive cable configured to transmit rotational motion from the motor to the impeller by rotation,

[0114] at least a portion of the drive cable comprises an inner layer and an outer layer that are coaxial with each other, and each layer comprises a plurality of wires arranged in a coiled configuration,

[0115] The ratio of the number of wires in the outer layer to the number of wires in the inner layer is between 2:3 and 2:5, and the ratio of the diameter of the wires in the outer layer to the diameter of the wires in the inner layer is between 3:2 and 5:2.

[0116] According to some applications of the present invention, there is further provided a device comprising:

[0117] A blood pump comprising:

[0118] Axial shaft;

[0119] an impeller disposed on the axial shaft;

[0120] a motor unit including a motor configured to drive the impeller so as to pump blood from a distal end of the impeller to a proximal end of the impeller by rotating the impeller in a given rotational direction;

[0121] a drive cable configured to extend from the motor unit to the axial shaft, the drive cable configured to transfer rotational motion from the motor to the impeller by rotation; and

[0122] a drive cable support tube, wherein the drive cable is configured to rotate within the drive cable support tube, at least a portion of the drive cable support tube comprising:

[0123] an inner layer and an outer layer, the inner layer and the outer layer comprising respective materials that are different from each other; and

[0124] A coil wire is embedded between the inner and outer layers, the coil wire being configured to maintain a substantially circular cross-section of the drive cable support tube even in regions where the drive cable support tube experiences substantial bending.

[0125] In general, in the specification and claims of this application, when the term "proximal" and related terms are used with respect to a device or a portion thereof, the term "proximal" and related terms should be interpreted to mean that when the device or a portion thereof is inserted into the body of a subject, the end of the device or a portion thereof is generally closer to the location through which the device is inserted into the body of the subject. When the term "distal" and related terms are used with respect to a device or a portion thereof, the term "distal" and related terms should be interpreted to mean that when the device or a portion thereof is inserted into the body of a subject, the end of the device or a portion thereof is generally farther from the location through which the device is inserted into the body of the subject.

[0126] The scope of the present invention includes the use of the apparatus and methods described herein in anatomical locations other than the left ventricle and aorta.Thus, a ventricular assist device and / or portions thereof are sometimes referred to herein (in the specification and claims) as a blood pump.

[0127] The present invention will be more fully understood from the following detailed description of embodiments of the invention taken in conjunction with the accompanying drawings, in which: BRIEF DESCRIPTION OF THE DRAWINGS

[0128] Figure 1A 、 Figure 1B 、 Figure 1C and Figure 1D is a schematic diagram of a ventricular assist device according to some applications of the present invention, the distal end of the ventricular assist device being configured for placement in the left ventricle of a subject;

[0129] Figure 1E and Figure 1F is a schematic diagram of a ventricular assist device including a braided structure and / or mesh in a distal region according to some applications of the present invention, the braided structure and / or mesh configured to separate a blood inlet opening of the ventricular assist device from an internal structure of a ventricle;

[0130] Figure 2 is a schematic diagram of a frame housing an impeller of a ventricular assist device according to some applications of the present invention;

[0131] Figure 3A 、 Figure 3B 、 Figure 3C 、 Figure 3D 、 Figure 3E and Figure 3F is a schematic diagram of an impeller or portion thereof of a ventricular assist device according to some applications of the present invention;

[0132] Figure 3Gi and Figure 3Gii is a picture of an impeller of a ventricular assist device according to some applications of the present invention;

[0133] Figure 4 is a schematic diagram of an impeller disposed inside a frame of a ventricular assist device according to some applications of the present invention;

[0134] 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;

[0135] Figure 6A and Figure 6Bis a schematic diagram of a ventricular assist device with an impeller of the ventricular assist device at various stages of a motion cycle relative to a frame of the ventricular assist device according to some applications of the present invention;

[0136] 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;

[0137] Figure 6D and 6E is a schematic diagram of a coupling element for coupling to an impeller bushing according to some applications of the present invention, the coupling element extending proximally and serving as a stop;

[0138] Figure 7A is a schematic diagram of a motor unit of a ventricular assist device according to some applications of the present invention;

[0139] Figure 7Bi and Figure 7Bii is a schematic diagram of a motor unit of a ventricular assist device according to some applications of the present invention;

[0140] Figure 8A is a graph showing how the length of a drive cable of a ventricular assist device changes as a function of the pressure gradient opposed by a blood pump impeller, as measured in an experiment;

[0141] Figure 8B and Figure 8C is a graph showing the variation of magnetic phase measurements performed on a blood pump as a function of the pressure gradient opposed by the impeller of the blood pump, as measured in an experiment;

[0142] Figure 9A 、 Figure 9B 、 Figure 9C 、 Figure 9D 、 Figure 9E 、 Figure 9F and Figure 9G is a schematic diagram of a motor unit support configured to support a motor unit on a patient's leg according to some applications of the present invention;

[0143] Figure 10A 、 Figure 10B and Figure 10C is a schematic diagram of a drive cable for a ventricular assist device according to some applications of the present invention;

[0144] Figure 10D is a schematic diagram of a drive cable support tube according to some applications of the present invention;

[0145] Figure 11A 、 Figure 11B 、 Figure 11C 、 Figure 11D and Figure 11E is a schematic diagram of an apparatus and method for cleaning a drive cable, radial bearing, and / or impeller bushing of a ventricular assist device according to some applications of the present invention;

[0146] Figure 12A and Figure 12B is a schematic diagram of a ventricular assist device according to some applications of the present invention, the ventricular assist device including a liner positioned on the inside of a frame housing an impeller;

[0147] Figure 13 is a schematic diagram of a ventricular assist device according to some applications of the present invention, the ventricular assist device having a frame housing an impeller, the frame defining a cylindrical portion, at least a distal portion of the cylindrical portion being uncovered;

[0148] Figure 14 is a schematic diagram of a ventricular assist device placed within the left ventricle of a subject, showing a cross-sectional view of the left ventricle, according to some applications of the present invention;

[0149] Figure 15A 、 Figure 15B 、 Figure 15C and Figure 15D 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;

[0150] Figure 16A and Figure 16B According to some applications of the present invention Figure 15D A schematic diagram of a ventricular assist device positioned within the left ventricle of a subject;

[0151] Figure 17Ai and Figure 17Aii is a schematic diagram of a ventricular assist device having a balloon disposed on a distal end portion thereof, the balloon configured to facilitate movement of an axial shaft relative to a wall of a ventricle, according to some applications of the present invention;

[0152] Figure 17Bi and Figure 17Bii is a schematic diagram of a ventricular assist device according to some applications of the present invention, the ventricular assist device having a joint configured to facilitate pivoting of a distal tip portion of the ventricular assist device relative to an axial shaft of the ventricular assist device;

[0153] Figure 17C is a schematic diagram of a ventricular assist device according to some applications of the present invention, the outer tube of the ventricular assist device being shaped with a predetermined curvature such that the axial shaft of the ventricular assist device remains in a substantially straight configuration when the axial shaft is positioned within the left ventricle of a subject;

[0154] Figure 17D is a schematic diagram of a ventricular assist device having a distal tip configured to anchor to tissue of the left ventricular apex;

[0155] Figure 18A 、 Figure 18B and Figure 18C is a schematic diagram of a distal radial support of a ventricular assist device according to a corresponding application of the present invention;

[0156] Figure 19A 、 Figure 19B 、 Figure 19C 、 Figure 19D and Figure 19E is a schematic diagram of a ventricular assist device according to some applications of the present invention, the ventricular assist device including a pump outlet tube configured to become curved as blood is pumped through the pump outlet tube, the pump outlet tube being rotatable relative to a distal tip portion of the ventricular assist device;

[0157] Figure 19F is a schematic diagram of a ventricular assist device according to some applications of the present invention, the ventricular assist device including a bending element made of a shape memory material and configured to provide a predetermined curvature to a portion of the ventricular assist device, the bending element being rotatable relative to a distal tip portion of the ventricular assist device;

[0158] Figure 20A 、 Figure 20B and Figure 20C is a schematic diagram of a ventricular assist device according to some applications of the present invention, wherein the axial shaft of the ventricular assist device includes a joint, such as a universal joint;

[0159] Figure 21 is a schematic diagram of a ventricular assist device including one or more blood pressure measurement tubes according to some applications of the present invention;

[0160] Figure 22A and Figure 22B is a schematic diagram of a sterile sleeve configured to form a seal between a delivery catheter and an outer tube of a ventricular assist device according to some applications of the present invention;

[0161] Figure 23A 、 Figure 23B and Figure 23C is a schematic diagram of a tip straightener according to some applications of the present invention, the tip straightener being used to straighten the distal tip of a ventricular assist device when inserting a guide wire into the distal tip of the device; and

[0162] Figure 24A 、 Figure 24B and Figure 24Cis a graph illustrating measurements performed during use of a left ventricular assist device according to some applications of the present invention.

[0163] Detailed description of the embodiments

[0164] Now refer to Figure 1A 、 Figure 1B and Figure 1C , which are schematic illustrations of a ventricular assist device 20 according to some applications of the present invention, the distal end of the ventricular assist device being configured to be positioned in a left ventricle 22 of a subject. Figure 1A An overview of a ventricular assist device system is shown, including a console 21 and a motor unit 23. (As described below, the motor unit is typically a handle that houses the motor.) Figure 1B A ventricular assist device is shown 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 pump outlet tube 24 that passes through the aortic valve 26 of the subject such that a proximal end 28 of the pump outlet tube is disposed in the aorta 30 of the subject and a distal end 32 of the pump outlet tube is disposed within the left ventricle 22. The pump outlet tube 24 is typically an elongated tube, and typically, the axial length of the pump outlet tube is substantially greater than its diameter. The scope of the present invention includes use of the apparatus and methods described herein in anatomical locations other than the left ventricle and aorta. Accordingly, the ventricular assist device and / or portions thereof are sometimes referred to herein (in the specification and claims) as a blood pump.

[0165] For some applications, a ventricular assist device is used to assist the function of the left ventricle of a subject 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 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 left ventricle of a subject 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 left ventricle of a subject for even longer periods 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 percutaneously, for example, using an external antenna magnetically coupled to the impeller.

[0166] like Figure 1B As shown, Figure 1B Steps for deploying a ventricular assist device in the left ventricle are shown, with the distal end of the ventricular assist device typically being guided to the left ventricle over a guidewire 10. During insertion of the distal end of the device into the left ventricle, a delivery catheter 143 is positioned over the distal end of the device. Once the distal end of the device is positioned in the left ventricle, the delivery catheter is typically retracted into the aorta and the guidewire is withdrawn from the subject's body. Typically, retraction of the delivery catheter causes the self-expanding component of 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 the subject's body to provide acute treatment to the subject. For some applications, in order to withdraw the left ventricular device from the subject's body at the conclusion of treatment, the delivery catheter is advanced over the distal end of the device, which causes the self-expanding component of 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 of the distal end of the device to assume a radially constrained configuration.

[0167] 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.

[0168] 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 segment 102 of the pump outlet tube 24 and is configured to pump blood from the left ventricle into the aorta by rotation. The pump outlet tube typically defines one or more blood inlet openings 108 at the distal end 32 of the pump outlet tube through which blood flows from the left ventricle into the pump outlet tube during impeller operation. For some applications, the proximal segment 106 of the pump outlet tube defines one or more blood outlet openings 109 through which blood flows from the pump outlet tube into the ascending aorta during impeller operation.

[0169] For some applications, a console 21 (e.g., a computer processor 25) is typically included. Figure 1A For example, a computer processor may control motor 74 (e.g., as shown) to control the impeller rotation. Figure 7A As shown), the motor 74 is provided in the motor unit 23 ( Figure 1A ) and the motor 74 is connected to the drive cable 130 (e.g., Figure 7A) drives the impeller to rotate. For some applications, the computer processor is configured to detect physiological parameters of the subject (e.g., left ventricular pressure, cardiac afterload, rate of change of left ventricular pressure, etc.) and control the rotation of the impeller in response thereto, as described in further detail below. Typically, the operations performed by the computer processor described herein convert the physical state of the memory into a different magnetic polarity, charge, etc., depending on the memory technology used, which is a real physical article that communicates with the computer processor. The computer processor 25 is typically a hardware device programmed with computer program instructions to produce a special-purpose computer. For example, when programmed to perform the techniques described herein, the computer processor 25 typically acts as a special-purpose ventricular assist computer processor and / or a special-purpose blood pump computer processor.

[0170] For some applications, the cleaning system 29 (in Figure 1A ) drives fluid (e.g., glucose solution) through various portions of the ventricular assist device 20, for example, to cool the various portions of the device and / or to flush debris from the various portions of the device. The cleaning system 29 will be described in further detail below.

[0171] Typically, along the distal segment 102 of the pump outlet tube 24, the frame 34 is disposed around the impeller 50 within the pump outlet tube. 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 segment 102 of the tube 24, at least a portion of the frame (and therefore the distal segment 102 of the tube 24) presents a substantially circular, elliptical, or polygonal cross-sectional shape. By presenting its substantially circular, elliptical, or polygonal cross-sectional shape, the frame is configured to maintain the distal portion of the pump outlet tube in an open state. Typically, during operation of the ventricular assist device, the distal portion of the pump outlet tube is configured to be placed within the body of a subject such that the distal portion of the pump outlet tube is at least partially disposed within the left ventricle.

[0172] For some applications, along the proximal section 106 of the pump outlet tube 24, the frame is not disposed within the pump outlet tube, and thus the pump outlet tube is not supported in an open position by the frame 34. The pump outlet tube 24 is typically made of a collapsible material that is impermeable to blood. For example, the pump outlet tube 24 can include polyurethane, polyester, and / or silicone. Alternatively or additionally, the pump outlet tube can be made of polyethylene terephthalate (PET) and / or polyether block amide (e.g., ). For some applications (not shown), the pump outlet tube is reinforced with a reinforcing structure (e.g., a braided reinforcing structure such as a braided nitinol tube). Typically, the proximal portion of the pump outlet tube is configured to be positioned such that it is at least partially disposed within the ascending aorta of the subject. For some applications, the proximal portion of the pump outlet tube passes through the subject's aortic valve, from the subject's left ventricle, into the subject's ascending aorta, such as Figure 1B shown.

[0173] As described above, the pump outlet tube typically defines one or more blood inlet openings 108 at the distal end of the pump outlet tube, and during impeller operation, blood flows from the left ventricle into the pump outlet tube via the blood inlet openings. For some applications, the proximal portion of the pump outlet tube defines one or more blood outlet openings 109, and during impeller operation, blood flows from the pump outlet tube into the ascending aorta via the blood outlet openings. Typically, the pump outlet 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 impeller operation, the pressure of the blood flow through the pump outlet 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 pump outlet tube is configured to collapse inward in response to the pressure outside the proximal portion of the pump outlet tube exceeding the pressure inside the proximal portion of the pump outlet tube. In this way, the proximal portion of the pump outlet tube acts as a safety valve, thereby preventing blood flow from the aorta from entering the left ventricle in the reverse direction.

[0174] Reference again Figure 1C For 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 pump outlet tube 24 extends to the distal end of the cylindrical portion 38 (or slightly proximal or distal thereto) such that the distal end of the pump outlet tube defines a single axially facing blood inlet opening 108, as shown. Figure 1C For some applications, within at least a portion of the frame 34, a liner 39 is positioned over the frame, as described below with reference to Figures 12A-12B As described above. Depending on the respective application, the liner partially or completely overlaps the pump outlet tube 24 over 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, both the pump outlet tube and the liner terminate before the distal end of the cylindrical portion of the frame, leaving the distal portion of the cylindrical portion of the frame uncovered, as described below with reference to Figure 13 As stated.

[0175] Typically, the pump outlet tube 24 includes a tapered proximal portion 42 and a cylindrical central portion 44. (Typically, the tapered proximal portion 36 is completely disposed within the proximal segment 106 described above, and the cylindrical central portion typically extends from within the proximal segment 106 to the distal segment 102.) The proximal tapered portion is typically such that the narrow end of the cone is proximal relative to the wide end of the cone. Typically, the blood outlet opening 109 is defined by the pump outlet tube 24 such that the opening extends at least partially along the proximal tapered portion 42 of the tube 24. For some such applications, the blood outlet opening is teardrop-shaped, such as Figure 1C Typically, the teardrop-shaped nature of the blood outlet opening, combined with the opening extending at least partially along the proximal tapered section of the tube 24, causes blood to flow out of the blood outlet opening at its location along flow lines that are substantially parallel to the longitudinal axis of the tube 24.

[0176] For some applications (not shown), the diameter of the pump outlet tube 24 varies along the length of the central portion of the pump outlet tube, so that the central portion of the pump outlet tube has a frusto-conical shape. For example, the central portion of the pump outlet 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 pump outlet tube has a diameter between 5 mm and 7 mm, while at its distal end, the central portion of the pump outlet tube has a diameter between 8 mm and 12 mm.

[0177] Reference 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.

[0178] Now refer to Figure 1D , Figure 1Dis a schematic diagram of a ventricular assist device 20 according to some applications of the present invention, wherein the pump outlet tube 24 extends to the end of the distal tapered portion 40 of the frame, and the pump outlet tube defines a plurality of lateral blood inlet openings 108. For such applications, the pump outlet tube typically defines a distal tapered portion 46 in which the narrow end of the cone is distal relative to the wide end of the cone. For some such applications, the pump outlet tube defines two to four lateral blood inlet openings. Typically, for such applications, the area defined by each blood inlet opening 108 is greater than 20 square millimeters (e.g., greater than 30 square millimeters) and / or less than 60 square millimeters (e.g., less than 50 square millimeters), for example, 20-60 square millimeters or 30-50 square millimeters. Alternatively or additionally, the outlet tube defines a greater number of smaller blood inlet openings (not shown), such as more than 10 small blood inlet openings, more than 50 small blood inlet openings, more than 100 small blood inlet openings, or more than 150 small blood inlet openings, such as 50-100 small blood inlet openings, 100-150 small blood inlet openings, or 150-200 small blood inlet openings. For some such applications, each small blood inlet opening defines an area greater than 0.1 square millimeter (e.g., greater than 0.3 square millimeter) and / or less than 5 square millimeters (e.g., less than 1 square millimeter), such as 0.1-5 square millimeters, 0.2-0.5 square millimeters, or 0.3-1 square millimeter.

