Modular bearings for blood flow assist systems

Abstract

A blood flow assist system can include a driven unit comprising an impeller that is rotatable about a longitudinal axis of the blood flow assist system and a drive unit configured to impart rotation to the driven unit. The drive unit can include a housing configured to support a drive magnet and a drive bearing separate from the housing. The system can include an interface disposed along an outside surface of the housing and along a connecting portion of the drive bearing, a mechanical connection formed between the housing and the drive bearing along the interface. A strain tensor across the interface can be discontinuous.

Description

MODULAR BEARINGS FOR BLOOD FLOW ASSIST SYSTEMSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 656,509, filed June 5, 2025, the entire contents of which are incorporated by reference herein in their entirety and for all purposes.BACKGROUNDField

[0002] The field relates to percutaneous medical devices and, in particular, to intravascular device such as intravascular blood pumps.Description of the Related Art

[0003] In the field of cardiac assist devices and mechanical circulatory support, implanted blood pumps are placed in direct communication with a heart chamber or in a blood vessel (e.g., in an aorta) and are then used to support the heart in pumping blood out of the heart chamber or in moving blood through the blood vessel (e.g. to enhance perfusion to the kidneys or other organs). Some blood pumps are intravascular blood pumps and are designed or adapted to draw in or discharge blood within blood vessels.SUMMARY

[0004] In one embodiment, a blood flow assist system can include: a driven unit comprising an impeller that is rotatable about a longitudinal axis of the blood flow assist system and a drive unit configured to impart rotation to the driven unit. The drive unit can include a housing configured to support a drive magnet; and a drive bearing separate from the housing. An interface can be disposed along a surface of the housing and along a connecting portion of the drive bearing, a mechanical connection formed between the housing and the drive bearing along the interface. A strain tensor across the interface can be discontinuous. For example, in some embodiments, the discontinuous strain tensor can change abruptly across a boundary between two or more components.

[0005] In some embodiments, the surface comprises an outside surface of the housing. In some embodiments, the housing comprises a first recess, the system further comprising a drive magnet disposed in the first recess. In some embodiments, the surface of the housing comprises a second recess at an end portion of the drive unit, the connectingportion of the drive bearing disposed in the second recess. In some embodiments, the first and second recesses are separated by a wall. In some embodiments, the interface comprises an interference fit between the drive bearing and the housing. In some embodiments, the interference fit comprises a friction fit, including a friction-enhancing element along the interface. In some embodiments, the friction-enhancing element comprises an O-ring disposed in a gap between the drive bearing and the housing. In some embodiments, the interference fit comprises a press fit. In some embodiments, the drive unit comprises a cover connected to the housing over the second recess to retain the drive bearing in the second recess. In some embodiments, the cover comprises an opening, a portion of the drive bearing extending through the opening. In some embodiments, the cover is welded to the housing. In some embodiments, the drive bearing comprises a first material, and wherein the housing comprises a second material different from the first material. In some embodiments, the first material is a polymer and the second material is a metal. In some embodiments, the housing comprises a projection, the drive bearing having a cavity that is disposed over the projection. In some embodiments, the housing and the drive bearing are composed of the same material. In some embodiments, the system can include a drive magnet, wherein the driven unit comprises a rotor assembly coupled with the impeller, the rotor assembly comprising a concave bearing surface and a rotor magnet configured to magnetically coupled with the drive magnet. In some embodiments, the drive bearing comprises a first material and the concave bearing surface comprises a second material that is different from the first material. In some embodiments, the first material is a polymer and the second material is a metal. In some embodiments, the drive bearing comprises a convex drive bearing shaped to fit within the concave bearing surface. In some embodiments, the convex drive bearing comprises a plurality of distally-projecting segments spaced apart circumferentially to define at least one channel between adjacent segments, the at least one channel extending outwardly from a central hollow. In some embodiments, the rotor assembly includes a second impeller disposed on a proximally-facing surface of the rotor assembly. In some embodiments, a first flow pathway is disposed along an exterior surface of the first impeller and a second flow pathway is disposed along a lumen extending through the impeller, the central hollow and at least one channel in fluid communication with the second flow pathway. In some embodiments, the system can include a pump housing, the impeller disposed in the pumphousing. In some embodiments, the system can include a plurality of struts coupled to or formed with the pump housing, the plurality of struts extending outwardly from the pump housing and configured to engage a blood vessel wall during operation of the blood flow assist system.

[0006] In another embodiment, a blood flow assist system can include: a driven unit comprising an impeller that is rotatable about an axis of rotation; and a drive unit configured to impart rotation to the driven unit. The drive unit can include: a housing supporting a drive magnet; and a drive bearing connected to the housing by way of an interference fit.

[0007] In some embodiments, the housing comprises a first recess, the system further comprising a drive magnet disposed in the first recess. In some embodiments, the housing comprises a second recess at an end portion of the drive unit, a connecting portion of the drive bearing disposed in the second recess, the first and second recesses separated by a wall. In some embodiments, the interference fit comprises a friction fit, including a friction-enhancing element along the interface. In some embodiments, the frictionenhancing element comprises an O-ring disposed in a gap between the drive bearing and the housing. In some embodiments, the interference fit comprises a press fit. In some embodiments, the drive bearing comprises a first material, and wherein the housing comprises a second material different from the first material. In some embodiments, the first material is a polymer and the second material is a metal. In some embodiments, the housing comprises a projection, the drive bearing having a cavity that is disposed over the projection. In some embodiments, the housing and the drive bearing are composed of the same material. In some embodiments, the system can include a drive magnet, wherein the driven unit comprises a rotor assembly coupled with the impeller, the rotor assembly comprising a concave bearing surface and a rotor magnet configured to magnetically coupled with the drive magnet. In some embodiments, the drive bearing comprises a first material and the concave bearing surface comprises a second material that is different from the first material. In some embodiments, the first material is a polymer and the second material is a metal. In some embodiments, the drive bearing comprises a convex drive bearing shaped to fit within the concave bearing surface. In some embodiments, the convex drive bearing comprises a plurality of distally-projecting segments spaced apart circumferentially to defineat least one channel between adjacent segments, the at least one channel extending outwardly from a central hollow.

