Ventricular assist device

Abstract

Devices and methods including a ventricular assist device (20) are described. An impeller (50) is placed within a left ventricle of a subject, the impeller defining a cavity (62) therethrough. A frame (34) is disposed about the impeller, with a proximal bearing (116) disposed at a proximal end of the frame and a distal bearing (118) disposed at a distal end of the frame. An axial shaft (92) passes through the proximal bearing (116), the cavity (62) defined by the impeller, and the distal bearing (118). A motion dampening spring (68) is disposed about the axial shaft (92) between a distal end of the impeller (50) and the distal bearing (118), the motion dampening spring (68) configured to dampen axial motion experienced by the impeller (50). Other applications are also described.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to the following applications:

[0003] Tuval's U.S. Provisional Patent Application No. 63 / 254,321, entitled "Ventricular assist device," filed on October 11, 2021; and

[0004] Tuval filed U.S. Provisional Patent Application No. 63 / 317,199 on March 7, 2022, entitled “Ventricular assist device”.

[0005] The two aforementioned U.S. provisional applications are incorporated herein by reference.

[0006] Field of the Invention

[0007] Some applications of this invention generally relate to medical devices. Specifically, some applications of this invention relate to ventricular assist devices and methods of using them.

[0008] background

[0009] Ventricular assist devices (VADs) are mechanical circulatory support devices designed to assist and unload the heart chambers to maintain or increase cardiac output. These VADs are used in patients with heart failure and those at risk of cardiac deterioration during percutaneous coronary intervention. Most commonly, left ventricular assist devices are administered to defective hearts to assist left ventricular function. In some cases, right ventricular assist devices are used to assist right ventricular function. These VADs may be designed for permanent implantation or placed on a catheter for temporary placement.

[0010] Overview of the Implementation Examples

[0011] According to some applications of the invention, the ventricular assist device includes a motion buffer spring. As described in further detail below, typically, during operation of the ventricular assist device, i.e., when the impeller of the ventricular assist device rotates, the impeller undergoes axial reciprocating motion. For some applications, when the impeller undergoes axial reciprocating motion, the motion buffer spring is configured to act as a shock absorber to cushion the motion. As the impeller moves distally from a contracted position to a diastolic position, the motion buffer spring becomes more compressed. For some applications, the impeller is configured to be radially constrained (i.e., crimped) by becoming axially elongated, and the motion buffer spring is configured to be compressed to accommodate the axial elongation of the impeller.

[0012] For some applications, the motion buffer spring is coupled to an elastomeric material (e.g., polyurethane and / or silicone) such that at least a portion of the axial shaft of the ventricular assist device between the distal end of the impeller and the distal radial bearing is covered by the elastomeric material. For some applications, coupling the elastomeric material to the spring reduces the risk of thrombosis and / or hemolysis caused by the spring, compared to a spring not coupled to the elastomeric material. It should be noted that the scope of this disclosure includes providing a motion buffer spring without the elastomeric material, which may be desirable in some cases. For some applications, the spring is coated with an elastomeric material, wherein the elastomeric material extends between adjacent windings of the spring. Alternatively, the spring is embedded within the elastomeric material. Typically, the elastomeric material is coupled to the motion buffer spring in such a way that the elastomeric material changes shape (e.g., by stretching and compression) to conform to the shape changes experienced by the motion buffer spring (e.g., when the motion buffer spring undergoes elongation and compression). Furthermore, typically, the elastomeric material is configured to undergo the aforementioned shape changes without breaking or collapsing, and without wrinkling when the spring is compressed.

[0013] For some applications, the proximal motion damping spring is located on the proximal side of the impeller. In some such applications, the proximal motion damping spring is positioned around the axial shaft between the proximal end of the impeller and the proximal support. In some applications, the pump head includes both a proximal motion damping spring (located on the proximal side of the impeller) and a distal motion damping spring (located on the distal side of the impeller), such that axial movement of the impeller in either the distal or proximal direction is damped by the motion damping spring.

[0014] For some applications, ventricular assist devices include a distal thrust support configured to prevent axial movement of the device's axial shaft in response to changes in the pressure gradient resisted by the impeller pumping (and typically, this prevents axial movement of the impeller in response to changes in the pressure gradient resisted by the impeller pumping). For some applications, the thrust support is housed within the device's frame. Typically, the thrust support is coupled to the frame via a connecting strut extending radially inward from the frame to the thrust support. Typically, to manufacture the frame, it is cut from a tube of shape memory alloy (e.g., nitinol). For some applications, the connecting strut is cut from the tube from which the frame was cut, such that the frame and the connecting strut form a single integral unit without needing to be joined together (e.g., via adhesives, welding, etc.). For some applications, the frame and the connecting strut are cut from a single piece of material to form a single integral unit. For some applications, the connecting struts and thrust supports are cut from the tubing of the cut frame, so that the frame, connecting struts, and thrust supports form a single integral unit without needing to be connected to each other (e.g., via adhesives, welding, etc.). Typically, for some applications, the frame, connecting struts, and thrust supports are cut from a single piece of material to form a single integral unit.

[0015] For some applications, a spring similar to the motion-damping spring described above is typically used in conjunction with a thrust support (or a thrust support of a different design positioned distal to the impeller). In some applications, after the impeller has expanded radially, the spring helps stabilize the impeller relative to the thrust support (e.g., the distal end of the impeller). Therefore, the spring acts as an impeller stabilizing spring. In some applications, the impeller is configured to be radially constrained (i.e., coiled) by becoming axially elongated, and the spring is configured to be compressed to accommodate the axial elongation of the impeller. Typically, when the impeller is in a radially constrained configuration during pump head insertion into the left ventricle, the impeller elongates axially such that the distal end of the impeller is positioned distally within the frame, and the impeller stabilizing spring is compressed to accommodate movement of the distal end of the impeller. Typically, the impeller stabilizing spring is positioned around an axial shaft between the distal end of the impeller and the thrust support.

[0016] Therefore, according to some applications of the present invention, an apparatus is provided, the apparatus comprising:

[0017] Ventricular assist device, the ventricular assist device comprising:

[0018] An impeller, configured to be placed in the left ventricle of a subject, the impeller defining a cavity through which the impeller extends;

[0019] The frame is configured to be arranged around the impeller;

[0020] A proximal support member is provided at the proximal end of the frame and a distal support member is provided at the distal end of the frame.

[0021] An axial shaft passing through the proximal support, the cavity defined by the impeller, and the distal support; and

[0022] A motion damping spring is disposed around the axial shaft between the distal end of the impeller and the distal support member, the motion damping spring being configured to dampen the axial movement experienced by the impeller.

[0023] In some applications, the impeller is configured to undergo axial reciprocating motion as the impeller rotates, and the motion damping spring is configured to dampen the axial reciprocating motion.

[0024] In some applications, the impeller is configured to be radially constrained by becoming axially elongated, and the motion buffer spring is configured to be compressed to accommodate the axial elongation of the impeller.

[0025] In some applications, the motion damping spring is attached to the distal end of the impeller.

[0026] In some applications, ventricular assist devices also include a proximal motion buffer spring disposed around an axial shaft between the proximal end of the impeller and a proximal support member, the motion buffer spring being configured to buffer the axial movement of the impeller in the proximal direction.

[0027] In some applications, the motion buffer spring is coupled to the distal support. In some applications, the device also includes a distal support housing surrounding the distal support, through which the motion buffer spring is coupled to the distal support.

[0028] In some applications, the device also includes an elastomeric material coupled to the motion buffer spring, such that at least a portion of the axial shaft located between the distal end of the impeller and the distal support is covered by the elastomeric material. In some applications, the motion buffer spring is coated with the elastomeric material. In some applications, the motion buffer spring is embedded in the elastomeric material. In some applications, the elastomeric material includes at least one of silicone resin and polyurethane.

[0029] In some applications, ventricular assist devices include a cleaning system configured to pump cleaning fluid through a cavity defined by an axial shaft, such that at least a portion of the cleaning fluid flows proximally across the interface between the axial shaft and the elastomeric material.

[0030] In some applications, the elastomeric material is coupled to the motion-damping spring in such a way that the elastomeric material changes shape to conform to the shape changes experienced by the motion-damping spring. In some applications, the elastomeric material is configured to undergo shape changes without breaking or collapsing. In some applications, the elastomeric material is configured not to wrinkle due to compression of the motion-damping spring.

[0031] In some applications, the ventricular assist device further includes a pump outlet tube configured to pass through the aortic valve of a subject, such that a proximal portion of the pump outlet tube is positioned within the subject's aorta and a distal portion of the pump outlet tube is positioned within the subject's left ventricle. The distal portion of the pump outlet tube extends to the distal end of the frame and defines one or more lateral blood inlet openings configured to allow blood to flow from the subject's left ventricle into the pump outlet tube.

[0032] In some applications, the porosity of the distal portion of the pump outlet tube defining the blood inlet openings is lower in the proximal region of the distal portion of the pump outlet tube than in the distal region of the distal portion of the pump outlet tube located distal to the proximal region. In some applications, the distal portion of the pump outlet tube has a porosity greater than 40%. In some applications, the distal portion of the pump outlet tube defines more than 10 blood inlet openings sized to (a) allow blood to flow from the subject's left ventricle into the tube, and (b) prevent structures from the subject's left ventricle from entering the frame. In some applications, the distal portion of the pump outlet tube defines more than 50 blood inlet openings sized to (a) allow blood to flow from the subject's left ventricle into the tube, and (b) prevent structures from the subject's left ventricle from entering the frame.

[0033] According to some applications of the present invention, an apparatus is also provided, the apparatus comprising:

[0034] A pump outlet tube is configured to pass through the aortic valve of the subject, such that the proximal end of the pump outlet tube is positioned within the aorta of the subject, and the distal end of the pump outlet tube is positioned within the left ventricle of the subject.

[0035] An impeller is configured to be disposed within the pump outlet pipe in the left ventricle and to pump blood through the pump outlet pipe.

[0036] A frame is arranged around the impeller, the frame defining a cylindrical portion and a proximal conical portion, the proximal conical portion being disposed proximal to the cylindrical portion and widening from the proximal end of the frame to the cylindrical portion of the frame;

[0037] At least one optical fiber, the proximal end of which is configured to be disposed outside the subject's body, and the distal portion of which is coupled to the proximal tapered portion of the frame, such that the distal end of which extends outside the pump outlet tube and is configured to be in direct fluid communication with the subject's left ventricular blood flow outside the pump outlet tube.

[0038] In some applications, the device also includes a light source and a photodetector disposed at the proximal end of the optical fiber and configured to detect blood pressure at the distal end of the optical fiber by guiding light through the optical fiber and detecting reflected light.

[0039] In some applications, the device also includes a computer processor configured to receive blood pressure detected at the distal end of the optical fiber and to control the pumping of blood by the impeller in response to the blood pressure detected at the distal end of the optical fiber.

[0040] In some applications, the device also includes a computer processor configured to receive blood pressure detected at the distal end of the optical fiber, and the computer processor is configured to derive at least one physiological parameter of the subject based at least in part on the blood pressure detected at the distal end of the optical fiber, the at least one physiological parameter of the subject being selected from the group consisting of: natural cardiac output, total cardiac output, arterial compliance, and peripheral resistance.

[0041] In some applications, the pump outlet tube defines one or more blood inlet openings through which blood is pumped into the pump outlet tube, and the distal end of the optical fiber is configured to be in direct fluid communication with the left ventricular blood flow of the subject at a location near the nearest side portion of the one or more blood inlet openings.

[0042] In some applications, the distal end of the optical fiber is exposed to blood with a pressure that reflects the blood pressure of the left ventricle itself and is unaffected by pressure changes in the vicinity of the one or more blood inlet openings due to fluid flow dynamics generated at the one or more blood inlet openings.

[0043] In some applications, the distal end of the optical fiber is configured to be in direct fluid communication with the subject's left ventricular blood flow at a location at least 1 cm from the nearest portion of the one or more blood inlet openings.

[0044] In some applications, the at least one optical fiber includes two or more optical fibers, and the device further includes a computer processor configured to receive blood pressure detected at the distal end of each of the optical fibers, and thereby determine whether the distal end of one of the optical fibers is not exposed to left ventricular blood flow. In some applications, in response to determining that the distal end of one of the optical fibers is not exposed to left ventricular blood flow, the computer processor determines the subject's left ventricular pressure based on blood pressure measured using different optical fibers of the two or more optical fibers.

[0045] According to some applications of the present invention, a method for determining the natural cardiac output of a subject receiving treatment with a percutaneous left ventricular assist device is also provided, the method comprising:

[0046] The percutaneous left ventricular assist device is used to pump blood from the subject's left ventricle to the subject's aorta;

[0047] The percutaneous left ventricular assist device is used to detect one or more pressure-related parameters and / or flow-related parameters;

[0048] During one or more cycles of vascular parameter determination, the rate at which blood is pumped by the percutaneous left ventricular assist device is varied;

[0049] When the percutaneous left ventricular assist device pumps blood at a corresponding rate, a mathematical model representing the subject's dynamic vascular system is applied;

[0050] Based on the difference between the mathematical model applied when the percutaneous left ventricular assist device pumps blood at the corresponding rate and the pressure-related parameters and / or the flow-related parameters, the vascular parameters of the subject are estimated.

[0051] The subject's natural cardiac output is estimated based on the pressure-related parameters and / or the flow-related parameters, as well as the subject's estimated vascular parameters.

[0052] According to some applications of the present invention, an apparatus for determining the natural cardiac output of a subject is also provided, the apparatus comprising:

[0053] A percutaneous left ventricular assist device configured to pump blood from the left ventricle of a subject to the subject's aorta; and

[0054] At least one computer processor, said computer processor being configured to:

[0055] The percutaneous left ventricular assist device is used to detect one or more pressure-related parameters and / or flow-related parameters.

[0056] During one or more cycles of vascular parameter determination, the rate at which blood is pumped by the percutaneous left ventricular assist device is varied.

[0057] When the percutaneous left ventricular assist device pumps blood at a corresponding rate, a mathematical model representing the subject's dynamic vascular system is applied.

[0058] Based on the difference between the mathematical model applied when the percutaneous left ventricular assist device pumps blood at the corresponding rate and the pressure-related parameters and / or the flow-related parameters, the vascular parameters of the subject are estimated, and

[0059] The subject's natural cardiac output is estimated based on the pressure-related parameters and / or the flow-related parameters, as well as the subject's estimated vascular parameters.

[0060] In some applications, the computer processor is configured to generate an output that indicates the subject's natural cardiac output.

[0061] In some applications, the computer processor is configured to apply a mathematical model representing the subject's dynamic vascular system by applying a Windkessel model of the aorta.

[0062] In some applications, the computer processor is configured to estimate a subject's vascular parameters by estimating one or more of the subject's aortic compliance, characteristic impedance, and peripheral resistance.

[0063] In some applications, the computer processor is configured to detect one or more pressure-related parameters and / or flow-related parameters by detecting the subject's aortic pressure. In some applications, the computer processor is also configured to detect one or more pressure-related parameters and / or flow-related parameters by detecting the subject's aortic flow via a percutaneous left ventricular assist device.

[0064] In some applications, the percutaneous left ventricular assist device includes a pump outlet tube with a known cross-sectional area and a pump, and the computer processor is configured to calculate the flow rate through the pump outlet tube of the percutaneous left ventricular assist device based on the known cross-sectional area of ​​the tube and the pressure difference generated by the pump of the percutaneous left ventricular assist device, and to detect the flow rate through the percutaneous left ventricular assist device.

[0065] In some applications:

[0066] The percutaneous left ventricular assist device includes a motor;

[0067] The pump of the percutaneous left ventricular assist device includes an impeller configured to pump blood by rotation by the motor; and

[0068] The computer processor is configured to determine the pressure differential generated by the pump of the percutaneous left ventricular assist device by measuring the power consumption of the motor when the motor rotates the impeller at a given rotational rate and using a predetermined relationship between the power consumption of the motor required to rotate the impeller at the given rotational rate and the pressure differential generated by the impeller.

[0069] In some applications, the computer processor is configured to determine the pressure differential generated by the pump of the percutaneous left ventricular assist device by measuring the subject's left ventricular pressure and aortic pressure.

[0070] According to some applications of the present invention, an apparatus is also provided, the apparatus comprising:

[0071] Ventricular assist device, the ventricular assist device comprising:

[0072] Axial shaft;

[0073] An impeller, which is mounted on the axial shaft, is configured to pump blood;

[0074] The frame, which is arranged around the impeller,

[0075] A distal thrust support, disposed within the frame, wherein the distal end of the axial shaft is configured to engage with the distal thrust support to prevent the axial shaft from undergoing axial movement in response to changes in the pressure gradient resisted by the impeller pumping blood; and

[0076] Multiple connecting struts extend radially inward from the frame to the distal thrust support and connect the thrust support to the frame, the frame and the connecting struts being formed as a single integral body.

[0077] In some applications, the frame, connecting struts, and thrust supports are all formed as a single integral unit.

[0078] In some applications, the ventricular assist device also includes an impeller stabilizing spring disposed around an axial shaft between the distal end of the impeller and a thrust support, the impeller stabilizing spring being configured to stabilize the distal end of the impeller. In some applications, the impeller is configured to be radially constrained by becoming axially elongated, and the impeller stabilizing spring is configured to be compressed to accommodate the axial elongation of the impeller. In some applications, the impeller stabilizing spring is coupled to the distal end of the impeller.

[0079] In some applications, ventricular assist devices also include a proximal support and a proximal impeller stabilizing spring, which is disposed around an axial shaft between the proximal end of the impeller and the proximal support.

[0080] In some applications, the impeller stabilizing spring is connected to the thrust support.

[0081] In some applications, the device also includes an elastomeric material coupled to the impeller stabilizing spring, such that at least a portion of the axial shaft located between the distal end of the impeller and the thrust support is covered by the elastomeric material. In some applications, the impeller stabilizing spring is coated with the elastomeric material. In some applications, the impeller stabilizing spring is embedded in the elastomeric material. In some applications, the elastomeric material includes at least one of silicone resin and polyurethane. In some applications, the ventricular assist device includes a cleaning system configured to pump cleaning fluid through a cavity defined by the axial shaft, such that at least a portion of the cleaning fluid flows proximally across the interface between the axial shaft and the elastomeric material.

[0082] In some applications, the elastomeric material is coupled to the impeller stabilizing spring in such a way that the elastomeric material changes shape to conform to the shape changes experienced by the impeller stabilizing spring. In some applications, the elastomeric material is configured to undergo shape changes without breaking or collapsing. In some applications, the elastomeric material is configured not to wrinkle due to compression of the impeller stabilizing spring.