[0179] Typically, the distal tapered portion 46 of the pump outlet tube is configured to reduce the risk of structures from the left ventricle (e.g., chordae tendineae, chordae carnosus and / or papillary muscles) entering the frame and potentially being damaged by the impeller and / or axial shaft (on which the impeller is mounted) and / or causing damage to the left ventricular assist device. Therefore, for some applications, the small blood inlet opening is shaped such that the width (or span) of the opening in at least one direction is less than 1 mm, e.g., 0.1-1 mm, or 0.3-0.8 mm. By defining such a small width (or span), typically, structures from the left ventricle (e.g., chordae tendineae, chordae carnosus and / or papillary muscles) are prevented from entering the frame. For some applications, the small blood inlet opening defines a generally rectangular (or elliptical) shape. For some such applications, the ratio of the length to the width of the small blood inlet opening is between 1.1:1 and 4:1, e.g., between 3:2 and 5:2. For some applications, by having such a shape, the small blood inlet opening is configured to (a) prevent structures from the left ventricle (e.g., chordae tendineae, sclera auricularis, and / or papillary muscles) from entering the frame, but (b) provide the portion of the pump outlet tubing defining the small blood inlet opening with a relatively high porosity. Typically, the portion of the pump outlet tubing defining the small blood inlet opening has a porosity greater than 40%, such as greater than 50% (where porosity is defined as the percentage of the area of the portion that is porous to blood flow).

[0180] Now refer to Figure 1E and Figure 1F , Figure 1E and Figure 1F is a schematic diagram of a ventricular assist device 20 that includes, in accordance with some applications of the present invention, a braided structure 260 and / or mesh 282 in a distal region of the device configured to separate a blood inlet opening of the ventricular assist device from the internal structure of the ventricle. Braided structure 260 is typically similar to that of US 2019 / 0209758 to Tuval. Figure 20B The braided structure 260 described is substantially similar to that of U.S. 2019 / 0209758 to Tuval, which is incorporated herein by reference. Figure 21 D, which is incorporated herein by reference.

[0181] refer to Figure 1E For some applications, a braided structure 260 (e.g., a braided metal or alloy, such as a shape memory alloy (e.g., Nitinol)) is disposed at a distal region of the device. For example, the braided material can be disposed at the distal end of the device. Alternatively or additionally, the device can include a distal tip element 107 (which is typically as described in reference Figure 14-16B ) and a braided material is disposed around a portion of the device so as to cover a portion of the distal tip element. For some applications, the braided material is disposed over at least a portion of the frame 34. For example, the braided material can surround a portion of the frame that extends distally from at least one longitudinal location along the frame where the blood outlet tube 24 ends and / or the liner 39 ends, to the distal end of the frame. For some applications, the braided structure is disposed to cover the blood inlet opening 108.

[0182] like Figure 1F As shown, for some applications, the outer surface of the distal tip element 107 includes a radially expandable mesh 282 that is configured to self-expand when the distal tip element 107 is positioned within the left ventricle of the subject. For some applications, the device includes a distal tip element that is substantially as described in reference Figure 14-16B The mesh is disposed around a portion of the device so as to cover a portion of the distal tip element. For some applications, the mesh is disposed over at least a portion of the frame 34. For example, the mesh can surround a portion of the frame extending distally from at least one longitudinal location along the frame where the blood outlet tube 24 ends and / or the liner 39 ends, to the distal end of the frame. For some applications, the mesh is disposed to cover the blood inlet opening 108.

[0183] Typically, the braided structure 260 and / or mesh 282 separates the one or more blood inlet openings 108 from the three-dimensional internal structure of the left ventricle. In this manner, the braided structure 260 and / or mesh 282 separates the one or more blood inlet openings 108 from the ventricular septum, chordae tendineae, papillary muscles, pilus carnosus, and / or the apex of the left ventricle. As an alternative to or in addition to the braided structure and / or mesh used to separate the one or more blood inlet openings 108 from the internal structure of the left ventricle, the cells of the frame 34 near the blood inlet opening 108 are configured to define an opening that is smaller than the openings in other portions of the frame. For example, the cells in the distal tapered portion of the frame can define an opening that is smaller than the opening defined by the cells in the proximal tapered portion of the frame. Alternatively or additionally, the cells in the distal tapered portion of the frame can define an opening that is smaller than the opening defined by the cells in the cylindrical portion of the frame.

[0184] Now refer to Figure 2 , Figure 2 is a schematic diagram of a frame 34 housing an impeller of a ventricular assist device 20 according to some applications of the present invention. As described above, the frame 34 is typically made of a shape memory alloy such as Nitinol, and the shape memory alloy of the frame is shaped so that the frame (and therefore the tube 24) assumes a generally circular, elliptical, or polygonal cross-sectional shape in the absence of any force applied to the pump outlet tube 24 and / or the frame 34. By assuming its generally circular, elliptical, or polygonal cross-sectional shape, the frame is configured to maintain the distal portion of the tube in an open state.

[0185] Typically, the frame is a stent-like frame in that it includes struts that in turn define the cells. More typically, the frame is covered by the pump outlet tube 24 and / or by a liner 39, as described below with reference to Figures 12A-12B As described below, for some applications, impeller 50 undergoes axial reciprocating motion relative to frame 34. Typically, during this motion of the impeller relative to the frame, the portion of the impeller defining the maximum span is located within cylindrical portion 38 of frame 34. In some cases, if the cells of cylindrical portion 38 of frame 34 are too large, pump outlet tube 24 and / or liner 39 may be stretched between the edges of the cells, causing pump outlet tube 24 and / or liner 39 to not define a circular cross-section. For some applications, if this occurs in the region of the impeller defining the maximum span, the gap between the impeller blade edge and tube 24 (and / or liner) at that location is not constant during the impeller's rotational cycle. For some applications, this may result in increased hemolysis compared to a situation where a constant gap existed between the impeller blade edge and tube 24 (and / or liner) at that location during the impeller's rotational cycle.

[0186] refer to Figure 2 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 disposed in its non-radially constrained configuration, the maximum cell width CW of each cell within the cylindrical portion of the frame (i.e., the distance from the inner edge of the strut at the central junction on one side of the cell to the inner edge of the strut at the central junction on the other side of the cell, as measured around the circumference of the cylindrical portion 38) is less than 2 mm, e.g., between 1.4 mm and 1.6 mm, or between 1.6 and 1.8 mm. Because the cells are relatively small, the pump outlet tube 24 (and / or liner) defines a substantially circular cross-section within the cylindrical portion of the frame.

[0187] Still refer to Figure 2 , and starting from the proximal end of the frame (on the left side of the figure), the frame typically defines the following parts: (a) a coupling portion 31 via which the frame is coupled to the proximal support 116 of the ventricular assist device (at Figure 4 ), (a) a proximal tapered portion 36, (c) a cylindrical portion 38, (d) a distal tapered portion 40, and (e) a distal strut junction 33. As shown, as the frame transitions from the proximal end of the frame to the center of the frame (e.g., as the frame passes through the coupling portion 31, through the proximal tapered portion 36, and transitions to the cylindrical portion 38), the struts 37 of the frame pass through junctions 35 where two struts branch off from a single strut in a Y-shape. As described in further detail below, the frame 34 is typically placed in a delivery catheter 143 in a radially constrained (i.e., crimped) configuration by the frame being axially elongated. Additionally, the frame typically transfers its radial narrowing to the impeller, and the impeller becomes radially constrained by axially elongating within the frame. For some applications, the struts of the frame configured in the manner described above facilitate transferring axial extension from the delivery catheter (or other device configured to crimp the frame) to the frame, which in turn facilitates transferring the axial extension to the impeller. This is because the pair of struts branching from each joint 35 are configured to pivot about the joint and move closer to each other, thereby closing.

[0188] Still refer to Figure 2 For some applications, when the frame is coupled to the axial shaft 92 (at Figure 4 ), the distal strut joint 33 is not circumferentially connected and is typically configured to remain open so that the impeller is placed within the frame via the distal end of the frame. The distal strut portion is then closed around the outside of the distal support 118, as described below with reference to Figure 5A-5B For some applications, the proximal end of the distal tip element 107 (e.g. Figure 1C) holds the distal strut portions in their closed configuration around the outside of the distal support 118.

[0189] Typically, when 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, 25-50 mm, or 30-45 mm. Typically, when disposed in its radially constrained configuration (within the delivery catheter 143), the length of the frame increases by 2 to 5 mm. Typically, when 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, 10-25 mm or 12-20 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.

[0190] Now refer to Figure 3A-3C , Figure 3A-3C is a schematic diagram of an impeller 50 or portion thereof according to some applications of the present invention. Typically, the impeller includes at least one outer helical elongated element 52 that 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. (As described in further detail below, the central axial spring typically includes a tube 70 at an intermediate position along its length. Moreover, as described below, the scope of the present application includes the use of other axial structures in place of the spring. Thus, in some aspects, the present application refers to "axial structure 54.") Typically, the impeller includes two or more helical elongated elements (e.g., three helical elongated elements, e.g., Figure 3A-3C For some applications, the helical elongated element and the central axial spring are made of a shape memory material (e.g., 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, for example, to reinforce the membrane of material. For illustrative purposes, the impeller is Figure 3A The film is shown without this material. Figure 3B and Figure 3C A perspective view of an impeller is shown in each case, wherein the film of material is supported between the helical elongate element and the spring.

[0191] Each helical elongate member defines a respective impeller blade together with a membrane extending from the helical elongate member to the spring, wherein the helical elongate member 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 over the spring. For some applications, suture 53 (e.g., polyester suture, such as Figure 3B and Figure 3C 10,864,310 to Schwammenthal, which is incorporated herein by reference. Typically, the suture is configured to facilitate bonding between a membrane of material (which is typically an elastomer, such as polyurethane or silicone) and a spring (which is typically a shape memory alloy, such as nitinol). For some applications, a suture (e.g., a polyester suture, not shown) is wrapped around spring 54. Typically, the suture is configured to facilitate bonding between a membrane of material (which is typically an elastomer, such as polyurethane or silicone) and a spring (which is typically a shape memory alloy, such as nitinol).

[0192] Figure 3C Enlarged views A and B of FIGURE 5 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 within the grooves, as shown in enlarged view B. Typically, by embedding the suture within the grooves, the suture does not increase the outer profile of the impeller, and the outer profile of the impeller is defined by the outer surface of the helical elongated member.

[0193] Typically, the proximal end of the spring 54 and the proximal end of the helical elongate element 52 extend from a proximal bushing (i.e., a sleeve support) 64 of the impeller such that the proximal end of the spring 54 and the proximal end of the helical elongate element 52 are disposed at substantially the same location and have similar radial distances from the longitudinal axis of the impeller. Similarly, typically, the distal end of the spring 54 and the distal end of the helical elongate element 52 extend from a distal bushing 58 of the impeller such that the distal end of the spring 54 and the distal end of the helical elongate element 52 are disposed at substantially the same location and have similar radial distances from the longitudinal axis of the impeller. Typically, the spring 54 and the proximal bushing 64 and distal bushing 58 of the impeller define a cavity therethrough such that the impeller defines a continuous cavity 62 therethrough (e.g., Figure 3C shown).

[0194] Now refer to Figure 4, which is a schematic diagram of an impeller 50 disposed within a frame 34 of a ventricular assist device 20 according to some applications of the present invention. For some applications, within at least a portion of the frame 34, a liner 39 is disposed on the frame, as described below with reference to Figures 12A-12B Depending on the application, the liner partially or completely overlaps the pump outlet tube 24 over the portion of the frame that is lined by the liner. For some applications, both the pump outlet tube and the liner terminate before the distal end of the cylindrical portion 38 of the frame, leaving the distal portion of the cylindrical portion of the frame uncovered, as described below with reference to Figure 13 For some applications, the pump outlet tube continues to cover the distal tapered portion of the frame, as described in reference Figure 1D As stated. Figure 4 In the application shown, the liner is positioned within the cylindrical portion of the frame and the pump outlet pipe 24 does not cover the cylindrical portion of the frame. However, the scope of this application includes the reference to Figure 4 The apparatus and method described herein are used in conjunction with Figure 1D 、 Figures 12A-12B or Figure 13 Any application described.

[0195] 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 has the largest span. 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 can effectively pump blood from the subject's left ventricle to 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.

[0196] For some applications, when both the impeller and frame 34 are arranged in a non-radially constrained configuration, the gap G between the outer edge of the impeller and the liner 39 at the location where the impeller spans the largest is greater than 0.05 mm (e.g., greater than 0.1 mm) and / or less than 1 mm (e.g., less than 0.4 mm), for example, 0.05-1 mm, or 0.1-0.4 mm. For some applications, when the impeller is arranged in its non-radially constrained configuration, the impeller outer diameter at the location where the impeller outer diameter is the largest is greater than 7 mm (e.g., greater than 8 mm) and / or less than 10 mm (e.g., less than 9 mm), for example, 7-10 mm, or 8-9 mm. For some applications, when frame 34 is configured in its non-radially constrained configuration, the inner diameter of frame 34 (measured from the inner side of liner 39 on one side of the frame to the inner side of the liner on the opposite side of the frame) is greater than 7.5 mm (e.g., greater than 8.5 mm) and / or less than 10.5 mm (e.g., less than 9.5 mm), such as 7.5-10.5 mm or 8.5-9.5 mm. For some applications, when frame 34 is configured in its non-radially constrained configuration, the outer diameter of frame 34 is greater than 8 mm (e.g., greater than 9 mm) and / or less than 13 mm (e.g., less than 12 mm), such as 8-13 mm or 9-12 mm.

[0197] Typically, the axial shaft 92 passes through the axis of the impeller 50 via the impeller cavity 62. More typically, the axial shaft is rigid, such as a rigid tube. (For some applications, a portion of the axial shaft is at least partially flexible, for example, as described in reference to Figures 20A-20C (As described above.) For some applications, the proximal bushing 64 of the impeller is coupled to the shaft such that the axial position of the proximal bushing relative to the shaft is fixed and the distal bushing 58 of the impeller is slidable relative to the shaft. The axial shaft itself is radially stabilized via proximal and distal radial supports 116, 118. In turn, the axial shaft radially stabilizes the impeller relative to the inner surface of the frame 34 by passing through the cavity 62 defined by the impeller, so that even relatively small gaps (e.g., the gaps described above) between the outer edges of the impeller's blades and the inner surface of the frame 34 are maintained during rotation of the impeller.

[0198] Reference 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 67 are typically flexible but substantially incapable of stretching along the axis defined by the elongated elements 67. Further typically, each of the elongated elements 67 is configured to be substantially non-resistant to compression. Instead, each elongated element 67 is configured to exert a tensile force on the helical elongated element 52 that prevents the helical elongated element 52 from moving radially outward, such that (in the absence of the elongated elements 67) the spacing between the helical elongated element 52 and the central axial spring 54 would be greater than the length of the elongated elements 67. For example, the elongated elements 67 may comprise a cord (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). In this manner, the elongated elements prevent the impeller from radially expanding by exerting a tensile force on the helical elongated element.

[0199] For some applications, the elongated element 67 holds the helical elongated element 52 (which defines the outer edges of the impeller's blades) within a given distance relative to the central axial spring 54. In this manner, the elongated element 67 is configured to prevent the outer edges of the impeller from being forced radially outward due to forces exerted on the impeller during rotation. In other words, the elongated element 67 acts as an impeller expansion prevention element. The elongated element 67 is thereby configured to maintain a gap between the outer edges of the impeller's blades and the inner surface of the frame 34 during rotation of the impeller. Typically, more than one (e.g., more than two) and / or fewer than eight (e.g., fewer than four) elongated elements 67 are used in the impeller, with each elongated element 67 typically being bifurcated (i.e., extending radially from the central axial spring 54 to the outer edge of the helical elongated element 52 and then returning from the helical elongated element to the central axial spring). For some applications, multiple elongate elements 67 are formed from a single string or wire, with each elongate element 67 extending from a spring to a corresponding helical elongate element 52 and back to central axial spring 54 .

[0200] For some applications, the impeller is manufactured in the following manner. The proximal bushing 64, the distal bushing 58 and the spiral elongated element 52 are cut from a tube of shape memory material (e.g., Nitinol). The cutting of the tube and the shaping of the shape memory material are typically performed in such a manner that the spiral elongated element and the bushing are defined by a tube of shape memory material, which is cut and shaped, for example, using a technique substantially similar to that described in US Pat. No. 10,039,874 to Schwammenthal. Typically, the spring 54 is inserted into the cut and shaped tube so that the spring extends along the length of the tube at least from the proximal bushing to the distal bushing. For some applications, the spring is inserted into the cut and shaped tube when the spring is in an axially compressed state, and the spring is configured to remain in place relative to the tube by applying a radial force on the proximal bushing and the distal bushing. Alternatively or additionally, multiple portions of the spring are welded to the proximal bushing and the distal bushing. For some applications, the spring is cut from a tube of 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 in a non-radially constrained configuration during operation of the impeller), there is substantially no gap between a coil of the spring and an adjacent coil thereof.

[0201] For some applications, after the spring 54 is inserted into the cut and shaped tube, the elongated element 67, as described above, is positioned to extend between the spring and one or more helical elongated elements 52, for example, in the following manner. A mandrel (e.g., a polyetheretherketone (PEEK) and / or polytetrafluoroethylene (PTFE) mandrel) is inserted through the cavity defined by the spring and the bushing. The cord or wire is then threaded so that the cord or wire (a) passes from the mandrel to the first helical elongated element in the helical elongated elements 52, (b) returns from the first helical elongated element in the helical elongated elements 52 to the mandrel, (c) passes around the mandrel to the second helical elongated element in the helical elongated elements 52, (d) returns from the second helical elongated element in the helical elongated elements 52 to the mandrel, and so on. Once the cord or wire has been threaded from the mandrel to each helical elongated element 52 and back again, the ends of the cord or wire are coupled to each other, for example, by tying them together. For some applications, a separate rope or wire is used for each helical elongate element 52. Typically, each rope or wire passes from the helical elongate element around the core shaft and back to the helical elongate element, with the ends of the rope tethered to each other. For some applications, as shown, at a longitudinal center position of the spring 54, the spring is shaped to define a tube 70 (i.e., the spring does not define a coil at this position), and the rope or wire is wrapped around the tube. For some applications, the rope or wire is not wrapped around the tube and does not pass through the longitudinal axis of the impeller. Instead, the rope or wire is secured relative to the tube 70 by a securing element 75 (e.g., a ring), as described below with reference to Figure 3F As described in further detail.