[0008] In another embodiment, a blood flow assist system can include: a driven unit comprising an impeller that is rotatable about a longitudinal axis of the blood flow assist system; and a drive unit configured to impart rotation to the driven unit. The drive unit can include: a housing including a first recess configured to receive one or more drive components; a drive bearing disposed in a second recess of the housing; and a cover disposed over the second recess and connected to the housing to retain the drive bearing in the second recess.

[0009] In some embodiments, the cover comprises an opening, a portion of the drive bearing extending through the opening. In some embodiments, the cover is welded to the housing. In some embodiments, the drive bearing comprises a first material, and wherein the housing comprises a second material different from the first material. In some embodiments, the first material is a polymer and the second material is a metal. In some embodiments, the housing and the drive bearing are composed of the same material. In some embodiments, the system can include a drive magnet, wherein the driven unit comprises a rotor assembly coupled with the impeller, the rotor assembly comprising a concave bearing surface and a rotor magnet configured to magnetically coupled with the drive magnet. In some embodiments, the drive bearing comprises a first material and the concave bearing surface comprises a second material that is different from the first material. In some embodiments, the first material is a polymer and the second material is a metal. In some embodiments, the drive bearing comprises a convex drive bearing shaped to fit within the concave bearing surface. In some embodiments, the convex drive bearing comprises a plurality of distally-projecting segments spaced apart circumferentially to define at least one channel between adjacent segments, the at least one channel extending outwardly from a central hollow.

[0010] In another embodiment, a medical system can include: a rotatable medical device; and a drive unit configured to impart rotation to the rotatable medical device. The drive unit can include: a housing; and a drive bearing separate from the housing and mechanically connected to a portion of the housing along an interface. An interface can be disposed along a surface of the housing and along a connecting portion of the drive bearing, amechanical connection formed between the housing and the drive bearing along the interface, wherein a strain tensor across the interface is discontinuous.

[0011] In some embodiments, the surface comprises an outside surface of the housing. In some embodiments, the housing comprises a first recess, the system further comprising a drive magnet disposed in the first recess. In some embodiments, the surface of the housing comprises a second recess at an end portion of the drive unit, the connecting portion of the drive bearing disposed in the second recess. In some embodiments, the first and second recesses are separated by a wall. In some embodiments, the interface comprises an interference fit between the drive bearing and the housing. In some embodiments, the interference fit comprises a friction fit, including a friction-enhancing element along the interface. In some embodiments, the friction-enhancing element comprises an O-ring disposed in a gap between the drive bearing and the housing. In some embodiments, the interference fit comprises a press fit. In some embodiments, the drive unit comprises a cover connected to the housing over the second recess to retain the drive bearing in the second recess. In some embodiments, the cover comprises an opening, a portion of the drive bearing extending through the opening. In some embodiments, the cover is welded to the housing. In some embodiments, the drive bearing comprises a first material, and wherein the housing comprises a second material different from the first material. In some embodiments, the first material is a polymer and the second material is a metal. In some embodiments, the housing comprises a projection, the drive bearing having a cavity that is disposed over the projection. In some embodiments, the housing and the drive bearing are composed of the same material. In some embodiments, the rotatable medical device comprises a blood flow assist system including a driven unit comprising an impeller that is rotatable about a longitudinal axis of the blood flow assist system. In some embodiments, the system can include a drive magnet, wherein the driven unit comprises a rotor assembly coupled with the impeller, the rotor assembly comprising a concave bearing surface and a rotor magnet configured to magnetically coupled with the drive magnet. In some embodiments, the drive bearing comprises a first material and the concave bearing surface comprises a second material that is different from the first material. In some embodiments, first material is a polymer and the second material is a metal. In some embodiments, the drive bearing comprises a convex drive bearing shaped to fit within the concave bearing surface. In some embodiments, theconvex drive bearing comprises a plurality of distally-projecting segments spaced apart circumferentially to define at least one channel between adjacent segments, the at least one channel extending outwardly from a central hollow. In some embodiments, the rotor assembly includes a second impeller disposed on a proximally-facing surface of the rotor assembly. In some embodiments, a first flow pathway is disposed along an exterior surface of the first impeller and a second flow pathway is disposed along a lumen extending through the impeller, the central hollow and at least one channel in fluid communication with the second flow pathway. In some embodiments, the system can include a pump housing, the impeller disposed in the pump housing. In some embodiments, the system can include a plurality of struts coupled to or formed with the pump housing, the plurality of struts extending outwardly from the pump housing and configured to engage a blood vessel wall during operation of the blood flow assist system.

[0012] In another embodiment, a drive unit for a medical device is disclosed. The drive unit can include: a housing enclosing a recess configured to retain one or more drive unit components; and a drive bearing having a first end with a bearing surface and a second end disposed between the bearing surface and the recess of the housing, the drive bearing separate from the housing and mechanically connected to a portion of the housing along an interface, wherein a strain tensor across the interface is discontinuous.