[0083] In some applications, the ventricular assist device further includes a pump outlet tube configured to pass through the aortic valve of a subject, such that a proximal portion of the pump outlet tube is positioned within the subject's aorta and a distal portion of the pump outlet tube is positioned within the subject's left ventricle. The distal portion of the pump outlet tube extends to the distal end of the frame and defines one or more lateral blood inlet openings configured to allow blood to flow from the subject's left ventricle into the pump outlet tube.

[0084] In some applications, the porosity of the distal portion of the pump outlet tube defining the blood inlet opening is lower in the proximal region of the distal portion of the pump outlet tube than in the distal region of the distal portion of the pump outlet tube located distal to the proximal region.

[0085] In some applications, the distal portion of the pump outlet tube has a porosity greater than 40%. In some applications, the distal portion of the pump outlet tube defines more than 10 blood inlet openings, which are sized to (a) allow blood to flow from the subject's left ventricle into the tube, and (b) prevent structures from the subject's left ventricle from entering the frame. In some applications, the distal portion of the pump outlet tube defines more than 50 blood inlet openings, which are sized to (a) allow blood to flow from the subject's left ventricle into the tube, and (b) prevent structures from the subject's left ventricle from entering the frame.

[0086] According to some applications of the present invention, an apparatus is also provided, the apparatus comprising:

[0087] Ventricular assist device, the ventricular assist device comprising:

[0088] Axial shaft;

[0089] An impeller, which is mounted on the axial shaft, is configured to pump blood;

[0090] The frame, which is arranged around the impeller,

[0091] A distal thrust support, wherein the distal end of the axial shaft is configured to engage with the distal thrust support to prevent the axial shaft from undergoing axial movement in response to changes in the pressure gradient resisted by the impeller pumping blood; and

[0092] An impeller stabilizing spring is disposed around the axial shaft between the distal end of the impeller and the thrust support, the impeller stabilizing spring being configured to stabilize the distal end of the impeller.

[0093] In some applications, the impeller is configured to be radially constrained by becoming axially elongated, and the impeller stabilizing spring is configured to be compressed to accommodate the axial elongation of the impeller.

[0094] In some applications, the impeller stabilizing spring is attached to the distal end of the impeller.

[0095] In some applications, ventricular assist devices also include a proximal support and a proximal impeller stabilizing spring, which is disposed around an axial shaft between the proximal end of the impeller and the proximal support.

[0096] In some applications, the impeller stabilizing spring is connected to the thrust support.

[0097] In some applications, the device also includes an elastomeric material coupled to the impeller stabilizing spring, such that at least a portion of the axial shaft located between the distal end of the impeller and the thrust support is covered by the elastomeric material. In some applications, the impeller stabilizing spring is coated with an elastomeric material. In some applications, the impeller stabilizing spring is embedded in an elastomeric material. In some applications, the elastomeric material includes at least one of silicone resin and polyurethane.

[0098] In some applications, ventricular assist devices include a cleaning system configured to pump cleaning fluid through a cavity defined by an axial shaft, such that at least a portion of the cleaning fluid flows proximally across the interface between the axial shaft and the elastomeric material.

[0099] In some applications, the elastomeric material is coupled to the impeller stabilizing spring in such a way that the elastomeric material changes shape to conform to the shape changes experienced by the impeller stabilizing spring. In some applications, the elastomeric material is configured to undergo shape changes without breaking or collapsing. In some applications, the elastomeric material is configured not to wrinkle due to compression of the impeller stabilizing spring.

[0100] According to some applications of the invention, a device for use with a percutaneous ventricular assist device is also provided, the percutaneous ventricular assist device including a self-expanding pump head and configured to be delivered to the left ventricle of a subject using a delivery catheter, wherein the pump head is disposed within the delivery catheter in a radially constrained configuration, the device comprising:

[0101] Packaging for the aforementioned ventricular assist device

[0102] The package is shaped to define a pump head chamber, in which the pump head is packaged in a non-radial constraint configuration.

[0103] A catheter retainer is reversibly coupled to the package, the catheter retainer being shaped to define an aperture and configured to secure the distal end of the delivery catheter within the aperture by coupling to the package, wherein the distal end of the delivery catheter is disposed within the aperture.

[0104] The packaging is configured such that the pump head is radially constrained by retracting into the distal end of the delivery conduit, while the distal end of the delivery conduit is secured within the orifice.

[0105] In some applications, the pump head chamber is configured to be filled with solution before the pump head retracts into the distal end of the delivery catheter. In some applications, the catheter retainer is configured to secure the distal end of the delivery catheter to a downwardly sloping surface, such that the distal end of the catheter is oriented downwards. In some applications, compared to securing the distal end of the catheter to a horizontal surface, the slope of the surface is configured to reduce the likelihood of air bubbles entering the distal end of the delivery catheter when the pump head retracts into the distal end.

[0106] Generally, 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 as meaning 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 as meaning 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.

[0107] The invention will be more fully understood from the following detailed description of embodiments thereof, taken in conjunction with the accompanying drawings, in which: Brief description of the attached diagram

[0109] Figure 1A , Figure 1B and Figure 1C This is a schematic diagram of a ventricular assist device according to some applications of the present invention, wherein the distal end of the ventricular assist device is configured to be placed in the left ventricle of a subject;

[0110] Figure 2 This is a schematic diagram of a frame housing an impeller for a ventricular assist device according to some applications of the present invention;

[0111] Figure 3A , Figure 3B , Figure 3C , Figure 3D and Figure 3E This is a schematic diagram of the impeller or a portion thereof of a ventricular assist device according to some applications of the present invention;

[0112] Figure 4 This is a schematic diagram of an impeller disposed inside the frame of a ventricular assist device according to some applications of the present invention;

[0113] Figure 5A and Figure 5B This is a schematic diagram of the impeller and frame of a ventricular assist device in a non-radial constraint state and a radial constraint state, respectively, according to some applications of the present invention;

[0114] Figure 5C This is an enlarged schematic diagram of the proximal end of the frame of a ventricular assist device according to some applications of the present invention;

[0115] Figure 6A and Figure 6B This is a schematic diagram of a ventricular assist device according to some applications of the present invention, showing the impeller of the ventricular assist device at various stages of its motion cycle relative to the frame of the ventricular assist device.

[0116] Figure 6C and Figure 6D This is a schematic diagram of a ventricular assist device including a motion-cushioning spring, according to some applications of the present invention;

[0117] Figure 7A This is a schematic diagram of the motor unit of a ventricular assist device according to some applications of the present invention;

[0118] Figure 7B and Figure 7C This is a schematic diagram of the motor unit of a ventricular assist device according to some applications of the present invention;

[0119] Figure 8A It is a graph showing how the length of the drive cable of the ventricular assist device changes with the pressure gradient resisted by the impeller of the blood pump as measured in experiments conducted according to some applications of the present invention;

[0120] Figure 8B and Figure 8C It is a graph indicating the change of the pressure gradient resisted by the impeller of the blood pump as measured in experiments conducted according to some applications of the present invention, based on magnetic phase measurements performed on the blood pump.

[0121] Figure 9A and Figure 9B This is a schematic diagram of a ventricular assist device including one or more blood pressure measuring tubes and / or optical fibers, according to some applications of the present invention;

[0122] Figure 10A and Figure 10B This is a schematic diagram of a ventricular assist device according to some applications of the present invention, the ventricular assist device including an inner liner located on the inside of a frame housing an impeller;

[0123] Figure 11A , Figure 11B , Figure 11C , Figure 11D and Figure 11E This is a schematic diagram of a pump outlet pipe according to some applications of the present invention, which defines a blood inlet opening at its distal end;

[0124] Figure 12A , Figure 12B and Figure 12C This is a schematic diagram of the drive cable of a ventricular assist device according to some applications of the present invention;

[0125] Figure 12D This is a schematic diagram of a drive cable support tube according to some applications of the present invention;

[0126] Figure 13 This is a schematic diagram of a ventricular assist device having a guide wire disposed within a guide wire cavity, according to some applications of the present invention;

[0127] Figure 14A and Figure 14B This is a schematic diagram of a dual-state lead wire according to some applications of the present invention;

[0128] Figure 15 This is a schematic diagram of a ventricular assist device with a distal thrust support according to some applications of the present invention; and

[0129] Figure 16A , Figure 16B , Figure 16C and Figure 16D This is a schematic diagram of packaging for packaging ventricular assist devices according to some applications of the present invention. Detailed Implementation

[0131] Now for reference Figure 1A , Figure 1B and Figure 1C These figures are schematic diagrams of a ventricular assist device 20 according to some applications of the present invention, wherein the distal end of the ventricular assist device is configured to be disposed in the left ventricle 22 of the subject. Figure 1A An overview of a ventricular assist device system including a console 21 and a motor unit 23 is shown. Figure 1B A ventricular assist device inserted into the left ventricle of a subject is shown, and Figure 1C The pump head 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 the proximal end 28 of the pump outlet tube is positioned within the subject's aorta 30, and the distal end 32 of the pump outlet tube is positioned within the left ventricle 22. The pump outlet tube 24 (which is sometimes referred to herein as the "blood pump tube") is typically an elongated tube, with its axial length typically much larger than its diameter. The scope of the invention includes the use of the devices and methods described herein in anatomical locations other than the left ventricle and aorta. Therefore, the ventricular assist device and / or portions thereof are sometimes referred to herein (in the specification and claims) as a blood pump.

[0132] In some applications, ventricular assist devices (VAPs) are used to assist left ventricular function in a subject during percutaneous coronary intervention (PCI). In this case, VAPs are typically used for a period of up to 6 hours (e.g., up to 10 hours), during which there is a risk of hemodynamic instability (e.g., during or immediately after PCI). Alternatively or additionally, VAPs are used to assist left ventricular function in patients with cardiogenic shock for a longer period (e.g., 2-20 days, or 4-14 days), which can include any low cardiac output state (e.g., acute myocardial infarction, myocarditis, cardiomyopathy, postpartum, etc.). In some applications, VAPs are used to assist left ventricular function in a subject for an even longer period (e.g., several weeks or months), for example, in bridge-to-recovery therapy. In some of these applications, the ventricular assist device is permanently or semi-permanently implanted, and the impeller of the ventricular assist device is percutaneously powered, for example, by using an external antenna magnetically coupled to the impeller.

[0133] like Figure 1B As shown, Figure 1B The steps for deploying a ventricular assist device in the left ventricle are illustrated. Typically, the distal end of the ventricular assist device is guided into the left ventricle via a guide wire 10. During insertion of the distal end of the device into the left ventricle, a delivery catheter 143 is positioned on the distal end of the device. Once the distal end of the device is positioned in the left ventricle, the delivery catheter is typically retracted into the aorta, and the guide wire is withdrawn from the subject's body. Typically, the retraction of the delivery catheter causes the self-expanding portion 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 to provide acute treatment. For some applications, in order to withdraw the left ventricular device from the subject at the end of treatment, the delivery catheter is advanced on the distal end of the device, causing the self-expanding portion 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, causing the self-expanding portion of the distal end of the device to assume a radially constrained configuration.

[0134] 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 ventricle of the subject under ultrasound guidance.

[0135] refer to Figure 1CThe diagram shows in more detail the pump head portion 27 of a ventricular assist device 20 according to some applications of the invention. Typically, an impeller 50 is disposed within the distal portion 102 of a pump outlet pipe 24 and configured to pump blood from the left ventricle into the aorta by rotation. The pump outlet pipe typically defines one or more blood inlet openings 108 at its distal end, through which blood flows from the left ventricle into the pump outlet pipe during impeller operation. Figure 1C As shown, for some applications, the pump outlet pipe defines a single axially oriented blood inlet opening. Alternatively, the pump outlet pipe defines multiple lateral blood inlet openings (e.g., as...). Figure 1B As shown below, and further described in detail below. For some applications, the proximal portion 106 of the pump outlet pipe defines one or more blood outlet openings 109 through which blood flows from the pump outlet pipe into the ascending aorta during impeller operation.

[0136] For some applications, this typically includes the console 21 of the computer processor 25 (such as...). Figure 1A (As shown) drives the impeller to rotate. For example, a computer processor can control motor 74 (such as...) Figure 7A As shown), motor 74 is installed in motor unit 23 (e.g. Figure 1A (as shown) inside, and via drive cable 130 (as shown) Figure 12A (As shown) 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, as described in further detail below. Typically, the operations performed by the computer processor described herein convert the physical state of a memory, which is a real physical artifact communicating with the computer processor, into having different magnetic polarities, charges, etc., depending on the memory technology used. The computer processor 25 is typically a hardware device programmed with computer program instructions to produce a dedicated computer. For example, when programmed to perform the techniques described herein, the computer processor 25 typically acts as a dedicated ventricular assist computer processor and / or a dedicated blood pump computer processor.

[0137] For some applications, cleaning system 29 (in) Figure 1A (As shown in the figure) Drive fluid (e.g., glucose solution) through multiple parts of the ventricular assist device 20, for example, to cool multiple parts of the device, clean and / or lubricate the interface between the rotating parts and the fixed support, and / or to flush away debris from multiple parts of the device.

[0138] Typically, a frame 34 is disposed within the pump outlet tube 24, surrounding the impeller 50, along the distal portion 102 of the pump outlet tube 24. The frame is typically made of a shape memory alloy (e.g., nitinol). For some applications, the shape memory alloy of the frame is shaped such that at least a portion of the frame (and therefore the distal portion 102 of the tube 24) presents a generally circular, elliptical, or polygonal cross-sectional shape when no force is applied to the distal portion 102 of the tube 24. By presenting its generally circular, elliptical, or polygonal cross-sectional shape, the frame is configured to hold 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 subject's body such that the distal portion of the pump outlet tube is at least partially disposed within the left ventricle.

[0139] For some applications, along the proximal portion 106 of the pump outlet tube 24, the frame is not disposed within the pump outlet tube, so the pump outlet tube is not supported by the frame 34 in the open position. The pump outlet tube 24 is typically made of a collapsible material that is impermeable to blood. For example, the pump outlet tube 24 may comprise polyurethane, polyester, and / or silicone. Alternatively or additionally, the pump outlet tube may be made of polyethylene terephthalate (PET) and / or polyether block amide (e.g., PEBAX®). For some applications (not shown), the pump outlet tube is reinforced with a reinforcing structure (e.g., a braided reinforcement structure such as braided nitinol tubing). 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 aortic valve of the subject, entering the ascending aorta from the left ventricle of the subject, such as... Figure 1B As shown.

[0140] As described above, the pump outlet tube typically defines one or more blood inlet openings 108 at its distal end, through which blood flows from the left ventricle into the pump outlet tube during impeller operation. For some applications, the proximal portion 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. Typically, the pump outlet tube defines multiple blood outlet openings 109, for example, between two and eight blood outlet openings (e.g., between two 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 open. For some applications, such as in the event of impeller failure, the proximal portion of the pump outlet tube is configured to collapse inward in response to 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 retrograde blood flow from the aorta into the left ventricle.

[0141] Refer again Figure 1C For some applications, frame 34 is shaped such that it defines a proximal conical portion 36, a central columnar portion 38, and a distal conical portion 40. Typically, the proximal conical portion is oriented proximal, i.e., oriented such that the narrow end of the cone is proximal to the wide end of the cone. More typically, the distal conical portion is oriented distally, i.e., oriented such that the narrow end of the cone is distal to the wide end of the cone. For some applications, a liner 39 is laid on the frame within at least a portion of frame 34 (e.g., along all or part of the central columnar portion of the frame). Figure 1C An embodiment of the pump head portion without the liner 39 is shown, but several figures illustrate embodiments of the pump head portion including the liner 39. Depending on the application, the liner and pump outlet pipe 24 partially or completely overlap the liner-lined portion of the frame, as referenced below. Figures 10A-10B As described in further detail.

[0142] Typically, the pump outlet tube 24 includes a tapered proximal portion 42 and a cylindrical central portion 44. The proximal tapered portion is typically oriented proximal, i.e., oriented such that the narrow end of the cone is proximal 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 segment of the tube 24. For some such applications, the blood outlet opening is teardrop-shaped, such as... Figure 1C As shown. Typically, the teardrop-shaped property of the blood outlet opening is combined with an opening that extends at least partially along the proximal conical segment of tube 24, such that blood flows out of the blood outlet opening at its location along a flow line substantially parallel to the longitudinal axis of tube 24.

[0143] For some applications (not shown), the diameter of the pump outlet pipe 24 varies along the length of its central portion, giving the central portion a truncated cone shape. For example, the central portion of the pump outlet pipe may widen from its proximal end to its distal end, or it may narrow from its proximal end to its distal end. For some applications, the central portion of the pump outlet pipe has a diameter between 5 mm and 7 mm at its proximal end, and between 8 mm and 12 mm at its distal end.

[0144] Refer again Figure 1CA typical ventricular assist device includes a distal end element 107 disposed distally relative to a frame 34, and the distal end element 107 includes an axial shaft receiving tube 126 and a distal end portion 120. Typically, the axial shaft receiving tube is configured to receive the distal portion of the axial shaft 92 of the pump head portion during axial reciprocating motion of the axial shaft (as described further in detail below) and / or during delivery of the ventricular assist device. (Typically, during delivery of the ventricular assist device, the frame remains in a radially constrained configuration, which typically results in the axial shaft being positioned relative to its position with respect to the frame during operation of the ventricular assist device, and in different positions with respect to the frame.) Typically, the distal end portion 120 is configured to take on a curved shape when deployed into the left ventricle of a subject, for example, as... Figure 1C As shown. For some applications, the curvature of the distal end portion is configured to provide a non-invasive end to the ventricular assist device 20. Alternatively or additionally, the distal end portion is configured to separate the blood inlet opening 108 of the ventricular assist device from the wall of the left ventricle.

[0145] like Figure 1BAs shown in the enlarged portion, for some applications, the pump outlet pipe 24 extends to the end of the distal tapered portion 40 of the frame, and the pump outlet pipe defines a plurality of lateral blood inlet openings 108, as described in further detail below. For such applications, the pump outlet pipe typically defines a distal tapered portion that faces distally, such that the narrow end of the cone is distal relative to the wide end of the cone. For some such applications (not shown), the pump outlet pipe defines two to four lateral blood inlet openings (e.g., four lateral blood inlet openings, as shown). Typically, for such applications, each blood inlet opening defines an area greater than 20 mm² (e.g., greater than 30 mm²) and / or less than 60 mm² (e.g., less than 50 mm²), such as 20 mm²–60 mm², or 30 mm²–50 mm². Alternatively or additionally, the outlet tube defines a greater number of smaller lateral blood inlet openings, for example, more than 10 blood inlet openings, more than 50 blood inlet openings, more than 200 blood inlet openings, or more than 400 blood inlet openings, for example, 50-100 blood inlet openings, 100-400 blood inlet openings, or 400-600 blood inlet openings. For some such applications, each blood inlet opening defines an area greater than 0.05 mm² (e.g., greater than 0.1 mm²) and / or less than 3 mm² (e.g., less than 1 mm²), for example, an area of ​​0.05 mm²-3 mm² or 0.1 mm²-1 mm². Alternatively, each blood inlet opening defines an area greater than 0.1 mm² (e.g., greater than 0.3 mm²) and / or less than 5 mm² (e.g., less than 1 mm²), for example, an area of ​​0.1 mm²-5 mm² or 0.3 mm²-1 mm². For example, see reference below. Figures 11A-11E This application will be described in more detail. Generally, with necessary modifications, the scope of this disclosure includes combinations such as Figure 1C As shown (and also as Figures 9A-9B , Figures 10A-10B and Figures 16A-16C (As shown) a pump outlet pipe defining a single axially facing blood inlet opening 108, or as Figure 1B As shown (and also as Figure 4 , Figures 5A-5B , Figures 6A-6D , Figures 11A-11E and Figure 13 (As shown) A pump outlet pipe defining multiple laterally facing blood inlet openings 108, in combination with other features of the ventricular assist device described herein.

