Ventricular assist device

Abstract

This application relates to ventricular assist devices. Apparatus and methods are described, the methods including placing an impeller (50) within a blood vessel of a subject, the impeller including at least one helical elongate element (52) and a spring (54) disposed within and coaxial with the helical elongate element. A material film (56) is supported between the helical elongate element and the spring. Blood is pumped through the blood vessel of the subject using the impeller. Other applications are also described.

Description

[0001] This application is a continuation of application number 201780066201.3, filed on October 23, 2017, having the title "Ventricular assist device".

[0002] Cross Reference to Related Applications

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

[0004] U.S. Provisional Patent Application 62 / 412,631 to Tuval, filed on October 25, 2016, entitled "Ventricular assist device"; and

[0005] U.S. Provisional Patent Application 62 / 543,540 to Tuval, filed on August 10, 2017, entitled "Ventricular assist device".

[0006] Both of the above cited applications are incorporated herein by reference.

[0007] Field of the Embodiments of the Invention

[0008] Some applications of the present invention relate generally to medical devices. In particular, some applications of the present invention concern ventricular assist devices and methods of use thereof.

[0009] BACKGROUND

[0010] Ventricular assist devices are used to assist patients with heart failure in circulating blood through the heart. Most commonly, left ventricular assist devices are used in patients with a defective heart in order to assist the function of the left ventricle. In some cases, right ventricular assist devices are used in order to assist the function of the right ventricle.

[0011] SUMMARY OF THE EMBODIMENTS

[0012] According to some applications of the invention, the impeller comprises a helical elongated element, a spring disposed inside and coaxial with the helical elongated element, and a material membrane supported between the helical elongated element and the spring. For some applications, the impeller comprises a portion of a ventricular assist device configured to assist a subject's ventricle in functioning normally, e.g., a left ventricular assist device configured to assist a subject's left ventricle in functioning normally. The ventricular assist device generally comprises an elongated tube configured to pass through a subject's aortic valve such that a proximal end of the tube is disposed within the subject's aorta and a distal end of the tube is disposed within the subject's left ventricle. The elongated tube comprises a frame formed of a self-expanding shape memory alloy and a blood-impermeable material disposed over the frame. The ventricular assist device comprises a pump, which generally comprises an impeller and a cage disposed around the impeller. The impeller is generally configured to pump blood out of the subject's left ventricle and into the subject's aorta by rotating. Generally, the impeller also prevents blood from flowing back from the aorta to the left ventricle through the aortic valve.

[0013] For some applications, the cage is integrally formed with the elongated tube such that the cage is disposed within the frame of the elongated tube at the proximal end of the elongated tube. Thus, the pump is disposed within a proximal portion of the elongated tube and a longitudinal axis of the pump is thereby aligned with a longitudinal axis of the elongated tube. Optionally, the cage is not integrally formed with the elongated tube.

[0014] Thus, according to some applications of the invention, there is provided an apparatus comprising:

[0015] an impeller, the impeller comprising:

[0016] at least one helical elongated element;

[0017] a spring disposed within and coaxial with the helical elongated element; and

[0018] a material membrane supported between the helical elongated element and the spring.

[0019] In some applications, the impeller comprises a plurality of helical elongated elements and the material membrane is supported between the plurality of helical elongated elements and the spring such that the impeller defines a plurality of blades.

[0020] In some applications, a pitch of the helical elongated element varies along a length of the helical elongated element when the impeller is disposed in a non-radially constrained configuration.

[0021] In some applications, a pitch of the helical elongated element is greater than 1 mm when the impeller is disposed in a non-radially constrained configuration.

[0022] In some applications, a pitch of the helical elongated element is less than 20 mm when the impeller is disposed in a non-radially constrained configuration.

[0023] In some applications, the impeller is configured to be placed within a blood vessel of a subject and to pump blood through the subject's blood vessel by rotation of the impeller.

[0024] In some applications, the impeller is configured to be placed in the subject's aorta and to pump blood from the subject's left ventricle by rotation of the impeller.

[0025] In some applications, the impeller is configured to be placed in a ventricle of a subject and to pump blood from the ventricle by rotation of the impeller.

[0026] In some applications, the impeller is configured to be placed in the subject's aorta and to prevent backflow of blood from the aorta into the subject's left ventricle.

[0027] In some applications, the impeller is configured to be radially constrained by the helical elongated element and the spring is axially elongated, and in response to the helical elongated element and the axially elongated spring, the membrane is configured to change shape without the material membrane breaking.

[0028] In some applications, the apparatus further comprises:

[0029] an elongated tube configured to pass through the subject's aortic valve such that a proximal end of the tube is disposed within the subject's aorta and a distal end of the tube is disposed within the subject's left ventricle, the elongated tube comprising:

[0030] a frame formed of a shape memory alloy; and

[0031] a blood-impermeable material disposed on the frame; and

[0032] a cage disposed about the impeller,

[0033] the elongated tube is configured to be disposed about the cage and the impeller, and the impeller is configured to pump blood from the left ventricle to the aorta by rotation.

[0034] In some applications, the spring, when disposed in its non-radially constrained configuration, is configured to stabilize the impeller relative to the elongated tube during rotation of the impeller by virtue of its rigidity such that a gap between an outer edge of the impeller and an inner surface of the elongated tube is maintained.

[0035] In some applications:

[0036] the spring defines an inner lumen therethrough, and

[0037] the impeller further comprises:

[0038] a proximal bushing and a distal bushing; and

[0039] a rigid shaft configured to extend from the proximal bushing to the distal bushing via an internal lumen defined by the spring, the rigid shaft configured to stabilize the impeller relative to the elongated tube during rotation of the impeller such that a gap between an outer edge of the impeller and an inner surface of the elongated tube is maintained.

[0040] In some applications, the cage is integrally formed with the frame of the elongated tube such that the cage is disposed within the frame of the elongated tube at a proximal end of the elongated tube, the impeller is thus disposed within a proximal portion of the elongated tube, and the longitudinal axis of the impeller is thus aligned with the longitudinal axis of the elongated tube.