[0013] In some embodiments, the interface is disposed along a surface of the housing and along a connecting portion of the drive bearing, a mechanical connection formed between the housing and the drive bearing along the interface. In some embodiments, the surface comprises an outside surface of the housing. In some embodiments, the drive unit can include a drive magnet disposed in the recess. In some embodiments, the surface of the housing comprises a second recess, the connecting portion of the drive bearing disposed in the second recess. In some embodiments, the recess and the second recess are separated by a wall. In some embodiments, the interface comprises an interference fit between the drive bearing and the housing. In some embodiments, the interference fit comprises a friction fit, including a friction-enhancing element along the interface. In some embodiments, the friction-enhancing element comprises an O-ring disposed in a gap between the drive bearing and the housing. In some embodiments, the interference fit comprises a press fit. In some embodiments, the drive unit can include a cover connected to the housing over the secondrecess to retain the drive bearing in the second recess. In some embodiments, the cover comprises an opening, a portion of the drive bearing extending through the opening. In some embodiments, the cover is welded to the housing. In some embodiments, the drive bearing comprises a first material, and wherein the housing comprises a second material different from the first material. In some embodiments, the first material is a polymer and the second material is a metal. In some embodiments, the housing comprises a projection, the drive bearing having a cavity that is disposed over the projection. In some embodiments, the housing and the drive bearing are composed of the same material.

[0014] In another embodiment, a drive unit for a medical device is disclosed. The drive unit can include: a housing; and a drive bearing connected to the housing by way of an interference fit.

[0015] In some embodiments, the interference fit comprises a friction fit, including a friction-enhancing element along the interface. In some embodiments, the friction-enhancing element comprises an O-ring disposed in a gap between the drive bearing and the housing. In some embodiments, the interference fit comprises a press fit. In some embodiments, the drive bearing component comprises a first material, and wherein the housing comprises a second material different from the first material. In some embodiments, the first material is a polymer and the second material is a metal. In some embodiments, the housing and the drive bearing component are composed of the same material.

[0016] In another embodiment, a drive unit for a medical device is disclosed. The drive unit can include: a housing having an outside surface defining a recess; a drive bearing component having a portion disposed in the recess of the housing; and a cover disposed over at least part of the recess to retain the drive bearing component in the second recess.

[0017] In some embodiments, the cover comprises an opening, a portion of the drive bearing component extending through the opening. In some embodiments, the cover is welded to the housing. In some embodiments, the drive bearing component comprises a first material, and wherein the housing comprises a second material different from the first material. In some embodiments, the first material is a polymer and the second material is a metal. In some embodiments, the housing and the drive bearing component are composed of the same material.

[0018] In another embodiment, a blood flow assist system can include: a driven unit comprising: an impeller assembly comprising a rotor assembly, a first impeller coupled with the rotor assembly, and a second impeller disposed on a proximally-facing surface of the rotor assembly, the impeller assembly rotatable about a longitudinal axis of the blood flow assist system, the rotor assembly comprising a rotor magnet and a concave bearing surface, wherein a first flow pathway is disposed along an exterior surface of the first impeller and a second flow pathway is disposed along a lumen extending through the first impeller. A drive unit can be configured to impart rotation to the driven unit, the drive unit comprising: a housing enclosing a drive magnet disposed therein, the drive magnet magnetically coupled with the rotor magnet; and a convex drive bearing separate from the housing and shaped to fit within the concave bearing surface, the convex drive bearing comprising a plurality of distally-projecting segments spaced apart circumferentially to define at least one channel between adjacent segments, the at least one channel in fluid communication with the second flow pathway, the convex drive bearing mechanically connected to a portion of the housing along an interface, wherein a strain tensor across the interface is discontinuous.

[0019] In some embodiments, the interface comprises an interference fit between the drive bearing and the housing. In some embodiments, the interference fit comprises a friction fit, including a friction-enhancing element along the interface. In some embodiments, the friction-enhancing element comprises an O-ring disposed in a gap between the drive bearing and the housing. In some embodiments, the interference fit comprises a press fit. In some embodiments, a cover can be connected to the housing to retain the drive bearing in a recess. In some embodiments, the cover comprises an opening, a portion of the drive bearing extending through the opening. In some embodiments, the housing comprises a projection, the drive bearing having a cavity that is disposed over the projection.

[0020] In another embodiment, a blood flow assist system can include: a driven unit comprising: an impeller assembly comprising a rotor assembly and an impeller coupled with the rotor assembly and rotatable about a longitudinal axis of the blood flow assist system, the rotor assembly comprising a rotor magnet and a concave bearing surface. The system can include a drive unit configured to impart rotation to the driven unit, the drive unit comprising: a housing enclosing one or more drive components; and a convex drive bearingcomponent shaped to fit within the concave bearing surface, the convex drive bearing component comprising a plurality of distally-projecting segments spaced apart circumferentially to define at least one channel between adjacent segments, the convex drive bearing component coupled with a portion of the housing along an interface, wherein a strain tensor across the interface is discontinuous.

[0021] In some embodiments, the interface comprises an interference fit between the drive bearing and the housing. In some embodiments, the interference fit comprises a friction fit, including a friction-enhancing element along the interface. In some embodiments, the friction-enhancing element comprises an O-ring disposed in a gap between the drive bearing and the housing. In some embodiments, the interference fit comprises a press fit. In some embodiments, a cover can be connected to the housing to retain the drive bearing in a recess. In some embodiments, the cover comprises an opening, a portion of the drive bearing extending through the opening. In some embodiments, the housing comprises a projection, the drive bearing having a cavity that is disposed over the projection.

[0022] In another embodiment, a method of manufacturing a drive unit for a medical device can include: providing a housing having a recess configured to enclose a drive component; and mechanically connecting a bearing to the housing along an interface such that a strain tensor across the interface is discontinuous.

[0023] In some embodiments, mechanically connecting comprises forming an interference fit between the bearing and the housing. In some embodiments, forming an interference fit comprises providing a friction-enhancing element along the interface to form a friction fit. In some embodiments, providing the friction-enhancing element comprises disposing an O-ring in a gap between the bearing and the housing. In some embodiments, mechanically connecting comprises providing a cover connected to the housing to retain the bearing in a second recess. In some embodiments, the cover comprises an opening, a portion of the bearing extending through the opening. In some embodiments, the housing comprises a projection, and wherein mechanically connecting comprise disposing a cavity of the bearing over the projection.