[0146] Now for reference Figure 2 , Figure 2This is a schematic diagram of a frame 34 housing the impeller of a ventricular assist device 20 according to some applications of the present invention. The frame 34 is typically made of a shape memory alloy such as nitinol, and the shape memory alloy is shaped such that the central portion of the frame (and therefore the tube 24) has a generally circular, elliptical, or polygonal cross-sectional shape when no force is applied to the pump outlet tube 24. By presenting its generally circular, elliptical, or polygonal cross-sectional shape, the frame is configured to keep the distal portion of the tube in the open state.

[0147] Typically, the frame is a support frame because it comprises pillars that sequentially define the cells. More typically, the frame is covered by the pump outlet pipe 24 and / or by the liner 39, as referenced below. Figures 10A-10B As described below, for some applications, the impeller 50 undergoes axial reciprocating motion relative to the frame 34. Typically, during the impeller's motion relative to the frame, the portion of the impeller defining its maximum span is located within the central cylindrical portion 38 of the frame 34. In some cases, if the cell of the central cylindrical portion 38 of the frame 34 is too large, the pump outlet pipe 24 and / or liner 39 are stretched between the edges of the cell, causing the pump outlet pipe 24 and / or liner 39 to not define a circular cross-section. For some applications, if this occurs in the region where the portion defining the impeller's maximum span is located, this results in a substantially non-constant clearance between the edge of the impeller blades and the pipe 24 (and / or liner) at that location during the impeller's rotation cycle. For some applications, this may lead to increased hemolysis compared to a substantially constant clearance between the edge of the impeller blades and the pipe 24 (and / or liner) at that location during the impeller's rotation cycle.

[0148] refer to Figure 2 At least in part, taking into account the problems described in the previous paragraph, within the central columnar portion 38 of frame 34, the frame defines a large number of relatively small cells. Typically, when the frame is configured with its non-radial constraint, the maximum cell width CW (i.e., the distance from the inner edge of the support at the center joint on one side of the cell to the inner edge of the support at the center joint on the other side of the cell, as measured around the circumference of columnar portion 38) of each cell within the columnar portion of the frame is less than 2 mm, for example, between 1.4 mm and 1.6 mm, or between 1.6 mm and 1.8 mm. Due to the relatively small size of the cells, the liner 39 defines a substantially circular cross-section within the columnar portion of the frame.

[0149] Still referencing Figure 2 And starting from the distal end of the frame (on the right side of the figure), the frame typically defines the following portion: (a) a connecting portion 31, through which the frame is connected to the distal support housing 118H of the ventricular assist device (in Figure 5A (b) the distal tapered portion 40, (c) the central cylindrical portion 38, (d) the proximal tapered portion 36, and (e) the proximal strut joint 33 are shown. As the frame transitions from the proximal end toward the center of the frame (e.g., from the proximal strut joint 33, through the proximal tapered portion 36, and to the central cylindrical portion 38), the struts 37 of the frame pass through joints 35, where two struts branch off from a single strut in a Y-shape. As described further below, typically, the frame 34 is placed in the delivery conduit 143 in a radially constrained (i.e., curled) configuration by being axially elongated within the frame. Furthermore, typically, the frame transmits its radial narrowing to the impeller, and the impeller becomes radially constrained by axial elongation within the frame. For some applications, the struts of the frame configured as described above facilitate the transmission of axial elongation from the delivery conduit (or other means configured to curl the frame) to the frame, which in turn facilitates the transmission of axial elongation to the impeller. This is because the pairs of struts branching from each joint 35 are configured to pivot around the joint and move closer to each other, thus closing.

[0150] Still referencing Figure 2 During the assembly of the ventricular assist device, the initial distal connection portion 31 is initially connected to the distal support housing 118H, for example, via a snap-fit ​​mechanism (e.g., Figure 5A (As shown). For some applications, the proximal strut joint 33 remains open at this stage so that the impeller is placed within the frame via the proximal end of the frame. Typically, Figure 2 The structure of the frame 34 shown is for applications where the pump outlet pipe extends to the distal end of the frame 34 (e.g., as...). Figure 1B (As shown). In this case, the impeller cannot be inserted via the distal end of the frame because the distal end of the frame is covered by the pump outlet pipe 24. During the assembly of the ventricular assist device, the proximal strut joint is closed after the impeller is inserted via the proximal end of the frame. For some applications, the proximal strut joint surrounds the proximal support housing 116H (in... Figure 5A The outer closure (as shown in the image) is as follows (see reference below). Figures 5A-5B Further detailed description. Typically, the fixing element 117 (e.g., Figure 5A The ring shown in the diagram surrounds the outer side of the proximal support housing 116H, keeping the strut joint in its closed configuration.

[0151] Typically, when frame 34 is configured in its non-radial constraint configuration, the total length of frame 34 is greater than 25 mm (e.g., greater than 30 mm) and / or less than 50 mm (e.g., less than 45 mm), for example, 25 mm–50 mm or 30 mm–45 mm. Typically, when frame 34 is configured in its radial constraint configuration (within delivery conduit 143), the length of frame is increased by 2 mm to 5 mm. Typically, when frame 34 is configured in its non-radial constraint configuration, the length of the central columnar portion of frame 34 is greater than 10 mm (e.g., greater than 12 mm) and / or less than 25 mm (e.g., less than 20 mm), for example, 10 mm–25 mm or 12 mm–20 mm. For some applications, the ratio of the length of the central columnar portion of the frame to the total length of the frame is greater than 1:4 and / or less than 1:2, for example, between 1:4 and 1:2.

[0152] Now for reference Figures 3A-3E , Figures 3A-3E This is a schematic diagram of an impeller 50 or a portion thereof according to some applications of the present invention. Typically, the impeller includes at least one outer helical elongated element 52 wound around a central axial spring 54, such that the helical structure defined by the helical elongated element is coaxial with the central axial spring. Typically, the impeller includes two or more helical elongated elements (e.g., three helical elongated elements, such as…). Figures 3A-3C (As shown). For some applications, the helical elongated element and the central axial spring are made of shape memory materials, such as nitinol shape memory alloys. Typically, each helical elongated element and the central axial spring is supported by a membrane 56 of material (e.g., an elastomer, such as polyurethane, and / or silicone) between them. For some applications, the membrane of the material includes nitinol sheets embedded therein, for example, to reinforce the membrane of the material. For illustrative purposes, the impeller in Figure 3A The text indicates that the material is not available. Figure 3B and Figure 3C Views of the impeller are shown, in which the material is supported between a helical elongated element and a spring. Figure 3D and Figure 3E They respectively showed the same as Figure 3B and Figure 3C The view shown is similar to that of the impeller, but some features of the impeller are different. Figure 3B and Figure 3C The features shown are described in detail below.

[0153] Each helical elongated element, together with a membrane extending from the helical elongated element to the spring, defines the blades of the corresponding impeller, wherein the helical elongated element defines the outer edge of the blade, and the axial spring defines the axis of the impeller. Typically, the membrane of material extends along the spring and covers the spring. For some applications, the suture 53 (e.g., polyester suture, such as...) Figures 3A-3C (As shown) The suture is wound around a helical elongated element. Typically, the suture is configured to facilitate bonding between a film of material (typically an elastomer, such as polyurethane, or silicone) and a helical elongated element (typically a shape memory alloy, such as nitinol). For some applications, the suture (e.g., polyester suture, not shown) is wound around a spring 54. Typically, the suture is configured to facilitate bonding between a film of material (typically an elastomer, such as polyurethane, or silicone) and a spring (typically a shape memory alloy, such as nitinol).

[0154] Typically, the proximal ends of spring 54 and helical elongated element 52 extend from the proximal bushing (i.e., sleeve support) 64 of the impeller, such that the proximal ends of spring 54 and helical elongated element 52 are positioned at similar radial distances from the longitudinal axis of the impeller. Similarly, typically, the distal ends of spring 54 and helical elongated element 52 extend from the distal bushing 58 of the impeller, such that the distal ends of spring 54 and helical elongated element 52 are positioned at similar radial distances from the longitudinal axis of the impeller. The helical elongated element typically rises gradually from the proximal bushing before reaching its maximum span, and then gradually descends towards the distal bushing. Typically, the helical elongated element is symmetrical along its length, such that the rising portion of its length is symmetrical with respect to the falling portion of its length. Typically, the impeller defines a cavity 62 through which it passes (e.g., Figure 3C As shown), the cavity typically extends through the impeller spring 54 and the proximal bushing 64 and the distal bushing 58 and is defined by the impeller spring 54 and the proximal bushing 64 and the distal bushing 58.

[0155] Now for reference Figure 4 This figure 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, a liner 39 is laid on the frame within at least a portion of the frame 34 (e.g., along all or part of the central columnar portion 38 of the frame). Depending on the application, the liner partially or completely overlaps with the pump outlet pipe 24 over the liner-laid portion of the frame, as referenced below. Figures 9A-9B As described in further detail.

[0156] like Figure 4As shown, typically, a gap G exists between the outer edge of the impeller 50 and the liner 39, even at the location of maximum impeller span. For some applications, it is desirable that the gap between the outer edge of the impeller blades and the liner 39 be relatively small so that the impeller can effectively pump blood from the subject's left ventricle into the subject's aorta. (Note that since the gap between the outer edge of the impeller 50 and the liner 39 is relatively small even at the location of maximum impeller span, and because of the shape of the impeller, the impeller functions as an axial flow impeller, in which the impeller pumps blood axially from the distal end to the proximal end of the pump outlet pipe 24.) It is also desirable to maintain the gap between the outer edge of the impeller blades and the inner surface of the frame 34 throughout the rotation of the impeller within the frame 34, for example, to reduce the risk of hemolysis.

[0157] For some applications, when both impeller 50 and frame 34 are configured in a non-radial constraint configuration and before impeller operation, at the position of maximum impeller span, the clearance G between the outer edge of the impeller and the liner 39 is greater than 0.05 mm (e.g., greater than 0.1 mm) and / or less than 1 mm (e.g., less than 0.4 mm), for example, 0.05 mm–1 mm, or 0.1 mm–0.4 mm. For some applications, when the impeller is configured in its non-radial constraint configuration and before impeller operation, at the position of maximum impeller outer diameter, the outer diameter of the impeller is greater than 7 mm (e.g., greater than 8 mm) and / or less than 10 mm (e.g., less than 9 mm), for example, 7 mm–10 mm, or 8 mm–9 mm. For some applications, when the frame 34 is configured in its non-radial constraint configuration, the inner diameter of the frame 34 (measured from the inside of the liner 39 on one side of the frame to the inside of the liner on the opposite side of the frame) is greater than 7.5 mm (e.g., greater than 8.5 mm), and / or less than 10.5 mm (e.g., less than 9.5 mm), for example, 7.5 mm–10.5 mm, or 8.5 mm–9.5 mm. For some applications, when the frame is configured in its non-radial constraint configuration, the outer diameter of the frame 34 is greater than 8 mm (e.g., greater than 9 mm), and / or less than 13 mm (e.g., less than 12 mm), for example, 8 mm–13 mm, or 9 mm–12 mm.

[0158] Typically, the axial shaft 92 passes through the impeller cavity 62 along the axis of the impeller 50. More typically, the axial shaft is rigid, such as a rigid tube. For some applications, the proximal bushing 64 of the impeller is coupled to the shaft such that the axial position of the proximal bushing relative to the shaft is fixed, and the distal bushing 58 of the impeller is slidable relative to the shaft. For example, the proximal bushing can be coupled, for example, via a snap-fit ​​mechanism, to a connecting element 65 disposed on the axial shaft (in... Figure 4(As shown in the diagram). (Alternatively, the distal bushing 58 of the impeller is coupled to the shaft such that the axial position of the distal bushing relative to the shaft is fixed, and the proximal bushing 64 of the impeller is slidable relative to the shaft.) The axial shaft itself is radially stabilized via the proximal radial support 116 and the distal radial support 118. Furthermore, 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, such that a relatively small gap (e.g., the gap as described above) is maintained even during impeller rotation, even between the outer edge of the impeller blades and the inner surface of the frame 34.

[0159] Refer again Figures 3A-3C For some applications, the impeller includes a plurality of elongated elements 67 extending radially from a central axial spring 54 to an outer helical elongated element 52. These elongated elements are typically flexible, but substantially non-stretchable along the axis defined by the elongated elements. More typically, each elongated element is configured not to exert a force on the helical elongated element unless a force is applied to the impeller causing the helical elongated element to move radially outward, such that (in the absence of elongated elements) the gap between the helical elongated element and the central axial spring is greater than the length of the elongated element. For example, the elongated elements may comprise ropes (e.g., polyester, and / or another polymer or a natural material containing fibers) and / or threads (e.g., nitinol thread, and / or threads made of different alloys or metals).

[0160] For some applications, the elongated element 67 holds the helical elongated element (which defines the outer edge of the impeller blades) within a given distance relative to the central axial spring. In this way, the elongated element is configured to prevent the outer edge of the impeller from being forced radially outward due to the forces applied to the impeller during impeller rotation. The elongated element is thus configured to maintain a gap between the outer edge of the impeller blades and the inner surface of the frame 34 during impeller rotation. 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, wherein each elongated element is typically folded in half (i.e., extending radially from the central axial spring 54 to the outer helical elongated element 52 and then returning from the helical elongated element to the central axial spring). For some applications, multiple elongated elements are formed by a single rope or single line, wherein each elongated element extends from the spring to the corresponding helical elongated element and returns to the spring.

[0161] Now for reference Figure 3D and Figure 3E , Figure 3D and Figure 3E This is a schematic diagram of an impeller 50 according to some applications of the present invention, the impeller including a single integrated anti-over-expansion element 72 defining a plurality of elongated elements 67. For example... Figures 3A-3CAs shown, for some applications, an element 72 (which defines a plurality of elongated elements 67) is used as an alternative to the elongated elements 67 to prevent impeller overextension. 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 rope and / or wire around a spring 54, the ring 73 of element 72 is positioned around the spring, for example, by positioning it around a tube 70, which is typically located at the longitudinal center of the spring. The ends of the individual elongated elements 67 are then coupled to the respective helical elongated elements 52. As mentioned above, the elongated elements 67 are typically flexible but substantially not stretchable along the axis defined by the elongated elements. More typically, each of the elongated elements 67 is configured to be substantially non-resistant to compression. More specifically, each elongated element 67 is configured to apply a tension force to the helical elongated element 52, preventing the helical elongated element 52 from moving radially outward, such that (in the absence of elongated element 67) the gap between the helical elongated element 52 and the central axial spring 54 will be greater than the length of the elongated element 67. When the force causing the helical elongated element 52 to move radially outward (in the absence of elongated element 67) is applied to the impeller, this anti-impeller over-expansion element is configured to prevent radial expansion of the impeller. 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 a fiber-containing natural material and / or nitinol (or a similar shape memory alloy).

[0162] Note that the scope of this application includes the use of a single integrated anti-impeller over-expansion element 72, whose impeller has the same characteristics as... Figures 3D-3E Different structures are shown. For example, a single integrated anti-impeller over-extension element 72 can be used with an impeller having an axial structure with a different construction than that of the spring 54. Typically, the axial structure defines a cavity therethrough, such that the impeller defines a cavity 62 therethrough.

[0163] For some applications, the material used to manufacture the film is an elastomer with a limiting elongation greater than 300%, for example, greater than 400%. Typically, this material has a relatively low molecular weight. For some applications, the material has a melt flow index (an indirect measure of molecular weight) of at least 4, for example, at least 4.3. For some applications, the material has a limiting tensile strength exceeding 6000 psi, for example, exceeding 7000 psi, or exceeding 7500 psi. For some applications, the material is a polycarbonate-based thermoplastic polyurethane, such as Carbothane. TM For some applications, AromaticCarbothane TM (e.g., Aromatic Carbothane) TM75A) is used. Typically, this material combines one or more of the following properties: no loss of outer diameter during the immersion process, fatigue resistance, resistance to deformities due to curling, and low loss of outer diameter during curling. Subsequently, the material is cured, such that it solidifies, for example, by drying.

[0164] Typically, impeller 50 is inserted into the left ventricle via a conduit, while impeller 50 is in a radially constrained configuration. In this configuration, both the helical elongated element 52 and the central axial spring 54 become axially elongated and radially constrained. Typically, the membrane 56 of a material (e.g., silicone and / or polyurethane) changes shape to correspond to the shape changes of the helical elongated element and the axially supporting spring (both of which support the membrane of the material). Typically, using a spring to support the inner edge of the membrane allows the membrane to change shape without breaking or collapsing because the spring provides a large surface area bound by the inner edge of the membrane. For some applications, using a spring to support the inner edge of the membrane reduces the diameter of the impeller that may be radially constrained compared to, for example, using a rigid shaft to support the inner edge of the membrane, because the diameter of the spring itself can be reduced by axially elongating the spring.

[0165] As described above, for some applications, the proximal bushing 64 of the impeller 50 is coupled to the axial shaft 92 such that the axial position of the proximal bushing relative to the shaft is fixed, while the distal bushing 58 of the impeller is slidable relative to the shaft. For example, the proximal bushing can be coupled, for instance, via a snap-fit ​​mechanism to a connecting element 65 disposed on the axial shaft (in... Figure 4 (As shown in the diagram). For some applications, when the impeller is radially constrained for insertion into the ventricle or removal from the subject, the impeller is axially elongated by sliding the distal bushing distally along the axial shaft. Alternatively (not shown), the distal bushing 58 of the impeller is coupled to the shaft such that the axial position of the distal bushing relative to the shaft is fixed, and the proximal bushing 64 of the impeller is slidable relative to the shaft. For some applications, when the impeller is radially constrained for insertion into the ventricle or removal from the subject, the impeller is axially elongated by sliding the proximal bushing proximally along the axial shaft. (As shown in the diagram). Figures 3A-3E As shown, after being released into the subject's body, the impeller exhibits its non-radial constraint configuration (where the impeller is typically set to a non-radial constraint configuration during impeller operation).