[0202] For some applications, at this stage, suture 53 (e.g., polyester suture) is wrapped around the helical elongated member 52 to facilitate bonding between the membrane of material (which is typically an elastomer, such as polyurethane or silicone) and the helical elongated member 52 (which is typically a shape memory alloy, such as Nitinol) in subsequent stages of impeller fabrication. For some applications, suture (e.g., polyester suture, not shown) is wrapped around the spring 54. Typically, the suture is configured to facilitate bonding between the membrane of material (which is typically an elastomer, such as polyurethane or silicone) and the spring (which is typically a shape memory alloy, such as Nitinol) in subsequent stages of impeller fabrication.

[0203] Typically, at this stage, the Figure 3A The structure 59 is shown. The structure comprises a cut and shaped tube defining the proximal and distal sleeves, the helical elongate element and the spring (and optionally, the elongate element and the suture). The structure is immersed in the material defining the membrane 56. For some applications, the assembled structure is immersed in the material with a mandrel positioned through the cavity defined by the spring and the bushing, however it should be noted that the mandrel is not inserted into the cavity. 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. For some applications, the assembled structure is rotated while the material dries, which generally helps to form a membrane of material having a substantially uniform thickness within each impeller blade. Once the material has dried, the mandrel is typically removed from the cavity defined by the bushing and spring.

[0204] Typically, the result of the above process is a continuous film of material extending between each helical elongated element and the spring, and also extending along the length of the spring to define a tube within which the spring is embedded. The portions of the film extending from each helical elongated element to the spring define the impeller blades. For applications where the impeller includes elongated element 67, the elongated element is typically embedded within these portions of the film.

[0205] Typically, the elongated member 67 is configured to limit the radial expansion of the impeller blades, as described in detail above. For some applications, the span to which the elongated member allows the impeller blades to expand is set using the following technique. As described in the previous paragraph, the ends of a string or wire are tied together within the respective blades. Typically, the ends of the string or wire in each blade are tied together so that the impeller blade span is set to be less than the desired impeller span, and some slack is left in the knot that ties the ends of the string or wire together. Subsequently, by tightening the knot between the ends of the string or wire within each blade, the outer edges of the impeller blades are pulled apart to increase the span of the impeller blades. This process is repeated and the impeller blade span is measured until the desired impeller blade span is achieved. Subsequently, the structure 59 with the tethered string or wire is immersed in the elastomeric material (from which the membrane 56 is made) and the elastomeric material is allowed to dry, so that the strings or wires remain tethered together at the desired impeller blade span.

[0206] Typically, the impeller 50 is inserted into the left ventricle via a catheter while the impeller 50 is in a radially constrained configuration. In the radially constrained configuration, both the helical elongated element 52 and the central axial spring 54 become axially elongated and radially constrained. Typically, a membrane 56 of material (e.g., silicone and / or polyurethane) changes shape to conform to the shape changes of the helical elongated element and the central axial spring (both of which support the membrane of material). Typically, the use of a spring to support the inner edge of the membrane allows the membrane to change shape without the membrane breaking or collapsing because the spring provides a large surface area to which the inner edge of the membrane is bound. For some applications, the use of a spring to support the inner edge of the membrane reduces the diameter of the impeller that can be radially constrained compared to, for example, using a rigid shaft to support the inner edge of the membrane because the diameter of the spring itself can be reduced by axially extending the spring.

[0207] As described above, for some applications, the proximal bushing 64 of the impeller 50 is coupled to the axial shaft 92 such that the proximal bushing is fixed in axial position relative to the shaft and the distal bushing 58 of the impeller is slidable relative to the shaft. For some applications, when the impeller is radially restrained for insertion into the heart chamber or for withdrawal from the subject, the impeller is axially extended by sliding the distal bushing distally along the axial shaft. Figure 3A-3C As shown, after being released within the body of a subject, the impeller assumes its non-radially constrained configuration (wherein the impeller is typically disposed in the non-radially constrained configuration during operation of the impeller).

[0208] Note that for illustrative purposes, in some of the figures, the impeller 50 is shown without reference to Figure 3A-3CAll features of the impeller shown and described herein. For example, some figures show impellers that do not include stitching 53 and / or elongated element 67. The scope of this application includes the use of any device and method described herein with respect to Figure 3A-3C An impeller having any of the characteristics shown and described.

[0209] For some applications, the following techniques are used to enhance the bonding of the elastomeric material to at least one helical elongated element in a manner that does not result in protrusion from the effective edge of the impeller blade. The helical elongated element is coated with a coupling agent prior to being immersed in the elastomeric material. Typically, a coupling agent is selected having at least two functional groups that are configured to bond to the helical elongated element and the elastomeric material, respectively. For example, a silane compound such as n-(2-aminoethyl)-3-aminopropyltrimethoxysilane can be used, the silane compound containing a first functional group (e.g., (OH)) that is configured to bond to the helical elongated element (which is typically made of an alloy such as nitinol) and the silane compound containing a second functional group (e.g., (NH2)) that is configured to bond to the elastomeric material. Typically, the functional groups in the coupling agent are only effective for a given time period (e.g., about one hour or less). Therefore, a layer of elastomeric material is applied around the helical elongated element during this time period. Typically, the layer of elastomeric material is the same elastomeric material or a similar elastomeric material as that used in the membrane 56. For example, a polycarbonate-based thermoplastic polyurethane such as Aromatic Carbothane TM (such as Aromatic Carbothane TM 75A) can be used in the film 56, and the coating layer can be the same polycarbonate-based thermoplastic polyurethane, or a similar polycarbonate-based thermoplastic polyurethane, such as (For example 90A).

[0210] For some applications, after the coating layer has been applied to the helical elongated element, the coated helical elongated element is sprayed with another layer of elastomeric material. Typically, the sprayed elastomeric material is the same elastomeric material as that used for membrane 56 or a similar elastomeric material. For example, a polycarbonate-based thermoplastic polyurethane, such as Aromatic Carbothane TM (such as Aromatic Carbothane TM 75A), can be used as the membrane 56, and the material to be sprayed can be the same polycarbonate-based thermoplastic polyurethane, or a similar polycarbonate-based thermoplastic polyurethane, such as (For example 90A). For some applications, applying the spray to the helical elongated member rounds the helical elongated member. Typically, when the helical elongated member has a circular cross-section, the elastomeric material forms a layer having a substantially uniform thickness at the interface with the helical elongated member. For some applications, as described in the previous paragraph, applying a layer of elastomeric material at least partially rounds the helical elongated member.

[0211] For some applications, after the spray has been applied to the spiral elongated element, the structure 59 is dipped into an elastomer from which the membrane 56 is made, e.g., as described above. For some applications, the material used to make the membrane is an elastomeric material having an ultimate elongation greater than 300%, e.g., greater than 400%. Typically, the material has a relatively low molecular weight. For some applications, the material has a melt flow index (which is an indirect measure of molecular weight) of at least 4, e.g., at least 4.3. For some applications, the material has an ultimate tensile strength greater than 6000 psi, e.g., greater than 7000 psi, or greater than 7500 psi. For some applications, the material is a thermoplastic polyurethane, e.g., Carbothane TM For some applications, use Aromatic Carbothane TM 75A. Typically, this material combines one or more of the following properties: no loss of outside diameter during immersion, fatigue resistance, resistance to deformation due to crimping, and low loss of outside diameter during crimping.

[0212] In light of the above description of applying the film 56 to the spiral elongated element, the scope of the present invention includes any technique for applying additional layers of the same elastomeric material, a different elastomeric material, and / or an intermediary material to the spiral elongated element, whether by spraying, dipping, or a different coating method, prior to immersing the spiral elongated element in the elastomeric material used to make the film 56. For some applications, the additional layers of elastomeric material are configured to round the spiral elongated element and / or serve as an intermediary to enhance the bond between the spiral elongated element and the film 56 of material. For some applications, an intermediary material (e.g., silane) is configured to act as an intermediary to enhance the bond between the spiral elongated element and the film 56 of material.

[0213] Now refer to Figure 3D and Figure 3E , Figure 3D and Figure 3E is a schematic diagram of an impeller 50 that, in accordance with some applications of the present invention, includes a single integrated impeller over-extension prevention element 72 defining a plurality of elongated elements 67. For illustrative purposes, Figure 3D and Figure 3EThe impeller is shown without the film 56 of material. For some applications, element 72 defines a ring 73 and a plurality of elongated elements 67 extending radially from the ring. For some applications, instead of threading a cord and / or wire around spring 54, ring 73 of element 72 is placed around the spring, for example, by being placed around tube 70, which is typically positioned at a longitudinally central location of the spring. The ends of each elongated element 67 are then coupled to a respective helical elongated element 52. As described above, elongated elements 67 are typically flexible but substantially incapable of stretching along the axis defined by the elongated elements. Further typically, each of elongated elements 67 is configured to be substantially non-resistant to compression. More specifically, each elongated element 67 is configured to exert a tensile force on helical elongated element 52 that prevents helical elongated element 52 from moving radially outward, such that (in the absence of elongated elements 67) the spacing between helical elongated element 52 and central axial spring 54 would be greater than the length of elongated element 67. The impeller over-extension prevention element is configured to prevent radial expansion of the impeller when forces acting on the impeller would cause helical elongated element 52 to move radially outward (in the absence of elongated element 67). Typically, a corresponding elongated element 67 is disposed within each impeller blade and is configured to prevent radial expansion of the impeller blade. For some applications, element 72 is made of polyester and / or another polymer or natural material containing fibers and / or Nitinol (or a similar shape memory alloy).

[0214] Note that the scope of this application includes Figure 3D-Figure 3E The single integrated impeller over-extension prevention element 72 is shown for use with impellers having different configurations. For example, the single integrated impeller over-extension prevention element 72 can be used with an impeller having an axial configuration that differs from the configuration of the spring 54. Typically, the axial configuration defines a cavity therethrough such that the impeller defines the cavity 62 therethrough.

[0215] Now refer to Figure 3F , which is a schematic diagram of an impeller 50, which, in accordance with some applications of the present invention, includes a securing element 75 configured to secure an elongated element 67 relative to a tube 70. For some applications, the rope or wire comprising the elongated element 67 is not wrapped around the tube 70 and does not pass through the longitudinal axis of the impeller. Instead, the rope or wire is secured relative to the tube 70 by the securing element 75. Typically, the rope or wire is secured to the outer surface of the tube 70 at a location on the outer surface of the tube proximate the maximum span of the helical elongated element to which the ends of the rope or wire are tethered. For some applications, the securing element includes a ring, as shown. For some such applications, the ring defines small notches (or eyelets) 80 through which the rope or wire passes between the ring and the tube 70.

[0216] Now refer to Figure 3Gi and Figure 3Gii , these figures are pictures of impellers 50 according to some applications of the present invention. As shown, for some applications, by manufacturing the impeller using the method described above, adjacent blades 51 of the impeller 50 are shaped to define a continuous U-shaped curved surface. As shown by curve 55, the curve 55 is added along at least a portion of the length of the impeller. Figure 3Gii As the film of elastomeric material 56 transitions from one blade to an adjacent blade, the film forms a continuous U-shaped curve. Note that the curvature of the film of material is substantially uninterrupted even at spring 54, which extends along the axis of the impeller. For some applications, the film of material exhibits the aforementioned curvature due to the impeller being formed in the manner described above. Typically, by defining a continuous U-shaped curved surface, the impeller blades are configured to provide smooth streamlines along which blood flows through the impeller, thereby improving the efficiency of the impeller in pumping blood and / or reducing the risk of hemolysis relative to a scenario where adjacent blades do not define a continuous curved surface (e.g., relative to a scenario where the curvature is interrupted at spring 54). For some applications, a substantially similar impeller is used, wherein the impeller has an axial structure configured differently from spring 54 (e.g., a cylindrical axial structure). Typically, the axial structure defines a cavity therethrough, such that the impeller defines cavity 62 therethrough. Alternatively, the impeller includes spring 54 (which includes tube 70) as the axial structure, as shown.

[0217] When viewed from the distal end of the impeller, the pressure side of each blade of the impeller (i.e., the side that pushes against blood during operation of the impeller) is convex in the distal region of the impeller, transitions to a substantially radial orientation in the region of the elongated element 67, and then becomes concave in the proximal region of the impeller. (For purposes of illustration, the opposite side of the impeller blade to the pressure side (i.e., the "non-pressure side") is shown in FIG. Figure 3Gii . ) Thus, when in use, blood pumped by the impeller is first pumped by the convex impeller surface and then by the concave impeller surface. For some applications, elongated element 67 is positioned approximately halfway along the length of the impeller blades and is configured to facilitate the transition of the film of material from having a convex curvature to having a concave curvature. Thus, typically, within the impeller blades in the region of elongated element 67, the blades are oriented substantially radially. Typically, by defining a concave surface in the proximal region of the impeller, the pressure side of the impeller blades is configured to increase the flow and / or pressure of blood even after blood has flowed and / or pressure has been applied thereto in the distal region of the impeller. Optionally (not shown), the pressure side of each impeller blade (i.e., the side that pushes against blood during operation of the impeller) is concave in the distal region of the impeller, transitions to a substantially radial orientation in the region of elongated element 67, and then becomes convex in the proximal region of the impeller.

[0218] Now refer to Figure 5A and Figure 5B, which are schematic illustrations of the impeller 50 and frame 34 of a ventricular assist device 20 in their non-radially constrained and radially constrained states, respectively, according to some applications of the present invention. The impeller and frame are typically configured in the radially constrained state during insertion of the impeller and frame into the subject through a catheter, and the impeller and frame are configured in the non-radially constrained state during operation of the impeller within the left ventricle of the subject. As described above, the pump outlet tube 24 is typically disposed over and extends proximally from at least a portion of the frame. However, for illustrative purposes, the pump outlet tube 24 is not disposed in the radially constrained state. Figure 5A-5B The frame and impeller are shown without the pump outlet pipe 24.

[0219] like Figure 5B As shown, the frame and impeller are typically held in a radially constrained configuration by the delivery conduit 143. Typically, in the radially constrained configuration of the impeller, the impeller has a total length greater than 15 mm (e.g., greater than 20 mm), and / or less than 30 mm (e.g., less than 25 mm), for example, 15-30 mm, or 20-25 mm. Further 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, 8-18 mm, or 10-15 mm. In addition, typically, when the impeller and frame 34 are arranged in a radially constrained configuration (e.g., Figure 5B ), the impeller has an outer diameter of less than 2 mm (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).

[0220] As mentioned above, typically, the axial shaft 92 passes through the cavity 62 of the impeller (the cavity 62 is Figure 3C ) passes through the axis of the impeller 50. Typically, the proximal bushing 64 of the impeller is coupled to the shaft via a coupling element 65 such that the axial position of the proximal bushing relative to the shaft is fixed and the distal bushing 58 of the impeller is slidable relative to the shaft. The axial shaft itself is radially stabilized via proximal and distal radial supports 116, 118.

[0221] Typically, the coupling portion 31 of the frame 34 is coupled to the proximal radial support 116, for example, via a snap-fit coupling and / or via welding. Typically, at the distal end of the frame 34, the distal strut engagement portion 33 is placed into a groove defined by the outer surface of the distal radial support 118, the groove being shaped to conform to the shape of the distal strut portion. As shown, 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. 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).

[0222] As described above, axial shaft 92 is radially stabilized via proximal and distal radial supports 116, 118. Furthermore, the axial shaft radially stabilizes the impeller relative to the inner surface of frame 34 by passing through cavity 62 defined by the impeller, such that, as described above, even relatively small gaps (e.g., gaps such as those described above) between the outer edges of the impeller's blades and the inner surface of frame 34 are maintained during impeller rotation. For some applications, axial shaft 92 is made of stainless steel, and proximal and / or distal supports 116, 118 are made of hardened steel. Typically, when the impeller and frame are crimped (i.e., radially constrained) for insertion into a subject, the distal bushing 58 of the impeller is configured to slide in a distal direction along the axial shaft, causing the impeller to become axially elongated, while the proximal bushing remains in an axially fixed position relative to the axial shaft. More generally, the impeller is changed from its radially constrained configuration to its non-radially constrained configuration, and vice versa, by sliding the distal bushing over the axial shaft while the proximal bushing remains in an axially fixed position relative to the axial shaft.

[0223] Typically, the impeller itself is not directly disposed within any radial or thrust bearings. Rather, supports 116 and 118 act as radial supports relative to the axial shaft. Typically, pump portion 27 (and ventricular assist device 20 more generally) does not include any thrust bearings configured to be disposed within the body of a subject and configured to resist thrust generated by rotation of the impeller. For some applications, one or more thrust bearings are disposed outside the body of the subject (e.g., in a housing such as a Figure 1A 、 Figure 7A-7BiiThe impeller is positioned within the motor unit 23 shown in FIG. 1 ), and the thrust generated by the rotation of the impeller is resisted only by one or more thrust bearings disposed outside the subject's body. For some applications, mechanical and / or magnetic elements are configured to maintain the impeller within a given axial position range. For example, a magnet (e.g., magnet 82, hereinafter referred to as magnet 82) disposed at the proximal end of the drive cable 130 (e.g., outside the subject's body) may be provided. Figure 7A ) can be configured to impart axial motion to the impeller, and / or to maintain the impeller within a given range of axial positions.

[0224] Now refer to Figure 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 the frame 34 by moving the axial shaft in an axial reciprocating motion, as described below with reference to Figure 7A-7Bii As further described in detail. Alternatively or additionally, the impeller and axial shaft are configured to reciprocate axially within frame 34 in response to forces acting on the impeller, without requiring the axial shaft to be actively driven to cause the axial shaft to move in an axially reciprocating manner. Typically, during a subject's cardiac cycle, the pressure differential between the left ventricle and the aorta varies from approximately zero during ventricular contraction (hereinafter referred to as "systole") to a relatively large pressure differential (e.g., 50 mmHg-70 mmHg) during ventricular relaxation (hereinafter referred to as "diastole"). For some applications, due to the increased pressure differential against which the impeller pumps during diastole (and because the drive cable 130 is stretchable), the impeller is pushed distally relative to frame 34 during diastole compared to its position relative to frame 34 during systole. Furthermore, because the impeller is connected to the axial shaft, the axial shaft moves forward. During systole, the impeller (and, therefore, the axial shaft) moves back to its systolic position. In this way, the axial reciprocating motion of the impeller and the axial shaft is generated in a passive manner, ie, the axial shaft and the impeller do not need to be actively driven in order for them to undergo such motion. Figure 6A shows the impeller and axial shaft disposed in their typical systolic position, and Figure 6B The impeller and axial shaft are shown disposed in their typical diastolic positions.