[0041] In some applications, the gap between the outer edge of the impeller and the inner surface of the elongated tube is less than 1 mm.

[0042] In some applications, the gap between the outer edge of the impeller and the inner surface of the elongated tube is less than 0.4 mm.

[0043] In some applications, the impeller is configured to be stabilized relative to the elongated tube such that a gap between the impeller and the elongated tube is maintained during rotation of the impeller.

[0044] In some applications, the cage is not integrally formed with the frame of the elongated tube.

[0045] In some applications, the device further comprises one or more support arms configured to extend from the cage to the frame of the elongated tube and configured to stabilize a distal end of the impeller relative to the frame of the elongated tube during rotation of the impeller such that a gap between an outer edge of the impeller and an inner surface of the elongated tube is maintained.

[0046] In some applications, the support arms are configured to be slidable relative to the frame of the elongated tube.

[0047] In some applications, the support arms are configured to be coupled to the frame of the elongated tube.

[0048] In some applications, the device further comprises a plurality of winged protrusions coupled to the elongated tube such that a plane defined by the winged protrusions is parallel to the longitudinal axis of the elongated tube, the winged protrusions configured to stabilize blood turbulence generated by rotation of the impeller by directing blood flow along the longitudinal axis of the elongated tube.

[0049] In some applications, the elongated tube is configured to be inserted into a body of a subject via a catheter when in the radially constrained configuration, and the winged protrusions are configured to become folded when the elongated tube is in its radially constrained configuration.

[0050] In some applications, the spring defines an internal lumen therethrough, and the impeller further comprises:

[0051] a proximal bushing and a distal bushing; and

[0052] a rigid shaft configured to extend from the proximal bushing to the distal bushing via an internal lumen defined by the spring.

[0053] In some applications, the rigid shaft is configured to maintain the proximal and distal bushings in alignment with one another.

[0054] In some applications, the impeller is configured to be placed within a body of a subject, and the rigid shaft is configured to be placed within the internal lumen defined by the spring after the spring is placed within the body of the subject.

[0055] In some applications, the impeller is configured to be placed within a body of a subject, and the rigid shaft is configured to be disposed within the internal lumen defined by the spring during placement of the impeller within the body of the subject.

[0056] In some applications, the impeller further comprises a proximal bushing and a distal bushing, and the spring, when disposed in its non-radially constrained configuration, is configured to maintain the proximal and distal bushings in alignment with one another by virtue of its rigidity.

[0057] In some applications, the spring, when disposed in its non-radially constrained configuration, is configured such that there is substantially no gap between a coil of the spring and its adjacent coil.

[0058] According to some applications of the present invention, there is provided a method, the method comprising:

[0059] placing an impeller within a blood vessel of a subject, the impeller comprising:

[0060] at least one helical elongated element;

[0061] a spring disposed within and coaxial with the helical elongated element; and

[0062] a material film supported between the helical elongated element and the spring;

[0063] pumping blood through the blood vessel of the subject using the impeller.

[0064] In some applications, placing the impeller within a blood vessel of a subject comprises placing the impeller within a blood vessel of a subject, the impeller comprising a plurality of helical elongated elements, and the material film is supported between the plurality of helical elongated elements and the spring such that the impeller defines a plurality of vanes.

[0065] In some applications, placing the impeller within a blood vessel of a subject comprises placing the impeller within a blood vessel of a subject such that a helical pitch of the helical elongated element varies along a length of the helical elongated element when the impeller is disposed within the blood vessel.

[0066] In some applications, placing the impeller within a blood vessel of a subject includes placing the impeller within a blood vessel of a subject such that, when the impeller is disposed within the blood vessel, the helical elongated element has a pitch of greater than 1 mm.

[0067] In some applications, placing the impeller within a blood vessel of a subject includes placing the impeller within a blood vessel of a subject such that, when the impeller is disposed within the blood vessel, the helical elongated element has a pitch of less than 20 mm.

[0068] In some applications, placing the impeller within a blood vessel of a subject includes placing the impeller within the aorta of a subject, and pumping blood through a blood vessel of a subject includes pumping blood from a chamber of the subject into the aorta.

[0069] In some applications, placing the impeller within a blood vessel of a subject includes placing the impeller in a chamber of the subject, and pumping blood through a blood vessel of a subject includes pumping blood out of a chamber of the subject.

[0070] In some applications, placing the impeller within a blood vessel of a subject includes placing the impeller in the aorta of a subject, and pumping blood through a blood vessel of a subject includes using the impeller to prevent backflow of blood from the aorta of the subject into the left ventricle of the subject.

[0071] In some applications, placing the impeller within a blood vessel includes catheter- inserting the impeller into a blood vessel of a subject by axially elongating the helical elongated element and the spring, thereby causing the material film to change shape without the material film breaking.

[0072] In some applications, the method further comprises:

[0073] placing an elongated tube into a body of a subject such that the elongated tube passes through an aortic valve of the subject, such that a proximal end of the tube is disposed within an aorta of the subject and a distal end of the tube is disposed within a left ventricle of the subject, the elongated tube comprising:

[0074] a frame formed of a shape memory alloy; and

[0075] a blood-impermeable material disposed on the frame;

[0076] wherein placing the impeller within a blood vessel includes placing the impeller within an aorta of a subject, the impeller is disposed within a cage, and the cage and the impeller are disposed within the elongated tube; and

[0077] wherein using the impeller to pump blood through a blood vessel of a subject includes pumping blood from the left ventricle to the aorta.

[0078] In some applications, rotating the impeller includes using rigidity of the spring to stabilize the impeller relative to the elongated tube such that a gap between an outer edge of the impeller and an inner surface of the elongated tube is maintained during rotation of the impeller.

[0079] In some applications, placing the impeller within a blood vessel includes placing the impeller within a blood vessel, the impeller further comprising:

[0080] a proximal hub and a distal hub; and

[0081] a rigid shaft configured to extend from the proximal hub to the distal hub via an inner lumen defined by the spring, the rigid shaft configured to stabilize the impeller relative to the elongated tube such that a gap between an outer edge of the impeller and an inner surface of the elongated tube is maintained during rotation of the impeller.