[0166] Now for reference Figure 5A and Figure 5BThese figures are schematic diagrams of the impeller 50 and frame 34 of a ventricular assist device 20, respectively in their non-radial restraint and radial restraint states, according to some applications of the invention. During catheter insertion into the subject, the impeller and frame are typically configured in a radial restraint state, while during impeller operation within the subject's left ventricle, the impeller and frame are configured in a non-radial restraint state. Also refer to... Figure 5C , Figure 5C This is an enlarged schematic diagram of the proximal end of the frame of a ventricular assist device according to some applications of the present invention.

[0167] like Figure 5B As shown, the frame and impeller are typically held in a radially constrained configuration by the delivery duct 143. Typically, in a radially constrained configuration of the impeller, the total length of the impeller is greater than 15 mm (e.g., greater than 20 mm) and / or less than 30 mm (e.g., less than 25 mm), for example, 15 mm–30 mm or 20 mm–25 mm. More typically, in a non-radially constrained configuration of the impeller, the length of the impeller is greater than 8 mm (e.g., greater than 10 mm) and / or less than 18 mm (e.g., less than 15 mm), for example, 8 mm–18 mm or 10 mm–15 mm. Even more typically, when the impeller and frame 34 are arranged in a radially constrained configuration (e.g.... Figure 5B As shown), the impeller has an outer diameter of less than 2 mm (e.g., less than 1.6 mm), and the frame has an outer diameter of less than 2.5 mm (e.g., less than 2.1 mm).

[0168] As described above, typically, the axial shaft 92 passes through the axis of the impeller 50 via the impeller cavity 62. Typically, the proximal bushing 64 of the impeller is connected 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. (Alternatively, the distal bushing 58 of the impeller is connected to the shaft such that the axial position of the distal bushing relative to the shaft is fixed, and the proximal bushing 64 of the impeller is slidable relative to the shaft.) The axial shaft itself is radially stabilized via a proximal radial support 116 and a distal radial support 118. Typically, the proximal support housing 116H is configured to surround and house the proximal support, and the distal support housing 118H is configured to surround and house the distal support. For some such applications, the radial supports and support housings are made of corresponding, different materials. For example, the radial support can be made of a first material with relatively high hardness, such as ceramic (e.g., zirconium oxide), and the support housing can be made of a second material that can be molded into the desired shape, such as a metal or alloy (e.g., stainless steel, cobalt chromium, and / or nickel titanate).

[0169] For some applications, the axial shaft 92 is made of metal or alloy, such as stainless steel. For some such applications, the area of ​​the axial shaft that contacts either the proximal support 116 or the distal support 118 during operation of the ventricular assist device is covered with a ceramic sleeve 240 (e.g., a zirconia sleeve). In this way, the radial interface between the axial shaft and the proximal and distal supports is a ceramic-ceramic interface. As described further in detail herein, typically, the impeller and the axial shaft are configured to undergo axial reciprocating motion during operation of the ventricular assist device. Therefore, for some applications, at locations along the axial shaft corresponding to each of the proximal and distal supports, the axial shaft is covered by a ceramic sleeve along a length greater than 5 mm, for example, greater than 7 mm. In this way, during the axial reciprocating motion of the axial shaft, the area of ​​the axial shaft that contacts the radial supports is covered by the ceramic sleeve.

[0170] For some applications, along the axial shaft portion covered by the ceramic sleeve, the shaft is shaped (e.g., by milling, molding, or different forming processes) to define one or more grooves or notches 95, such as... Figure 5C A cross-sectional view is shown. Alternatively or additionally (not shown), the inner surface of the ceramic sleeve is shaped to define one or more grooves or notches. For some such applications, in order to bond the sleeve to the axial shaft, an adhesive is injected into the grooves or notches, and then the adhesive diffuses from the grooves or notches across the interface between the axial shaft and the sleeve.

[0171] For some applications, the proximal support housing 116H and the distal support housing 118H perform additional functions. Referring first to the proximal support housing, as described above, for some applications, the proximal strut joint 33 of the frame 34 closes around the outer side of the proximal support housing. For some applications, the outer surface of the proximal support housing defines a groove shaped to receive the proximal strut joint. For example, as shown, the proximal strut joint has a widened head, and the groove defined by the outer surface of the proximal support housing is shaped to conform to the widened head of the proximal strut joint. Typically, a retaining element 117 (which typically includes a ring) holds the strut joint in its closed configuration around the outer side of the proximal support housing 116H. For some applications, additional portions of the ventricular assist device are coupled to the proximal support housing. For some applications, a drive cable 130 extends from outside the subject's body to the axial shaft 92 and is coupled to the axial shaft. Typically, the drive cable rotates within a first outer tube 140, which serves as a support tube for the drive cable and extends from outside the subject's body to the proximal support housing. For some applications, the first outer tube is disposed within a second outer tube 142, which also extends from outside the subject's body to the proximal support housing. For some applications, the first outer tube 140 and / or the second outer tube 142 are coupled to the proximal support housing (e.g., using adhesive). For example, the first outer tube 140 may be coupled to the inner surface of the proximal support housing, and the second outer tube 142 may be coupled to the outer surface of the proximal support housing.

[0172] Referring now to the distal support housing 118H, for some applications, the distal connecting portion 31 of the frame 34 is connected to the outer surface of the distal support housing 118H, for example, via a snap-fit ​​mechanism. For example, the outer surface of the proximal portion 119 of the distal support housing may include a snap-fit ​​mechanism to which the distal connecting portion 31 of the frame 34 is connected. For some applications, the distal support 118 is disposed within the proximal portion 119 of the distal support housing, such as... Figure 5AAs shown. As described above, for some applications, the pump outlet tube 24 extends to the distal end of the frame 34 and defines a lateral blood inlet opening 108. For some such applications, a coupling portion 41 (e.g., a tubular coupling portion) extends distally from the pump outlet tube and is coupled to the distal support housing to anchor the distal end of the pump outlet tube. For some applications, the intermediate portion 123 of the distal support housing defines a ridged or threaded outer surface to which the coupling portion 41 of the pump outlet tube is coupled (e.g., by adhesive). For some applications, the outer surface is ridged to enhance the connection between the distal support housing and the coupling portion 41 of the pump outlet tube. For some applications, the outer surface is threaded to enhance the connection between the distal support housing and the coupling portion 41 of the pump outlet tube and to facilitate the application of adhesive between the outer surface and the coupling portion 41 of the pump outlet tube, as referenced below. Figure 12B Further detailed description. For some applications, the distal portion 121 of the distal support housing is configured to reinforce the area to which the distal end of the shaft 92 of the distal end element 107 moves (e.g., the axial shaft receiving tube 126 or a portion thereof). Typically, the distal end element 107 is coupled to the outer surface of the distal portion 121 of the distal support housing (e.g., via adhesive). For some applications, at least a portion of the outer surface of the distal portion 121 of the distal support housing is ridged and / or threaded to enhance the connection between the distal end element 107 and the distal support housing.

[0173] As described above, the axial shaft 92 is radially stabilized via a proximal radial support 116 and a distal radial support 118. Furthermore, the axial shaft, by passing through the cavity 62 defined by the impeller, radially stabilizes the impeller relative to the inner surface of the frame 34 and the liner 39, such that, as described above, even the relatively small gap (e.g., the gap described above) between the outer edge of the impeller blades and the liner 39 is maintained during impeller rotation. Typically, the impeller itself is not directly disposed within any radial support or thrust support. Instead, supports 116 and 118 act as radial supports relative to the axial shaft. Typically, the pump head portion 27 (and more generally, the ventricular assist device 20) does not include any thrust support configured to be disposed within the subject's body and configured to resist the thrust generated by the rotation of the impeller. For some applications, one or more thrust supports are disposed outside the subject's body (e.g., in situations such as...). Figure 1A and Figures 7A-7CWithin the motor unit 23 shown, resistance to the thrust generated by the rotation of the impeller is provided solely by one or more thrust supports disposed outside the subject's body. For some applications, mechanical and / or magnetic elements are configured to hold the impeller within a given axial position range. For example, a magnet (e.g., magnet 82, hereinafter referred to) disposed near the proximal end of the drive cable (e.g., outside the subject's body). Figure 7A (As described) can be configured to apply axial movement to the impeller and / or hold the impeller within a given axial position range.

[0174] Now for reference Figure 6A and Figure 6B These figures are schematic diagrams of a ventricular assist device 20 according to some applications of the invention, showing the impeller 50 of the ventricular assist device relative to the frame 34 of the ventricular assist device at various stages of the motion cycle. For some applications, when the impeller pumps blood through the tube 24 by rotation, an axial shaft 92 (on 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 shown below. Figure 7A Further detailed description. Alternatively or additionally, the impeller and axial shaft are configured to reciprocate axially within the frame 34 in response to forces acting on the impeller, without requiring active drive of the axial shaft to move in a reciprocating manner. Typically, during a subject's cardiac cycle, the pressure differential between the left ventricle and the aorta changes from approximately zero during ventricular systole (hereinafter "systole") to a relatively large pressure differential (e.g., 50 mmHg–70 mmHg) during ventricular diastole (hereinafter "diastole"). For some applications, due to the increased pressure differential resisted by the impeller pumping during diastole (and because the drive cable 130 is stretchable), the impeller is pushed distally relative to the frame 34 during diastole compared to its position relative to the frame 34 during systole. Consequently, the axial shaft moves forward because the impeller is connected to it. During systole, the impeller (and consequently the axial shaft) returns to its systolic position. In this way, the axial reciprocating motion of the impeller and the axial shaft is generated passively, that is, it is not necessary to actively drive the axial shaft and impeller to make them undergo this motion. Figure 6A and Figure 6B The impeller and axial shaft are shown at corresponding positions within the frame 34 during the aforementioned axial reciprocating motion cycle.

[0175] In some applications, the portion of the axial shaft in contact with the proximal support 116 and the distal support 118 changes continuously due to its axial reciprocating motion. In some such applications, assuming all else is equal, the frictional force exerted on the axial shaft by the supports is distributed over a larger area of ​​the axial shaft compared to when the axial shaft does not move relative to the supports, thereby reducing wear on the axial shaft. Alternatively or additionally, by reciprocating relative to the supports, the axial shaft removes any residue, such as blood residue, from the interface between the axial shaft and the supports.

[0176] For some applications, such as Figure 6A As shown, at the closest position of the impeller during its rotation cycle, the proximal end of the impeller is positioned within the proximal conical segment of the frame 34. For some applications, at the farthest position of the impeller during its rotation cycle, the distal end of the impeller is positioned at the distal end of the cylindrical segment of the frame 34. Alternatively, as... Figure 6B As shown, even at the farthest position of the impeller during its motion cycle, the distal end of the impeller is positioned proximal to the distal end of the cylindrical segment of the frame 34. Typically, throughout the entire cardiac cycle, the segment with the largest impeller span is positioned 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 positioned within the proximal conical segment of the frame.

[0177] Refer again Figure 6A and Figure 6B Typically, the distal end element 107 is a single integrated element comprising both the axial shaft receiving tube 126 and the distal end portion 120. Typically, the axial shaft receiving tube is configured to receive the distal portion of the axial shaft 92 of the pump head portion during axial reciprocating motion of the axial shaft (as described further in detail below) and / or during delivery of the ventricular assist device. (Typically, during delivery of the ventricular assist device, the frame is held in a radially constrained configuration, which typically results in the axial shaft being positioned differently relative to its setting with respect to the frame during operation of the ventricular assist device.) For some applications, the distal end portion 120 is configured to be flexible, such that the distal end portion is configured not to cause tissue damage to the subject even if it comes into contact with tissue (e.g., tissue of the left ventricle). For example, the distal end portion 120 or the entire distal end element may be made of silicone, polyethylene terephthalate (PET), and / or polyether block amide (e.g., PEBAX®). For some applications, the distal portion defines a cavity 122 that passes through it. For some such applications, during insertion of the ventricular assist device into the left ventricle, the guide wire 10 ( Figure 1BFirst, it is inserted into the left ventricle according to, for example, known techniques. Then, the distal portion of the ventricular assist device is guided into the left ventricle by advancing the distal portion of the guide wire, wherein the guide wire is disposed within the cavity 122. For some applications, a duckbill valve 390 (or a hemostatic valve of a different type) is disposed at the distal end of the cavity 122 of the distal portion 120.

[0178] Typically, during the insertion of the ventricular assist device into the ventricle of a subject, the delivery catheter 143 is positioned on the impeller 50 and frame 34, and the impeller and frame are maintained in their radially constrained configuration. For some applications, such as Figure 1B As shown, during insertion of the delivery catheter into the subject's ventricle, the distal distal element 107 extends distally from the delivery catheter. For some applications, the distal distal element has a protrusion 110 towards its proximal end. (Reference) Figure 5B (It shows the pump head portion disposed within the delivery catheter 143.) For some applications, during insertion of the ventricular assist device into the ventricle of a subject, the delivery catheter extends to the proximal side of the protrusion, such that the delivery catheter and the protrusion form a smooth, continuous surface. The distal side of the protrusion 110 is tapered, such that the vascular system is exposed to the tapered diameter variation and not exposed to any edges caused by the abrupt change in diameter at the interface between the delivery catheter and the distal terminal element.

[0179] For some applications, the distal distal element 107 defines a total curvature resembling a question mark or a tennis racket, wherein the distal distal element defines a straight proximal portion and a bulge on one side of the longitudinal axis of the straight proximal portion. Typically, as described above, the ventricular assist device is introduced into the ventricle of a subject via a guideline. The distal distal portion 120 defines a cavity 122 such that the distal distal portion is maintained in a straight configuration during the introduction of the ventricular assist device into the subject's ventricle (e.g., as in...). Figure 1B (As shown in the left view). For some applications, the distal end portion is configured to exhibit its curved shape when the guide wire is removed.

[0180] Refer again Figures 6A-6BFor some applications, the axial shaft receiving tube 126 extends proximally from the distal end portion 120 of the distal end element 107. As described above, typically, the axial shaft undergoes axial reciprocating motion during operation of the impeller 50. The axial shaft receiving tube 126 defines a cavity 127 configured to receive the axial shaft when it extends beyond the distal support 118. For some applications, the axial shaft receiving tube defines a stop 128 at its distal end, configured to prevent the axial shaft from being pushed beyond the stop. For some applications, the stop includes a rigid member inserted (e.g., embedded) into the distal end of the shaft receiving tube. Alternatively (not shown), the stop includes a shoulder between the cavity 127 of the axial shaft receiving tube and the cavity 122 of the distal end portion 120.

[0181] Typically, during normal operation of the impeller, the axial shaft does not contact the stop 128, even when the drive cable 130 (in) Figure 5A This is also true when the ventricular assist device 20 is extended to its maximum extent (e.g., during diastole). However, during the retraction of the ventricular assist device 20 from the subject's ventricle, as the delivery catheter is advanced over the impeller 50 and frame 34, the stop 128 is configured to prevent the axial shaft from protruding into the distal portion. In some cases, there is a risk of the drive cable snapping during the advancement of the delivery catheter over the frame and impeller. Without the stop 128, in this situation, the axial shaft might protrude into the distal portion. The stop 128 prevents this from happening, even in the event of drive cable snapping.

[0182] It should be noted that at the proximal end of frame 34, the proximal radial support 116 also acts as a stop by preventing the proximal bushing 64 of the connecting element 65 and / or impeller 50 from moving beyond the proximal radial support. Typically, during normal operation of the impeller, the connecting element 65 and the proximal bushing 64 do not contact the proximal radial support 116. However, the proximal radial support 116 is configured to prevent the connecting element 65 and / or the proximal bushing 64 of the impeller 50 from migrating proximal from within the frame, for example, when the impeller and frame are held in a radially constrained (i.e., coiled) configuration within the delivery duct 143. Typically, the connecting element and / or the proximal bushing extends proximal to prevent the central region of the impeller (where the impeller is at its maximum span) from sliding proximal into the proximal tapered portion of frame 34. For example, during the contraction phase of the impeller's motion cycle (in Figure 6AAs shown in the diagram, if the impeller slides further proximally beyond a given amount, the connecting element will contact the proximal radial support 116, thereby preventing further proximal movement of the impeller. For some applications, the connecting element and / or the proximal bushing extends proximally such that its total length is greater than 1.5 mm, for example, greater than 4 mm. For some applications (not shown), a separate stop element is provided proximally on the axial shaft relative to the connecting element and / or the proximal bushing 64. Typically, the stop element is configured as described with reference to the connecting element. That is, if the impeller slides further proximally beyond a given amount, the stop element element will contact the proximal radial support 116, thereby preventing further proximal movement of the impeller.

[0183] Typically, during operation of the ventricular assist device and throughout the entire axial reciprocating cycle of the impeller, the impeller is positioned relatively very close to the distal end portion. For example, the distance from the impeller to the distal end portion can be within the farthest 50% of tube 24, such as the farthest 30% (or the farthest 20%), throughout the entire axial reciprocating cycle of the impeller.

[0184] Now for reference Figure 6C and Figure 6D , Figure 6C and Figure 6D This is a schematic diagram of a ventricular assist device including a motion-damping spring 68 according to some applications of the invention. As described in further detail below, typically, during operation of the ventricular assist device (i.e., when the impeller rotates), the impeller undergoes axial reciprocating motion. For some applications, when the impeller undergoes axial reciprocating motion, the motion-damping spring is configured to act as a shock absorber to cushion the motion. Figure 6C This shows the impeller in the contraction phase of its motion cycle, and Figure 6D The diagram illustrates the impeller in the relaxation phase of its motion cycle. As shown, the motion buffer spring becomes more compressed as the impeller moves distally from its contracted position to its relaxed position. For some applications, the impeller is configured to be radially constrained (i.e., coiled) by becoming axially elongated, and the motion buffer spring is configured to be compressed to accommodate the axial elongation of the impeller. Typically, when the impeller is in the radially constrained configuration, the impeller elongates axially during pump head insertion into the left ventricle, causing the distal end of the impeller to be further distalized within frame 34, and the spring relative to... Figure 6D The configuration of the impeller and spring shown is further compressed.

[0185] Typically, a motion damping spring is disposed around an axial shaft 92 between the distal end of the impeller (e.g., the distal bushing 58 of the impeller) and the distal support 118. In some applications, the motion damping spring is coupled to the distal support 118 or the distal support housing 118H and extends proximally along the axial shaft 92 from the distal support or the distal support housing 118H. Typically, in this configuration, the motion damping spring remains stationary as the impeller rotates, and the impeller is configured to rotate relative to the motion damping spring. Alternatively or additionally, the motion damping spring is coupled to the distal end of the impeller (e.g., the distal bushing 58 of the impeller) and / or extends distally along the axial shaft 92 from the distal end of the impeller (e.g., the distal bushing 58 of the impeller). In some such applications, the motion damping spring is configured to rotate with the impeller. Alternatively, a motion buffer spring extends from a radial support disposed around the distal end of the impeller (e.g., the distal bushing 58 of the impeller), such that the motion buffer spring remains stationary as the impeller rotates, and the impeller is configured to rotate relative to the motion buffer spring.