[0225] For some applications, by moving in an axial reciprocating motion, the portion of the axial shaft in contact with the proximal and distal supports 116, 118 is continuously varied. For some such applications, assuming all else is equal, in this manner, the frictional forces exerted on the axial shaft by the supports are distributed over a larger area of the axial shaft than if the axial shaft were not moved relative to the supports, thereby reducing wear on the axial shaft. Alternatively or additionally, by moving in an axial reciprocating motion relative to the supports, the axial shaft clears any residue, such as blood residue, from the interface between the axial shaft and the supports.

[0226] For some applications, when the frame 34 and impeller 50 are in their non-radially constrained configuration (e.g., when the frame and impeller are deployed within the left ventricle), the length of the frame exceeds the length of the impeller by at least 2 mm (e.g., at least 4 mm, or at least 8 mm). Typically, the proximal support 116 and the distal support 118 are each 2 mm to 4 mm long (e.g., 2 mm to 3 mm). More typically, the impeller and the axial shaft are configured to reciprocate axially within the frame along at least the length of each of the proximal and distal supports, or at least 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 these supports.

[0227] For some applications, the range of impeller motion is as follows Figure 6A-6B As shown, Figure 6A Indicates the impeller is in a proximal-most arrangement during the cardiac cycle (typically, the impeller is set to this arrangement during systole), and Figure 6B Indicates the most distal arrangement of the impeller during the cardiac cycle (typically, the impeller is set to this arrangement during diastole). Figure 6A As shown, for some applications, at the most proximal position of the impeller, the proximal end of the impeller is positioned at position I P At this location I P In the proximal tapered 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 positioned at position I D At this location I D At the distal end of the cylindrical segment of the frame 34. For the purposes of this application, the distal end of the frame P to I DThe entire segment of the frame 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.

[0228] Reference again Figure 6A and Figure 6B , and also refer to Figure 6C , Figure 6C is an enlarged schematic illustration of a distal end element 107 according to some applications of the present invention, the distal end element 107 including the axial shaft receiving tube 126 and the distal end portion 120 of the ventricular assist device 20. Typically, the distal end element 107 is a single integrated element including both the axial shaft receiving tube 126 and the distal end portion 120. For some applications, the distal end element 107 is configured to be soft such that the distal end portion is configured to not cause tissue damage to the subject even if the distal end portion comes into contact with tissue (e.g., tissue of the left ventricle). For example, the distal end element 107 can be made of silicone, polyethylene terephthalate (PET), and / or polyether block amide (e.g., ). For some applications, the distal tip portion defines a lumen 122 therethrough. For some such applications, during insertion of a ventricular assist device into the left ventricle, the guide wire 10 ( Figure 1B ) is first inserted into the left ventricle according to, for example, known techniques. The distal tip portion of the ventricular assist device is then guided to the left ventricle by advancing the distal tip portion over a guidewire disposed within lumen 122. For some applications, a duckbill valve 390 (or a different type of hemostatic valve) is disposed at the distal end of lumen 122 of distal tip portion 120.

[0229] Typically, during insertion of the ventricular assist device into a ventricle of a subject, delivery catheter 143 is placed over impeller 50 and frame 34 and holds the impeller and frame in their radially constrained configuration. For some applications, 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 its proximal end, 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.

[0230] It should be noted that Figures 6A-6C(and some other figures) are shown as defining a complete loop in which the distal end of the distal tip portion (with the duckbill valve 390 disposed therein) spans a more proximal portion of the distal tip portion. Typically, the distal tip portion remains partially straightened due to having a guide wire inserted therethrough (during insertion of a ventricular assist device into the left ventricle), even after the guide wire is removed from the distal tip portion. Typically, the partial straightening of the distal tip portion is such that when the distal tip portion is disposed within the left ventricle, in the absence of external forces acting on the distal tip portion, the distal tip portion does not define a complete loop, e.g., as Figure 1B 、 Figure 15D and Figure 16A For some applications, to insert the guide wire through the distal tip portion, a method such as the following reference is used. Figures 23A-23C Straightening element 270 is described in further detail below. Other aspects of the distal tip portion shape are described in further detail below.

[0231] Now refer to Figure 6D and Figure 6E , which are schematic illustrations of impeller 50, wherein, according to some applications of the present invention, a proximal bushing 64 of the impeller is coupled to a coupling element 65 that extends proximally to act as a stop. Figure 6D The impeller is shown in the contraction phase of the impeller's motion cycle, and Figure 6E The impeller is shown in the expanded phase of its motion cycle. Typically, the coupling element extends proximally to prevent the central region of the impeller (where the impeller is at its maximum span) from sliding proximally into the proximal tapered portion of the frame 34. For example, during the contraction phase of the impeller's motion cycle (at Figure 6D ), if the impeller slides further proximally beyond a given amount, the proximally extending coupling element will contact the proximal radial support 116, thereby preventing further proximal movement of the impeller. For some applications, the coupling element extends proximally so that it has a total length greater than 1.5 mm, for example greater than 4 mm. For some applications (not shown), as an alternative to or in addition to the proximally extending coupling element, a separate stop element is provided on the axial shaft proximally relative to the coupling element. Typically, the stop is configured as described with reference to the proximally extending coupling element. That is, if the impeller slides further proximally beyond a given amount, the stop element will contact the proximal radial support 116, thereby preventing further proximal movement of the impeller.

[0232] Now refer to Figure 7A, 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. As shown, the motor unit is typically a handle that is configured to be positioned outside the body of a subject and houses the motor. Therefore, the motor unit may alternatively be referred to as a handle unit.

[0233] For some applications, the console 21 ( Figure 1A ) that controls the rotation of impeller 50 is also configured to control the reciprocating motion of the axial shaft. Typically, both types of motion are generated using motor unit 23. The scope of the present invention includes controlling reciprocating motion of any frequency. For some applications, an indication of the subject's cardiac cycle is detected (e.g., by detecting the subject's ECG), and the reciprocating motion of the axial shaft is synchronized with the subject's cardiac cycle.

[0234] Typically, the motor unit 23 includes a motor 74 that is configured to impart rotational motion to the impeller 50 via a drive cable 130. As described in further detail below, the motor is typically magnetically coupled to the drive cable. For some applications, an axial motion driver 76 is configured to drive the motor so as to move in an axial reciprocating motion (as indicated by the double-headed arrow 79). Typically, due to the magnetic coupling of the motor to the drive cable, the motor imparts reciprocating motion to the drive cable, which in turn imparts the motion to the impeller. As described above and below, for some applications, the drive cable, impeller, and / or axial shaft reciprocate 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.

[0235] For some applications, the magnetic coupling between the motor and the drive cable is as follows: Figure 7A As shown. Figure 7AAs shown, at least one or more drive magnets 77 (e.g., two drive magnets 77) are coupled to the motor via a drive magnet housing 78. For some applications, the drive magnet housing includes a ring 81 (e.g., a steel ring), and the drive magnets are adhered to the inner surface of the ring. For some applications, as shown, a spacer 85 is adhered to the inner surface of the ring 81 between the two drive magnets. At least one driven magnet 82 is disposed between the drive magnets such that there is an axial overlap between the drive magnet and the driven magnet. The driven magnet is coupled to a pin 131 that extends beyond the distal end of the driven magnet 82, wherein the pin is coupled to the proximal end of the drive cable 130. For example, the driven magnet can be cylindrical and define a hole therethrough, and the pin 131 can be adhered to the inner surface of the driven magnet that defines the hole. For some applications, the driven magnet is cylindrical and the magnet includes a north pole and a south pole that are separated from each other along the length of the cylinder along a line 83 that bisects the cylinder, as shown. For some applications, the driven magnet is housed within cylindrical housing 87. Typically, pin 131 defines a cavity 133 through which guidewire 10 is inserted through the pin.

[0236] Note that in Figure 7A In the illustrated application, the drive magnet is disposed outside the driven magnet. However, the scope of the present application includes configurations in which the drive and driven magnets are reversed (mutatis mutandis). For example, the proximal end of the drive cable can be coupled to two or more driven magnets that are disposed around the drive magnet such that there is axial overlap between the driven and drive magnets.

[0237] As mentioned above, typically, the cleaning system 29 (e.g. Figure 1A 8 (shown in FIG2 ) is used with a ventricular assist device 20. Typically, motor unit 23 includes an inlet port 86 and an outlet port 88 for use with a purge system. For some applications, a purge fluid is continuously or periodically pumped into the ventricular assist device via inlet port 86 and out of the ventricular assist device via outlet port 88. Other aspects of the purge system are described below.

[0238] Typically, the magnet 82 and the pin 131 are maintained in an axially fixed position relative to each other within the motor unit 23. (For some applications, the magnet 82 does have less freedom of axial and / or rotational movement relative to other components of the motor unit (e.g., the drive magnet 77). For some applications, this movement is measurable, as described in further detail below.) Typically, the proximal end of the drive cable is coupled to the pin 131 and thereby maintained in an axially fixed position relative to the pin. Typically, the drive cable 130 extends from the pin 131 to the axial shaft 92 and thereby at least partially fixes the axial position of the axial shaft and, in turn, the impeller 50. For some applications, the drive cable is stretchable to some extent. For example, the drive cable can be made of a stretchable coiled wire, as described in further detail below. The drive cable typically allows the axial shaft (and therefore the impeller) to assume a range of axial positions (by the drive cable becoming more or less stretched), but limits the axial movement of the axial shaft and impeller to a certain range of motion (by maintaining the proximal end of the drive cable in a relatively fixed axial position and limiting the stretchability of the drive cable).

[0239] Now refer to Figure 7Bi and Figure 7Bii , these figures are schematic diagrams of motor units 23 according to some applications of the present invention. In general, as Figure 7Bi and Figure 7Bii The motor unit 23 shown is similar to Figure 7A Motor units shown, unless otherwise stated, are Figure 7Bi and Figure 7Bii The motor unit 23 shown comprises Figure 7A Components similar to the motor unit 23 shown are shown. For some applications, the motor unit includes a heat sink 90 configured to dissipate heat generated by the motor. Alternatively or additionally, the motor unit includes a vent port 93 configured to facilitate dissipation of 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 motion and / or axial reciprocating motion of components of the ventricular assist device.

[0240] As described above, for some applications, impeller 50 and axial shaft 92 are configured to reciprocate axially within frame 34 in response to forces acting on the impeller, without actively driving the axial shaft to move in an axially reciprocating motion. Typically, during a subject's cardiac cycle, the pressure differential between the left ventricle and the aorta varies from approximately zero during systole to a relatively large pressure differential (e.g., 50 mmHg-70 mmHg) during diastole. For some applications, due to the increased pressure differential against which the impeller pumps during diastole (and because the drive cable is stretchable), the impeller is urged distally relative to frame 34 during diastole, relative to its position relative to frame 34 during systole. Furthermore, because the impeller is connected to the axial shaft, the axial shaft moves forward. During systole, the impeller (and, therefore, the axial shaft) returns to its systolic position. In this way, the axial reciprocating motion of the impeller and the axial shaft is generated in a passive manner, ie, the axial shaft and the impeller do not need to be actively driven in order for them to undergo such motion.

[0241] Now refer to Figure 8A , 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 by an experiment). 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). The pressure gradient resisted by the impeller varies in a pulsating manner to represent the pulsation of the pressure gradient typically resisted by the impeller when pumping blood from the left ventricle to the aorta. Simultaneously, the movement of the drive cable is imaged, and the change in drive cable length is determined via analysis of the images. Figure 8A The graph shown in shows the measured drive cable length as a function of pressure gradient. Figure 8A As shown in , as the pressure gradient against which the impeller pumps increases, the drive cable becomes longer and longer. Figure 8A As 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.

[0242] For some applications, during operation of the ventricular assist device, console 21 ( Figure 1A) is configured to measure an indication of pressure exerted on the impeller (indicative of a pressure differential between the left ventricle and the aorta) by measuring tension in drive cable 130 and / or an indication of axial movement of the drive cable. For some applications, based on the measured indications, the computer processor detects events in the subject's cardiac cycle, determines the subject's left ventricular pressure, and / or determines the subject's cardiac afterload. For some applications, the computer processor controls rotation of the impeller and / or, in response thereto, controls axial reciprocating motion of the axial shaft.

[0243] Reference again Figure 7A For some applications, ventricular assist device 20 includes sensor 84. For example, the sensor may include a magnetometer (e.g., a Hall sensor) disposed within motor unit 23, such as Figure 7A As shown. (In some cases, the sensor 84 is referred to as a magnetometer 84.) For some applications, it is the case that, because the driven magnet is held in position relative to the drive magnet by magnetic coupling rather than a rigid mechanical connection, the axial reciprocating motion of the impeller causes measurable reciprocating motion of the inner driven magnet 82 relative to the outer one or more drive magnets 77. Note that, typically, the axial motion of the magnets 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. For some applications, the magnetometer measures the change in the magnetic field generated by one of the magnets in order to measure the axial motion of the drive cable 130 and, in turn, determine the pressure against which the impeller is pumping. For example, the inner driven magnet 82 can be longer in the axial direction than the outer drive magnet 77. Because the inner magnet is longer than the outer magnet, the magnetic field lines emanating from the inner magnet are not transmitted to the outer magnet, and the magnetic flux generated by these field lines, measured by the magnetometer, changes due to the drive cable and, in turn, causes the inner magnet to move axially. During operation, motor 74 rotates, thereby generating an AC signal in the magnetometer having a frequency typically between 200 Hz and 800 Hz. Typically, when the tension in the drive cable changes due to the subject's cardiac cycle, this generates a low-frequency envelope in the signal measured by the magnetometer, which typically has a frequency of 0.5 Hz-2 Hz. For some applications, a computer processor measures the low-frequency envelope and derives the subject's cardiac cycle from the measured envelope.

[0244] For some applications, the magnetometer measurement results are initially calibrated so that the change in magnetic flux per unit pressure change resisted by the impeller pumping (i.e., per unit change in the pressure difference between the left ventricle and the aorta, or per unit change in the pressure gradient) is known. It is known that in most subjects, during systole, the left ventricular pressure is equal to the aortic pressure. Therefore, for some applications, the subject's aortic pressure is measured, and then the subject's left ventricular pressure at a given time is calculated by a computer processor based on the following: (a) the measured aortic pressure, and (b) the difference between the magnetic flux measured by the magnetometer at that time and the magnetic flux measured by the magnetometer during systole (when the pressure in the left ventricle is assumed to be equal to the pressure of the aorta). For example, the subject's aortic pressure can be measured by measuring the pressure in the channel 224 defined by the delivery catheter 143, as described in further detail below. For some applications, the above-mentioned techniques are used to determine alternative or additional physiological parameters. For example, events in the subject's cardiac cycle and / or the subject's cardiac afterload can be determined.

[0245] For some applications, techniques similar to those described in the previous paragraph are typically used, but different parameters are measured to determine left ventricular blood pressure at a given time (and / or different physiological parameters, such as events in the subject's cardiac cycle and / or the subject's cardiac afterload) instead of or in addition to measurements using a magnetometer. For example, typically, there is a relationship between the amount of power (and / or current) required to drive the impeller at a given rotational rate and the pressure differential generated by the impeller. (Note that a portion of the pressure differential generated by the impeller is used to overcome the pressure gradient against which the impeller is pumping, while a portion of the pressure differential generated 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 (and / or current) consumption required to rotate the impeller at a given rotational rate and (b) the pressure differential generated by the impeller is known. For some applications, the subject's aortic pressure is measured and the subject's left ventricular pressure at a given time is calculated by a computer processor based on (a) the measured aortic pressure, (b) the motor power (and / or current) consumption required to rotate the impeller at a given rotation rate at a given time, and (c) a predetermined relationship between the motor power (and / or current) consumption required to rotate the impeller at a given rotation rate and the pressure differential generated by the impeller. For some applications, the above techniques are performed while maintaining the impeller rotation rate at a constant rate. Alternatively or additionally, the impeller rotation rate is varied and the variation in the impeller rotation rate is accounted for in the above calculations. For some applications, the above techniques are used to determine alternative or additional physiological parameters. For example, events in the subject's cardiac cycle and / or the subject's cardiac afterload can be determined.

[0246] Typically, tube 24 has a known cross-sectional area (when the tube is in an open state due to blood flowing through the tube). For some applications, the flow rate through tube 24 generated by the impeller is determined based on the determined pressure differential generated by the impeller and the known cross-sectional area of the tube. For some applications, this flow calculation incorporates calibration parameters to account for factors such as flow resistance, which are specific to the ventricular assist device (or type of ventricular assist device) for which the calculation is performed. For some applications, a ventricular pressure-volume loop is derived based on the determined ventricular pressure.

[0247] Reference again Figure 7AFor some applications, in addition to the magnetometer 84 configured to measure the magnetic flux density generated by the driven magnet, a second magnetometer 84A (e.g., a second Hall sensor) measures an indication of the magnetic flux density generated by the driving magnet. For some applications, the second magnetometer measures the magnetic flux density of the motor, which indicates the magnetic flux density circulation of the driving magnet because the motor directly drives the driving magnet to rotate. Typically, when the impeller rotates, such as when pumping blood, a torque is generated on the impeller. Further typically, the intensity of the torque depends on various parameters, such as the flow rate generated by the impeller, the rotation rate of the impeller, and / or the pressure gradient resisted by the impeller pumping. For some applications, the torque generated on the impeller generates a measurable torque on the internal driven magnet 82 relative to the external driving magnet 77 because the driven magnet is held in place relative to the driving magnet by magnetic coupling rather than a rigid mechanical connection. Note that the torque typically generated on the driven magnet is much smaller than the torque generated on the impeller because the torque generated on the impeller is not transmitted along the length of the drive cable. However, it is typically the case that the torque generated on the impeller is at least partially transferred to the driven magnet via the drive cable.

[0248] The torque transmitted to the driven magnet typically causes a phase difference between the signal measured by the magnetometer 84 (which measures the magnetic flux density of the driven magnet) and the signal measured by the second magnetometer 84A (which measures the magnetic flux density of the motor and / or drive magnet). For some applications, when the torque on the impeller changes, this causes a change in the phase difference between the signal measured by the magnetometer 84 and the signal measured by the second magnetometer 84A. For some applications, a computer processor detects the change in the above-mentioned phase difference and determines a physiological parameter of the subject at least in part in response to the change in the above-mentioned phase difference. For example, based at least in part on the change in the phase difference, the computer processor can determine the difference between the subject's left ventricular pressure and the subject's aortic pressure, the subject's left ventricular pressure, events in the subject's cardiac cycle, the subject's cardiac afterload and / or different physiological parameters. For some applications, the technology described in this paragraph is used as an alternative to the above-mentioned technology for determining physiological parameters using magnetic flux density measurement and / or power consumption measurement. Alternatively, two or more of these technologies are used in combination with each other. For example, a physiological parameter of a subject may be determined based on a mathematical model incorporating two or more measurements, and / or one of the techniques may be used to validate an estimate of a physiological parameter of a subject made using another of the techniques.