[0082] In some applications, placing the impeller within an aorta of a subject includes placing the impeller within an aorta of a subject, the cage being integrally formed with the frame of the elongated tube such that the cage is disposed within the frame of the elongated tube at the proximal end of the elongated tube, the impeller thereby being disposed within a proximal portion of the elongated tube, and a longitudinal axis of the impeller thereby being aligned with a longitudinal axis of the elongated tube.

[0083] In some applications, placing the impeller within an aorta of a subject includes placing the impeller within an aorta of a subject such that a gap between an outer edge of the impeller and an inner surface of the elongated tube is less than 1 mm.

[0084] In some applications, placing the impeller within an aorta of a subject includes placing the impeller within an aorta of a subject such that the gap between the outer edge of the impeller and the inner surface of the elongated tube is less than 0.4 mm.

[0085] In some applications, placing the impeller within an aorta of a subject includes placing the impeller within an aorta of a subject such that the impeller is stabilized relative to the elongated tube such that a gap between the impeller and the elongated tube is maintained during rotation of the impeller.

[0086] In some applications, placing the impeller within an aorta of a subject includes placing the impeller within an aorta of a subject, the cage not being integrally formed with the frame of the elongated tube.

[0087] In some applications, placing the impeller within the subject's aorta includes placing the impeller within the subject's aorta with one or more support arms configured to extend from the cage to the frame of the elongated tube and configured to stabilize a distal end of the impeller relative to the frame of the elongated tube during rotation of the impeller such that a gap between an outer edge of the impeller and an inner surface of the elongated tube is maintained.

[0088] In some applications, placing the impeller within the subject's aorta includes placing the impeller within the subject's aorta with the support arms configured to be slidable relative to the frame of the elongated tube.

[0089] In some applications, placing the impeller within the subject's aorta includes placing the impeller within the subject's aorta with the support arms coupled to the frame of the elongated tube.

[0090] In some applications, placing the elongated tube into the subject's body includes placing the elongated tube into the subject's body with a plurality of winged protrusions coupled to the elongated tube such that a plane defined by the winged protrusions is parallel to a longitudinal axis of the elongated tube, the winged protrusions configured to stabilize blood turbulence generated by rotation of the impeller by directing blood flow in a direction along the longitudinal axis of the elongated tube.

[0091] In some applications, placing the elongated tube into the subject's body includes placing the elongated tube into the subject's body via a catheter when the elongated tube is in a radially constrained configuration, the winged protrusions configured to become folded when the elongated tube is in its radially constrained configuration.

[0092] In some applications, placing the impeller within the blood vessel includes placing the impeller within the blood vessel, the impeller further comprising:

[0093] a proximal hub and a distal hub; and

[0094] a rigid shaft configured to extend from the proximal hub to the distal hub via an internal lumen defined by the spring.

[0095] In some applications, rotating the impeller includes using the rigid shaft to maintain the proximal hub and the distal hub in alignment with each other during rotation of the impeller.

[0096] In some applications, placing the impeller within the blood vessel includes placing the spring within the blood vessel, and placing the rigid shaft within the internal lumen defined by the spring after placing the spring within the blood vessel.

[0097] In some applications, placing the impeller within the blood vessel comprises placing the impeller within the blood vessel while the rigid shaft is disposed within the lumen defined by the spring.

[0098] In some applications, the impeller comprises a proximal bushing and a distal bushing, and wherein rotating the impeller comprises using the rigidity of the spring to maintain the proximal bushing and the distal bushing in alignment with each other during rotation of the impeller.

[0099] In some applications, placing the impeller within the blood vessel comprises placing the impeller within the blood vessel such that there is substantially no gap between the coils of the spring and their adjacent coils.

[0100] The present application will be more fully understood from the following detailed description of embodiments of the application, taken in conjunction with the accompanying drawings, in which: BRIEF DESCRIPTION OF DRAWINGS

[0101] FIG. 1A and FIG. 1B is a schematic view of a ventricular assist device according to some applications of the present application arranged in a left ventricle of a subject;

[0102] FIG. 2 is a schematic view of a pump comprising an impeller and a cage according to some applications of the present application;

[0103] FIG. 3 is a schematic view of a frame of an elongated tube of a ventricular assist device and a cage of an impeller of a ventricular assist device according to some applications of the present application;

[0104] FIG. 4A and FIG. 4B is a schematic view of a ventricular assist device according to some further applications of the present application;

[0105] FIG. 5A and FIG. 5B is a schematic view of a ventricular assist device according to some applications of the present application FIG. 4A and FIG. 4B is a schematic view of respective cross-sectional views of an impeller of a ventricular assist device shown in

[0106] FIG. 5C is a schematic view of a cross-sectional view of a ventricular assist device according to some applications of the present application FIG. 4A and FIG. 4B is a schematic view of a cross-sectional view of a ventricular assist device according to some applications of the present application

[0107] FIG. 5D is a schematic view of an impeller of a ventricular assist device according to some applications of the present application in a radially constrained configuration FIG. 4A and FIG. 4B is a schematic view of an impeller of a ventricular assist device according to some applications of the present application in a radially constrained configuration

[0108] FIG. 6A andFIG. 6B is a schematic view of a stator of a ventricular assist device according to some applications of the present application; and

[0109] FIG. 7A , FIG. 7B and FIG. 7C is a schematic view of a ventricular assist device including a centrifugal pump according to some applications of the present application. DETAILED DESCRIPTION

[0110] Reference is now made to FIG. 1A and FIG. 1B which are schematic views of a ventricular assist device 20 disposed in a left ventricle 22 of a subject according to some applications of the present application. The ventricular assist device includes an elongated tube 24 that passes through the aortic valve 26 of the subject such that a proximal end 28 of the elongated tube is disposed in the aorta 30 of the subject and a distal end 32 of the tube is disposed in the left ventricle 22. The elongated tube generally includes a radially expandable frame 34 formed of a self-expanding shape memory alloy such as Nitinol, and a blood impermeable material 36 disposed on the frame. For example, the blood impermeable material can include polyurethane, polyester and / or silicone. Generally, the frame provides rigidity to the elongated tube and the blood impermeable material provides blood impermeability to the elongated tube. Further, generally, the shape memory alloy of the frame is shaped such that the frame assumes its tubular shape without any force exerted on the tube. Generally, the device 20 is inserted into the left ventricle via a catheter (e.g., via the brachial artery) while the tube is in a radially constrained state. Upon release from the catheter, the tube automatically assumes its tubular shape due to expansion of the frame. A pump 40 is disposed within the elongated tube (e.g., as shown, within a proximal portion of the elongated tube) and is configured to pump blood through the elongated tube from the left ventricle into the aorta to assist the left ventricle in its normal operation.