[0186] For some applications, the motion buffer spring is coupled to an elastomeric material 69 (e.g., polyurethane and / or silicone) such that at least a portion of the axial shaft 92 located between the distal end of the impeller and the distal radial support is covered by the elastomeric material. For some applications, coupling the elastomeric material to the spring reduces the risk of thrombosis and / or hemolysis caused by the spring, compared to a spring not being coupled to the elastomeric material. Note that the scope of this disclosure includes providing a motion buffer spring without the elastomeric material, which may be desirable in some cases.

[0187] Figure 6C and Figure 6D A spring coated with an elastomeric material is shown, wherein the elastomeric material extends between adjacent windings of the spring. Alternatively, the spring is embedded within the elastomeric material. Typically, the elastomeric material is generally similar to the elastomeric material of the membrane 56 used in the impeller 50. Furthermore, typically, the elastomeric material is coupled to the motion buffer spring in a manner substantially similar to that described above regarding the coupling of the membrane of the elastomeric material to the spring of the impeller. Typically, the elastomeric material is coupled to the motion buffer spring in such a manner that the elastomeric material changes shape (e.g., by stretching and compression) to conform to the shape changes experienced by the motion buffer spring (e.g., when the motion buffer spring experiences elongation and compression). Furthermore, typically, the elastomeric material is configured to undergo the aforementioned shape changes without breaking or collapsing, and without wrinkling when the spring is compressed.

[0188] As described above, cleaning fluid is typically pumped between outer tubes 140 and 142. Typically, within the pump head, a portion of the cleaning fluid flows through a cavity defined by the axial shaft 92 and then exits the axial shaft near the distal support 118 to clean the interface between the axial shaft and the distal support. For some applications, the cleaning system is configured such that the cleaning fluid flows from the distal support to the proximal side along the interface between the axial shaft and the elastomeric material. In this way, the interface between the axial shaft and the elastomeric material is cleaned and / or lubricated.

[0189] For some applications (not shown), a proximal motion damping spring is disposed on the proximal side of the impeller. For some such applications, the proximal motion damping spring is disposed around the axial shaft 92 between the proximal end of the impeller (e.g., the proximal bushing 64 of the impeller) and the proximal support 116. For some applications, the proximal motion damping spring is coupled to the proximal support 116 or the proximal support housing 116H and extends distally along the axial shaft 92 from the proximal support or the proximal support housing. Typically, in this case, the proximal motion damping spring remains stationary as the impeller rotates, and the impeller is configured to rotate relative to the motion damping spring. Alternatively or additionally, the proximal motion damping spring is coupled to the proximal end of the impeller (e.g., the proximal bushing 64 of the impeller) and / or extends distally along the axial shaft 92 from the proximal end of the impeller (e.g., the proximal bushing 64 of the impeller). For some such applications, the motion damping spring is configured to rotate with the impeller. Alternatively, a proximal motion buffer spring extends from a radial support disposed around the proximal end of the impeller (e.g., the proximal bushing 64 of the impeller), such that the motion buffer spring remains stationary as the impeller rotates, and the impeller is configured to rotate relative to the motion buffer spring.

[0190] For some applications, the pump head includes a proximal motion buffer spring (located on the proximal side of the impeller) and a distal motion buffer spring (located on the distal side of the impeller), such that axial movement of the impeller in the distal or proximal direction is buffered by the motion buffer spring.

[0191] Now for reference Figure 7A This is a schematic exploded view of the motor unit 23 of a ventricular assist device 20 according to some applications of the present invention. For some applications, the console 21 ( Figure 1A The computer processor 25, which controls the rotation of the impeller 50, is also configured to control the reciprocating motion of the axial shaft. For some such applications, both types of motion are generated using the motor unit 23. The scope of the invention includes controlling reciprocating motion at any frequency. For some applications, an indication of a 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.

[0192] Typically, motor unit 23 includes a motor 74 configured to apply rotational motion to impeller 50 via drive cable 130. As described further below, typically, the motor is magnetically coupled to the drive cable. For some applications, axial motion driver 76 is configured to drive the motor to move in an axial reciprocating motion (as indicated by double-headed arrow 79). Typically, due to the magnetic coupling between the motor and the drive cable, the motor applies reciprocating motion to the drive cable, which in turn applies that 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 pressure gradients resisted by the impeller pumping blood. Typically, for such applications, motor unit 23 does not include axial motion driver 76.

[0193] In some applications, the magnetic coupling between the motor and the drive cable is as follows: Figure 7A As shown. Figure 7A As shown, a set of drive magnets 77 are coupled to a 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 gasket 85 is adhered to the inner surface of the ring 81 between two drive magnets. A driven magnet 82 is disposed between the drive magnets such that there is axial overlap between the drive magnets and the driven magnets. 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 a drive cable 130. For example, the driven magnet may be cylindrical and define a hole through it, and the pin 131 may be adhered to the inner surface of the driven magnet defining 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 by a line 83 that bisects the cylinder, as shown. For some applications, the driven magnet is housed within a cylindrical housing 87. Typically, pin 131 defines the guide wire cavity 133.

[0194] Note that in Figure 7A In the illustrated application, the driving magnet is disposed outside the driven magnet. However, the scope of this application includes reversing the configuration of the driving and driven magnets (with necessary modifications). For example, the proximal end of the drive cable may be coupled to two or more driven magnets arranged around the driving magnet such that there is axial overlap between the driven and driving magnets.

[0195] As described above, typically, the cleaning system 29 (such as...) Figure 1A(As shown) Used with ventricular assist device 20. Typically, motor unit 23 includes an inlet port 86 and an outlet port 88 for use with a cleaning system. In some applications, cleaning fluid is continuously or periodically pumped into the ventricular assist device via inlet port 86 and pumped out of the ventricular assist device via outlet port 88.

[0196] Typically, magnet 82 and pin 131 are held in an axially fixed position within motor unit 23. Typically, the proximal end of the drive cable is coupled to pin 131 and thus held in an axially fixed position by the pin. Typically, drive cable 130 extends from pin 131 to axial shaft 92, thereby at least partially fixing the axial position of the axial shaft, and consequently fixing the impeller 50. For some applications, the drive cable is to some extent stretchable. For example, the drive cable may be made of stretchable coiled wire. The drive cable typically allows the axial shaft (and consequently the impeller) to present a range of axial positions (becoming more or less stretched by the drive cable), but limits the axial movement of the axial shaft and impeller to a certain range of motion (by holding the proximal end of the drive cable in an axially fixed position, and limiting the stretchability of the drive cable).

[0197] As described above, for some applications, the impeller 50 and the axial shaft 92 are configured to reciprocate axially within the frame 34 in response to forces acting on the impeller, without requiring active driving of the axial shaft to move in a reciprocating manner. Typically, during a subject's cardiac cycle, the pressure gradient between the left ventricle and the aorta changes from approximately zero during systole to a relatively large pressure gradient (e.g., 50 mmHg–70 mmHg) during diastole. For some applications, due to the increased pressure gradient resisted by the impeller pumping during diastole (and because the drive cable is stretchable), the impeller is pushed distally relative to the frame 34 during diastole compared to its position relative to the frame 34 during systole. Consequently, the axial shaft moves forward because the impeller is connected to it. During systole, the impeller (and consequently the axial shaft) returns to its systolic position. In this way, the axial reciprocating motion of the impeller and the axial shaft is generated passively, that is, it is not necessary to actively drive the axial shaft and impeller to make them undergo this motion.

[0198] Now for reference Figure 7B and Figure 7C These figures are schematic diagrams of motor unit 23 according to some applications of the present invention. Generally, as... Figure 7B and Figure 7C The motor unit 23 shown is similar to Figure 7A The motor unit shown, unless otherwise specified, is as follows: Figure 7B and Figure 7CThe motor unit 23 shown includes and Figure 7A The motor unit 23 shown is a similar component. For some applications, the motor unit includes a radiator 90 configured to dissipate heat generated by the motor. Alternatively or additionally, the motor unit includes a vent 93 configured to further dissipate heat generated by the motor. For some applications, the motor unit includes vibration dampers 94 and 96 configured to dampen vibrations of the motor unit caused by the rotational and / or axial reciprocating motion of components of the ventricular assist device.

[0199] Now for reference Figure 8A This figure is a graph showing the change in the length of the drive cable of a ventricular assist device (VAD) as a function of the pressure gradient resisted by the VAD impeller (as measured experimentally). The impeller and drive cable described herein are used to pump a glycerol-based solution through a chamber 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 pumping varies in a pulsatile manner to represent the pulsatile nature of the pressure gradient resisted by the impeller as it pumps 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 image analysis. Figure 8A The graph shown illustrates how the measured drive cable length changes with the pressure gradient. Figure 8A As shown, as the pressure gradient resisted by the impeller pump increases, the drive cable becomes longer and longer. Figure 8A As shown and described above, typically, in response to changes in pressure resisted by the impeller pumping blood (e.g., the pressure difference between the left ventricle and the aorta), the impeller reciprocates relative to the frame 34. Furthermore, the movement of the impeller causes the drive cable 130 to extend more or less.

[0200] For some applications, during the operation of the ventricular assist device, console 21 ( Figure 1A The computer processor 25 is configured to measure the pressure applied to the impeller (indicating the pressure differential between the left ventricle and the aorta) by measuring the tension in the drive cable 130 and / or the indication of the axial movement of the drive cable. In 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. In some applications, the computer processor controls the rotation of the impeller and / or, in response, controls the axial reciprocating motion of the axial shaft.

[0201] Refer again Figure 7AFor some applications, the ventricular assist device 20 includes a sensor 84. For example, the sensor may include a magnetometer (e.g., a Hall effect sensor) disposed within the motor unit 23. Figure 7A As shown. (In some cases, sensor 84 is referred to as magnetometer 84.) In some applications, the axial reciprocating motion of the impeller causes a measurable reciprocating motion of the internal driven magnet 82 relative to one or more external drive magnets 77 because the driven magnet is held in place relative to the drive magnet by a magnetic connection rather than a rigid mechanical connection. Note that typically, the axial motion of the magnet is substantially less than the axial motion of the impeller because the entire range of motion of the impeller is not transmitted along the length of the drive cable (which is typically stretchable to some extent). In 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, consequently, determine the pressure that the impeller pumps against. For example, the internal driven magnet 82 may be longer in the axial direction than the external drive magnet 77. Because the internal magnet is longer than the external magnet, the magnetic field lines emanating from the internal magnet are not transmitted to the external magnet, and the magnetic flux generated by these field lines, as measured by the magnetometer, varies due to the drive cable, and consequently causes axial movement of the internal magnet. During operation, motor 74 rotates, thereby generating an AC signal in the magnetometer, typically with a frequency between 200 Hz and 800 Hz. Typically, as 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, typically with a frequency of 0.5 Hz to 2 Hz. For some applications, a computer processor measures the low-frequency envelope and derives the subject's cardiac cycle from the measured envelope.

[0202] For some applications, the magnetometer measurements are initially calibrated such that the change in magnetic flux per unit pressure change resisted by the impeller pump (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, the left ventricular pressure equals the aortic pressure during systole. 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: (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 aortic pressure). 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 techniques described above 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.

[0203] For some applications, techniques similar to those described in the preceding paragraph are typically used, but as an alternative or supplement to measurements using a magnetometer, 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). 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 resisted by the impeller pumping, and another portion 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 these components typically changes during the cardiac cycle. For some applications, calibration measurements are performed such that the relationship between (a) the motor power consumption (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 a computer processor calculates the subject's left ventricular pressure at a given time based on (a) the measured aortic pressure, (b) the motor power (and / or current) consumption required to rotate the impeller at a given rotational 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 rotational rate and the pressure difference generated by the impeller. For some applications, the above technique is performed while keeping the impeller rotational rate constant. Alternatively or additionally, the impeller rotational rate is varied, and the variation in the impeller rotational rate is taken into account in the above calculations. For some applications, the above technique is 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.

[0204] Typically, tube 24 has a known cross-sectional area (when the tube is open due to blood flow). For some applications, the flow rate through tube 24 generated by the impeller is determined based on a defined pressure differential generated by the impeller and the known cross-sectional area of ​​the tube. For some applications, this flow rate calculation incorporates calibration parameters to account for factors such as flow resistance, which correspond to the specificity of the ventricular assist device (or type of ventricular assist device) being performed. For some applications, a ventricular pressure-volume loop is derived based on a defined ventricular pressure.

[0205] Refer 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 the indication of the magnetic flux density generated by the driving magnet. In some applications, the second magnetometer measures the magnetic flux density of the motor, indicating the magnetic flux density cycle of the driving magnet, since the motor directly drives the driving magnet to rotate. Typically, torque is generated on the impeller when it rotates to pump blood. More typically, the strength of the torque depends on various parameters, such as the flow rate generated by the impeller, the impeller's rotational speed, and / or the pressure gradient resisted by the impeller pumping. In some applications, the torque generated on the impeller produces 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 a magnetic coupling rather than a rigid mechanical coupling. Note that the torque generated on the driven magnet is typically 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, typically, the torque generated on the impeller is transmitted at least in part to the driven magnet via the drive cable.

[0206] The torque transmitted to the driven magnet typically causes a phase difference between the signal measured by magnetometer 84 (which measures the magnetic flux density of the driven magnet) and the signal measured by second magnetometer 84A (which measures the magnetic flux density of the motor and / or drive magnet). In some applications, this causes a change in the phase difference between the signal measured by magnetometer 84 and the signal measured by second magnetometer 84A when the torque on the impeller changes. In some applications, a computer processor detects the change in the aforementioned phase difference and determines physiological parameters of the subject in at least a partial response to the change in the 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. In some applications, the techniques described in this paragraph are used as alternatives to the aforementioned techniques for determining physiological parameters using magnetic flux density measurements and / or power consumption measurements. Alternatively, two or more of these techniques may be used in combination. For example, a subject's physiological parameters can be determined based on a mathematical model that includes two or more measurements, and / or one of the techniques can be used to validate an estimate of the subject's physiological parameters made using another of the techniques.

[0207] Now for reference Figure 8B and Figure 8C , Figure 8B and Figure 8C The graph illustrates the correlation between the phase difference signal and the pressure gradient resisted by the impeller 50 pump, according to some applications of the present invention.

[0208] Figure 8B The graphs shown illustrate 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 for each measurement). The pressure gradient resisted by the impeller pump was estimated using a linear regression model based on the phase difference signal, the flux amplitude signal, and the current consumed by the motor. Figure 8B The graph shown illustrates the relationship between the estimated pressure gradient and the measured pressure gradient. As illustrated, the linear regression model, combined with phase difference measurements, provides a reliable method for estimating the pressure gradient resisted by the impeller pump.

[0209] Figure 8C The graphs shown illustrate 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., where the pressure gradient varies pulsatilely). The pressure gradient resisted by the impeller pump 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 diagram shows the estimated pressure gradient superimposed on the measured pressure gradient. As illustrated, the spatial state model combined with phase difference measurements provides a reliable method for estimating the pressure gradient resisted by the impeller pump.

[0210] According to the above, and in some applications of the invention, the magnetic phase difference between one or more driven magnets and one or more driving magnets is measured, and physiological parameters of a subject are determined at least in part in response to this magnetic phase difference. For example, based at least in part on changes 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, events in the subject's cardiac cycle, the subject's cardiac afterload, and / or different physiological parameters. For some applications, the physiological parameters are determined based on a combination of phase difference measurements and one or more additional measurements, such as magnetic flux amplitude measurements, power consumed by the motor, and / or current consumed by the motor. Typically, such measurements are combined in mathematical models (e.g., linear regression models) and / or spatial state models.

[0211] Now for reference Figure 9A and Figure 9B , Figure 9A and Figure 9B This is a schematic diagram of a ventricular assist device comprising one or more blood pressure measuring tubes 222 and / or fibers 228, according to some applications of the present invention.

[0212] Figure 9AThis 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, typically, the ventricular assist device includes a pump outlet tube 24 passing through the aortic valve of a subject, such that the proximal end of the tube is disposed within the subject's aorta, while the distal end of the tube is disposed within the subject's left ventricle. Typically, a blood pump (which typically includes an impeller 50) is disposed within the tube 24 within the subject's left ventricle and is configured to pump blood from the left ventricle into the subject's aorta through the tube 24. For some applications, the ventricular blood pressure measuring tube 222 is configured to extend at least to the 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 subject's blood flow outside the tube 24. Typically, the opening 214 is configured to be located proximal to the blood pump (e.g., proximal to the impeller 50) within the subject's left ventricle. A pressure sensor 216 (in...) Figure 1A (Illustrated schematically) Measuring blood pressure within the ventricular blood pressure measuring tube. Typically, by measuring blood pressure within the left ventricular blood pressure measuring tube, the pressure sensor thereby measures the subject's blood pressure (i.e., left ventricular blood pressure) outside tube 24. Typically, the blood pressure measuring tube 222 extends from outside the subject's body to an opening 214 at the distal end of the tube, and the pressure sensor 216 is positioned towards the proximal end of the tube, for example, outside the subject's body. For some applications, a computer processor 25 ( Figure 1A It receives the measured blood pressure reading and controls the blood pumping performed by the impeller in response to the measured blood pressure.

[0213] For some applications, ventricular assist devices include two or more such ventricular blood pressure measuring tubes 222, for example, such as Figure 9A The ventricular blood pressure measuring tube 222 is shown. For some applications, based on the blood pressure measured in each left ventricular blood pressure measuring tube, the computer processor 25 determines whether the opening of one of the two or more ventricular blood pressure measuring tubes is blocked. For example, this may occur due to the opening coming into contact with the ventricular septum wall and / or different ventricular portions. Typically, in response to determining that the opening of one of the two or more ventricular blood pressure measuring tubes is blocked, the computer processor determines the subject's left ventricular pressure based on the blood pressure measured in another of the two or more ventricular blood pressure measuring tubes.

[0214] For some applications, the 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 the tube 24. Typically, during insertion of the ventricular assist device into a subject, a portion of the ventricular blood pressure measuring tube 222 extending from within the tube 24 to at least the outer surface of the tube 24 is configured to be disposed within the groove, such that this portion of the ventricular blood pressure measuring tube does not protrude from the outer surface of the outer tube.

[0215] For some applications (not shown), the distal portion of the blood pressure measuring tube 222 is disposed outside the pump outlet tube 24. For example, the blood pressure measuring tube 222 may extend from the outer tube 142 to the proximal end of the pump outlet tube 24, after which the blood pressure measuring tube may be embedded in the outer surface of the pump outlet tube 24, for example, as in Tuval's US 10,881,770. Figure 16D As shown, this patent is incorporated herein by reference.