[0249] Now refer to Figure 8B and Figure 8C , which show graphs of the correlation between the phase difference signal and the pressure gradient against which the impeller 50 is pumping, according to some applications of the present invention.

[0250] Figure 8BThe graph shown in Figure 1 shows the results of an experiment in which a ventricular assist device as described herein was used to pump blood against a corresponding pressure gradient within a static extracorporeal system (i.e., the pressure gradient was constant at each measurement). A linear regression model was used to estimate the pressure gradient against which the impeller pumped, based on the phase difference signal, the magnetic flux amplitude signal, and the current consumed by the motor. Figure 8B The graph shown shows the estimated pressure gradient versus the measured pressure gradient. As shown, the linear regression model combined with the phase difference measurements provides a reliable method for estimating the pressure gradient opposed by the impeller pumping.

[0251] Figure 8C The graphs shown in Figure 1 show the results of an experiment in which a ventricular assist device as described herein was used to pump blood against a corresponding pressure gradient in a static extracorporeal system (i.e., in which the pressure gradient varied in a pulsatile manner). The pressure gradient against which the impeller pumped was estimated using a spatial state model based on the phase difference signal, the flux amplitude signal, and the current consumed by the motor. Figure 8C The graph shown shows the estimated pressure gradient superimposed on the measured pressure gradient. As shown, the spatial state model combined with the phase difference measurement provides a reliable method for estimating the pressure gradient opposed by the impeller pumping.

[0252] In accordance with the foregoing, and in accordance with some applications of the present invention, a magnetic phase difference between one or more driven magnets and one or more driving magnets is measured, and a physiological parameter of a subject is determined at least in part in response to the magnetic phase difference. For example, based at least in part on changes in the phase difference, a computer processor can determine a difference between the subject's left ventricular pressure and the subject's aortic pressure, the subject's left ventricular pressure, events in the subject's cardiac cycle, the subject's cardiac afterload, and / or various physiological parameters. For some applications, the physiological parameter is determined based on the phase difference measurement in combination with one or more additional measurements, such as a flux amplitude measurement, the power consumed by the motor, and / or the current consumed by the motor. Typically, such measurements are combined in a mathematical model, such as a linear regression model, and / or a spatial state model.

[0253] Now refer to Figures 9A-9G , which are schematic diagrams of various views of a motor unit support 170 configured to support a motor unit 23 on a patient's leg 172 according to some applications of the present invention. For some applications, a ventricular assist device is inserted into the patient via a femoral access point 173, and the motor unit support is configured to be placed on the patient's thigh below the femoral access point, as shown. Typically, the motor unit support is configured to at least partially isolate the patient's leg from vibration and / or heat generated by the motor unit during operation of the motor unit.

[0254] For some applications, the motor unit support includes a curved base 176 configured to be placed on the patient's thigh, and a motor unit dock 178 on which the motor unit rests. Typically, a gap 179 exists between the motor unit dock and the curved base of the motor unit support, such that the patient's leg is separated from the motor unit by the gap, the gap being used to at least partially isolate the patient's leg from vibration and / or heat generated by the motor unit during operation of the motor unit. For some applications, the motor unit support is configured to receive a strap 174 through the gap for securing the motor unit support to the patient's leg. Typically, the strap is elastic and / or adjustable to fit the patient's leg.

[0255] Typically, the motor unit support includes a coupling element 180 for coupling the motor unit dock to the motor unit (e.g., at Figure 9D As described above, for some applications, the motor unit includes a vent port 93 configured to help dissipate heat generated by the motor. For some such applications, the coupling element includes a snap-fit coupling element, such as Figure 9E As shown, the snap-fit coupling element is configured to couple the motor unit dock to the motor unit by snapping the coupling element into the ventilation port of the motor unit. For some applications, the motor unit includes ventilation ports on both sides of the motor unit so that either side of the motor unit can be coupled to the motor unit dock.

[0256] Now refer to Figure 10A 、 Figure 10B and Figure 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, the rotational motion of the motor is 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., at Figure 5A The connection between the distal end of the drive cable and the proximal end of the axial shaft is shown in the left enlarged portion of FIG. ). For some applications, the drive cable includes a plurality of wires 134 arranged in a coiled configuration to impart sufficient strength and flexibility to the drive cable so that a portion of the cable can remain within the aortic arch (e.g., corresponding to the aortic arch). Figure 10A For some applications, the drive cable includes multiple coaxial coiled wire layers. For example, Figures 10A-10C As shown, the drive cable may include an outer layer 136 and an inner layer 138 that are coaxial with each other and each layer includes a coiled wire.

[0257] Typically, the drive cable is disposed within a first outer tube 140 that is configured to remain stationary while the drive cable undergoes rotational and / or axial reciprocating motion. The first outer tube is configured to effectively act as a support tube for the drive cable along its length. Therefore, the first outer tube is also referred to herein as the drive cable support tube. Figure 10D The drive cable support tube is described in further detail. For some applications, the drive cable support tube is disposed within the second outer tube 142, which is typically made of a material having greater flexibility than the drive cable support tube (e.g., nylon and / or polyether block amide) and typically has a greater thickness than the drive cable support tube.

[0258] Typically, during insertion of the impeller and frame into the left ventricle, the impeller 50 and frame 34 are held in a radially constrained configuration by the delivery catheter 143. As described above, to position the impeller and frame in a non-radially constrained configuration, the delivery catheter is retracted. For some applications, such as Figure 10A As shown, during operation of the left ventricular device, the delivery catheter remains in the subject's aorta and the outer tube 142 is positioned inside the delivery catheter. (Although Figure 10A The distal end of the delivery catheter is shown disposed within the aortic arch, but for some applications, during operation of the left ventricular device, the distal end of the delivery catheter is disposed within the descending aorta. 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, Figure 10A The channels shown in FIG are not to scale. ) For some such applications, the subject's aortic blood pressure is measured by measuring the blood pressure within channel 224. For example, pressure sensor 216 (in Figure 1A 224 and can be configured to measure the aortic pressure of the subject by measuring the blood pressure within channel 224. Typically, to retract the left ventricular device from the subject, the delivery catheter is advanced over the impeller and frame, causing the impeller and frame to assume their radially constrained configuration. The catheter is then withdrawn from the subject.

[0259] For some applications, the drive cable 130 is constructed from multiple coaxial layers, each of which includes multiple coiled wires 134. For example, Figures 10A-10CAs shown, the drive cable includes an outer layer 136 and an inner layer 138, each layer including coiled wire. Typically, when rotation of the impeller begins, if the direction of rotation of the impeller is such that rotation of the drive cable in that direction causes the coiled wire of the drive cable to at least partially tighten, this will also cause the impeller to advance relative to the frame due to the coiled wire tightening (i.e., winding such that the radius of the coil decreases) and thereby axially lengthening. For some applications, at least a portion of the drive cable is configured such that (a) in response to the impeller pumping blood from the left ventricle to the aorta by rotating in a predetermined rotational direction, (b) rotation of the drive cable in that direction causes the coiled wire of the drive cable to at least partially unwind along a portion of the drive cable, causing the portion of the drive cable to axially shorten (e.g., become loose, thereby increasing the radius of the coil). For some applications, the impeller is configured to rotate in a counterclockwise direction when viewed from the proximal end of the impeller to the distal end of the impeller, and the coiled wire in each layer of the drive cable is configured for left-handed placement. When the impeller rotates in a counterclockwise direction, the back pressure exerted on the coiled wires of each layer of the drive cable causes them to partially unwind, thereby shortening each layer of the drive cable. Alternatively, the impeller is configured to rotate in a clockwise direction when viewed from the proximal end of the impeller to the distal end of the impeller, and the coiled wires in each layer of the drive cable are configured for right-hand placement.

[0260] Reference again Figure 6A and 6B , which illustrate the range of axial reciprocating motion of the impeller within the frame 34 during the cardiac cycle according to some applications of the present invention. As described above, Figure 6A Indicates the impeller is in a proximal-most arrangement during the cardiac cycle (typically, the impeller is set to this arrangement during systole), and Figure 6B Indicates the most distal arrangement of the impeller during the cardiac cycle (typically, the impeller is set to this arrangement during diastole). Figure 6A As shown, for some applications, at the most proximal position of the impeller, the proximal end of the impeller is positioned at position I P At this location I P In the proximal tapered section of the frame 34. Figure 6B As shown, for some applications, at the impeller's most distal position, the impeller's distal end is disposed at a position Id that is at the distal end of the cylindrical segment of frame 34 .

[0261] Reference again Figures 10A-10CTypically, by configuring the drive cable in the manner described above, when the impeller and drive cable begin to rotate, the length of the frame 34 does not need to accommodate the distal movement of the impeller caused by axial elongation of the drive cable due to tightening of the device cable. Note that for some applications, the drive cable does not shorten due to the drive cable support tube 140 limiting the extent to which the drive cable can unwind and thereby shorten axially (and / or for other reasons). Furthermore, for some applications, although in theory the drive cable would shorten if the impeller rotated in the absence of any fluid, in practice the drive cable does not shorten when the impeller rotates in the subject's bloodstream. This is because, when the impeller rotates in the subject's bloodstream, the back pressure of the blood pumped by the impeller pushes the impeller distally, thereby counteracting the unwinding of the drive cable (which would cause the drive cable to shorten). For some applications, during diastole, the drive cable actually lengthens relative to when the impeller is stationary due to the increased pressure gradient against which the impeller pumps relative to during systole. Typically, even in such applications, at least during retraction, the drive cable is configured so as not to become elongated while stationary relative to the impeller because the winding of the coil is configured as described above.

[0262] For some applications, in addition to configuring the orientation of the coiled wire within the drive cable in the manner described above, the drive cable is initially held within frame 34 in a preloaded (i.e., pre-tensioned) state such that the drive cable is already stretched even before the drive cable and impeller begin to rotate. That is, even before the drive cable and impeller begin to rotate, the drive cable is in a stretched state relative to the drive cable's rest state (i.e., the state of the drive cable in the absence of any external forces acting on the drive cable). For example, coupling element 65 (which, in some applications, extends proximally, as described above with reference to FIG. 1 ) may be positioned proximally. Figure 6D-6E) can engage the proximal support 116, for example, to maintain the drive cable in a preloaded state. Typically, (a) because the orientation of the coiled wire within the drive cable is configured in the manner described above, and / or (b) because the drive cable is maintained within the frame 34 in a preloaded state, in this case, when the impeller and drive cable begin to rotate, the drive cable does not become elongated, even during diastole (e.g., even when the impeller is pumping against a pressure gradient of 50-70 mmHg). For some applications, the drive cable does not become elongated, even during diastole, until the impeller is rotating at a rotational rate exceeding 6,000 RPM or exceeding 8,000 RPM. For some applications, by configuring the drive cable in this manner, the amount of lengthening of the drive cable during the cardiac cycle is limited to less than 5 mm (and typically less than 4 mm), even when the impeller is rotating at more than 20,000 RPM. Furthermore, for some applications, by configuring the drive cables in this manner, the widest portion of the impeller (typically located at the center of the length of the impeller) is positioned within the proximal half of frame 34 for more than 50% of the duration of the cardiac cycle, even when the impeller is rotating at over 20,000 RPM.

[0263] For some applications, the ventricular assist device is configured such that, even during diastole, even when the impeller rotates at more than 20,000 RPM, there is an axial distance between the impeller position at its maximum diameter and the blood inlet opening. For example, the ventricular assist device is configured such that, during diastole, even when the impeller rotates at more than 20,000 RPM, there is an axial distance of more than 3 mm (e.g., more than 5 mm) between the impeller position at its maximum diameter and the blood inlet opening. For some such applications, this reduces hemolysis (relative to if there were a smaller axial distance or no axial distance between the impeller position at its maximum diameter and the blood inlet opening) and / or improves the efficacy of the impeller by reducing turbulence by allowing blood streamlines entering the blood inlet opening to become at least partially aligned with the longitudinal axis of the impeller before being pumped by the impeller.

[0264] Typically, there are fewer coiled wires in the outer layer 136 of the drive cable than in the inner layer 138, and each wire is wider than the wires in the inner layer. For example, the ratio of the number of wires in the outer layer to the number of wires in the inner layer can be between 2:3 and 2:5. For some applications, the outer layer contains 4-8 wires, while the inner layer contains 10-14 wires. For some applications, the ratio of the wire diameter in the outer layer to the wire diameter in the inner layer is between 3:2 and 5:2. For some applications, the wire diameter in the outer layer is between 0.15 mm and 0.2 mm, while the wire diameter in the outer layer is between 0.075 mm and 0.125 mm. Typically, the coiled wires in both layers are made of an alloy. For some applications, the inner diameter of the drive cable (i.e., the diameter of the cavity 132) is between 0.4 mm and 0.7 mm. Further typically, the outer diameter of the drive cable (defined by the outer layer 138) is between 1 mm and 1.2 mm. For some applications, 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, 1-1.4 m, or 1.1-1.3 m. Typically, the diameters of cavity 122 and cavity 133 are substantially similar to the diameter of cavity 132.

[0265] For some applications, the drive cable includes a first (distal) portion and a second (proximal) portion. Typically, the first portion is configured to be positioned in the aortic arch of a subject, while the second portion is configured to be positioned along the descending aorta and typically extends to the motor unit 23, outside the subject's body. Typically, at locations where the drive cable 130 makes a significant bend, such as the aortic arch, it is desirable that the drive cable be relatively flexible. However, a drive cable with greater flexibility is typically also more axially stretchable than a drive cable with less flexibility. Therefore, for some applications, there is a trade-off between desiring the drive cable to be flexible enough to conform to the curvature of the aortic arch, but on the other hand not desiring the drive cable to undergo significant axial stretching (which could result in a loss of control over the axial position of the impeller). For some applications, corresponding portions of the drive cable have corresponding degrees of flexibility. For example, a first portion of the drive cable configured to be positioned in the aortic arch may have a first degree of flexibility, while a second portion of the drive cable configured to be positioned in the descending aorta may have a second degree of flexibility, the first degree of flexibility being greater than the second degree of flexibility.

[0266] For some applications, the distal portion of the drive cable is configured to have greater flexibility than the proximal portion due to the coils of wire 134 in the distal portion having different parameters than those used in the proximal portion. For some applications, the distal portion has parameters that are substantially similar to those described above (i.e., with respect to the inner and outer layers). For some applications, the proximal portion of the guide wire comprises a single layer of coiled wire. Typically, there are fewer coiled wires in the proximal portion of the drive cable than in the outer layer of the distal portion of the drive cable. Typically, the ratio of the number of wires in the outer layer of the distal portion of the drive cable to the number of wires in the proximal portion of the drive cable is between 3:2 and 5:2. For some applications, there are 3 to 6 wires in the proximal portion of the drive cable. Typically, the diameter of the coiled wire in the proximal portion of the drive cable is even greater than the diameter of the coiled wire in the outer layer of the distal portion of the drive cable. For some applications, the ratio of the wire diameter in the proximal portion to the wire diameter in the outer layer of the distal portion of the drive cable is between 3:2 and 5:2. For some applications, the wire diameter within the distal portion of the drive cable is between 0.2 mm and 0.35 mm. Typically, the inner and outer diameters of both the distal and proximal portions of the drive cable are similar (or identical) to each other, and are typically as described above.

[0267] Now refer to Figure 10D , which is a schematic diagram of a first outer tube 140 that serves as a drive cable support tube according to some applications of the present invention. For some applications, the drive cable support tube includes an outer layer 141 and an inner layer 144, each typically made of a biocompatible polymer material, and a coil 153 embedded between the outer and inner layers. For some applications, the outer layer 141 is made of Pebax, the inner layer 144 is made of PTFE and / or polyimide (e.g., a mixture of PTFE and / or polyimide), and the coil is made of an alloy (e.g., stainless steel). Typically, the inner layer includes a material configured to provide a low level of friction and high wear resistance. Furthermore, the outer layer is typically configured to provide additional strength to the drive cable support tube while still providing the drive cable support tube with sufficient flexibility to enable it to conform to the curvature of, for example, the aortic arch. Typically, the coil is configured so that the substantially circular cross-section of the drive cable support tube is maintained even in areas where the drive cable support tube experiences significant bending (e.g., within the aortic arch). Typically, without the coil, the drive cable support tube will have a tendency to flatten and form an oval cross-section in these areas.

[0268] Now refer to Figure 11A 、 Figure 11B 、 Figure 11C 、 Figure 11D and Figure 11E, which are schematic illustrations of apparatus and methods for cleaning the drive cable 130, radial supports 116, 118, and / or impeller bushing 58 of a ventricular assist device 20, according to some applications of the present invention.

[0269] First, refer to Figure 11A Typically, the axial shaft and drive cable define a continuous lumen 132 therethrough. For some applications, the left ventricular device is guided to the aorta and left ventricle by placing the axial shaft and cable over the 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 end portion of the distal end element 107. The guide wire passes through the lumen 122 (of the distal end portion) and then into the lumen 132 defined by the axial shaft at that point. The guide wire then continues through the lumen 132 until it reaches the proximal end of the drive cable. From the proximal end of the drive cable, the guide wire passes through a 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 cavity 133. Subsequently, the axial position of driven magnet 82 (with pin 131 positioned therein) is fixed so as to be positioned between driving magnets 77, as shown in FIG. Figure 7A For example, a portion of the motor unit 23 in which the driven magnet is disposed may be secured using a latch element 150 (e.g. Figure 11B ) is coupled to a portion of the motor unit in which the drive magnet 77 is disposed. For some applications, as described below with reference Figures 23A-23C The described technique is used to insert a guidewire into distal tip element 107. For some applications, by using the axial shaft and cable lumen 132 in the manner described above, it is not necessary to provide an additional guidewire guide for use during insertion of left ventricular assist device 20.

[0270] For some applications, cavity 132 is additionally cleaned by ventricular assist device cleaning system 29 (e.g., Figure 1A Typically, during rotation of the drive cable, both the first outer tube 140 and the second outer tube 142 remain stationary. For some applications, the cleaning system 29 is connected to the inlet port 86 and the outlet port 88 (at Figure 7A-7Bii 、 Figure 11B and Figure 11C) controls the flow of a purge fluid (e.g., a fluid containing glucose or dextrose) through the drive cable 130. The fluid is configured to remove air from the space between the drive cable and the outer tube and / or reduce friction between the drive cable 130 (which rotates) and the outer tube 140 (which remains stationary during drive cable rotation), and / or reduce friction between the axial shaft 92 and the proximal support 116 and / or the distal support 118.