[0111] FIG. 2is a schematic view of a pump 40 according to some applications of the present application. Pump 40 generally includes a radially expandable impeller 42 disposed within a radially expandable cage 44. Generally, pump 40 is inserted into the left ventricle via a catheter, with the impeller and cage in a radially constrained configuration. The impeller and cage generally include a shape memory alloy (e.g., nitinol) that is shaped such that the impeller and cage assume a non-radially constrained (i.e., radially expanded) configuration in the absence of any radially constraining force acting on the impeller and cage. Thus, generally, the cage and impeller radially expand upon release from the distal end of the catheter via which the cage and impeller are inserted. For some applications, an engagement mechanism engages the impeller and cage relative to one another such that the impeller also becomes radially constrained in response to the cage becoming radially constrained, e.g., according to the apparatus and methods described in WO 14 / 141284 to Schwammenthal, which is incorporated by reference herein. Generally, pump 40 is substantially similar to the blood pumps described in WO 14 / 141284 to Schwammenthal, WO 15 / 177793 to Schwammenthal, and / or WO 16 / 185473 to Schwammenthal, all of which are incorporated by reference herein. Generally, pump 40 pumps blood from the left ventricle into the aorta via the elongated tube via impeller rotation. For some applications, a rotation cable 46 FIG. 1B ) rotates the impeller. Generally, the rotation cable is rotated by a motor (not shown) disposed outside or inside the subject.

[0112] For some applications, pump 40 is disposed at the proximal end of the elongated tube such that the pump is disposed within the aorta. For some applications, the pump is disposed at the distal end of the elongated tube such that the pump is disposed within a chamber of the subject.

[0113] Reference is now made to FIG. 3 , FIG. 3is a schematic view of a frame 34 of an elongated tube 24 of a ventricular assist device 20 and a cage 44 of a pump 40 according to some applications of the present application. As shown, for some applications, the cage is integrally formed with the frame of the elongated tube such that the cage is disposed within the frame of the elongated tube at the proximal end of the elongated tube. Typically, because the cage is disposed within the frame of the elongated tube at the proximal end of the elongated tube, the pump 40 is disposed within the proximal portion of the elongated tube and the longitudinal axis of the pump is aligned with the longitudinal axis of the elongated tube. For some applications, the frame 34 of the elongated tube 24 and the cage 44 are cut from a single piece (e.g., a single tube) of shape memory material (e.g., a shape memory alloy such as Nitinol). Typically, because the frame is cut from a single piece of shape memory material, the region of the tube in which the cage is disposed is able to be radially compressed to a smaller diameter than if the cage were cut from separate pieces of shape memory material and be inserted within the elongated tube, or vice versa, all else being equal.

[0114] Reference is now made to FIG. 4A , FIG. 4A is a schematic view of a ventricular assist device 20 according to some applications of the present application. For some applications, the pump 40 is substantially as shown in FIG. 4A Typically, the pump includes an impeller 50 including an outer helical elongated element 52 wrapped around a central axial spring 54 such that the helical piece defined by the helical elongated element is coaxial with the central axial spring. For some applications, the helical elongated element and the central axial spring are made of a shape memory material, such as a shape memory alloy such as Nitinol. Typically, the helical elongated element and the central axial spring are supported by a thin film 56 of material (e.g., a polymer such as polyurethane and / or silicone) therebetween. The helical elongated element, the axial spring, and the thin film define an impeller blade, with the helical elongated element defining the outer edge of the impeller blade (and thereby the outer edge of the impeller) and the axial spring defining the axis of the impeller blade. For some applications, a suture (e.g., a polyester suture, not shown) is wrapped around the helical elongated element, such as described in WO 14 / 141284, which is incorporated by reference herein. Typically, the suture is configured to facilitate bonding between the thin film of material (typically a polymer such as polyurethane or silicone) and the helical elongated element (typically a shape memory alloy such as Nitinol). For some applications, a suture (e.g., a polyester suture, not shown) is wrapped around the spring 54. Typically, the suture is configured to facilitate bonding between the thin film of material (typically a polymer such as polyurethane or silicone) and the spring (typically a shape memory alloy such as Nitinol).

[0115] Generally, the proximal end of the spring 54 and the proximal end of the helical elongated element 52 are each coupled to a proximal bushing (i.e., sleeve bearing) 64 of the impeller, such that the proximal ends of the spring 54 and the helical elongated element 52 are each disposed at a similar radial distance from the longitudinal axis of the impeller. Similarly, generally, the distal end of the spring 54 and the distal end of the helical elongated element 52 are each coupled to a distal bushing 58 of the impeller, such that the distal ends of the spring 54 and the helical elongated element 52 are each disposed at a similar radial distance from the longitudinal axis of the impeller.

[0116] For some such applications, the frame 34 of the elongated tube 24 does not include a cage formed integrally therewith, as described above with reference to FIG. 3 . Rather, for some such applications, the distal bushing 58 of the impeller is stabilized relative to the elongated tube by one or more support arms 60 extending radially outward from the distal bushing of the impeller to the frame 34 of the elongated tube 24. As shown in FIG. 4A , for some applications, the support arms are not coupled to the frame 34 of the elongated tube, but are instead configured to engage the inner surface of the elongated tube, thereby stabilizing the distal bushing of the impeller relative to the elongated tube. For such applications, the support arms are generally configured to be movable relative to the elongated tube by the support arms sliding along the inner surface of the elongated tube. Optionally, even if the support arms are not integrally formed with the frame 34 of the elongated tube, the support arms are coupled to the frame 34 of the elongated tube (e.g., by welding, stitching, and / or adhesive), such that the support arms are not movable relative to the elongated tube at least at the locations where the support arms are coupled to the frame of the elongated tube. Further optionally, the device includes support arms that are integrally formed with the frame 34 of the elongated tube, as shown in FIG. 4B .