[0024] In another embodiment, a method can include: delivering a pump to a treatment location in a blood vessel of a patient, the pump comprising a driven unit including a rotatable impeller; and imparting rotation to the driven unit by way of a drive unit to causethe impeller to rotate, the drive unit comprising a housing configured to support a drive magnet, and a drive bearing separate from the housing, an interface disposed along a surface of the housing and along a connecting portion of the drive bearing, a mechanical connection formed between the housing and the drive bearing along the interface, wherein a strain tensor across the interface is discontinuous.

[0025] In some embodiments, the method can include expanding a support structure connected to the pump to position the pump in the blood vessel.BRIEF DESCRIPTION OF THE DRAWINGS

[0026] These and other features, aspects and advantages are described below with reference to the drawings, which are intended for illustrative purposes and should in no way be interpreted as limiting the scope of the embodiments. Furthermore, various features of different disclosed embodiments can be combined to form additional embodiments, which are part of this disclosure. In the drawings, like reference characters denote corresponding features consistently throughout similar embodiments. The following is a brief description of each of the drawings. Any text descriptions in the figures is a statement of one or more examples and not intended to be limiting.

[0027] FIG. 1A is a schematic perspective, partially-exploded view of a blood flow assist system, according to various embodiments.

[0028] FIG. IB is a schematic perspective view of a pump at a distal portion of the blood flow assist system of FIG. 1A.

[0029] FIG. 1C is a schematic perspective, partially-exploded view of the pump of FIG. IB.

[0030] FIG. ID is a schematic side sectional view of a motor housing according to various embodiments.

[0031] FIG. IE is a schematic perspective view of a motor and a motor mount support.

[0032] FIG. IF is a schematic perspective view of a distal end of a power lead having lumens shaped to received conductors that are configured to supply power to the motor.

[0033] FIG. 1G is a schematic perspective view of a proximal end portion of the power lead.

[0034] FIG. 1H is a schematic side view of the pump disposed in a collapsed configuration in a delivery sheath.

[0035] FIG. II is a schematic perspective view of a retrieval feature used to remove the pump, according to some embodiments.

[0036] FIG. 1J is a cross-sectional view of an alternative embodiment in which a drive shaft is coupled to a motor configured to be disposed outside the patient when the pump is in use.

[0037] FIG. 2A is a schematic perspective view of a drive bearing according to various embodiments.

[0038] FIG. 2B is a front end view of the drive bearing of FIG. 2A.

[0039] FIG. 2C is a side view of the drive bearing of FIG. 2A.

[0040] FIG. 2D is a schematic front end view of a drive bearing according to another embodiment.

[0041] FIG. 2E is a schematic front end view of a drive bearing according to another embodiment.

[0042] FIGS 2F and 2G illustrate additional examples of drive units according to various embodiments.

[0043] FIG. 2H is a schematic perspective view of a drive bearing according to another embodiment having enhanced bearing surfaces with eave-like extensions.

[0044] FIG. 21 is a schematic perspective view of a drive bearing according to another embodiment having an enhanced continuous annular bearing surface.

[0045] FIGS. 2J and 2K are a schematic perspective and bottom views of a drive bearing according to another embodiment having an enhanced continuous annular bearing surface.

[0046] FIG. 3A is a schematic perspective view of a modular drive bearing according to one embodiment, in which the drive bearing comprises a cone bearing.

[0047] FIG. 3B is a schematic cross-sectional view of the modular drive bearing of FIG. 3 A.

[0048] FIG. 3C is a schematic top perspective view of a modular drive bearing according to another embodiment, in which the drive bearing comprises a segmented cone bearing.

[0049] FIG. 3D is a schematic bottom perspective view of the modular drive bearing of FIG. 3C.

[0050] FIG. 3E is a schematic cross-sectional view of the modular drive bearing of FIG. 3C.

[0051] FIG. 3F is a schematic top perspective view of a modular drive bearing according to another embodiment, in which the drive bearing utilizes a cover to retain the drive bearing in a recess of a housing.

[0052] FIG. 3G is a schematic cross-sectional view of the modular drive bearing of FIG. 3F.

[0053] FIG. 3H is a schematic cross-sectional view of a modular drive bearing, according to another embodiment, in which the drive bearing is connected to a projection of a housing.

[0054] FIG. 31 is a schematic perspective view of a portion of a drive unit including a modular drive bearing according to another embodiment.

[0055] FIG. 3J is a schematic perspective view of a portion of a drive unit including a modular drive bearing according to another embodiment.

[0056] FIG. 4A is a schematic perspective view of an integrated rotor core comprising an impeller shaft with flow tube and a secondary impeller.

[0057] FIG. 4B is a schematic perspective view of a proximal portion of the integrated rotor core of FIG. 4 A.

[0058] FIG. 4C is a sectional view taken along the longitudinal axis of the rotor core of FIG. 4B.

[0059] FIG. 4D is a schematic proximal end view of the integrated rotor core of FIG. 4C.

[0060] FIG. 5A is a schematic perspective, exploded view of a segmented cone bearing comprising a proximal portion of the integrated rotor core and the drive bearing.

[0061] FIG. 5B is a distal end sectional view of the secondary impeller and drive bearing.DETAILED DESCRIPTION

[0062] Refer now to the drawings wherein depicted elements are not necessarily shown to scale and wherein like or similar elements are designated by the same reference numeral through the several views.

[0063] Referring to the drawings in general, it will be understood that the illustrations are for the purpose of describing particular implementations of the disclosure and are not intended to be limiting thereto. While most of the terms used herein will be recognizable to those of ordinary skill in the art, it should be understood that when not explicitly defined, terms should be interpreted as adopting a meaning presently accepted by those of ordinary skill in the art.