[0271] Reference again Figure 11A For some applications, a cleaning fluid is pumped between the first outer tube 140 and the second outer tube 142, and an opening 146 is provided in the first outer tube near the proximal support. For some applications, the cleaning fluid is pumped through a cleaning fluid passage 226 defined between the first outer tube and the second outer tube, as described below with reference to Figure 21 For some applications, the cleaning fluid flows between the first outer tube 140 and the drive cable 130 via the opening 146, as shown in FIG. Figure 11A 14. In this manner, the interface between the drive cable 130 (which rotates) and the outer tube 140 (which serves as the drive cable support tube and remains stationary during drive cable rotation) is cleaned. For some applications, some cleaning fluid additionally flows to the interface between the axial shaft and the proximal support 116, thereby cleaning that interface (and / or reducing friction at that interface), as shown in FIG. Figure 11A 14 is shown as the cleaning fluid flow arrow 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.

[0272] As mentioned above (ref. Figures 10A-10C ), the drive cable typically includes multiple coiled wires. For some applications, the cleaning fluid enters the cavity 132 defined by the drive cable through the gaps in the coiled wires. Once the cleaning fluid is disposed in the cavity 132, the cleaning fluid flows in the proximal and distal directions, such as Figure 11A As shown by arrow 151. Figure 11A As shown by arrow 152, the cleaning fluid flowing in the distal direction typically flows out of the distal end of the cavity 132 and flows toward the cavity 122 defined by the distal tip portion. At the end of the distal tip portion, the cleaning fluid is typically prevented from flowing out of the distal tip portion by a duckbill valve 390. Therefore, some of the cleaning fluid typically flows toward the interface between the axial shaft and the distal support 118, thereby cleaning the interface (and / or reducing friction at the interface), as shown in FIG. Figure 11A 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.

[0273] As described above, once the cleaning fluid is disposed within the cavity 132, the cleaning fluid flows in both the proximal and distal directions, as shown in FIG. Figure 11A As shown by arrow 151. Now refer to Figure 11B Typically, at the proximal end of ventricular assist device 20, the purge fluid flows in the direction of arrow 156 out of the proximal end of cavity 132 and then out of the proximal end of cavity 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 on driven magnet 82. For some applications, the purge fluid then flows in the direction of arrow 158 out of outlet port 88. Typically, the purge fluid is then disposed of. Alternatively, the purge fluid is pumped back into the device via inlet port 86.

[0274] With reference to the above description of the cleaning process typically used for the ventricular assist device 20, it should be noted that cavities 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.

[0275] Now refer to Figure 11C For some applications, the ventricular assist device includes an additional purge fluid inlet port 89, which is typically used to pump purge fluid into the channel 224 between the delivery catheter 143 and the outer tube 142. For some applications, the purge fluid is pumped into the channel at a sufficiently low pressure that aortic blood pressure can still be detected through the channel, as described elsewhere in this application. For some applications, rather than continuously pumping purge fluid into the 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. For example, pressure sensor 216 (which is in Figure 1A ) can be set at different locations within the channel 224, within the port 89 and / or in fluid communication with the channel 224.

[0276] refer to Figure 11D and Figure 11EFor some applications, the axial shaft 92 includes a cleaning fluid aperture configured to allow cleaning fluid to flow from the cavity 132 defined by the axial shaft 92. For some applications, the axial shaft defines a cleaning fluid aperture 190 adjacent the distal bushing 58 of the impeller 50. As described above, for some applications, the distal bushing is configured to be slidable relative to the axial shaft. For some such applications, the interface between the distal bushing and the axial shaft is cleaned by cleaning fluid flowing from the cleaning fluid aperture 190. For some applications, the axial shaft defines an aperture 192 adjacent the distal radial support 118. For some such applications, the interface between the distal radial support and the axial shaft is cleaned by cleaning fluid flowing from the cleaning fluid aperture 192. For some applications, the axial shaft defines an aperture 194 adjacent the proximal radial support 116. For some such applications, the interface between the distal radial support and the axial shaft is cleaned by cleaning fluid flowing from the cleaning fluid aperture 194.

[0277] Now refer to Figure 12A and Figure 12B , which are schematic diagrams of a ventricular assist device 20 that, according to some applications of the present invention, includes a liner 39 lining the interior of a frame 34 that houses an impeller 50. (For illustrative purposes, the liner 39 on the side of the device facing out of the page and the pump outlet tube 24 are shown in FIG. Figures 12A-12B ) For some applications, a liner 39 is disposed within frame 34 to provide a smooth inner surface through which blood is pumped by the impeller. Typically, by providing a smooth surface, the covering material reduces hemolysis caused by the impeller pumping blood relative to pumping blood between the impeller and the struts of frame 34. For some applications, the liner comprises polyurethane, polyester, and / or silicone. Alternatively or additionally, the liner comprises polyethylene terephthalate (PET) and / or polyether block amide .

[0278] 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). Figures 12A-12B For some applications, the pump outlet tube 24 also covers the cylindrical portion 38 of the frame 34, e.g., around the outside of the frame, so that the pump outlet tube 24 and the liner 39 overlap over at least 50% of the length of the liner, e.g., over the entire length of the cylindrical portion of the frame 34, e.g., as shown in FIG. Figure 12A For some applications, there is only a partial overlap between the pump outlet tube 24 and the liner 39, e.g. Figure 12BAs shown. For example, the pump outlet tube 24 can 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 positioned within the overlap region between the pump outlet tube and the liner, such that there is no longitudinal position in which the impeller, pump outlet tube 24, frame 34, and liner 39 all overlap one another. As described above, reference Figure 1D For some applications, the pump outlet tube 24 extends to the end of the distal tapered portion 40 of the frame and defines a plurality of lateral blood inlet openings. For some such applications, the cylindrical portion of the frame is lined with a liner 39 .

[0279] Typically, over any overlapping areas between the liner 39 and the pump outlet tube 24, the liner is shaped to form a smooth surface (e.g., to reduce hemolysis, as described above), and the pump outlet tube 24 is shaped to conform to the struts of the frame 34 (e.g., as described above). Figure 12A Typically, over the overlapping area between the liner 39 and the pump outlet tube 24, the pump outlet tube and the liner are coupled to one another, for example, via vacuum, via adhesive, and / or using a thermoforming process, such as described below.

[0280] For some applications, the liner 39 and the pump outlet tube 24 are made of different materials. For example, the liner can be made of polyurethane, while the pump outlet 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 pump outlet tube is made. For some applications where the liner and the pump outlet tube overlap along at least a portion of the frame 34 (e.g., along a cylindrical portion of the frame 34), the pump outlet tube and the liner are bonded to each other and / or to the frame in the following manner. Initially, the liner is placed over a mandrel. Subsequently, the frame is placed over the liner. Subsequently, the pump outlet tube 24 is placed around the outside of the frame. For some applications, in order to mold the pump outlet 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 pump outlet tube 24 but lower than the thermoforming temperature of the liner 39. Typically, a mandrel is used to heat the frame from the inside of the frame. Typically, when the frame is heated to the above-mentioned temperature, the outer tube (which is typically made of silicone) applies pressure to the pump outlet tube 24, causing the pump outlet tube 24 to be pushed radially inward so that the pump outlet tube conforms to the shape of the struts of the frame, such as Figure 12A For some applications, the combination of the frame, liner, and the portion of the pump outlet tube 24 disposed about the frame is then shaped to the desired shape and size using shaping techniques known in the art.

[0281] For some applications (not shown), the density of the struts of the frame at the distal end of the cylindrical portion of the frame is greater than the density of the struts within the rest of the cylindrical portion of the frame. For some such applications, the increased density of the struts of the frame at the distal end of the cylindrical portion of the frame helps to bond the liner and / or pump outlet tube to the frame. For some applications, the liner and / or pump outlet tube does not extend all the way to the end of the cylindrical portion of the frame, for example, as described in reference Figure 13 For some such applications, at the longitudinal location along the cylindrical portion of the frame where the liner and / or pump outlet tube terminates, the density of the struts of the frame is increased relative to other locations along the cylindrical portion of the frame.

[0282] Now refer to Figure 13 , which is a schematic diagram of a ventricular assist device 20 according to some applications of the present invention, in which at least a distal portion 333 of cylindrical portion 38 of frame 34 is uncovered. For some applications, during an axial reciprocating cycle of the impeller, even when the impeller is positioned at its most distal position within frame 34, the portion of the impeller at its maximum span does not advance beyond a given position within the cylindrical portion of the frame (e.g., as described above with reference to FIG. 1 ). Figures 10A-10C For some applications, a portion of the frame (which is disposed distally beyond this location) is not covered by the pump outlet tube 24 or the liner 39. (Note that for illustrative purposes, the frame is shown without the liner 39. However, for some applications, the frame is lined with the liner 39. Typically, even in such applications, the distal portion 333 of the cylindrical portion of the frame is not covered by the pump outlet tube 24 or the liner 39.)

[0283] For some applications, the uncovered distal portion of the cylindrical portion of the frame acts to actually widen the entrance because (e.g. Figure 13 (as indicated by the blood flow arrows in ) blood flows from the sides of the cylindrical portion of the frame into the cylindrical portion of the frame. For some applications, this reduces hemolysis produced by the impeller pumping the blood. Alternatively or additionally, the diameter of the pump portion 27 can be reduced when the pump portion is in its radially constrained configuration by leaving a portion of the cylindrical portion of the frame uncovered. For example, the pump portion can be radially constrained such that the widest portion of the impeller overlaps with the uncovered portion of the cylindrical portion of the frame so as to reduce the diameter of the pump portion of the ventricular assist device (relative to if the widest portion of the impeller overlaps with the covered portion of the cylindrical portion of the frame, such that the widest portion of the impeller overlaps with the frame and the covering material).

[0284] For some applications, the ventricular assist device is configured such that, even during diastole, an axial distance exists between the impeller position at its maximum diameter and the blood inlet opening. For example, the ventricular assist device is configured such that, during diastole, an axial distance greater than 3 mm (e.g., greater than 5 mm) exists between the impeller position at its maximum diameter and the blood inlet opening (e.g., as described above with reference to FIG. Figures 10A-10C For some such applications, this reduces hemolysis (relative to if there were less or no axial distance between the impeller at its maximum diameter and the blood inlet opening) and / or improves the efficacy of the impeller by reducing turbulence by allowing the streamlines of blood entering the blood inlet opening to become at least partially aligned with the longitudinal axis of the impeller before being pumped by the impeller.

[0285] Now refer to Figure 14 , which is a schematic diagram of a ventricular assist device 20 placed within a left ventricle 22 of a subject (showing a cross-sectional view of the left ventricle) in accordance with some applications of the present invention. For illustrative purposes, Figure 14 The aortic valve 26 is shown overlaid on a cross-section of the left ventricle, although the aortic valve lies in a different plane than the plane of the main cross-sectional view. Figures 15A-15D , which are schematic illustrations of a distal tip element 107 of a ventricular assist device according to some applications of the present invention, the distal tip element 107 being at least partially curved to define a curvature similar to a question mark, and also with reference to Figure 16A and Figure 16B , which are diagrams of a device disposed within the left ventricle of a subject, according to some applications of the present invention. Figure 15C-15D Schematic diagram of a ventricular assist device.

[0286] For some applications, the ventricular assist device is guided by a guidewire, which is used to insert the ventricular assist device 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., Figure 14Typically, 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 directed 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. Figure 14 and Figures 16A-16B shown.

[0287] Typically, as described above, the ventricular assist device is introduced into the ventricle of the subject over a guidewire. Distal tip portion 120 defines a cavity 122 such that the distal tip portion is maintained in a straight configuration during introduction of the ventricular assist device into the ventricle of the subject. For some applications, the distal tip portion is configured to assume its curved shape when the guidewire is removed. Note that Figures 15A-15D The shape of the distal tip portion 120 when initially formed is shown. Typically, due to the insertion of a guide wire through the lumen 122 (thereby temporarily straightening the distal portion), the curvature of the distal tip portion when deployed into the left ventricle of a subject is less than Figures 15A-15D For example, Figure 15C The curvature of the distal end portion is shown such that the curved portion of the distal end portion forms a complete loop. However, Figure 15C The distal end of Figure 16A is shown within the left ventricle of a subject, and the distal tip portion does not form a complete loop.

[0288] As described above, the distal end portion 120 typically forms a portion of the distal end element 107, which also includes the axial shaft receiving tube 126. Typically, the distal end element 107 is configured such that in its unconstrained configuration (i.e., in the absence of any forces acting on the distal end portion), the distal end element is at least partially curved. For some applications, within a given plane, the distal end 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 end element 107 defines a longitudinal axis 348. The curved portion of the distal end element 107 curves away from the longitudinal axis 348 in a first direction and then passes through an inflection point and curves in an opposite direction relative to the longitudinal axis 348. For example, as Figures 15A-15B As shown, in the plane of the paper, the distal tip element bends first toward the top of the paper and then toward the bottom of the paper, and as shown Figure 15C-15DAs shown, in the plane of the paper, the distal tip element bends first toward the bottom of the paper and then toward the top of the paper. Typically, when formed as Figures 15A-15D As shown, the distal tip element defines an overall curvature similar to a question mark or a tennis racket, with the distal tip element defining a ridge 351 on one side of the longitudinal axis of the straight proximal portion of the distal tip element. For some applications, the ridge is generally shaped as a semi-ellipse. (It should be noted that in this context, the term "semi-ellipse" includes a semi-circle. It should also be noted that in some cases, the tip does not define a precise semi-ellipse, but rather a ridge that is substantially similar to a semi-ellipse.)

[0289] like Figures 15A-15B As shown, for some applications, after passing the inflection point, the distal tip element continues to bend so that the distal tip element crosses back over the longitudinal axis 348 . Figure 15A An example is shown in which the end of the distal tip element has not yet crossed back onto the longitudinal axis again, and a large gap exists between the distal end of the distal tip element and the proximal end of the curved portion. Figure 15B 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 15C-15D 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.

[0290] refer to Figure 15C Typically, a hemostatic valve (e.g., duckbill valve 390) is disposed within a distal segment of the distal tip portion 120 and is configured to prevent blood from flowing into the cavity 122. Typically, the duckbill valve has a maximum width of less than 3 mm, such as less than 2 mm, and typically, the entire duckbill valve is disposed within a distal segment of the distal tip portion, which is disposed within a distal-most 10 mm of the distal tip portion, such as within a 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 end of the valve faces away from the distal end of the distal tip portion 120). Typically, the curvature of the curved portion of the distal tip element 107 is configured to provide an atraumatic tip to the ventricular assist device 20 when deployed within the left ventricle of the subject. More typically, the distal tip element is configured to separate the inlet opening 108 of the ventricular assist device from the wall of the left ventricle.

[0291] Now refer to Figure 16A and Figure 16B , first note that these figures show a cross-sectional view of the left ventricle 22, with the septal wall 338 disposed on the left side of the page and the free wall 334 disposed on the right side of the page. In this view, the left atrium 359 and the left atrial appendage 358 are visible above the left ventricle, and the right ventricle 340 is visible to the left of the left ventricle. Note that, as Figures 16A-16B (as well as Figure 17Ai-Figure 17D ) shows a view of the aorta and left ventricle that differs from, for example, Figure 1B The view shown. Figure 1B are schematic illustrations provided for illustrative purposes and do not necessarily appropriately depict the scale and orientation of the ventricular assist device relative to the anatomy.

[0292] 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.

[0293] Typically, distal tip element 107 is inserted into the left ventricle such that ridge 351 bulges toward septal wall 338. When arranged in this configuration, in response to distal tip element 107 being pushed toward the apex (e.g., due to advancement of the device by the physician or in response to movement of the left ventricle), blood inlet opening 108 is typically pushed toward free wall 334 and away from septal wall 338 (at Figure 16B Typically, this is due to the proximal straight portion 346 pivoting about the question mark-shaped curved portion, as shown. In contrast, other shaped tips, if arranged in a similar orientation, may result in the blood inlet opening being pushed toward the septum wall. For example, if the distal tip element has a pigtail tip (where the tip is curved along a single direction of curvature) that is oriented such that the pigtail curve is located on the free wall side of the longitudinal axis of the straight portion of the distal tip element, then 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.

[0294] refer to Figure 14-16B In all of the figures in the drawings, it is noted that the scope of the present invention includes the use of a question mark or tennis racket shaped distal tip element in combination with any ventricular assist device, even without other features and / or portions of the distal tip element 107 (e.g., the axial shaft receiving tube 126). It is also noted that typically, the curvature of the distal tip portion is all within a single plane.

[0295] Now refer to Figure 17Ai and Figure 17Aii, which are schematic illustrations of a ventricular assist device 20 having a balloon 220 disposed on its distal end element 107 that is configured to facilitate movement of the axial shaft 92 relative to the wall of the ventricle, according to some applications of the present invention.

[0296] As described above, typically, the axial shaft 92 passes through the axis of the impeller 50 via the cavity 62 of the impeller. More typically, the axial shaft is rigid, such as a rigid tube. The axial shaft itself 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 cavity 62 defined by the impeller. For some applications, the axial shaft enters the axial shaft receiving tube 126 of the distal end element 107. Typically, if the axial shaft bends, the friction between the axial shaft and the distal and radial supports will increase. Therefore, it is typically desirable to maintain the axial shaft in a straight configuration. For some applications, the balloon 220 provides the distal end of the distal end element with freedom of movement relative to the wall of the left ventricle in a manner that does not cause the proximal end of the distal end portion (which defines the axial shaft receiving tube) to undergo substantial movement. For example, as Figure 17Ai and Figure 17Aii As shown by the arrow near the apex 342 in FIG, the balloon can be rotated relative to the apex without causing substantial movement of the axial shaft receiving tube. Thus, even if the balloon undergoes movement relative to the apex (e.g., from Figure 17Ai to Figure 17Aii For some applications, a cleaning fluid is used, such as that of US2020 / 0237981 of Tunal. Figure 13 D. The balloon 220 is filled with the technique described in US2020 / 0237981, which is incorporated herein by reference.