[0117] Reference is now made to FIG. 4B , FIG. 4B is a schematic illustration of a device 20 according to some applications of the present application, which includes support arms 59 that are integrally formed with the frame 34 of the elongated tube 24, the support arms being coupled to the frame 34 at coupling points 61. Generally, the support arms are configured to extend from the distal bushing of the impeller to the coupling points, and are configured to thereby stabilize the distal bushing of the impeller relative to the elongated tube.

[0118] With regard to FIG. 4A-FIG. 4BThe impeller 50 is disposed at the proximal end of the elongated tube, such that during use of the device 20, the impeller is disposed within the aorta, and pumps blood from the left ventricle into the aorta by rotating within the aorta. For some applications (not shown), the impeller is disposed at the distal end of the elongated tube, such that during use of the device 20, the impeller is disposed within the ventricle, and pumps blood out of the ventricle by rotating within the ventricle. Generally, in the context of the present application, the term "blood vessel" should be interpreted to include a ventricle. Similarly, an impeller described as being placed within a blood vessel should be interpreted to include an impeller placed within a ventricle.

[0119] Reference is now made to FIG. 5A and FIG. 5B , FIG. 5A and FIG. 5B are schematic illustrations of cross sections of the impeller 50 according to some applications of the present application, respectively perpendicular to the longitudinal axis of the impeller, and along the longitudinal axis of the impeller. Reference is also made to FIG. 5C , FIG. 5C is a schematic illustration of a cross section of the ventricular assist device 20 according to some applications of the present application, along the longitudinal axis of the device. For example, as FIG. 5B indicated in FIG. 1, the spring 54 defines a lumen 62 therethrough. For some applications, a rigid shaft 63 is disposed along the lumen, at least from the proximal hub 64 of the impeller to the distal hub 58. The rigid shaft is configured to transmit rotational motion from the proximal hub to the distal hub, and / or to keep the distal hub and the proximal hub aligned with each other and with the longitudinal axis of the elongated tube. Alternatively or additionally, the spring 54 itself acts as a shaft. Thus, for some applications, the spring transmits rotational motion from the proximal hub to the distal hub, and / or to keep the distal hub and the proximal hub aligned with each other and with the longitudinal axis of the elongated tube. For some such applications, the spring is configured such that when the spring is disposed in a non-radially constrained configuration, there is substantially no gap between the coils of the spring and the coils adjacent thereto.

[0120] Reference is now made to FIG. 5D , which FIG. 5Dis a schematic view of an impeller 50 in a radially constrained (i.e., axially elongated) configuration according to some applications of the present application. Typically, the pump 40 is inserted into the left ventricle of a subject via a catheter, with the impeller 50 in its radially constrained configuration. As shown, in the radially constrained configuration, both the helical elongated element 52 and the central axial spring 54 become axially elongated and are radially constrained. Typically, a thin film 56 of material (e.g., silicone) changes shape to conform to the shape change of both the helical elongated element and the axial support spring, both of which support the thin film of material. Typically, the use of a spring to support the inner edge of the thin film allows the thin film to change shape without the thin film becoming torn or collapsing inward onto the shaft disposed within the inner lumen 62, as the spring provides a large surface area to which the inner edge of the thin film is bonded. For some applications, the use of a spring to support the inner edge of the thin film reduces the diameter to which the impeller can be radially constrained relative to if, for example, a rigid shaft were used to support the inner edge of the thin film, as the diameter of the spring itself can be reduced by axially elongating the spring. As described above and as shown in FIG. 6B, for some applications, a rigid shaft 63 is disposed along the inner lumen 62 (defined by the spring 54) at least from the proximal hub 64 of the impeller to the distal hub 58. For certain applications, the rigid shaft is disposed within the inner lumen even during the period in which the impeller is inserted into the left ventricle of a subject via a catheter. Optionally, once the impeller has been released from the insertion catheter, the rigid shaft travels into the inner lumen 62 and is disposed within the inner lumen 62 along with the ventricle of the subject. FIG. 5C

[0121] Again referring to FIG. 6B, FIG. 5A ​G between the outer edge of the impeller blades and the inner surface of the elongated tube 24, even at locations where the span of the impeller is at its maximum. For some applications, it is desirable for the gap between the outer edge of the impeller blades and the elongated tube 24 to be relatively small, so that the impeller effectively pumps blood from the subject’s left ventricle into the subject’s aorta. However, it is also desirable to maintain a gap between the outer edge of the impeller blades and the elongated tube 24, for example, so as to reduce the risk of hemolysis. For some applications, the gap G between the outer edge of the impeller and the inner surface of the elongated tube 24 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), at locations where the span of the impeller is at its maximum. As described above, for some applications, the distal bushing 58 of the impeller is stabilized relative to the elongated tube by one or more support arms 60 or support arms 59. For some applications, by stabilizing the distal bushing 58 of the impeller relative to the elongated tube, even a relatively small gap between the outer edge of the impeller blades and the elongated tube 24 (e.g., a gap as described above) can be maintained during rotation of the impeller. Alternatively or additionally, a rigid shaft is inserted along the axis of the impeller via the inner lumen 62 defined by the spring 54, and the rigid shaft stabilizes the distal bushing 58 of the impeller relative to the elongated tube, such that even a relatively small gap between the outer edge of the impeller blades and the elongated tube 24 (e.g., a gap as described above) can be maintained during rotation of the impeller. Further, alternatively or additionally, the spring 54 is sufficiently rigid to stabilize the distal bushing 58 of the impeller relative to the elongated tube, such that even a relatively small gap between the outer edge of the impeller blades and the elongated tube 24 (e.g., a gap as described above) can be maintained during rotation of the impeller.