[0064] Intravascular medical procedures allow numerous possibilities for therapy with many benefits and advantages over open procedures. Devices and methods used to access the vasculature and close the access point after therapy are known in the art in connection with the Seidinger technique. Intravascular procedures can be divided into those that take place in the venous system and those that take place in the arterial system. Procedures on the arterial side are made more challenging by the higher blood pressure and smaller vessel size (than corresponding veins). Intravascular procedures can also be divided into those that leave a device behind and those that do not. Stents are typical devices that are left behind. Devices that are placed in the vasculature in intravascular procedures may be passive (like stents) or active (powered devices like blood pumps). Active devices may have batteries or power leads that pass through the wall of the blood vessel. Once outside the blood vessel, such power leads may be connected to components implanted in the body or may pass through the skin to the outside of the body.

[0065] Intravascular procedures that place an active device in the arterial system and have a power lead passing through the wall of the artery are atypical medical devices. The challenges of small vessel size and high blood pressure should be accounted for in such procedures. One such device is a catheter-deployed blood pump, also known as a percutaneous mechanical circulatory support (pMCS) device. Intravascular pump systems disclosed herein can be used for temporary or long-term cardiac or renal support in patients indicated for heart failure, post-myocardial infarction, and other heart-related illnesses.I. OVERVIEW OF BLOOD FLOW ASSIST SYSTEMS

[0066] Various embodiments disclosed herein relate to a blood flow assist system 1 configured to provide circulatory support to a patient, as illustrated in FIGS. 1A-1J. The system 1 can be sized for intravascular delivery to a treatment location within the circulatory system of the patient, e.g., to a location within the descending aorta of the patient. As shown in FIG. 1A, the system 1 can have a proximal end 21 with a connector 23 configured to connect to an external control system, e.g., a console (not shown). The connector 23 can provide electrical communication between the control system and an elongate lead (e.g., an elongate power lead 20) extending distally along a longitudinal axis L from the connector 23 and the proximal end 21. The connector 23 can be disposed at a proximal portion of the lead 20. The power lead 20 can comprise an elongate body that electrically and mechanically connects to a pump 2 at or near a distal end 22 of the blood flow assist system 1, with the distal end 22 spaced apart from the proximal end 21 (which can also serve as a proximal end of the lead 20) along the longitudinal axis L. In other embodiments the power lead can extend from an opposite end of the pump 2 as is illustrated in FIG. 1A or there can be multiple power leads. The description of the system 1 that are provided throughout this application can be combined with the combinations of power leads, tethers, and other operational members discussed below. As explained herein, the power lead 20 can also serve as a flexible tether configured to oppose loads applied in opposite directions at opposite ends of the power lead 20.

[0067] The pump 2 can comprise a pump head 50 including a pump housing 35 connected to a drive unit 9 that includes a motor housing 29. A retrieval feature 48 can be provided at a proximal end portion of the pump 2. In some embodiments, the retrieval feature can be coupled with the distal end of the power lead 20 between the power lead 20 and the motor housing 29. After a procedure, the clinician can remove the pump 2 from the patient by engaging a tool (e g., a snare, a clamp, hook, etc.) with the retrieval feature 48 to pull the pump 2 from the patient. For example, the retrieval feature 48 can comprise a neck 49 (e.g., a reduced diameter section) at a proximal curved portion 51c of the motor housing 29 and an enlarged diameter section disposed proximal the neck 49. The enlarged diameter section can comprise a first curved portion 51a and a second curved portion 51b, as shown in FIGS. IB, 1C, and II. The first and second curved portions 51a, 51b can comprise convexsurfaces, e.g., convex ball portions. The first and second curved portions 51a, 51b can have different radii of curvature. For example, as shown in FIG. II, the first curved portion 51a can have a larger radius of curvature than the second curved portion 51b. The first curved portion 51a can be disposed on opposing sides of the retrieval feature 48 in some embodiments. The second curved portion 51b can be disposed around the first curved portion 51a and can have a radially-outward facing surface and a proximally-facing convex surface coupled to the distal end of the power lead 20. The neck 49 can have a first depth at a first circumferential position of the retrieval feature 48 and a second depth less than the first depth at a second circumferential position of the retrieval feature 48 spaced apart from the first circumferential position.

[0068] Beneficially, as shown in FIG. II, one or more first planes Pl extending parallel to the longitudinal axis L and intersecting the first curved portion 51a can have a first angle or taper between the proximal curved portion 51c of the motor housing 29 and the first curved portion 51a. One or more second planes P2 extending parallel to the longitudinal axis L and intersecting the second curved portion 51b can have a second angle or taper (which is different from the first angle or taper) between the proximal curved portion 51c of the motor housing 29 and the second curved portion 51b. The first angle or taper can provide a gradual, continuous (generally monotonically decreasing) geometric transition between the proximal curved portion 51c of the motor housing 29 and the power lead 20, which can provide for smooth blood flow and reduce the risk of thrombosis. The second curved portion 51b can serve as a lobe that extends radially outward, e.g., radially farther out than the first curved portion 51a. The second curved portion 51b can be used to engage with a retrieval device or snare to remove the pump 2 from the anatomy. Some cross sections through the longitudinal axis of the retrieval feature 48 can contain a substantial neck e.g., a local minimum in the radius of curvature measured along its central axis) while other cross sections through the longitudinal axis of the retrieval feature 48 can contain an insubstantial local minimum or no local minimum. In the illustrated embodiment, there are two first curved portions 51a that can serve as a dual lobe retrieval feature. In other embodiments, more or fewer lobes can be provided to enable pump retrieval while ensuring smooth flow transitions between the motor housing 29 and power lead 20.