[0216] As described above, for some applications, the drive cable 130 extends from a motor outside the subject's body to an axial shaft 92, on which the impeller 50 is mounted. Typically, the drive cable is housed 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 measuring tube 222 includes a channel between the first outer tube 140 and the second outer tube 142, such as... Figure 9A The cross-section is shown. In this regard, it should be noted that the blood pressure measuring tube should be understood as a continuous cavity extending from the pressure sensor 216 to the outside of the pump outlet tube 24 within the left ventricle of the subject, regardless of whether the structure of the cavity varies along its length. As mentioned above, a cleaning fluid is typically pumped between the outer tubes 140 and 142, and for some applications, the cleaning fluid is pumped through channel 226. Typically, the blood pressure measuring tube 222 occupies a larger cross-sectional area defined between the outer tubes 140 and 142 than the cleaning fluid channel 226, such as Figure 9A As shown. For example, the ratio of (a) the cross-sectional area occupied by the blood pressure measuring tube defined between outer tubes 140 and 142 to (b) the cross-sectional area occupied by the cleaning fluid channel 226 defined between outer tubes 140 and 142 is typically greater than 3:2, greater than 3:1, or greater than 5:1. For some applications, the blood pump measuring tube occupies a relatively large proportion of the cross-sectional area defined between outer tubes 140 and 142 in order to transmit blood pressure outside the pump outlet tube 24 in the left ventricle of the subject proximally to the pressure sensor 216.

[0217] refer to Figure 9B For some applications, optical fiber 228 is configured to extend to at least the outer surface 213 of tube 24, such that the distal end 230 of the optical fiber is directly exposed to patient blood flow outside tube 24. Typically, the optical fiber extends from the proximal end of an optical fiber located outside the subject's body (e.g., within motor unit 23) to the distal end 230. Furthermore, typically, a light source and a photodetector (not shown) are located at the proximal end of the optical fiber and configured to detect blood pressure at the distal end of the optical fiber by guiding light through the optical fiber and detecting reflected light.

[0218] Typically, the distal end 230 of the optical fiber 228 is configured proximal to the blood pump (e.g., proximal to the impeller 50) within the left ventricle of the subject. Typically, by measuring the blood pressure at the distal end 230 of the optical fiber 228, a pressure sensor thereby measures the blood pressure (i.e., left ventricular blood pressure) of the subject outside the tube 24. For some applications, a computer processor 25 ( Figure 1A It receives the measured blood pressure reading and controls the blood pumping performed by the impeller in response to the measured blood pressure.

[0219] For some applications, ventricular assist devices include two or more such optical fibers 228, for example, as Figure 9B The optical fiber 228 is shown. For some applications, based on blood pressure measured using each fiber in the optical fiber, the computer processor 25 determines whether the distal end of one of the fibers is not exposed to left ventricular blood flow. This may occur, for example, due to contact between the distal end of one fiber and the wall of the interventricular septum and / or a different intraventricular portion. Typically, in response to determining that the distal end of one fiber is not exposed to left ventricular blood flow, the computer processor determines the subject's left ventricular pressure based on blood pressure measured using different fibers in two or more of the optical fibers 228.

[0220] For some applications, the optical fiber is disposed within the outer tube 142 along its length. Typically, at the distal end of the outer tube, the optical fiber is coupled to the proximal tapered portion 36 of the frame 34, such that the optical fiber extends radially to the outer surface of the pump outlet tube 24. For example, as... Figure 9B As shown, the optical fiber can be stitched or tied to the proximal tapered portion of the frame 34 using a connecting element 232 (e.g., a wire). For some applications (not shown), the distal portion of the optical fiber 228 is positioned outside the pump outlet tube 24. For example (not shown), the optical fiber 228 can extend from the outer tube 142 to the proximal end of the pump outlet tube 24, and thereafter the optical fiber can be coupled to the outer surface of the tube pump outlet tube 24.

[0221] Referring to the blood pressure measuring tube 222 and the optical fiber 228, it is noted that the distal end of the tube or optical fiber is typically in direct fluid communication with the subject's left ventricular blood flow at a location near the nearest portion of the blood inlet opening 108 (e.g., at least 1 cm, or at least 1.5 cm, near the nearest portion of the blood inlet opening 108). Therefore, the distal end of the tube or optical fiber is typically exposed to blood with a pressure reflecting the left ventricular blood pressure itself, and is unaffected by any pressure changes occurring near the blood inlet opening due to fluid flow dynamics generated at the blood inlet opening.

[0222] Based on the techniques described above, typically, for example, a combination of any of the techniques described herein for determining flow through a ventricular assist device and any of the techniques described herein for determining left ventricular pressure, computer processor 25 is configured to determine pressure and flow-related parameters of the subject's left ventricle. For some applications, using the aforementioned parameters, the computer processor is configured to estimate the subject's natural cardiac output (i.e., stroke volume), total cardiac output, arterial compliance, and / or peripheral resistance. For some applications, the aforementioned parameters are determined using a mathematical model that represents the aorta and / or left ventricle as a dynamic vascular system.

[0223] For example, according to the Windkessel model of the aorta, the relationship between flow rate and pressure in the aorta can be described by the following equation:

[0224]

[0225] in These are instantaneous arterial pressure and blood flow, and the variables are... These are aortic compliance, characteristic impedance, and peripheral resistance.

[0226] During the operation of the ventricular assist device 20, Equation 1 can be rewritten as follows:

[0227]

[0228] The subscripts n and p represent the contributions of natural cardiac function and ventricular assist device function to flow velocity and aortic pressure, respectively.

[0229] For some applications, in the first step, the subject's vascular parameters are estimated ( To this end, the impeller rotation speed is varied during one or more vascular parameter determination cycles. Typically, the vascular parameter determination cycle lasts for several cardiac cycles (e.g., 1–10 or 2–6 cardiac cycles), or only for a few cardiac cycles during diastole (e.g., 1–10 or 2–6 cardiac cycles). It is assumed that the subject's parameters remain substantially constant during the vascular parameter determination cycle. (Alternatively, a mathematical model simulating this variation can be used to account for any changes in the subject's vascular parameters caused by the change in impeller rotation speed.)

[0230] For the two operating conditions of the ventricular assist device (i.e., when the impeller operates at its normal operating speed, and when the impeller rotates at a varying speed during the period of vascular parameter determination), Equation 2 can be rewritten as Equation 3 and Equation 4, respectively, where the symbols 1 and 2 included in the subscripts represent the first operating condition and the second operating condition.

[0231]

[0232] The effect of ventricular assist devices on the vascular system can be characterized by subtracting Equation 4 from Equation 3, as shown in Equation 5.

[0233]

[0234] Based on the techniques described above, typically, for example, a combination of any of the techniques described herein for determining flow through a ventricular assist device and any of the techniques described herein for determining left ventricular pressure, computer processor 25 is configured to determine pressure and flow-related parameters of the subject's left ventricle. Therefore, only the vascular parameters (aortic compliance, characteristic impedance, and peripheral resistance) are unknown. Typically, known values ​​of the pressure and flow-related parameters of the subject's left ventricle are used, for example, model identification techniques (e.g., linear regression) to estimate the subject's vascular parameters (aortic compliance, characteristic impedance, and peripheral resistance).

[0235] For some applications, after estimating the subject's vascular parameters, the total cardiac output and the subject's natural cardiac output are estimated based on Equation 3 using the subject's left ventricular pressure and flow-related parameters (which are typically determined in real time using the sensors described herein) and the subject's vascular parameters (determined as above by changing the speed of the impeller rotation).

[0236] For some applications, techniques broadly similar to those described above are used, but different mathematical models are employed to represent the subject's dynamic vascular system (e.g., the subject's aorta and / or left ventricle) in order to determine vascular parameters, natural cardiac output, and / or alternative or additional physiological parameters. Typically, the mathematical model is of the same type as the Windkessel model, as it interprets the shape of the aortic waveform based on the interaction between stroke volume and aortic compliance.

[0237] Generally, the scope of this application includes a method in which:

[0238] a) Use one or more sensing devices and methods described herein to determine one or more pressure-related parameters and / or flow-related parameters (e.g., the subject's aortic pressure, the subject's left ventricular pressure, and / or flow through a ventricular assist device).

[0239] b) Change the speed of impeller rotation during one or more cycles of vascular parameter determination;

[0240] c) Apply a mathematical model representing the subject’s dynamic vascular system (e.g., the subject’s aorta and / or the subject’s left ventricle) to two operating conditions of the ventricular assist device (i.e., when the impeller is operating at its normal operating speed, and when the impeller rotates at a varying speed during a vascular parameter determination period).

[0241] d) Estimate the subject’s vascular parameters (e.g., aortic compliance, characteristic impedance, and peripheral resistance) based on the differences between mathematical models under each of the two operating conditions of the ventricular assist device, and the known pressure-related and / or flow-related parameters.

[0242] e) Estimate the subject’s natural cardiac output and / or additional cardiac parameters based on known pressure-related and / or flow-related parameters, as well as the subject’s estimated vascular parameters (e.g., aortic compliance, characteristic impedance, and peripheral resistance).

[0243] More generally, the above steps can be summarized as follows:

[0244] a) Using a percutaneous left ventricular assist device to pump blood from the subject's left ventricle to the subject's aorta;

[0245] b) Detect one or more pressure-related parameters and / or flow-related parameters using a percutaneous left ventricular assist device (e.g., using the sensing devices and methods described herein);

[0246] c) The rate at which the percutaneous left ventricular assist device pumps blood varies during one or more cycles of defined vascular parameters, and a mathematical model representing the dynamic vascular system of the subject is applied when the percutaneous left ventricular assist device pumps blood at the corresponding rate.

[0247] d) Estimate the subject’s vascular parameters based on the difference between the mathematical model applied when the percutaneous left ventricular assist device pumps blood at the corresponding rate and the pressure-related parameters and / or flow-related parameters;

[0248] e) Estimate the subject’s natural cardiac output and / or additional cardiac parameters based on pressure-related parameters and / or flow-related parameters, as well as the subject’s estimated vascular parameters.

[0249] Typically, the above steps are repeated as needed during the operation of a ventricular assist device.

[0250] Now for reference Figure 10A and Figure 10B , Figure 10A and Figure 10BThis is a schematic diagram of a ventricular assist device 20 according to some applications of the present invention, which includes a liner 39 lining the inside of a frame 34 housing an impeller 50. For some applications, the liner 39 is disposed inside the frame 34 to provide a smooth inner surface (e.g., a smooth inner surface having a generally circular cross-sectional shape) through which blood is pumped by the impeller. Typically, by providing a smooth surface, the covering material reduces hemolysis caused by blood pumped by the impeller compared to blood being pumped between the impeller and the struts of the frame 34. For some applications, the liner comprises polyurethane, polyester, and / or silicone. Alternatively or additionally, the liner comprises polyethylene terephthalate (PET) and / or polyether block amide (PEBAX®).

[0251] Typically, the liner is disposed on the inner surface of at least a portion of the central columnar portion 38 of the frame 34. For some applications, the pump outlet pipe 24 also covers the central columnar portion 38 of the frame 34, for example, around the outer side of the frame, such that the pump outlet pipe 24 and the liner 39 overlap for at least 50% of the liner's length, for example, over the entire length of the columnar portion of the frame 34, such as... Figure 10A As shown. For some applications, there is only partial overlap between the pump outlet pipe 24 and the liner 39, for example, as... Figure 10B As shown. For example, the pump outlet pipe 24 may overlap the liner along less than 50% (e.g., less than 25%) of the liner length. In 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 overlapping area between the pump outlet pipe and the liner, thus eliminating a longitudinal position where the impeller, pump outlet pipe 24, frame 34, and liner 39 all overlap each other. Figure 10A and Figure 10B As shown, for some applications, a single axially oriented blood inlet opening 108 is defined at the distal end of the pump outlet pipe and / or liner. Alternatively, the liner is disposed on the inner surface of at least a portion of the central cylindrical portion 38 of the frame 34, and the pump outlet pipe extends to the distal end of the frame and defines a plurality of lateral blood inlet openings 108. For example, reference is made below. Figures 11A-11E This application will be described in further detail.

[0252] Typically, in the overlapping area between the liner 39 and the pump outlet pipe 24, the liner is shaped to form a smooth surface (e.g., to reduce hemolysis, as described above), and the pump outlet pipe 24 is shaped to conform to the struts of the frame 34 (e.g., as...). Figure 10A (As shown in the cross-section). Furthermore, the lining typically has a generally circular cross-section (e.g., due to the relatively small cell width within the central columnar portion of the frame, as referenced above). Figure 2(as described above). For some applications, in the overlapping area between the liner 39 and the pump outlet pipe 24, the pump outlet pipe and the liner are joined together, for example, via vacuum, via adhesive, and / or using a thermoforming process.

[0253] For some applications, the liner 39 and the pump outlet pipe 24 are made of different materials. For example, the liner may be made of polyurethane, while the pump outlet pipe may be made of polyether block amide (PEBAX®). Typically, for this application, the material used to manufacture the liner has a higher thermoforming temperature than the material used to manufacture the pump outlet pipe. Alternatively, the liner 39 and the pump outlet pipe 24 may be made of the same material. For example, both the liner and the pump outlet pipe may be made of polyurethane or polyether block amide (PEBAX®).

[0254] For some applications, the pump outlet pipe and the liner are joined to each other and / or to the frame in the following ways. For some applications, the liner is directly joined to the inner surface of the frame before the pump outlet pipe is joined to the outside of the frame. Note that by joining the liner directly to the inner surface of the frame (rather than simply joining the liner to the pump outlet pipe, thereby sandwiching the frame between the liner and the pump outlet pipe), any bubbles, wrinkles, and other discontinuities in the smoothness of the surface provided by the liner are typically avoided. For some applications, techniques similar to those described above, used to enhance the bonding between the helical elongated elements of the elastomeric membrane and the impeller, are used to enhance the bonding between the inner surfaces of the liner and the frame. For some applications, the frame is initially treated to enhance the bonding between the inner surfaces of the liner and the frame. For some applications, the treatment of the frame includes applying plasma treatment to the frame (e.g., to the inner surface of the frame), immersing the frame in a coupling agent having at least two functional groups (e.g., a silane solution) configured to bond with the frame and the material used to manufacture the liner, respectively, and / or immersing the frame in a solution containing the material used to manufacture the liner (e.g., a polyurethane solution). For some applications, the liner is made of an elastomeric material (e.g., polyurethane), and the coupling agent is a silane solution, such as a solution of n-(2-aminoethyl)-3-aminopropyltrimethoxysilane, wherein the silane contains a first functional group (e.g., (OH)) configured to bond with the frame (which is typically made of an alloy, such as nitinol), and the silane contains a second functional group (e.g., (NH2)) configured to bond with the elastomeric material.

[0255] For some applications, a solution containing the material used to manufacture the liner (e.g., a polyurethane solution) is then sprayed onto the central column portion of the frame. Once the inner surface of the frame has been treated, the liner is bonded to the inner surface of the central column portion of the frame (e.g., bonded to the inner surface of the central column portion of the frame). Typically, the liner (which is shaped as a tube) is placed on a mandrel, the frame is placed on the liner, and pressure is applied through a heat-shrinking process. Furthermore, the liner and frame assembly is typically heated in an oven.

[0256] After the liner has been attached to the frame, a portion of the pump outlet pipe 24 is positioned to surround the outside of the frame. As mentioned above, for some applications, the liner 39 and the pump outlet pipe 24 are made of different materials. For example, the liner may be made of polyurethane, while the pump outlet pipe may be made of polyether block amide (PEBAX®). Typically, for such applications, the material used to manufacture the liner has a higher thermoforming temperature than the material used to manufacture the pump outlet pipe. For some applications, in order to mold the pump outlet pipe 24 to conform to the struts of the frame 34 without causing deformation of the liner, the frame is heated to a temperature higher than the thermoforming temperature of the pump outlet pipe 24 but lower than the thermoforming temperature of the liner 39.

[0257] Typically, a mandrel is used to heat the frame from within. Typically, when the frame is heated to the aforementioned temperature, an outer tube (typically made of silicone) applies pressure to the pump outlet pipe 24, causing the pump outlet pipe 24 to be pushed radially inward so that it conforms to the shape of the frame's support pillars, such as... Figure 10A The cross-section is shown. For some applications, at this stage, the mandrel placed inside the liner and heating the liner is shorter than the length of the liner. The mandrel is typically placed inside the liner such that a margin is left outside the mandrel at each end of the liner. Typically, the liner acts as a shield to prevent the pump outlet pipe from overheating and from being damaged by the heating of the mandrel. Placing the liner on the mandrel in the manner described above prevents the mandrel from direct contact with the frame and / or the pump outlet pipe. For some applications, the combination of the frame, the liner, and the portion of the pump outlet pipe 24 disposed around the frame is then shaped to the desired shape and size using shaping techniques known in the art.

[0258] Now for reference Figures 11A-11E , Figures 11A-11EThis is a schematic diagram of a pump outlet tube 24 or a portion thereof according to some applications of the invention, configured to define a lateral blood inlet opening 108 at its distal end. For some applications, the pump outlet tube extends substantially to the distal end of the distal tapered portion 40 of the frame 34. In such applications, the pump outlet tube typically defines a distal tapered portion 46, which is distally oriented, i.e., oriented such that the narrow end of the tapered portion is distal relative to the wide end of the tapered portion. Typically, the pump outlet tube includes a connecting portion 41 (e.g., a tubular connecting portion, as shown) extending distally from the pump outlet tube. As described above, the connecting portion is coupled to the distal support housing to anchor the distal end of the pump outlet tube.

[0259] For some applications (not shown), the pump outlet tube defines two to four lateral blood inlet openings. Typically, for such applications, each blood inlet opening defines an area greater than 20 mm² (e.g., greater than 30 mm²) and / or less than 60 mm² (e.g., less than 50 mm²), such as 20-60 mm² or 30-50 mm². Alternatively or additionally, the outlet tube defines a greater number of smaller blood inlet openings 108, such as more than 10, more than 50, more than 100, or more than 150 blood inlet openings, such as 50-100, 100-150, or 150-200. For some applications, the blood inlet openings are sized to (a) allow blood to flow from the subject's left ventricle into the tube, and (b) prevent structures from the subject's left ventricle from entering the frame. Typically, for such applications, the distal tapered portion 46 of the pump outlet pipe 24 is configured to reduce the risk of structures from the left ventricle (e.g., chordae tendineae, cardiac columns, and / or papillary muscles) entering the frame 34 and potentially being damaged by the impeller and / or axial shaft and / or causing damage to the left ventricular assist device. Therefore, for some applications, the blood inlet opening is shaped such that the width (or span) of the opening is less than 1 mm in at least one direction, for example, 0.1 mm–1 mm or 0.3 mm–0.8 mm. By defining such a small width (or span), typically, structures from the left ventricle (e.g., chordae tendineae, cardiac columns, and / or papillary muscles) are prevented from entering the frame 34. For some such applications, each blood inlet opening defines an area greater than 0.05 mm² (e.g., greater than 0.1 mm²) and / or less than 3 mm² (e.g., less than 1 mm²), for example, an area of ​​0.05 mm²–3 mm² or 0.1 mm²–1 mm². Alternatively, each blood inlet opening may be defined as having an area greater than 0.1 square millimeters (e.g., greater than 0.3 square millimeters) and / or less than 5 square millimeters (e.g., less than 1 square millimeter), such as an area of ​​0.1 square millimeters to 5 square millimeters or 0.3 square millimeters to 1 square millimeter.