[0297] Now refer to Figure 17Bi and Figure 17Bii , which are schematic illustrations of a ventricular assist device 20 according to some applications of the present invention, the device having a joint 230 configured to facilitate pivoting of its distal tip portion 120 relative to its axial shaft. As described above, for some applications, the distal tip element 107 includes an axial shaft receiving tube 126 and a distal portion 120. For some applications, the joint 230 allows the distal tip portion 120 to move relative to the axial shaft receiving tube 126. For example, the joint 230 can be a ball joint as shown, and / or it can be a swivel joint, and / or a universal joint. Thus, even if the distal tip portion undergoes motion relative to the apex 342 of the left ventricle (such as from Figure 17Bi to Figure 17Bii ), the axial shaft 92 also remains in a substantially straight configuration. For some such applications, the distal end portion 120 is shaped as described above.

[0298] Now refer to Figure 17C , which is a schematic diagram of a ventricular assist device according to some applications of the present invention, wherein outer tubes 140 and / or 142 are formed with a predetermined curvature such that the axial shaft 92 of the ventricular assist device remains in a substantially straight configuration when the axial shaft is disposed within the left ventricle 22 of the subject.

[0299] As mentioned above Figures 10A-10C As described, for some applications, the drive cable 130 is disposed within a first outer tube 140, which is configured to act as a drive cable support tube, and the first outer tube 140 remains stationary when the drive cable undergoes rotational and / or axial reciprocating motion. The first outer tube is configured to effectively act as a support along the length of the drive cable. For some applications, the first outer tube 140 is disposed within a second outer tube 142. For some applications, at least one of the first outer tube and the second outer tube is shaped so that the portion of the outer tube disposed within the aortic arch has a predetermined radius of curvature RC, which is greater than 18 mm and / or less than 32 mm (e.g., less than 24 mm), for example, 18-32 mm or 18-24 mm. For some applications, by defining such a radius of curvature, the axial shaft enters the left ventricle at such an angle that when the distal end portion of the ventricular assist device is disposed near the apex 342, the axial shaft is in a substantially straight configuration.

[0300] Now refer to Figure 17D , which is a schematic diagram of a ventricular assist device 20 according to some applications of the present invention, the device having a distal tip 240 configured to be anchored to tissue at the apex 342 of the left ventricle. For some applications, distal tip 240 is a screw-shaped element (e.g., a corkscrew-shaped element as shown), and the distal tip is configured to be screwed into tissue at the apex to anchor the distal end of the ventricular assist device to the apex. Typically, anchoring the distal tip at the apex reduces movement of the pump portion 27 relative to the internal structures of the left ventricle and thereby reduces the risk of damage to the internal structures of the left ventricle that may be caused by such movement.

[0301] Now refer to Figure 18A 、 Figure 18B and Figure 18C , these figures are schematic diagrams of distal radial supports 118 of ventricular assist devices according to corresponding applications of the present invention.

[0302] refer to Figure 18AFor some applications, the radial support is disposed within a support housing 119. For some such applications, the radial support and the support housing are made of corresponding, different materials from one another. For example, the radial support can be made of a first material having a relatively high hardness (e.g., ceramic), and the support housing can be made of a second material that is relatively easy to form into a desired shape, such as a metal or alloy (e.g., stainless steel, cobalt chromium, and / or nitinol). For some applications, the proximal radial support 116 is also disposed within the support housing, wherein the proximal radial support and the support housing are made of corresponding, different materials from one another (in a manner generally similar to that described with reference to the distal radial support 118). As described above, for some applications, the ventricular assist device includes a distal extension 121 that is configured to reinforce a region of the distal terminal element (in which the distal end of the shaft 92 moves) (e.g., the axial shaft receiving tube 126 described below, or a portion thereof). For applications where the distal radial support 118 is disposed within a support housing 119, the distal extension 121 typically comprises an extension extending from the support housing 119 rather than from the distal radial support itself. As described above, typically, at the distal end of the frame 34, the distal strut engagement portion 33 is placed into a recess defined by the outer surface of the distal radial support 118, the recess being shaped to conform to the shape of the distal strut portion. For some applications, the outer surface of the support housing (rather than the outer surface of the support) is shaped to define such a recess (the recess being formed by the distal strut engagement portion 33). Figure 18A and Figure 18B denoted by reference numeral 127 in FIG.

[0303] Now refer to Figure 18B , for some applications, a layer of material 123 is disposed between the radial support 118 and the support housing 119. For some applications, the material is configured to allow some movement of the radial support relative to the support housing, and / or to cushion such movement. For example, the layer of material may include a layer of elastomeric material. For some applications, the proximal radial support 116 has a similar configuration, wherein a material (e.g., an elastomeric material) is disposed between the radial support and the support housing, the material being configured to allow some movement of the radial support relative to the support housing, and / or to cushion such movement. For some such applications, by allowing movement between the radial support and the support housing, the layer of material allows some movement of the rigid axial shaft relative to the frame 34. For some applications, in this manner, the axial shaft 92 is permitted to become slightly misaligned with the longitudinal axis of the frame.

[0304] refer to Figure 18CFor some applications, an outer surface 125 of the distal radial support 118, which is adjacent to the inner surface of the support housing 119, has a convex curve. For some applications, the convexly curved outer surface of the support is configured to allow some movement of the radial support relative to the support housing. For some applications (not shown), the inner radial surface of the support housing (which is adjacent to the outer surface of the support) has a convex curve, for example to allow some movement of the radial support relative to the support housing. For some applications, the proximal radial support 116 has a similar configuration, wherein the outer surface of the support and / or the inner radial surface of the support housing has a convex curve. For some such applications, by allowing movement between the radial support and the support housing, the above-described shape of the support and / or the support housing allows movement of the rigid axial shaft relative to the frame 34. For some applications, in this manner, the axial shaft is allowed to become slightly misaligned with the longitudinal axis of the frame.

[0305] For some applications, the length of the radial supports allows the rigid axial shaft to move relative to the frame 34, such that the axial shaft is allowed to be slightly misaligned with the longitudinal axis of the frame. For example, the length of each of the proximal and distal radial supports can be less than 2 mm, less than 1.5 mm, or less than 1 mm, e.g., 0-1.5 mm, or 0.5-1 mm.

[0306] Now refer to Figure 19A , which is a schematic diagram of a ventricular assist device 20 according to some applications of the present invention, wherein the pump outlet tube 24 of the device is configured to become curved as blood is pumped through the pump outlet tube, and the pump outlet tube is rotatable relative to the distal end portion 120 of the ventricular assist device. Also refer to Figure 19B , which is in accordance with some applications of the present invention in the absence of other components of a ventricular assist device Figure 19A Schematic diagram of the pump outlet pipe 24. Figure 19C , which is disposed within the aorta 30 and left ventricle 22 of a subject according to some applications of the present invention. Figures 19A-19B Schematic diagram of a ventricular assist device 20. Note that Figure 19C The views of the aorta and left ventricle shown are different from e.g. Figure 1B The view shown. Figure 1B is a schematic illustration provided for illustrative purposes and does not necessarily accurately depict the scale and orientation of the ventricular assist device relative to the anatomy. Note also that Figure 19C The views of the aorta and left ventricle shown are different from e.g. Figures 16A-16B and Figure 17Ai-Figure 17D The view shown. Figure 19C 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.

[0307] As described above, for some applications, along the proximal portion of the pump outlet tube 24, the frame 34 is not disposed within the tube, and thus the tube is not supported in an open position by the frame 34. The tube 24 is typically made of a collapsible material that is impermeable to blood. For example, the tube 24 may include polyurethane, polyester, and / or silicone. Alternatively or additionally, the tube may be made of polyethylene terephthalate (PET) and / or polyether block amide. Typically, the proximal portion of the tube is configured to be placed such that it is at least partially disposed within the ascending aorta of the subject. For some applications, the proximal portion of the tube passes through the aortic valve of the subject, from the left ventricle of the subject into the ascending aorta of the subject, such as Figure 1B As described above, the tube typically defines one or more blood inlet openings 108 at the distal end of the tube through which blood flows from the left ventricle into the tube during impeller operation. For some applications, the proximal portion of the tube defines one or more blood outlet openings 109 through which blood flows from the tube into the ascending aorta during impeller operation. During impeller operation, blood pressure through the tube typically maintains the proximal portion of the tube in an open state.

[0308] For some applications, the pump outlet tube 24 is pre-formed so that during operation of the impeller, when the pressure of blood flow through the tube holds the proximal portion of the tube in an open state, the tube is curved. Typically, the curvature is such that when the proximal end of the tube is positioned within the aorta, at least a portion of the tube is positioned within the left ventricle and curves away from the posterior wall of the left ventricle, toward the apex of the left ventricle, and / or toward the free wall. Further, more typically, the curvature is such that when the proximal end of the tube is positioned within the aorta, at least a portion of the tube is positioned within the left ventricle and curves away from the septal wall of the left ventricle, toward the apex of the left ventricle, and / or toward the free wall. For some applications, the curvature of the tube maintains a spacing 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, the sclera chordae, and / or the papillary muscles 341), such as Figure 19C shown.

[0309] Typically, the tube 24 is preformed using blow molding in a curved mold, or preformed using a forming mold after the blow molding process or immersion process. Typically, the distal portion of the tube (wherein the frame 34, impeller 50, and axial shaft 92 are provided) is maintained in a straight and open configuration by the frame 34. The portion of the tube located proximal to the frame 34 and disposed within the left ventricle is typically shaped to define the above-mentioned curvature. For some applications, the curvature is such that the angle gamma between the longitudinal axis of the tube at the proximal end of the tube and the longitudinal axis of the tube at the distal end of the tube is greater than 90 degrees (e.g., greater than 120 degrees, or greater than 140 degrees), and / or less than 180 degrees (e.g., less than 160 degrees, or less than 150 degrees), for example, 90 degrees to 180 degrees, 90 degrees to 160 degrees, 120 degrees to 160 degrees, or 140 degrees to 150 degrees. For some applications, the curvature of the tube is such that the surface of the tube located inside the bend defines a radius of curvature R that is greater than 10 mm, such as greater than 20 mm, and / or less than 200 mm (e.g., 100 mm), such as 10 mm to 200 mm, or 20 mm to 100 mm. (In Figure 19B A dotted circle with a dashed line across its diameter is shown to indicate how the radius of curvature R is measured.

[0310] Note that, as referenced Figures 19A-19C As described, the pump outlet tube 24 is configured such that (a) in the absence of blood flowing through the tube, the tube typically collapses in response to the pressure outside the tube exceeding the pressure inside the tube, and (b) when blood flows through the tube at a sufficient rate such that the pressure inside the tube exceeds the pressure outside the tube, the tube assumes its pre-formed curved configuration. It should also be noted that when the tube 24 assumes its curved configuration, the tube typically causes the portion of the drive cable 130 disposed within the curved portion of the tube to also become curved, as shown in FIG. Figure 19A and Figure 19C 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, outer tubes 140 and / or 142 (which are disposed around the drive cable) are shaped to define a bend, and the outer tubes cause the drive cable and tube 24 to assume the curved shape. For some applications, both outer tubes 140 and / or 142 and tube 24 are shaped to define a curved shape.

[0311] Now refer to Figure 19D-19E , these figures are schematic diagrams of a ventricular assist device 20 having a pump outlet tube 24 configured to become curved as blood is pumped through the tube, according to some applications of the present invention. Figure 19D and Figure 19E , tube 24 is shown without other components of the ventricular assist device (eg, impeller 50, frame 34, etc.) for illustrative purposes. Figure 19Eis disposed within the aorta 30 and left ventricle 22 of a subject according to some applications of the present invention, Figure 19D Schematic diagram of a ventricular assist device 20. Figure 19E The view of the left ventricle shown is similar to Figure 19C For some applications, the inlet opening 108 and / or outlet opening 109 are arranged in a non-axisymmetric configuration about the tube 24. Typically, the tube 24 defines the location of the inlet opening and / or outlet opening so that the tube 24 becomes curved and / or remains as shown in FIG. Figures 19A-19C The curvature of described tube 24. For example, as shown in the figure, the blood inlet hole can be arranged on one side of the inboard of the bend of tube 24 (or on the inboard of the desired bend of 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 tube 24 is pulled toward this area (as shown by arrow 310). Alternatively or additionally, blood outlet opening 109 can be arranged on one side of the inboard of the bend of tube 24 (or on the inboard of the desired bend of tube). As blood flows out of the blood outlet opening, blood impacts the aortic wall, which causes the proximal end of tube 24 to be pushed in the opposite direction (i.e. the direction of arrow 312).

[0312] As reference Figures 19A-19C Typically, as Figure 19E As shown, the curvature of the pump outlet tube is such that the spacing 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, the sclera and / or the papillary muscles 341) is maintained. Typically, the curvature is such that when the proximal end of the tube is positioned within the aorta, at least a portion of the tube is positioned within the left ventricle and curves away from the posterior wall of the left ventricle, toward the apex of the left ventricle and / or toward the free wall. Further, more typically, the curvature is such that when the proximal end of the tube is positioned within the aorta, at least a portion of the tube is positioned within the left ventricle and curves away from the septal wall of the left ventricle, toward the apex of the left ventricle and / or toward the free wall.

[0313] For some applications, when the ventricular assist device is deployed into the left ventricle, the distal tip portion is deployed first. As described above, the distal tip portion is typically deployed in a given orientation relative to the left ventricular anatomy. Typically, after the distal tip portion is deployed, the pump outlet tube is deployed. In some cases, the distal tip portion has already been deployed in a desired orientation relative to the left ventricular anatomy, and the curved portion of the tube is not positioned in the desired orientation within the left ventricle. Therefore, for some applications, the distal tip portion is retracted via joint 212 (which allows the pump outlet tube to rotate relative to the distal tip portion of the ventricular assist device, such as Figures 19A-19EThe joint may be a rotary joint and / or a ball joint (e.g., as shown by arrow 210 in FIG. 1 ) connected to the pump outlet pipe (directly or indirectly). Figure 17Bi-Figure 17Bii ball joint 230 shown), and / or universal joints (e.g., Figures 20A-20C For some applications, the connector is disposed within the proximal portion of the distal tip element 107. Alternatively or additionally, a connector is disposed between the distal tip portion 120 and the axial shaft receiving tube 126 (e.g., as shown in FIG. Figure 17Bi-Figure 17Bii shown).

[0314] Now refer to Figure 19F , which is a schematic diagram of a ventricular assist device 20 according to some applications of the present invention, the ventricular assist device including a bending element 218 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. Figures 19A-19E As an alternative to or in addition to the above, the ventricular assist device includes a bending element 218. 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 a hole or slit so that the tube can be preformed into a desired curved shape. For example, the Nitinol element can be a Nitinol "hypotube" (i.e., a Nitinol tube having microengineered features along its length) as known in the art. Typically, the bending element 218 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.

[0315] For some applications, the bending element is shaped to have a curvature that is substantially similar to the reference Figures 19A-19E The curvature described relative to tube 24. For some applications, the curvature is such that the angle omega 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, 90-180 degrees, 90-160 degrees, 120-160 degrees, or 140-150 degrees. For some applications, the curvature of the tube is such that the surface of the bending element located inside the bend defines a radius of curvature greater than 10 mm, 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 in reference Figures 19A-19CAs described, the curvature of the tube typically maintains a spacing between the blood inlet 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, the sclera, and / or the papillary muscles 341). Figure 19C Typically, the curvature is such that when the proximal end of the tube is positioned within the aorta, at least a portion of the tube is positioned within the left ventricle and curves away from the posterior wall of the left ventricle, toward the apex of the left ventricle, and / or toward the free wall. Still more typically, the curvature is such that when the proximal end of the tube is positioned within the aorta, at least a portion of the tube is positioned within the left ventricle and curves away from the septal wall of the left ventricle, toward the apex of the left ventricle, and / or toward the free wall.

[0316] For some applications, when the ventricular assist device is deployed within the left ventricle, the distal tip portion is deployed first. As described above, the distal tip portion is typically deployed in a given orientation relative to the left ventricular anatomy. Typically, after the distal tip portion is deployed, the bending element 218 is deployed. In some cases, the distal tip portion has already been deployed in a desired orientation relative to the left ventricular anatomy and the bending element 218 is not positioned within the left ventricle in the desired orientation. Therefore, for some applications, the distal tip portion is rotated relative to the distal tip portion of the ventricular assist device via the connector 212 (which allows the pump outlet tube to rotate relative to the distal tip portion of the ventricular assist device, such as Figures 19A-19E 210) is coupled to the bending element 218 (directly or indirectly). For example, the joint may be a rotary joint and / or a ball and socket joint (e.g., as shown in FIG. Figure 17Bi-Figure 17Bii ball joint 230 shown), and / or universal joints (e.g., Figures 20A-20C For some applications, the connector is disposed within the proximal portion of the distal tip element 107. Alternatively or additionally, a connector is disposed between the distal tip portion 120 and the axial shaft receiving tube 126 (e.g., as shown in FIG. Figure 17Bi-Figure 17Bii shown).

[0317] refer to Figures 19A-19F Note that for some applications, tube 24 adopts a curved shape as outer tube 142 is anchored to the aorta and distal tip portion 120 becomes anchored to the left ventricular inner wall (e.g., the free wall near the apex), as described above. Note also that Figures 16A-16B The curvature of the tube shown is less than Figures 19A-19F The curvature of the tube is shown because Figures 16A-16B Different views of the device are shown. Figures 16A-16B In the view shown, the curvature is typically not as good as Figures 19A-19F The view shown is obvious.

[0318] Now refer to Figures 20A-20C, which are schematic diagrams of a ventricular assist device 20 according to some applications of the present invention, wherein the axial shaft 92 of the device includes a joint 232 (e.g., a universal joint as shown). As shown, the joint is typically disposed within a portion of the axial shaft that is configured to be disposed between the proximal bushing 64 and the distal bushing 58 of the impeller. Note that in Figure 20A In the figures, portions of the impeller (e.g., membrane 56 and spring 54 of material) are not shown for illustration purposes and to provide visibility of that portion of the axial shaft which is typically disposed between proximal and distal bushings 64, 58 of the impeller within a cavity 62 defined by the impeller (e.g., cavity 62 is located between the proximal and distal bushings 64, 58 of the impeller). Figure 3A-3C Alternatively, the joint is provided at a different location along the axial shaft, such as proximal to the impeller or distal to the impeller.

[0319] For some applications, a joint 232 is disposed between a proximal portion 234 of the axial shaft and a distal portion 236 of the axial shaft, with the proximal portion 234 and the distal portion 236 being coupled to one another by the joint such that the proximal portion and the distal portion can bend relative to one another by the joint. Typically, the joint allows the axial shaft to adopt a shape that is consistent with the curvature of other portions of the left ventricular device and / or the anatomy of the subject. For some applications, the joint is configured to allow the axial shaft to conform to the curvature of the frame 34 such that even if the frame 34 becomes slightly bent, the proximal portion of the axial shaft remains coaxially disposed relative to the proximal support 116 and the distal portion of the axial shaft remains coaxially disposed relative to the distal support 118.