[0069] As shown in FIGS. 1B-1C, IE, and II, the neck 49 can be disposed between the curved portions 51a, 51b and a proximally-facing convex surface 51c of the motor housing 29. In the illustrated embodiment, the retrieval feature 48 can be coupled to or integrally formed with the motor housing 29. In other arrangements, the retrieval feature 48 can be disposed at other locations of the pump 2. As shown, the retrieval feature 48 can be symmetrical and continuously disposed about the longitudinal axis L. In other arrangements, the retrieval feature 48 can comprise a plurality of discrete surfaces spaced apart circumferentially and / or longitudinally. In the illustrated embodiments, the motor housing 29 (and motor) can be part of the pump 2 and disposed inside the vasculature of the patient in use. In other embodiments, however, the motor housing 29 (and motor) can be disposed outside the patient and a drive cable can connect to the impeller 6.

[0070] As shown in FIGS. 1A-1C, the drive unit 9 can be configured to impart rotation to an impeller assembly 4 disposed in the pump housing 35 of the pump head 50. As explained herein, the drive unit 9 can include a drive magnet 17 (see FIG. ID) and a motor 30 (see FIGS. ID- IE) disposed in the motor housing 29 capped by a distal drive unit cover 11. The motor 30 is shown schematically in FIG. ID. The drive unit cover 11 can be formed with or coupled to a drive bearing 18. The drive magnet 17 can magnetically couple with a corresponding driven or rotor magnet (not shown) of the impeller assembly 4 that is disposed proximal the impeller 6 within the shroud 16. The power lead 20 can extend from the treatment location to outside the body of the patient, and can provide electrical power (e.g, electrical current) and / or control to the motor 30. Accordingly, no spinning drive shaft extends outside the body of the patient in some embodiments. As explained herein, the power lead 20 can energize the motor 30, which can cause the drive magnet 17 to rotate about the longitudinal axis L, which can serve as or be aligned with or correspond to an axis of rotation. Rotation of the drive magnet 17 can impart rotation of the rotor magnet and a primary or first impeller 6 of the impeller assembly 4 about the longitudinal axis L. For example, as explained herein, the rotor magnet (which can be mechanically secure to an impeller shaft 5) can cause the impeller shaft 5 (which can serve as a flow tube) and the first impeller 6 to rotate to pump blood. In other embodiments, the drive unit 9 can comprise a stator or other stationary magnetic device. The stator or other magnetic device can be energized, e.g, with alternating current, to impart rotation to the rotor magnet. In theillustrated embodiments, the impeller 6 can have one or a plurality of blades 40 extending radially outward along a radial axis R that is radially transverse to the longitudinal axis L. For example, the first impeller 6 can have a plurality of (e.g., two) longitudinally-aligned blades 40 that extend radially outwardly from a common hub and that have a common length along the longitudinal axis L. The curvature and / or overall profile can be selected so as to improve flow rate and reduce shear stresses. Skilled artisans would appreciate that other designs for the first impeller 5 may be suitable.

[0071] As shown in FIGS. 1A-1C, the impeller assembly 4 can be disposed in a shroud 16. The impeller shaft 5 can be supported at a distal end by a sleeve bearing 15 connected to a distal portion of the shroud 16. A support structure such as a localization system 100 (discussed further below) can comprise a base portion 36 coupled with the sleeve bearing 15 and / or the shroud 16. In some embodiments, the base portion 36, the sleeve bearing 15, and / or the shroud 16 can be welded together. In other embodiments, the sleeve bearing 15 and / or the shroud 16 can be formed as one part. The base portion 36 of the support structure or localization system 100 (which can be part of or serve as a support structure), the sleeve bearing 15, and the shroud 16 can cooperate to at least partially define the pump housing 35, as shown in FIGS. 1A and 1C. The localization system 100 can comprise a plurality of self-expanding struts 19 having convex contact pads 24 configured to contact a blood vessel wall to maintain spacing of the pump housing 35 from the wall of the blood vessel in which the pump housing 35 is disposed. In FIGS. 1A-1C, the struts 19 of the localization system 100 are illustrated in an expanded, deployed configuration, in which the contact pads 24 extend radially outward to a position in which the contact pads 24 would contact a wall of a blood vessel within which the pump 2 is disposed to at least partially control position and / or orientation of the pump head 50 relative to the blood vessel wall, e.g., to anchor, the pump 2 during operation of the system 1. The localization system 100 can be supplemented by, replaced by or combined with other combinations of localization components, as is discussed, that can allow for mechanical support with or without combining mechanical support with electrical signal lines. This is one advancement by which the system 1 as so modified can achieve a smaller delivery profile. Other ways to provide a smaller delivery profile are discussed below in connection with FIGS. 22A-22F in which variants of the struts 19 can be received in a recessed configuration of a component ofthe pump 2, e.g., a pump housing. These refinements can be combined with other descriptions herein of the system 1.

[0072] A first fluid port 27 can be provided distal the impeller assembly 4 at a distal end of the pump housing 35. The shroud 16 can comprise a proximal ring 26 coupled with the motor housing 29 and a plurality of second fluid ports 25 formed in a proximal portion of the shroud 16 adjacent e.g., immediately distal) the proximal ring 26. As shown in FIG. 1C, the second fluid ports 25 can comprise openings formed between axially- extending members 60 (also referred to as pillars) that extend along the longitudinal axis L (which may also serve as a longitudinal axis of the pump head 2 and / or pump housing 35) between the proximal ring 26 and a cylindrical section 59 of the shroud 16. In some embodiments, the axially-extending members 60 can be shaped or otherwise be configured to serve as vanes that can shape or direct the flow of blood through the second fluid ports 25. For example, in various embodiments, the axially-extending members 60 can be angled, tapered, or curved (e.g., in a helical pattern) to match the profile of the impeller blades 40 and / or to accelerate blood flow through the pump 2. In other embodiments, the axially- extending members 60 may not be angled to match the blades 40. In some embodiments, the first fluid port 27 can comprise an inlet port into which blood flows. In such embodiments, the impeller assembly 4 can draw blood into the first fluid port 27 and can expel the blood out of the pump 2 through the second fluid ports 25, which can serve as outlet ports. In other embodiments, however, the direction of blood flow may be reversed, in which case the second fluid ports 25 may serve as fluid inlets and the first fluid port 27 may serve as a fluid outlet.