[0122] Generally, when the impeller 50 is in the non-radially constrained configuration (e.g., within the subject’s heart chamber), the pitch of the helical elongated element 52 is greater than 1 mm (e.g., greater than 6 mm), and / or less than 20 mm (e.g., less than 10 mm). Generally, all else being equal, the greater the pitch of the helical elongated element (and thus the impeller blades), the greater the blood flow generated by the impeller. Thus, as described, when the impeller 50 is in the non-radially constrained configuration, the pitch of the helical elongated element 52 is generally greater than 1 mm (e.g., greater than 6 mm). On the other hand, during diastole, it is generally desirable for the impeller to block backflow from the subject’s aorta to the subject’s left ventricle. Generally, all else being equal, the smaller the pitch of the helical elongated element (and thus the impeller blades), the greater the blockage provided by the impeller. Thus, as described, when the impeller 50 is in the non-radially constrained configuration, the pitch of the helical elongated element 52 is generally less than 20 mm (e.g., less than 10 mm).

[0123] For some applications, the pitch of the helical elongated element (and thus the impeller blades) varies along the length of the helical elongated element, at least when the impeller is in the non-radially constrained configuration. Typically, for such applications, the pitch gradually increases from the distal end of the impeller (i.e., the end that is inserted further into the subject's body and placed upstream relative to the direction of antegrade blood flow) to the proximal end of the impeller (i.e., the end that is placed downstream relative to the direction of antegrade blood flow), such that the pitch increases in the direction of blood flow. Typically, the blood flow velocity increases along the impeller, in the direction of blood flow. Thus, the pitch is increased in the direction of blood flow, in order to further accelerate the blood.

[0124] For some applications (not shown), the impeller 50 is substantially as shown in FIG. 4A-FIG. 5D WO 14 / 141284, which is incorporated herein by reference, but the impeller includes a plurality of helical elongated elements. For example, the impeller can include two or three helical elongated elements. Typically, a thin film of material is supported between the plurality of helical elongated elements and the spring, such that the impeller defines a plurality of blades. Typically, the number of impeller blades corresponds to the number of helical elongated elements arranged on the impeller, e.g., as substantially described in Schwammenthal's WO 14 / 141284, which is incorporated herein by reference.

[0125] Reference is now made to FIG. 6A and FIG. 6B , FIG. 6A and FIG. 6B are schematic illustrations of a stator 65 of a ventricular assist device 20, in accordance with some applications of the present application. For the purposes of illustration, FIG. 6B the stator is shown without some other elements of the ventricular assist device. For some applications, as shown, the stator 65 is arranged within the proximal portion of the frame 34 of the elongated tube 24. Typically, the stator includes a plurality (e.g., more than 2 and / or less than 8) of wing-shaped protrusions 66 that extend from the frame 34 when the device 20 is in the non-radially constrained configuration, and are made of a flexible material (e.g., a polymer, such as polyurethane and / or silicone). The wing-shaped protrusions are typically configured to define a plane that is parallel to the elongated tube longitudinal axis, and thus to stabilize the blood turbulence created by the impeller by directing the blood flow in the direction of the elongated tube longitudinal axis.

[0126] Note that, as shown in FIG. 6A , typically, the elongated tube 24 includes a blood impermeable material 36 arranged on the tube frame 34. For example, as described hereinabove, the blood impermeable material can include polyurethane, polyester or silicone. Note that, typically, the elongated tube includes a blood impermeable material, even so, for the purposes of illustration, the blood impermeable material of the tube is not shown in all the drawings of the present application.

[0127] As FIG. 6BAs shown in FIG. 1, for some applications, the suture 68 is wrapped around portions of the frame 34 in order to facilitate coupling between the winged protrusions and the frame 34 according to the techniques described above. For some applications, the winged protrusions extend from the frame 34 to an axial support element 69. Typically, the axial support element is a tubular element formed of metal, plastic and / or polymer (e.g., polyurethane and / or silicone). For some applications, the stator 65 is integrally formed with the frame 34 of the elongated tube 24. Alternatively or additionally, the stator is formed separately from the elongated tube.

[0128] As described above, typically, the device 20 is inserted into the subject's ventricle via a catheter, while the elongated tube 24 is in a radially constrained state. Upon release from the catheter, the tube automatically assumes its tubular shape due to the self-expansion of the frame 34 of the elongated tube 24. Typically, the stator is inserted into the subject's left ventricle within the elongated tube. During insertion, the winged protrusions of the stator are in a folded state, and do not significantly increase the minimum diameter by which the elongated tube can be radially constrained relative to the case in which the winged protrusions are not contained with respect to the tube. When the frame 34 of the elongated tube expands, the winged protrusions are configured to automatically assume their winged configuration due to their coupling to the frame 34.

[0129] It is noted that although FIG. 1A and FIG. 1B a ventricular assist device 20 in a subject's left ventricle is shown, for some applications, the device 20 is placed within the subject's right ventricle, such that the device crosses the subject's pulmonary valve, and the techniques described herein are applied mutatis mutandis. Alternatively or additionally, the device 20 and / or a portion thereof (e.g., the impeller 50, even without the elongated tube 24) is placed within a different part of the subject's body in order to assist in pumping blood from that part. For example, the device 20 and / or a portion thereof (e.g., the impeller 50, even without the elongated tube 24) can be placed in a blood vessel, and can be used to pump blood through the blood vessel. For some applications, with the necessary modifications, the device 20 and / or a portion thereof (e.g., the impeller 50, even without the elongated tube 24) is configured to be placed within the subclavian vein or jugular vein at the junction of the vein with the lymphatic duct, and to be used to increase the flow of lymph fluid from the lymphatic duct to the vein.

[0130] Reference is now made to FIG. 7A , FIG. 7A is a schematic illustration of a ventricular assist device 70 including a centrifugal pump 72, according to some applications of the present application. Reference is also made to FIG. 7B and FIG. 7C show a three-dimensional cross-sectional view and a two-dimensional cross-sectional view, respectively, of a centrifugal pump, according to some applications of the present application.