[0260] Typically, the portion of the pump outlet tube that defines the blood inlet opening has a porosity greater than 40%, for example greater than 50%, or greater than 60% (where porosity is defined as the percentage of the area of ​​that portion that is porous for blood flow). Thus, on the one hand, the blood inlet opening is relatively small (to prevent left ventricular structures from entering the frame), but on the other hand, the porosity of the portion of the pump outlet tube that defines the blood inlet opening is relatively high to allow sufficient blood to flow into the pump outlet tube.

[0261] For some applications, each blood inlet opening has a circular or polygonal shape. For other applications, each blood inlet opening has a hexagonal shape, such as... Figures 11A-11D As shown. Typically, using openings with a hexagonal shape allows the portion of the pump outlet tube defining the blood inlet opening to have a relatively high porosity (e.g., as described above), while providing sufficient material between the blood inlet openings to prevent tearing and / or stretching of the material. Figure 11B As shown, for some applications, the width W of the gap between adjacent hexagonal (or other polygonal) holes is greater than 0.01 mm (e.g., greater than 0.04 mm) and / or less than 0.1 mm (e.g., less than 0.08 mm), for example, 0.01 mm–0.1 mm, or 0.04 mm–0.08 mm. For some applications, the distance D between opposite sides of each hexagon (or other type of polygon) is greater than 0.2 mm (e.g., greater than 0.4 mm) and / or less than 0.8 mm (e.g., less than 0.6 mm), for example, 0.2 mm–0.8 mm, or 0.4 mm–0.6 mm. Figure 11B As shown, typically each polygon encloses a circle (such that any structure that cannot pass through such a circle cannot pass through the polygon). Typically, the diameter of the circle enclosed by the polygon is equal to the distance D, for example greater than 0.2 mm (e.g., greater than 0.4 mm) and / or less than 0.8 mm (e.g., less than 0.6 mm), such as 0.2 mm–0.8 mm, or 0.4 mm–0.6 mm.

[0262] Figure 11D A section of the distal tapered portion 46 of the pump outlet pipe 24 according to some applications of the present invention is shown. Figure 11D In the view shown, this section is unfolded and laid flat for illustrative purposes. (As shown...) Figure 11DAs shown, for some applications, the width W1 of the gap between hexagonal (or other type of polygonal) holes in the proximal region 46P of the distal tapered portion 46 of the pump outlet pipe 24 is greater than the width W of the gap between hexagonal (or other type of polygonal) holes in the distal region 46D of the distal tapered portion 46 of the pump outlet pipe. For some applications, the ratio of the width of the gap between adjacent blood inlet openings in the proximal region of the distal portion of the pump outlet pipe to the width of the gap between adjacent blood inlet openings in the distal region of the distal portion of the pump outlet pipe is greater than 3:2, for example, between 3:2 and 5:2. Typically, for such applications, the distance D1 between opposite sides of each hexagon (or other type of polygon) in the proximal region 46P of the distal tapered portion 46 of the pump outlet pipe 24 is less than the distance D between opposite sides of each hexagon (or other type of polygon) in the distal region 46D of the distal tapered portion 46 of the pump outlet pipe. (As mentioned above, typically, distances D and D1 also represent the diameters of the circles enclosed by polygons of separately defined dimensions.) For some applications, the ratio of the diameter of the circle enclosed by each blood inlet opening in the distal region of the distal portion of the pump outlet tube to the diameter of the circle enclosed by each blood inlet opening in the proximal region of the distal portion of the pump outlet tube is greater than 7:6, for example, between 7:6 and 4:3. Furthermore, typically, the distal tapered portion of the pump outlet tube 24 has higher porosity in the distal region 46D of the distal tapered portion 46 of the pump outlet tube compared to the proximal region 46P of the distal tapered portion 46 of the pump outlet tube. For example, the ratio of porosity in the distal region 46D to that in the proximal region 46P is greater than 4:3 or greater than 3:2. For some applications, the proximal region extends along a length greater than 0.5 mm and / or less than 2 mm (e.g., less than 1.5 mm), for example, between 0.5 mm and 2 mm or between 0.5 mm and 1.5 mm. For some applications, the total length of the distal tapered portion is greater than 6 mm and / or less than 12 mm (e.g., less than 10 mm), for example, between 6 mm and 12 mm or 6 mm and 10 mm.

[0263] As referenced above Figures 9A-9BTypically, the pump outlet pipe is connected to the frame 34 via heating. For some applications, the gap between blood inlet orifices is wider in the proximal region 46P of the distal tapered portion 46 of the pump outlet pipe 24 than the gap between blood inlet orifices in the distal region 46D, and / or the blood inlet orifices are smaller and / or have lower porosity than in the distal region 46D, in order to prevent and / or reduce damage (e.g., tearing, thinning, and / or stretching) that may occur to the material defining the blood inlet orifices during the aforementioned heating process. For some applications, due to the application of the aforementioned heating process, any difference between the gap size between the blood inlet orifices and / or the size of the blood inlet orifices themselves and / or the porosity between the distal region 46D and the proximal region 46P is reduced or even eliminated.

[0264] Typically, the width W of the gap between the hexagonal (or other type of polygonal) holes and the distance D between opposite sides of each hexagon (or other type of polygon) within the distal region 46D of the distal tapered portion 46 of the pump outlet pipe are as described above. For some applications, the width W1 of the gap between adjacent hexagonal (or other polygonal) holes within the proximal region 46P of the distal tapered portion 46 of the pump outlet pipe 24 is greater than 0.05 mm (e.g., greater than 0.07 mm) and / or less than 0.2 mm (e.g., less than 0.15 mm), for example, 0.05 mm–0.2 mm, or 0.07 mm–0.15 mm. For some applications, the distance D1 between opposite sides of each hexagon (or other type of polygon) within the proximal region 46P of the distal tapered portion 46 of the pump outlet pipe 24 is greater than 0.1 mm (e.g., greater than 0.3 mm) and / or less than 0.6 mm (e.g., less than 0.5 mm), for example, 0.1 mm–0.6 mm, or 0.3 mm–0.5 mm.

[0265] The scope of this disclosure includes lateral blood inlet openings of non-uniform size and / or shape (e.g., circular, rectangular, polygonal, and / or hexagonal lateral blood inlet openings) arranged in any configuration along the distal tapered portion 46 of the pump outlet pipe. Similarly, the scope of this disclosure includes the distal tapered portion 46 of the pump outlet pipe defining a lateral blood inlet opening, the lateral blood inlet opening being arranged such that the distal tapered portion has non-uniform porosity, the porosity varying between different regions of the distal tapered portion. For some applications, the shape and / or size of the lateral blood inlet opening, and / or the porosity of the distal tapered portion, are varied to result in varying hemodynamics at different regions of the distal tapered portion. Alternatively or additionally, the shape and / or size of the lateral blood inlet opening, and / or the porosity of the distal tapered portion, are varied to result in a variation in the shape of the distal tapered portion along its length.

[0266] Now for reference Figure 11E , Figure 11E This is an enlarged schematic diagram of the interface between the distal end of the pump outlet pipe 24 and the distal end element 107. Typically, the pump outlet pipe includes a connecting portion 41 (e.g., a tubular connecting portion, as shown) extending distally from the pump outlet pipe. As described above, the connecting portion is connected to the distal support housing 118H to anchor the distal end of the pump outlet pipe. Also as described above, typically, the pump outlet pipe is connected to the outer side of the central columnar portion of the frame. For some applications, the distal tapered portion 46 of the pump outlet pipe itself is not coupled to the distal tapered portion 40 of the frame. Instead, the distal tapered portion 46 of the pump outlet pipe is held in place relative to the distal tapered portion 40 of the frame because the connecting portion 41 is connected to the distal support housing 118H and the pump outlet pipe is connected to the outer side of the central columnar portion of the frame. Alternatively, the distal tapered portion 46 of the pump outlet pipe is directly connected to the distal tapered portion 40 of the frame (e.g., via heat shrink).

[0267] As described above, for some applications, the connecting portion 41 is coupled to the outer surface of portion 123 of the distal support housing 118H. For some applications, the connecting portion 41 defines a hole 111 (e.g., toward the distal end of the connecting portion), such as... Figure 11E As shown. For some applications, the adhesive is applied via a hole between the outer surfaces of the connecting portion 41 and the portion 123 of the distal support housing 118H. For some applications, the outer surface of the portion 123 of the distal support housing 118H is threaded. Typically, the threaded outer surface allows the adhesive to spread gradually and uniformly between the connecting portion 41 and the outer surfaces of the portion 123 of the distal support housing 118H. Furthermore, the connecting portion is typically transparent, making the diffusion of the adhesive visible through the connecting portion. Therefore, for some applications, the application of the adhesive is terminated once the adhesive has sufficiently diffused between the connecting portion 41 and the outer surfaces of the portion 123 of the distal support housing 118H (e.g., once the outer surface of the portion 123 is covered with adhesive).

[0268] Now for reference Figure 12A , Figure 12B and Figure 12C , Figure 12A , Figure 12B and Figure 12C This is a schematic diagram of the 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., in...). Figure 5AOne of the enlarged portions shows the connection between the distal end of the drive cable and the proximal end of the axial shaft. For some applications, the drive cable comprises multiple wires 134 arranged in a coiled configuration to provide sufficient strength and flexibility to allow a portion of the cable to remain within the aortic arch while the cable rotates and moves in an axial reciprocating motion. For some applications, the drive cable comprises multiple coaxial coiled layers. For example, as... Figures 12A-12C As shown, the drive cable may include an outer layer 136 and an inner layer 138, which are coaxial with each other, and each layer includes a coiled wire.

[0269] Typically, the drive cable is housed within a first outer tube 140, which is configured to remain stationary as the drive cable undergoes rotational and / or axial reciprocating motion. The first outer tube is configured to effectively function as a support tube for the drive cable along its length. Therefore, the first outer tube is also referred to herein as a drive cable support tube. Reference will be made below. Figure 12D The drive cable support tube is described in further detail. For some applications, the drive cable support tube is disposed within a second outer tube 142, which is typically made of a material with 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.

[0270] 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 allow the impeller and frame to present a non-radially constrained configuration, the delivery catheter is retracted. For some applications, such as Figure 12A As shown, during the 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 12A The distal end of the delivery catheter positioned within the aortic arch is shown, but for some applications, during operation of the left ventricular device, the distal end of the delivery catheter is positioned 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 this is for illustrative purposes only.) Figure 12A (The channels shown are not to scale.) For some such applications, the aortic blood pressure of the subject is measured by measuring the blood pressure within channel 224. For example, pressure sensor 216 (in... Figure 1A (Illustrated schematically) may be in fluid communication with channel 224 and may be configured to measure the subject's aortic pressure 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 such that the impeller and frame exhibit their radially constrained configuration. The catheter is then withdrawn from the subject.

[0271] Now for reference Figure 12D , Figure 12D This is a schematic diagram of a first outer tube 140 according to some applications of the invention, which acts as a drive cable support tube. 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 comprises a material configured to provide a low level of friction and high abrasion resistance. Furthermore, the outer layer is typically configured to provide additional strength to the drive cable support tube while still providing sufficient flexibility to allow the drive cable support tube to conform to the curvature of, for example, the aortic arch. Typically, the coil is configured such that the drive cable support tube maintains a substantially circular cross-section even in areas where the drive cable support tube undergoes significant bending (e.g., within the aortic arch). Typically, in the absence of coils, the drive cable support tube will tend to be flat and form an elliptical cross-section in these areas.

[0272] Now for reference Figure 13 , Figure 13 This is a schematic diagram of a ventricular assist device according to some applications of the invention, having a guide wire 10 disposed within a guide wire cavity 122. In some such applications, during insertion of the ventricular assist device into the left ventricle, for example, the guide wire 10 is first inserted into the left ventricle according to known techniques. Then, the distal end portion of the ventricular assist device is guided into the left ventricle by advancing the distal end portion of the guide wire, wherein the guide wire is disposed within the cavity 122. In some applications, a duckbill valve 390 (or a hemostatic valve of a different type) is disposed at the distal end of the distal end portion 120 of the cavity 122.

[0273] Now for reference Figure 14A and Figure 14B , Figure 14A and Figure 14B This is a schematic diagram of a guide wire 10 according to some applications of the present invention, wherein the guide wire is configured to have two states. See reference... Figure 13 As described, typically, the distal end of the ventricular assist device is guided to the left ventricle via a guide wire 10. Typically, the end of the guide wire is expected to be flexible during the advancement of the guide wire through the subject's vascular system and when the end of the guide wire is positioned within the subject's left ventricle to avoid injury to the subject's vascular system and / or left ventricle.

[0274] After the distal end of the ventricular assist device is guided into the left ventricle, the impeller 50 and frame 34 of the ventricular assist device unfold via a retractable delivery catheter, which typically results in the impeller and frame having a non-radially constrained configuration. Typically, at this stage, the end of the guide wire retracts proximally through the distal end portion 120 and from the pump portion. In some cases, after the guide wire has been retracted in the manner described above, it is desirable to reinsert the guide wire through the distal end portion 120 and out of the duckbill valve 160, which is positioned towards the distal end of the distal end portion. This may be desirable, for example, if the pump portion has migrated from its correct position and needs to be repositioned within the left ventricle. However, if the end of the guide wire remains flexible (as described above), it is not possible to advance the end of the guide wire through the narrow end of the proximal-facing duckbill valve 160. Therefore, for some applications, the guide wire is configured such that its end can define two states: a flexible state and a rigid state.

[0275] For some applications, the guide wire 10 includes an outer coil 250 and an inner reinforcing wire 252. When the distal end of the guide wire is to be in a flexible state, the inner reinforcing wire retracts from the distal end of the guide wire, so that the distal portion of the outer coil does not have the reinforcing wire disposed therein. For some applications, the guide wire can be releasably locked in this state to prevent the distal end of the guide wire from becoming stiff and damaging the subject's vascular system and / or left ventricle. For example, as... Figure 14A As shown, for some applications, one or more locking elements 254 extend radially from the proximal portion of the reinforcing wire and protrude between the windings of the outer coil to prevent the reinforcing wire from advancing. For some applications, at the proximal end 256 of the outer coil, there is a larger gap between the windings of the coil than at the more distal portion of the outer coil, such that the locking element protrudes between the windings of the outer coil at the proximal end. For some applications, to convert the distal end of the lead wire to a hardened state, the locking element 254 is pushed radially inward, such that the locking element 254 is positioned within the outer coil, and the reinforcing wire advances distally, such that the reinforcing wire is positioned within the outer coil even at the distal end of the lead wire. For some applications, as the reinforcing wire advances distally, the locking element remains positioned within the outer coil because the locking element is now positioned within a portion of the outer coil where the windings of the coil are positioned close enough to each other that these windings prevent the locking element from protruding between them.

[0276] Now for reference Figure 15 This is a schematic diagram of a ventricular assist device 20 according to some applications of the present invention, which includes a distal thrust support 260. Typically, the support 260 serves as both a distal radial support and a distal thrust support. Figure 15The top view of the ventricular device shown illustrates the device in its radially constrained (i.e., coiled) configuration, while the bottom view illustrates the device in its non-radially constrained configuration, with arrows indicating movement of the various parts of the device between these two configurations. Some applications of the invention described above are directed to ventricular assist devices that do not include any thrust supports disposed within the subject's body and are configured to allow axial reciprocating movement of the impeller 50 and the axial shaft 92. For some alternative applications, the ventricular assist device does include a thrust support configured to prevent the axial shaft 92 from undergoing axial movement in response to changes in the pressure gradient resisted by the impeller pumping (and typically, thereby preventing the impeller from undergoing axial movement in response to changes in the pressure gradient resisted by the impeller pumping).

[0277] For some applications, as shown, the thrust support 260 is disposed within the frame 34. For example, the thrust support may be disposed within a cylindrical portion of the frame or within a distal tapered portion of the frame. For some applications at the distal end of an axial shaft, the axial shaft defines a widened portion 262 configured to engage the thrust support and prevent axial movement of the axial shaft (and thus the impeller). (Furthermore, the widened portion of the axial shaft is radially constrained by the support 260, such that the support also functions as a distal radial support.) Typically, the thrust support is coupled to the frame via a connecting strut 264 that extends radially inward from the frame to the thrust support. Typically, to manufacture the frame 34, the frame is cut from a tube of shape memory alloy (e.g., nitinol). For some applications, the connecting strut 264 is cut from the tube from which the frame is cut, such that the frame and the connecting strut form a single integral body without needing to be joined together (e.g., via adhesive, welding, etc.). In general, for some applications, the frame and connecting struts are cut from a single piece of material to form a single integral unit. For some applications, the connecting strut 264 and thrust support 260 are themselves cut from the tubes of the cut frame, so that the frame, connecting struts, and thrust support form a single integral unit without needing to be joined together (e.g., via adhesives, welding, etc.). Typically, for some applications, the frame, connecting struts, and thrust support 260 are themselves cut from a single piece of material to form a single integral unit.

[0278] For some applications, it is typically similar to a motion buffer spring 68 (such as...). Figures 6C-6DThe spring (shown) is used in conjunction with the thrust support 260 (or with a thrust support of a different design located on the distal side of the impeller). In some applications, after the impeller has radially expanded, the spring helps stabilize the impeller relative to the thrust support (e.g., the distal end of the impeller). Therefore, the spring acts as an impeller stabilizing spring. In some applications, the impeller is configured to be radially constrained (i.e., coiled) by becoming axially elongated, and the spring is configured to be compressed to accommodate the axial elongation of the impeller. Typically, when the impeller is in a radially constrained configuration during pump head insertion into the left ventricle, the impeller elongates axially such that the distal end of the impeller is located distally within the frame 34, and the impeller stabilizing spring is compressed to accommodate movement of the distal end of the impeller.