[0073] As shown in FIGS. 1A-1D, the system 1 comprises the drive unit 9 with the motor 30 that can be sealed in the motor housing 29. The drive magnet 17 can be rotatable by the motor 30 by way of a motor shaft 51. The motor 30 can electrically connect to the power lead 20. The power lead 20 can serve as a flexible tether that comprises an elongate tension member configured to oppose loads applied in opposite directs at opposite ends of the power lead 20. In one embodiment the power lead 20 is hollow, as discussed further below. As shown in FIGS. ID and IF, the power lead 20 can comprise an insulating body having a central lumen 55 and a plurality of (e.g, three) outer lumens 56A-56C extending along a length of the power lead 20. One or more electrical conductors (such asthe elongate conductors 73a-73c shown in FIG. IL) can be disposed in the hollow elongate power lead 20 and can be configured to convey current to the motor 30 from a source, such as the external control system. For example, in some embodiments, the outer lumens 56A- 56C can be sized and shaped to receive corresponding electrodes or electrical wires (not shown in FIGS. 1F-1G, but illustrated in the arrangement of FIG. IL) to provide electrical power to the motor 30. For example, the lumens 56A-56C can receive wires configured to supply ground and drive voltage to corresponding windings on the motor. The electrodes or conductors can extend through corresponding openings 57A-57C of a motor mounting support 54 configured to support the motor 30.

[0074] The central lumen 55 can be sized and shaped to receive an elongate stiffening member or guidewire (not shown). In some embodiments, the stiffening member or guidewire can be inserted through a proximal opening 65 at the proximal end 21 (see FIG. 1G) into the central lumen 55 during delivery to help guide the pump 2 to the treatment location or maintain the pump 2 in a given location. In some embodiments, as explained in Section II, the stiffening member can be inserted into the proximal opening 65 and advanced through the central lumen 55 to bear against the pump 2 to facilitate removal of a pump delivery system. The stiffening member or guidewire can be easily inserted and removed when finished. As shown in FIG. 1G, the connector 23 near the proximal end 21 of the system 1 (e.g., at a proximal end portion of the lead 20) can have a plurality of electrical contacts 58A-58C electrically connected to the wires or conductors in the corresponding outer lumens 56A-56C. As shown, the contacts 58A-58C can be disposed on an outer surface of the lead 20. The contacts 58A-58C can comprise rings spaced apart by an insulating material 70 and can be configured to electrically connect to corresponding electrical components in the control system or console (not shown). It should be appreciated that, in some medical devices (c. ., in some percutaneous blood pumps or other types of devices), any of the lumens 55, 56A-56C can be used for other functions, such as, for example, the delivery of fluid to the target location and / or the removal of fluid from the target location. The lumens 55 and / or 56A-56C can be used to provide any suitable type of communication with the target location, including, e.g., one or more of mechanical communication (for example, by way of providing access for a guidewire, stiffening element, lead attachment device, actuating wire for a slip ring, electrical communication (for example,by way of one or more elongate conductor(s)), and / or fluid communication (serving as, for example, a fluid delivery or outlet lumen).

[0075] In some embodiments, the lead 20 can have an outer jacket 75 comprising an insulating material that can be the same as or different from the insulating material 70. In various embodiments, the outer jacket 75 can comprise a polymer. In some arrangements, the outer jacket 75 can comprise silicone. However, the use of silicone in the lead 20 may generate excessive frictional forces between the lead 20 and an inner delivery catheter of a delivery system, which may make delivery and / or retrieval more difficult for the clinician. Accordingly, in various embodiments, the outer jacket 75 can comprise a polyurethane outer surface, e.g., a polyurethane coating. Beneficially, the use of polyurethane for the insulating material of the outer jacket 75 can provide a reduced-friction interface between the power lead 20 and the delivery catheter, which can provide an easier delivery and / or retrieval process. Additional details related to the delivery and retrieval of the system 1 may be found throughout U.S. Provisional Application No. 63 / 386,485, filed December 7, 2022, the entire contents of which are incorporated by reference herein in their entirety and for all purposes.

[0076] In addition, as shown in FIG. 1G, a transverse opening 68 can extend through a sidewall 69 of the lead 20. As shown in FIG. 1G, the transverse opening 68 can be disposed at the proximal end portion of the lead 20 adjacent the proximal end 21 of the lead 20, e.g., spaced distally from the proximal end 21 by a small distance (e.g., by less than 10 cm, less than 5 cm, less than 1 cm from the proximal end 21). The transverse opening 68 can be disposed between a proximal-most contact 58C and the proximal end 21. The transverse opening 68 can be used during assembly to position the lead 20 within the proximal handle 201 as explained below.

[0077] Beneficially, the blood flow assist system 1 can be delivered percutaneously to a treatment location in the patient. FIG. 1H shows the pump 2 disposed within an elongate sheath 28. As shown, the struts 19 are held in a collapsed configuration by the inner wall of the sheath 28. As discussed further below, the struts 19 can be configured to collapse in a controlled manner, e.g., with at least a portion deflected away from inner wall of the sheath 28 when disposed in the sheath. As shown, the struts 19 can comprise knees 102, which can serve to space distal ends of the struts 19 (e.g., at or near the contact pads 24 or hooks) from the inner wall of the sheath 28, such that there is a space 46between the contact pads 24 or hooks and the inner wall of the sheath 28 in the collapsed configuration within the sheath 28.