[0131] For some applications, the ventricular assist device assists the pumping of a ventricle (e.g., the left ventricle 22) by using a centrifugal pump to pump blood out of the subject's left ventricle and into the subject's aorta 30. For some applications, a catheter 74 is inserted into the subject's vasculature, which extends from the centrifugal pump 72 to the subject's ventricle. As shown in FIG. 1, the centrifugal pump 72 is implanted in the subject's abdomen, and the catheter 74 extends from the centrifugal pump 72 to the subject's left ventricle 22. As shown in FIG. 1, the centrifugal pump 72 is implanted in the subject's abdomen, and the catheter 74 extends from the centrifugal pump 72 to the subject's left ventricle 22. FIG. 7B and FIG. 7C Typically, the catheter 74 defines concentric tubes 76 and 78. Blood is pumped out of the subject's left ventricle via a first tube (e.g., the inner tube 76, as shown by the dashed arrow in FIG. 1 indicating the direction of blood flow) in the concentric tubes, and blood is pumped into the subject's aorta via a second tube (e.g., the outer tube 78, as shown in FIG. 1) in the concentric tubes. Typically, the first and second tubes are inserted into the subject's body via a single insertion point, such as the femoral artery 80, as shown in FIG. 1, or via different insertion points, such as the subclavian artery. For some applications, the centrifugal pump 72 defines an additional tube 82 via which blood pressure is measured. FIG. 7C and FIG. 7C Typically, the first and second tubes are inserted into the subject's body via a single insertion point, such as the femoral artery 80, as shown in FIG. 1, or via different insertion points, such as the subclavian artery. For some applications, the centrifugal pump 72 defines an additional tube 82 via which blood pressure is measured. FIG. 7A

[0132] The scope of the application includes combining any of the devices and methods described herein with any of the devices and methods described in one or more of the following applications, all of which are incorporated by reference herein:

[0133] International Patent Application PCT / IL2017 / 051092 to Tuval, filed September 28, 2017, entitled "Blood vessel tube," U.S. Provisional Patent Application 62 / 401,403 to Tuval, filed September 29, 2016;

[0134] International Patent Application PCT / IL2016 / 050525 (published as WO 16 / 185473) to Schwammenthal, filed May 18, 2016, entitled "Blood pump," which claims priority to U.S. Provisional Patent Application 62 / 162,881 to Schwammenthal, filed May 18, 2015, entitled "Blood pump";

[0135] International Patent Application PCT / IL2015 / 050532 (published as WO 15 / 177793) to Schwammenthal, filed May 19, 2015, entitled "Blood pump," which claims priority to U.S. Provisional Patent Application 62 / 000,192 to Schwammenthal, filed May 19, 2014, entitled "Blood pump";

[0136] ​International Patent Application PCT / IL2014 / 050289 to Schwammenthal, filed March 13, 2014, entitled "Renal pump" (published as WO 14 / 141284), which claims priority to (a) U.S. Provisional Patent Application 61 / 779,803 to Schwammenthal, filed March 13, 2013, entitled "Renal pump", and (b) U.S. Provisional Patent Application 61 / 914,475 to Schwammenthal, filed December 11, 2013, entitled "Renal pump";

[0137] U.S. Patent Application 14 / 567,439 to Tuval, filed December 11, 2014, entitled "Curved catheter" (published as US 2015 / 0157777), which claims priority to U.S. Provisional Patent Application 61 / 914,470 to Tuval, filed December 11, 2013, entitled "Curved catheter", and

[0138] International Patent Application PCT / IL2013 / 050495 to Tuval, filed June 6, 2013, entitled "Prosthetic renal valve" (published as WO 13 / 183060), which claims priority to U.S. Provisional Patent Application 61 / 656,244 to Tuval, filed June 6, 2012, entitled "Prosthetic renal valve".

[0139] Accordingly, according to some applications of the present application, there is provided the following inventive concepts:

[0140] Inventive Concept 1. An apparatus comprising:

[0141] A left heart assist device configured to assist a subject's left ventricle to function normally, the left heart assist device comprising:

[0142] An elongated tube configured to pass through the subject's aortic valve such that a proximal end of the tube is disposed within the subject's aorta and a distal end of the tube is disposed within the subject's left ventricle, the elongated tube comprising:

[0143] A frame formed of a shape memory alloy; and

[0144] A blood-impermeable material disposed on the frame;

[0145] A rotatable impeller configured to pump blood from the subject's left ventricle to the subject's aorta by rotation; and

[0146] a plurality of wing-shaped protrusions coupled to the elongated tube such that a plane defined by the wing-shaped protrusions is parallel to a longitudinal axis of the elongated tube, the wing-shaped protrusions configured to stabilize blood turbulence resulting from rotation of the impeller by directing blood flow in a direction along the longitudinal axis of the elongated tube.

[0147] Concept 2. The apparatus according to Concept 1, wherein the elongated tube is configured to be inserted into the subject’s body via a catheter when in the radially constrained configuration, and wherein the wing-shaped protrusions are configured to become folded when the elongated tube is in its radially constrained configuration.

[0148] Concept 3. A method comprising:

[0149] placing an elongated tube within a subject’s body such that the elongated tube passes through the subject’s aortic valve, such that a proximal end of the tube is disposed within the subject’s aorta, and a distal end of the tube is disposed within the subject’s left ventricle, the elongated tube comprising:

[0150] a frame formed of a shape memory alloy, and

[0151] a blood-impermeable material disposed on the frame; and

[0152] pumping blood from the subject’s left ventricle to the subject’s aorta by rotating an impeller disposed within the elongated tube,

[0153] a plurality of wing-shaped protrusions coupled to the elongated tube such that a plane defined by the wing-shaped protrusions is parallel to a longitudinal axis of the elongated tube, the wing-shaped protrusions configured to stabilize blood turbulence resulting from rotation of the impeller by directing blood flow in a direction along the longitudinal axis of the elongated tube.

[0154] Concept 4. The method according to Concept 3, wherein placing the elongated tube into the subject’s body comprises placing the elongated tube into the subject’s body via a catheter when the elongated tube is in a radially constrained configuration, the wing-shaped protrusions configured to become folded when the elongated tube is in its radially constrained configuration.