[0320] Figure 21 is a schematic diagram of a ventricular assist device including one or more blood pressure measuring tubes 222 according to some applications of the present invention. As described above, the ventricular assist device typically includes a pump outlet tube 24 that passes through the aortic valve of the subject such that the proximal end of the tube is disposed within the subject's aorta and the distal end of the tube is disposed within the subject's left ventricle. Typically, a blood pump (which typically includes an impeller 50) is disposed within tube 24, within the subject's left ventricle, and is configured to pump blood from the left ventricle into the subject's aorta through tube 24. For some applications, the ventricular blood pressure measuring tube 222 is configured to extend to at least an outer surface 213 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 patient's blood flow outside of 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 1ATypically, the pressure sensor measures the blood pressure of the subject outside of tube 24 (i.e., the left ventricular blood pressure) by measuring the blood pressure in the left ventricular blood pressure measuring tube. Typically, the blood pressure measuring tube 222 extends from the outside of the subject to an opening 214 at the distal end of the tube, and the pressure sensor 216 is positioned toward the proximal end of the tube, for example, outside the subject's body. For some applications, the computer processor 25 ( Figure 1A ) receives an indication of the measured blood pressure and controls the pumping of blood by the impeller in response to the measured blood pressure.

[0321] For some applications, the ventricular assist device includes two or more such ventricular blood pressure measurement tubes 222, such as Figure 21 ventricular blood pressure measurement tube 222 is shown in FIG. For some applications, based on the blood pressure measured within each left ventricular blood pressure measurement tube, computer processor 25 determines whether the opening of one of the two or more ventricular blood pressure measurement tubes is blocked. This may occur, for example, due to the opening contacting the intraventricular septal wall and / or a different intraventricular portion. Typically, in response to determining that the opening of one of the two or more ventricular blood pressure measurement tubes is blocked, the computer processor determines the subject's left ventricular pressure based on the blood pressure measured within another of the two or more ventricular blood pressure measurement tubes.

[0322] For some applications, outer tube 142 defines a groove 215 in a portion of the outer surface of the outer tube that is configured to be disposed within tube 24. Typically, during insertion of a ventricular assist device into a subject, the portion of ventricular blood pressure measuring tube 222 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.

[0323] For some applications (not shown), the distal portion of the blood pressure measurement tube 222 is disposed outside of the pump outlet tube 24. For example, the blood pressure measurement tube 222 can extend from the outer tube 142 to the proximal end of the pump outlet tube 24, after which the blood pressure measurement tube can be embedded in the outer surface of the pump outlet tube 24, as shown, for example, in FIG16D of US 10,881,770 to Tuval, which is incorporated herein by reference.

[0324] As described above, for some applications, the drive cable 130 extends from the 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 first outer tube 140 and the second outer tube 142, as described above. For some applications, the proximal portion of the blood pressure measurement tube 222 includes a passageway between the first outer tube 140 and the second outer tube 142, such as Figure 212 is a cross-sectional view of the embodiment of the present invention. In this regard, it should be noted that the blood pressure measurement tube should be understood to refer to the continuous cavity within the left ventricle of the subject extending from the pressure sensor 216 to the outside of the pump outlet tube 24, regardless of whether there are structural changes in the cavity along the length of the cavity. As described above, a cleaning fluid is also typically pumped between the outer tube 140 and the outer tube 142, and for some applications, the cleaning fluid is pumped through the channel 226. Typically, the blood pressure measurement tube 222 occupies more of the cross-sectional area defined between the outer tube 140 and the outer tube 142 than the cleaning fluid channel 226. Figure 21 For example, the ratio of (a) the cross-sectional area defined between outer tube 140 and outer tube 142 occupied by the blood pressure measurement tube to (b) the cross-sectional area defined between outer tube 140 and outer tube 142 occupied by the cleaning fluid channel 226 is typically greater than 3:2, greater than 3:1, or greater than 5:1. For some applications, the blood pump measurement tube occupies a relatively large proportion of the cross-sectional area defined between outer tube 140 and outer tube 142 in order to communicate the blood pressure outside of pump outlet tube 24 within the subject's left ventricle proximally to pressure sensor 216.

[0325] Now refer to Figure 22A and Figure 22B , which are schematic illustrations of a sterile sleeve 242 configured to form a seal between a delivery catheter 143 and the outer tube 142 of a ventricular assist device 20, according to some applications of the present invention. For some applications (not shown), the delivery catheter 143 is inserted into an artery (e.g., a femoral artery or a radial artery) of a subject via an introducer sheath (not shown), which is inserted into an incision in the artery and typically remains in place within the artery throughout operation of the ventricular assist device. For such applications, a sterile sleeve (substantially similar to Figures 22A-22B A sleeve (not shown) is typically positioned between the delivery catheter 143 and an introducer sheath (not shown) to allow movement between the delivery catheter and the introducer sheath while maintaining the sterility of the arteriotomy.

[0326] For some alternative applications, the VAD is initially inserted into the arteriotomy via an introducer sheath, which is then removed for the remainder of the VAD operation. For example, the VAD can be inserted via a peel-away introducer sheath. Subsequently, the delivery catheter is typically placed in direct contact with the arteriotomy. Typically, this reduces the diameter of the device positioned within the arteriotomy during the remainder of the procedure, relative to a scenario where the introducer sheath remains within the arteriotomy during the entire operation of the VAD. For example, the outer diameter of the delivery catheter may be less than 3.3 mm (i.e., 10 French), and this is the diameter that passes through the incision once the introducer sheath is removed. The inner diameter of the delivery catheter is typically less than 3 mm (i.e., 9 French), for example, the inner diameter may be 2.7 mm (i.e., 8 French). In contrast, if the introducer sheath remains in place during the entire operation of the VAD, this will increase the diameter of the device that passes through the incision because the thickness of the introducer sheath wall must be additionally accommodated by the incision. For example, it may increase the diameter by 0.3-0.6 mm (i.e., approximately 1-2 French).

[0327] For some such applications, the delivery catheter is advanced until the distal end of the delivery catheter is positioned at a given location within the subject's aorta (e.g., within the ascending aorta). Subsequently, the pump portion 27 of the ventricular assist device is advanced relative to the distal end of the delivery catheter by advancing the outer tube 142 relative to the delivery catheter. For such applications, the sterile sleeve 242 forms a seal between the delivery catheter 143 and the outer tube 142 of the ventricular assist device 20, e.g., allowing the outer tube to move relative to the delivery catheter while maintaining the sterility of the arteriotomy. For some such applications, the ventricular assist device is provided to the user in the form of a kit comprising the sterile sleeve 242 positioned in an appropriate location between the outer tube 142 and the delivery catheter 143.

[0328] Now refer to Figures 23A-23C , which is a schematic diagram of an end straightening element 270 for straightening the distal end portion 120 of the ventricular assist device 20 during insertion of the guidewire 10 through the distal end portion 120 of the ventricular assist device 20 according to some applications of the present invention. As described above, the ventricular assist device is typically inserted into a ventricle of a subject over the guidewire 10, with the ventricular assist device being disposed in a radially constrained (i.e., crimped) configuration within a delivery catheter 143 (e.g., as shown in FIG. Figure 1BTypically, a guide wire is first inserted into the ventricular assist device at the distal end of the distal tip element 107. For some applications, to facilitate insertion of the guide wire through the distal end of the distal tip element (i.e., through the distal tip portion 120), a tip straightening element 270 is positioned around the distal tip element, for example to maintain the distal tip element in a straightened configuration. Typically, the straightening element is a housing that defines a straightened cavity 271. The straightening element is positioned around the distal tip element such that the distal tip element is disposed in a straightened configuration within the cavity 271 and the guide wire is inserted into the distal end of the distal tip element (i.e., through the distal portion 120), for example, as Figure 23B For some applications, the straightening element is configured to be removable from the distal tip element, while the guide wire is disposed in the distal tip element. For example, the straightening element may be scored, perforated, and / or have a slit 272 (as shown) passing along its length to facilitate removal of the straightening element from the distal tip element, e.g., Figure 23C shown.

[0329] Now refer to Figure 24A 、 Figure 24B and Figure 24C , which are graphs showing measurement results performed during use of a left ventricular assist device according to some applications of the present invention. The left ventricular assist device described herein was deployed in a porcine heart. The porcine arterial pulsation was measured using an intra-aortic pressure sensor while the left ventricular assist device was operated at a corresponding rotational rate. Based on in vitro tests performed on the device, the device was calibrated to determine the flow rate generated by the device when the impeller rotated at a corresponding rotational rate. Figure 24A A plot of arterial pulsation versus flow produced by the device is shown, as measured in experiments conducted on pigs (using a predetermined correspondence between impeller rotation rate and flow). Figure 24A The points shown in the figure are fitted into a curve, and the curve is extrapolated to the y-intercept (i.e., the arterial pulsation is zero), as shown in Figure 24B As shown in the figure, by extrapolating the curve, the flow rate at zero arterial pulsation is estimated to be 5.6 L / min. In the same pig, cardiac output was measured using a Swan-Ganz catheter when the left ventricular assist device was inactive. The pig's natural cardiac output, measured by the Swan-Ganz catheter, was 5.2 L / min, which is similar to the flow rate at zero arterial pulsation estimated by extrapolating the flow / arterial pulsation curve. It is assumed that, at zero arterial pulsation, the left ventricular device largely replaces the heart's natural function and that the flow rate generated by the pump at this value provides a reasonable approximation to the subject's natural cardiac output.

[0330] Based on the above experimental results, for some applications of the present invention, during operation of a ventricular assist device, a subject's arterial pulsation is measured and parameters derived from the subject's arterial pulsation. Typically, as the impeller rotation rate increases, the flow rate generated by the blood pump increases. Typically, the flow rate generated by the blood pump is non-pulsatile because the blood pump is a continuous-flow blood pump rather than a pulsatile blood pump. Therefore, typically, as the impeller rotation rate increases and the flow rate generated by the blood pump increases, the subject's arterial pulsation decreases. In some applications, the subject's arterial pulsation is measured as the impeller rotation rate changes. Based on these measurement results, a relationship between the arterial pulsation and the impeller rotation rate and / or pump flow rate is derived. In some applications, based on this relationship, the subject's natural cardiac output can be derived. For some such applications, the relationship between the subject's arterial pulsation and pump flow rate is extrapolated to determine what the pump flow rate would be when the subject's arterial pulsation reaches zero. Based on these results, it is assumed that at this value, the pump is replacing the heart's natural function, and the flow rate generated by the pump at this value provides an approximation of the subject's natural cardiac output.

[0331] About Reference Figures 1A-24C All aspects of the ventricular assist device 20 described, it should be noted that although Figure 1A and Figure 1B A 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 subject's pulmonary valve and the techniques described herein are applied. For some applications, components of the device 20 are applicable to different types of blood pumps. For example, aspects of the present invention may be applicable to 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, and the like. Alternatively or additionally, the device 20 and / or a portion thereof (e.g., the impeller 50, even without the tube 24) may be placed in a different part of the subject's body to assist in pumping blood from that part. For example, the device 20 and / or a portion thereof (e.g., the impeller 50, even without the tube 24) may be placed in a blood vessel and may be used to pump blood through the 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 present invention includes use of the apparatus and methods described herein in anatomical locations other than the left ventricle and aorta, ventricular assist devices and / or portions thereof are sometimes referred to herein (in the specification and claims) as blood pumps.

[0332] The scope of the present invention includes combining any of the apparatus and methods described herein with any of the apparatus and methods described in one or more of the following applications, all of which are incorporated herein by reference:

[0333] Tuval’s US 2020 / 0237981, filed on January 23, 2020, and titled “Distal tip element for a ventricular assist device,” claims priority to:

[0334] U.S. Provisional Patent Application 62 / 796,138, filed by Tuval on January 24, 2019, entitled “Ventricular assist device”;

[0335] U.S. Provisional Patent Application 62 / 851,716, filed by Tuval on May 23, 2019, entitled “Ventricular assist device”;

[0336] U.S. Provisional Patent Application No. 62 / 870,821, filed by Tuval on July 5, 2019, entitled “Ventricular assist device”; and

[0337] Tuval’s U.S. provisional patent application 62 / 896,026, titled “Ventricular assist device,” filed on September 5, 2019.

[0338] Tuval’s US 10,881,770, which is a continuation of Tuval’s international application No. PCT / IB2019 / 050186, filed on January 10, 2019, entitled “Ventricularassist device” (published as WO19 / 138350), claims the following priority:

[0339] U.S. Provisional Patent Application 62 / 615,538, filed by Sohn on January 10, 2018, entitled “Ventricular assist device”;

[0340] U.S. Provisional Patent Application 62 / 665,718, filed by Sohn on May 2, 2018, entitled “Ventricular assist device”;

[0341] U.S. Provisional Patent Application 62 / 681,868, filed by Tuval on June 7, 2018, entitled “Ventricular assist device”; and

[0342] U.S. Provisional Patent Application 62 / 727,605, filed by Tuval on September 6, 2018, entitled “Ventricular assist device”;

[0343] Tuval’s US 2019 / 0269840, which is the U.S. national phase application of Tuval’s international patent application PCT / IL2017 / 051273, filed on November 21, 2017 (published as WO18 / 096531), entitled “Bloodpumps,” which claims priority to Tuval’s U.S. provisional patent application No. 62 / 425,814, filed on November 23, 2016;

[0344] Tuval’s US 2019 / 0175806, a continuation of Tuval’s international application No. PCT / IL2017 / 051158, filed on October 23, 2017 (published as WO18 / 078615), entitled “Ventricular assist device,” which claims priority to Tuval’s US 62 / 412,631, filed on October 25, 2016, and Tuval’s US 62 / 543,540, filed on August 10, 2017;

[0345] Tuval’s US 2019 / 0239998, which is the U.S. national phase application of Tuval’s international patent application PCT / IL2017 / 051092, filed on September 28, 2017 (published as WO18 / 061002), entitled “Bloodvessel tube,” which claims priority to Tuval’s U.S. provisional patent application No. 62 / 401,403, filed on September 29, 2016;

[0346] US 2018 / 0169313 to Schwammenthal, which is the U.S. national phase application of Schwammenthal’s international patent application PCT / IL2016 / 050525, filed on May 18, 2016, and entitled “Blood pump,” published as WO 16 / 185473, which claims priority to U.S. provisional patent application 62 / 162,881, filed on May 18, 2015, and entitled “Blood pump”;

[0347] US 10,583,231 to Schwammenthal, which is the U.S. national phase of Schwammenthal’s international patent application PCT / IL2015 / 050532, filed on May 19, 2015, entitled “Blood pump” (published as WO 15 / 177793), which claims priority to Schwammenthal’s U.S. provisional patent application 62 / 000,192, filed on May 19, 2014, entitled “Blood pump”;

[0348] Schwammenthal’s U.S. Patent No. 10,039,874, which is the U.S. national phase of Schwammenthal’s international patent application PCT / IL2014 / 050289, filed on March 13, 2014, and entitled “Renal pump,” published as WO 14 / 141284, which claims priority to (a) Schwammenthal’s U.S. provisional patent application No. 61 / 779,803, filed on March 13, 2013, and entitled “Kidney pump,” and (b) Schwammenthal’s U.S. provisional patent application No. 61 / 914,475, filed on December 11, 2013, and entitled “Renal pump”;

[0349] U.S. Patent No. 9,764,113, entitled “Curved catheter,” issued to Tuval on September 19, 2017, claiming priority to U.S. Provisional Patent Application No. 61 / 914,470, filed by Tuval on December 11, 2013, entitled “Curved catheter”; and

[0350] Tuval’s US 9,597,205 is the U.S. national phase of Tuval’s international patent application PCT / IL2013 / 050495, filed on June 6, 2013, and entitled “Prosthetic renal valve,” published as WO 13 / 183060, which claims priority to Tuval’s U.S. provisional patent application 61 / 656,244, filed on June 6, 2012, and entitled “Prosthetic renal valve.”

[0351] Those skilled in the art will recognize that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described hereinabove, as well as variations and modifications of the present invention that are not in the prior art and that would occur to those skilled in the art upon reading the foregoing description.

Claims

1. A device comprising: A ventricular assist device, comprising: an impeller configured to be placed within the left ventricle of a subject; motor; a drive magnet coupled to the motor and configured to be rotated by the motor; a driven magnet magnetically coupled to the driving magnet and configured to be rotated by the driving magnet; a drive cable extending from the driven magnet and configured to transfer rotational motion from the driven magnet to the impeller; a set of sensors configured to detect a magnetic phase difference between the driven magnet and the driving magnet; and A computer processor is configured to receive the detected magnetic phase difference and determine a physiological parameter of the subject responsive at least in part to the detected magnetic phase difference.

2. The device according to claim 1, wherein The set of sensors is further configured to measure a magnetic flux amplitude signal, and wherein the computer processor is configured to determine a physiological parameter of the subject based at least in part on a combination of the magnetic flux amplitude signal and the detected magnetic phase difference.

3. The device according to claim 1, wherein The computer processor is configured to determine a pressure differential between a left ventricle of the subject and an aorta of the subject responsive at least in part to a magnetic phase difference between the driven magnet and the driving magnet.

4. The apparatus according to claim 1, wherein The computer processor is configured to determine a left ventricular pressure of the subject responsive at least in part to a magnetic phase difference between the driven magnet and the driving magnet.

5. The apparatus according to claim 1, wherein The computer processor is configured to determine an event in a cardiac cycle of the subject responsive at least in part to a magnetic phase difference between the driven magnet and the driving magnet.

6. The device according to any one of claims 1 to 5, wherein: The set of sensors includes a first magnetometer configured to measure a magnetic phase of the driven magnet and a second magnetometer configured to measure a magnetic phase of the driving magnet.

7. The apparatus according to claim 6, wherein The second magnetometer is configured to measure the magnetic phase of the drive magnet by measuring the magnetic phase of the motor.

8. The apparatus according to any one of claims 1 to 5, wherein: The computer processor is configured to receive a signal indicative of a current draw of the motor and to determine a physiological parameter of the subject based at least in part on a combination of the current draw of the motor and the detected magnetic phase difference.

9. The apparatus according to claim 8, wherein The set of sensors is further configured to measure a magnetic flux amplitude signal, and wherein the computer processor is configured to determine a physiological parameter of the subject based at least in part on a combination of the current draw of the motor, the magnetic flux amplitude signal, and the detected magnetic phase difference.

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