[0279] Typically, an impeller stabilizing spring is disposed around the axial shaft 92 between the distal end of the impeller (e.g., the distal bushing 58 of the impeller) and the thrust support 260. In some applications, the impeller stabilizing spring is coupled to and extends proximally from the thrust support 260 along the axial shaft 92. Typically, in this configuration, the impeller stabilizing spring remains rotationally stationary as the impeller rotates, and the impeller is configured to rotate relative to the impeller stabilizing spring. Alternatively or additionally, the impeller stabilizing spring is coupled to the distal end of the impeller (e.g., the distal bushing 58 of the impeller) and / or extends distally along the axial shaft 92 from the distal end of the impeller (e.g., the distal bushing 58 of the impeller). In some such applications, the impeller stabilizing spring is configured to rotate with the impeller. Alternatively, the impeller stabilizing spring extends from a radial support disposed around the distal end of the impeller (e.g., the distal bushing 58 of the impeller), such that the impeller stabilizing spring remains stationary as the impeller rotates, and the impeller is configured to rotate relative to the impeller stabilizing spring. For some applications, the impeller stabilizing spring is coupled to an elastomeric material 69 (e.g., coated with elastomeric material 69 or embedded within elastomeric material 69) (also... Figures 6C-6D (as shown in the figure), where the combination of elastomeric material and spring is generally formed and functions in a manner substantially similar to that described above in reference to motion buffer spring 68.

[0280] For some applications, such as those mentioned above... Figures 6C-6D The impeller stabilizing spring is disposed on the proximal side of the impeller around the axial shaft. For some applications, the impeller stabilizing spring is disposed on both the proximal and distal sides of the impeller around the axial shaft. In some applications, when the pump head expands, the combination of the proximal and distal impeller stabilizing springs disposed around the axial shaft serves to hold the impeller axially in the appropriate position and / or limit the axial movement of the impeller.

[0281] For some applications, the thrust support 260 is used in conjunction with the pump outlet pipe 24, such as... Figures 11A-11E As shown and referenced Figures 11A-11E As described, the pump outlet tube defines a lateral blood inlet opening 108 at its distal end. As described above, for some applications, the blood inlet opening is sized to (a) allow blood to flow from the subject's left ventricle into the tube, and (b) prevent structures from the subject's left ventricle from entering the frame. Typically, for such applications, the distal tapered portion 46 of the pump outlet tube 24 is configured to reduce the risk of structures from the left ventricle (e.g., chordae tendineae, cardiac columns, and / or papillary muscles) entering the frame 34 and potentially being damaged by the impeller and / or rod and / or causing damage to the left ventricular assist device. For such applications, the dimensions and other characteristics of the pump outlet tube and the blood inlet opening are generally as described in the references. Figures 11A-11E Roughly described.

[0282] like Figure 15 As shown, when the thrust support 260 is disposed within the frame 34, the axial shaft 92 does not extend to the distal end of the frame 34. For example, as Figure 15 As shown, in a non-radially constrained configuration of the frame, the distal end of the axial shaft is positioned within a cylindrical portion of the frame, typically proximal to the blood inlet opening of the ventricular assist device. For some such applications, even when left ventricular structures (e.g., chordae tendineae, trabeculae, and / or papillary muscles) enter the frame through the blood inlet opening, the axial shaft's proximal termination at the blood inlet opening reduces or prevents any damage to the axial shaft or other parts of the ventricular assist device. For some such applications, even when left ventricular structures (e.g., chordae tendineae, trabeculae, and / or papillary muscles) enter the frame through the blood inlet opening, the axial shaft's proximal termination at the blood inlet opening reduces or prevents any damage to such structures.

[0283] Now for reference Figure 16A , Figure 16B , Figure 16C and Figure 16DThese figures are schematic diagrams of packaging 270 for packaging a ventricular assist device 20 according to some applications of the invention. Typically, packaging 270 is enclosed within a sealed wrapping 272 to enhance the sterility of the packaging. Packaging 270 is typically shaped to define a pump head chamber 274 in which the pump head of the ventricular assist device (e.g., impeller 50 and frame 34) is packaged. For some applications, a catheter retainer 276 is reversibly coupled to packaging 270. The catheter retainer is shaped to define an aperture 278. As part of the process of packaging the ventricular assist device within packaging 270, the distal end of the delivery catheter 143 is secured within the aperture by coupling the catheter retainer to the packaging, thereby positioning the distal end of the delivery catheter within the aperture. For some applications, the pump head chamber defines a vertical protrusion 280 around which the distal end portion 120 is positioned to secure the distal end of the pump head within the pump head chamber.

[0284] For some applications, in order to open the ventricular assist device packaging and prepare for its use, the top cover 271 of the packaging is removed to expose the pump head chamber 274. For some applications, the pump head chamber is then filled with a solution 282 (e.g., saline), such as... Figure 16B As shown. Subsequently, the pump head retracts into the distal end of the delivery conduit 143 to radially constrain the pump head, as from... Figures 16B to 16D The transformation is shown. For some applications, the catheter retainer is configured to secure the distal end of the delivery catheter to a downwardly inclined surface 284, such that the distal end of the catheter is oriented downwards. Typically, this is in the case of a horizontal orientation relative to the distal end of the catheter, which reduces the likelihood of air bubbles entering the distal end of the delivery catheter when the pump head retracts into the distal end of the delivery catheter.

[0285] Regarding references Figures 1A-15 All aspects of the described ventricular assist device 20 should be noted, although Figure 1A and Figure 1BA ventricular assist device 20 is shown in the left ventricle of a subject; however, for some applications, the ventricular assist device 20 is placed in the right ventricle of the subject, such that the device passes through the subject's pulmonary valve, and the technique described herein (with necessary modifications) is applied. For some applications, components of device 20 are adapted to different types of blood pumps. For example, aspects of the invention can be applied to pumps used to pump blood from the vena cava and / or right atrium into the right ventricle, from the vena cava and / or right atrium into the pulmonary artery, and / or from the renal vein into the vena cava. These aspects may include features of tube 24 (e.g., tube curvature), impeller 50, features of pump head portion 27, drive cable 130, etc. Alternatively or additionally, device 20 and / or a portion thereof (e.g., impeller 50, even without tube 24) are placed within different parts of the subject's body to assist in pumping blood from those parts. Alternatively or additionally, device 20 and / or a portion thereof (e.g., impeller 50, even without tube 24) may be placed within different parts of the subject's body to assist in pumping blood from those parts. For example, device 20 and / or a portion thereof (e.g., impeller 50, even without 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 a portion thereof (e.g., impeller 50, even without tube 24) (with necessary modifications) is configured to be placed within the subclavian or jugular vein, at the junction of the vein and lymphatic vessels, and to increase the flow rate of lymphatic fluid from the lymphatic vessels into the vein. Because the scope of the invention includes the use of the devices 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.

[0286] The scope of this invention includes combining any device and method described herein with any device and method described in one or more of the following applications, all of which are incorporated herein by reference:

[0287] Tuval filed International Application No. PCT / IB2022 / 051990, entitled "Ventricular assist device," on March 7, 2022, which claims the following priority:

[0288] Tuval's U.S. Provisional Patent Application No. 63 / 158,708, entitled "Ventricular assist device," filed on March 9, 2021, and...

[0289] Tuval filed U.S. Provisional Patent Application No. 63 / 254,321 on October 11, 2021, entitled “Ventricular assist device”.

[0290] Zipory filed International Application No. PCT / IB2021 / 052590 (published as WO 21 / 198881) on March 29, 2021, entitled “Centrifugal and mixed-flow impellers for use with a blood pump,” which claims priority to Zipory’s U.S. Application US 63 / 003,955, entitled “Ventricular assist device,” filed on April 02, 2020.

[0291] Tuval's US 2022 / 0226632, which is the U.S. national phase of PCT application No. PCT / IB2021 / 052857 (published as WO 21 / 205346) entitled "Ventricular assist device" filed on April 6, 2021, claims the following priority:

[0292] Tuval filed U.S. Provisional Patent Application No. 63 / 006,122 on April 7, 2020, entitled “Ventricular assist device”.

[0293] Tuval's U.S. Provisional Patent Application No. 63 / 114,136, entitled "Ventricular assist device," filed November 16, 2020; and

[0294] Tuval filed U.S. Provisional Patent Application No. 63 / 129,983 on December 23, 2020, entitled “Ventricular assist device”.

[0295] Tuval's US 2020 / 0237981, filed on January 23, 2020, entitled "Distal tip element for a ventricular assist device," claims the following priority:

[0296] Tuval filed U.S. Provisional Patent Application No. 62 / 796,138 entitled “Ventricular assist device” on January 24, 2019;

[0297] Tuval filed U.S. Provisional Patent Application No. 62 / 851,716 on May 23, 2019, entitled “Ventricular assist device”.

[0298] Tuval's U.S. Provisional Patent Application No. 62 / 870,821, filed July 5, 2019, entitled "Ventricular assist device"; and

[0299] Tuval filed U.S. Provisional Patent Application No. 62 / 896,026 on September 5, 2019, entitled “Ventricular assist device”.

[0300] Tuval's US 2019 / 0209758 is a continuation application to Tuval's international application PCT / IB2019 / 050186 (published as WO 19 / 138350) entitled "Ventricular assist device," filed on January 10, 2019. This international application claims the following priority:

[0301] Sohn filed U.S. Provisional Patent Application No. 62 / 615,538 entitled “Ventricular assist device” on January 10, 2018;

[0302] Sohn filed U.S. Provisional Patent Application No. 62 / 665,718 on May 2, 2018, entitled “Ventricular assist device”.

[0303] Tuval's U.S. Provisional Patent Application No. 62 / 681,868, filed June 7, 2018, entitled "Ventricular assist device"; and

[0304] Tuval filed U.S. Provisional Patent Application No. 62 / 727,605 on September 6, 2018, entitled “Ventricular assist device”.

[0305] Tuval's US 2019 / 0269840 is the U.S. national phase of Tuval's international patent application PCT / IL2017 / 051273 (published as WO 18 / 096531) entitled "Bloodpumps," filed November 21, 2017. This international patent application claims priority to Tuval's U.S. provisional patent application 62 / 425,814, filed November 23, 2016.

[0306] Tuval's US 2019 / 0175806 is a continuation application of Tuval's international application PCT / IL2017 / 051158 (published as WO 18 / 078615) entitled "Ventricular assist device," filed on October 23, 2017. This international application claims priority to Tuval's US 62 / 412,631, filed on October 25, 2016, and US 62 / 543,540, filed on August 10, 2016.

[0307] Tuval's US 2019 / 0239998 is the U.S. national phase of Tuval's international patent application PCT / IL2017 / 051092 (published as WO 18 / 061002), filed on September 28, 2017, entitled "Bloodvessel tube," which claims priority to Tuval's U.S. provisional patent application 62 / 401,403, filed on September 29, 2016.

[0308] Schwammenthal's US 2018 / 0169313 is the U.S. national phase of its international patent application PCT / IL2016 / 050525 (published as WO 16 / 185473) entitled "Blood pump," filed May 18, 2016. This international patent application claims priority to Schwammenthal's U.S. provisional patent application 62 / 162,881 entitled "Blood pump," filed May 18, 2015.

[0309] Schwammenthal's US 2017 / 0100527 is the U.S. national phase of its international patent application PCT / IL2015 / 050532 (published as WO 15 / 177793) entitled "Blood pump," filed May 19, 2015. This international patent application claims priority to Schwammenthal's U.S. provisional patent application 62 / 000,192 entitled "Blood pump," filed May 19, 2014.

[0310] Schwammenthal's US 10,039,874, which is the US national phase (published as WO14 / 141284) of Schwammenthal's international patent application PCT / IL2014 / 050289 entitled "Renal pump" filed on March 13, 2014, claims priority to (a) Schwammenthal's US Provisional Patent Application 61 / 779,803 entitled "Renal pump" filed on March 13, 2013, and (b) Schwammenthal's US Provisional Patent Application 61 / 914,475 entitled "Renal pump" filed on December 11, 2013;

[0311] U.S. Patent 9,764,113, entitled "Curved catheter," was granted to Tuval on September 19, 2017, claiming priority from Tuval's U.S. Provisional Patent Application 61 / 914,470, also entitled "Curved catheter," filed on December 11, 2013; and

[0312] Tuval's US 9,597,205 is the U.S. national phase of its international patent application PCT / IL2013 / 050495 (published as WO 13 / 183060) entitled "Prosthetic renal valve," filed June 6, 2013. This international patent application claims priority to Tuval's U.S. provisional patent application 61 / 656,244 entitled "Prosthetic renal valve," filed June 6, 2012.

[0313] Those skilled in the art will recognize that the present invention is not limited to what has been specifically shown and described above. Rather, the scope of protection of the present invention includes both combinations and sub-combinations of the various features described above, as well as variations and modifications of the invention that would arise to those skilled in the art upon reading the foregoing description and that are not found in the prior art.

Claims

1. An apparatus comprising: Ventricular assist device, the ventricular assist device comprising: An impeller, configured to be placed in the left ventricle of a subject, the impeller defining a cavity through which the impeller extends; A frame, configured to be arranged around the impeller; A proximal support member is provided at the proximal end of the frame and a distal support member is provided at the distal end of the frame. An axial shaft passing through the proximal support, the cavity defined by the impeller, and the distal support; and A motion damping spring is disposed around the axial shaft between the distal end of the impeller and the distal support member, the motion damping spring being configured to dampen the axial movement experienced by the impeller.

2. The device according to claim 1, wherein, The impeller is configured to undergo axial reciprocating motion as it rotates, and the motion buffer spring is configured to provide cushioning for the axial reciprocating motion.

3. The device according to claim 1, wherein, The impeller is configured to be radially constrained by becoming axially elongated, and wherein the motion buffer spring is configured to be compressed to accommodate the axial elongation of the impeller.

4. The device according to claim 1, wherein, The motion buffer spring is connected to the distal end of the impeller.

5. The device according to claim 1, wherein, The ventricular assist device further includes a proximal motion buffer spring disposed around the axial shaft between the proximal end of the impeller and the proximal support, the proximal motion buffer spring being configured to buffer the axial movement of the impeller in the proximal direction.

6. The device according to any one of claims 1-5, wherein, The motion buffer spring is connected to the distal support.

7. The device of claim 6, further comprising a distal support housing disposed around the distal support, wherein, The motion buffer spring is connected to the distal support via the distal support housing.

8. The device according to any one of claims 1-5, further comprising an elastomeric material coupled to the motion buffer spring such that at least a portion of the axial shaft located between the distal end of the impeller and the distal support is covered by the combination of the motion buffer spring and the elastomeric material.

9. The device according to claim 8, wherein, The motion-cushioning spring is coated with the elastomeric material.

10. The device according to claim 8, wherein, The motion-absorbing spring is embedded within the elastomeric material.

11. The device according to claim 8, wherein, The elastomer material includes at least one of silicone resin and polyurethane.

12. The device according to claim 8, wherein, The ventricular assist device includes a cleaning system configured to pump cleaning fluid through a cavity defined by the axial shaft, such that at least a portion of the cleaning fluid flows proximally across the interface between the axial shaft and the combination of the motion buffer spring and the elastomeric material.

13. The device according to claim 8, wherein, The elastomeric material is connected to the motion buffer spring in such a way that the elastomeric material changes shape to conform to the shape change experienced by the motion buffer spring.

14. The device according to claim 13, wherein, The elastomeric material is configured to undergo shape changes without breaking or collapsing.

15. The device according to claim 13, wherein, The elastomeric material is configured not to wrinkle due to compression of the motion-cushioning spring.

16. The device according to any one of claims 1-5, wherein, The ventricular assist device further includes a pump outlet tube configured to pass through the aortic valve of a subject, such that a proximal portion of the pump outlet tube is disposed within the subject's aorta and a distal portion of the pump outlet tube is disposed within the subject's left ventricle. The distal portion of the pump outlet tube extends to the distal end of the frame and defines one or more lateral blood inlet openings configured to allow blood to flow from the subject's left ventricle into the pump outlet tube.

17. The device according to claim 16, wherein, The porosity of the distal portion of the pump outlet tube defining the blood inlet opening is lower in the proximal region of the distal portion of the pump outlet tube than in the distal region of the distal portion of the pump outlet tube located distal to the proximal region.

18. The device according to claim 16, wherein, The distal portion of the pump outlet pipe has a porosity greater than 40%.

19. The device according to claim 16, wherein, The distal portion of the pump outlet tube defines more than 10 blood inlet openings, which are sized to (a) allow blood to flow from the subject's left ventricle into the tube, and (b) prevent structures from the subject's left ventricle from entering the frame.

20. The device according to claim 19, wherein, The distal portion of the pump outlet tube defines more than 50 blood inlet openings, which are sized to (a) allow blood to flow from the subject's left ventricle into the tube, and (b) prevent structures from the subject's left ventricle from entering the frame.

21. An apparatus comprising: Ventricular assist device, the ventricular assist device comprising: Axial shaft; An impeller, which is mounted on the axial shaft, is configured to pump blood; The frame, which is arranged around the impeller, A distal thrust support, wherein the distal end of the axial shaft is configured to engage with the distal thrust support to prevent the axial shaft from undergoing axial movement in response to changes in the pressure gradient resisted by the impeller pumping blood; and An impeller stabilizing spring is disposed around the axial shaft between the distal end of the impeller and the distal thrust support, the impeller stabilizing spring being configured to stabilize the distal end of the impeller.

22. The device according to claim 21, wherein, The impeller is configured to be radially constrained by becoming axially elongated, and wherein the impeller stabilizing spring is configured to be compressed to accommodate the axial elongation of the impeller.

23. The device according to claim 21, wherein, The impeller stabilizing spring is connected to the distal end of the impeller.

24. The device according to claim 21, wherein, The ventricular assist device also includes a proximal support and a proximal impeller stabilizing spring, the proximal impeller stabilizing spring being disposed around the axial shaft between the proximal end of the impeller and the proximal support.

25. The device according to claim 21, wherein, The impeller stabilizing spring is connected to the distal thrust support.

26. The device according to any one of claims 21-25, further comprising an elastomeric material coupled to the impeller stabilizing spring such that at least a portion of the axial shaft located between the distal end of the impeller and the distal thrust support is covered by the combination of the impeller stabilizing spring and the elastomeric material.

27. The device according to claim 26, wherein, The impeller stabilizing spring is coated with the elastomeric material.

28. The device according to claim 26, wherein, The impeller stabilizing spring is embedded within the elastomer material.

29. The device according to claim 26, wherein, The elastomer material includes at least one of silicone resin and polyurethane.

30. The device according to claim 26, wherein, The ventricular assist device includes a cleaning system configured to pump cleaning fluid through a cavity defined by the axial shaft, such that at least a portion of the cleaning fluid flows proximally across the interface between the axial shaft and the combination of the impeller stabilizing spring and the elastomeric material.

31. The device according to claim 26, wherein, The elastomeric material is connected to the impeller stabilizing spring in such a way that the elastomeric material changes shape to conform to the shape change experienced by the impeller stabilizing spring.

32. The device according to claim 31, wherein, The elastomeric material is configured to undergo shape changes without breaking or collapsing.

33. The device according to claim 31, wherein, The elastomeric material is configured not to wrinkle due to compression of the impeller stabilizing spring.

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