[0155] Concept 5. An apparatus comprising:

[0156] a left heart assist device configured to assist a subject’s left ventricle in normal operation, the left heart assist device comprising:

[0157] an elongated tube configured to pass through the subject’s aortic valve, such that a proximal end of the tube is disposed within the subject’s aorta, and a distal end of the tube is disposed within the subject’s left ventricle, the elongated tube comprising:

[0158] a frame formed of a shape memory alloy; and

[0159] a blood-impermeable material disposed on the frame; and

[0160] a pump comprising a rotatable impeller and a cage arranged around the rotatable impeller,

[0161] the cage is integrally formed with the elongated tube such that the cage is arranged within the frame of the elongated tube at the proximal end of the elongated tube, whereby the pump is arranged within the proximal portion of the elongated tube and the longitudinal axis of the pump is thereby aligned with the longitudinal axis of the elongated tube.

[0162] Inventive Concept 6. A method comprising:

[0163] placing a left ventricular assist device configured to assist a subject's left ventricle in functioning normally within the subject's body, the left ventricular assist device comprising:

[0164] an elongated tube configured to pass through the subject's aortic valve such that a proximal end of the tube is arranged within the subject's aorta and a distal end of the tube is arranged within the subject's left ventricle, the elongated tube comprising:

[0165] a frame formed of a shape memory alloy, and

[0166] a blood-impermeable material arranged on the frame, and

[0167] a pump comprising a rotatable impeller and a cage arranged around the rotatable impeller,

[0168] the cage is integrally formed with the elongated tube such that the cage is arranged within the frame of the elongated tube at the proximal end of the elongated tube, whereby the pump is arranged within the proximal portion of the elongated tube and the longitudinal axis of the pump is thereby aligned with the longitudinal axis of the elongated tube; and

[0169] pumping blood from the subject's left ventricle to the subject's aorta by the rotatable impeller.

[0170] Inventive Concept 7. A blood pump for pumping blood from a first location within a subject's body to a second location within the subject's body, the blood pump comprising:

[0171] a first tube for pumping blood away from the first location;

[0172] a second tube for pumping blood to the second location, the first tube and the second tube being coaxial relative to each other; and

[0173] a centrifugal pump configured to pump blood through the first tube and the second tube.

[0174] Inventive Concept 8. A method comprising:

[0175] pumping blood from a first location within a subject's body to a second location within the subject's body by:

[0176] pumping blood away from the first location via a first tube;

[0177] pumping blood to the second location via a second tube, the first tube and the second tube coaxial relative to each other; and

[0178] pumping blood through the first tube and the second tube using a centrifugal pump.

[0179] Those skilled in the art will realize that the present application is not limited to the examples thereof described above. Rather, the scope of the present application includes combinations and sub-combinations of the various features described above as well as variations and modifications thereof which will occur to those skilled in the art upon reading the foregoing description.

Claims

1. An apparatus comprising: Impeller, the impeller comprising: At least one spiral-shaped elongated element; A spring, the spring being arranged inside the helical elongated element and coaxial with the helical elongated element; and A thin film of material is supported between the helical elongated element and the spring; An elongated tube configured to pass through the aortic valve of a subject, such that the proximal end of the elongated tube is positioned within the subject's aorta and the distal end of the elongated tube is positioned within the subject's left ventricle, the elongated tube comprising: A frame formed of shape memory alloy; and Blood-impermeable material arranged on the frame. The elongated tube is configured to be arranged around the impeller, and the impeller is configured to pump blood from the left ventricle to the aorta by rotation. The device is configured such that the gap between the outer edge of the impeller and the inner surface of the elongated tube is less than 1 mm during impeller rotation. in: The spring defines the inner cavity that passes through it. The impeller also includes: Proximal bushing and distal bushing; and The device also includes a rigid shaft configured to extend from the proximal bushing to the distal bushing via the inner cavity defined by the spring, the rigid shaft being configured to stabilize the impeller relative to the elongated tube during impeller rotation, such that the gap between the outer edge of the impeller and the inner surface of the elongated tube is maintained.

2. The device according to claim 1, wherein, The impeller includes a plurality of helical elongated elements, and the material film is supported between the plurality of helical elongated elements and the spring, such that the impeller defines a plurality of blades.

3. The device according to claim 1, wherein, The impeller is configured to be placed inside the subject's aorta.

4. The device according to claim 1, wherein, The impeller is configured to be placed in the left ventricle of the subject.

5. The device according to claim 1, wherein, The impeller is configured to be radially constrained by the helical elongated element, and the spring is axially elongated, wherein in response to the axial elongation of the helical elongated element and the spring, the material film is configured to change shape without the material film breaking.

6. The device according to claim 1, wherein, When the spring is arranged in its non-radial constraint configuration, it is configured to stabilize the impeller relative to the elongated tube by means of its rigidity, such that the gap between the outer edge of the impeller and the inner surface of the elongated tube is maintained.

7. The device according to claim 1, wherein, The gap between the outer edge of the impeller and the inner surface of the elongated tube is less than 0.4 mm.

8. The device according to claim 1, wherein, The impeller is configured to be stable relative to the elongated tube, such that the gap between the impeller and the inner surface of the elongated tube is maintained during the rotation of the impeller.

9. The device according to claim 1, wherein, The rigid shaft is configured to keep the proximal bushing and the distal bushing aligned with each other.

10. The device according to claim 1, wherein, After the spring is placed inside the subject's body, the rigid shaft is configured to be placed within the cavity defined by the spring.

11. The device according to claim 1, wherein, The rigid shaft is configured to be positioned within the cavity defined by the spring during the placement of the impeller inside the subject's body.

12. The device according to any one of claims 1-5, wherein, When the spring is arranged in its non-radial constraint configuration, it is configured to keep the proximal bushing and the distal bushing aligned with each other by means of its rigidity.

13. The device according to claim 12, wherein, When the spring is arranged in its non-radial constraint configuration, it is constructed such that there is substantially no gap between the coil of the spring and its adjacent coil.

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