[0078] The knees 102 can be of the same configuration for each of the struts 19 in one embodiment. In such an embodiment, the struts 19 may all collapse or fold in the same manner within the sheath 28. In another embodiment the knee 102 of one or more struts 19 can be differentiated from the knee 102 of one or more other struts 19 such that the struts are collapsed or folded in different manners. As explained herein, in various embodiments, the struts can be longitudinally-aligned or longitudinally-offset or staggered. For example, a pair of opposing struts 19 (e.g., disposed radially opposite one another) can have knees 102 that cause the opposing strut of the pair to collapse prior to the collapsing of other struts 19 of the pump 2. In one example, the pump 2 has four struts 19. Two opposing struts 19 are configured to bend at the knees 102 prior to the bending of the knees of the other struts 19. As such, the two opposing struts 19 can be collapsed to a position between the other two struts to provide a compact arrangement. The knees 102 can be configured such that some struts undergo a greater degree of bending or collapsing. Thus the space 46 between the contact pads 26 and the inner wall of the sheath 28 can be two to six (and in some cases three to four) times greater for one or more, e.g., a pair of, struts than for one or more, e.g., another pair of struts 19, which can be provided to avoid tangling of the struts. Accordingly, in various embodiments, some struts may be structured to collapse first when engaged with the sheath 28, and the remaining struts can collapse as the sheath 28 induces the collapsing of the initial struts.

[0079] In some embodiments, one or more struts comprises knees 102 that can control the order of collapsing of the struts. For example one or more struts can have a knee 102 positioned more proximally compared to the position of the knees 102 of one or more other struts. In one example, two opposing struts 19 can have knees 102 disposed more proximally than are the knees 102 of another strut 19. In one example, a first set of opposing struts 19 have knees 102 disposed more proximally than a second set of struts 19 disposed approximately 90 degrees offset from the first set of struts 19. This can allow the first set of struts to be more completely folded by distal advancement of the sheath 28 before a more complete folding of the second set of struts 19. In a further variation, knees 102 can be longitudinally spaced apart on adjacent stmts 19 so that adjacent stmts fold at different timesor rates. The illustrated embodiments includes the knees 102, but in other embodiments, no knees may be provided. For example, the struts 19 can be retracted at different rates by hinges and / or by modifying material thickness or properties in or along the length of one or more struts 19 to control the timing or rate of folding upon advancing the sheath 28. A living hinge structure can be formed along the length of one or more struts 19 to control timing, rate, and / or sequence of retraction of the struts 19. In one example, an area of reduced thickness transverse to the length of a strut 19 causes the strut to fold or bend when a sheath is advanced across the reduced thickness area. By offsetting the longitudinal position of reduced thickness areas in the struts 19, the sequence of retraction can be controlled.

[0080] In the collapsed configuration, the struts 19 can be compressed to a diameter or major lateral dimension at one or more locations that is approximately the same as (or slightly smaller than) the diameter of the shroud 16. Thus, as shown in the collapsed configuration of FIG. 1H, at least a portion of the struts 19 are compressed to a diameter or major lateral dimension that is smaller than the major lateral dimension or diameter of the pump housing 35, shroud 16 and / or the drive unit 9. In some embodiments, at least a portion of the struts has a major lateral dimension that is no more than a major lateral dimension of the pump housing 35. In some embodiments, at least a portion of the struts has a major lateral dimension that is less than a major lateral dimension of the pump housing 35 and / or the motor housing 29. The patient can be prepared for the procedure in a catheterization lab in a standard fashion, and the femoral artery can be accessed percutaneously or by a surgical approach. The sheath 28 (or a dilator structure within the sheath 28) can be passed over a guidewire and placed into the treatment location, for example, in the descending aorta. After the sheath 28 is placed (and the dilator removed), the pump 2 can be advanced into the sheath 28, with the pump 2 disposed in the mid-thoracic aorta, approximately 4 cm below the takeoff of the left subclavian artery. In other embodiments, the pump 2 and sheath 28 can be advanced together to the treatment location. Positioning the pump 2 at this location can beneficially enable sufficient cardiac support as well as increased perfusion of other organs such as the kidneys. Once at the treatment location, relative motion can be provided between the sheath 28 and the pump 2 (e.g., the sheath 28 can be retracted relative to the pump 2, or the pump 2 can be advanced out of the sheath 28). The struts 19 of the localization system can self-expand radially outwardly along the radial axis R due to stored strain energy into thedeployed and expanded configuration shown in FIGS. 1 A-1C. In some embodiments, such as those in which the vasculature is accessed by the femoral artery, the struts 19 can extend distally, e.g., distally beyond a distal end of the shroud 16 and / or the impeller 6. In other embodiments, as explained herein, the pump 2 can be delivered percutaneously through a subclavian artery. In such embodiments, the struts 19 may extend proximally, e.g., proximal the pump housing 35 and / or the motor housing 29. In still other embodiments, multiple pluralities of struts may extend proximally and distally relative to the pump 2. The convex contact pads 24 can engage the blood vessel wall to stabilize (e. ., assist in anchoring) the pump 2 in the patient’s vascular system. Once at the treatment location, the clinician can engage the control system to activate the motor 30 to rotate the impeller assembly 4 to pump blood.

[0081] Thus, in some embodiments, the pump 2 can be inserted into the femoral artery and advanced to the desired treatment location in the descending aorta. In such arrangements, the pump 2 can be positioned such that the distal end 22 is upstream of the impeller 6, e.g., such that the distally-located first fluid port 27 is upstream of the second fluid port(s) 25. In embodiments that access the treatment location surgically or percutaneously via the femoral artery, for example, the first fluid port 27 can serve as the inlet to the pump 2, and the second ports 25 can serve as the outlet(s) of the pump 2. The struts 19 can extend distally beyond a distal end of the pump housing 35. In other embodiments, however, the pump 2 can be inserted percutaneously through the left subclavian artery and advanced to the desired treatment location in the descending aorta. In such arrangements, the pump 2 can be positioned such that the distal end 22 of the system 1 is downstream of the impeller 6, e.g., such that the distally-located first fluid port 27 is downstream of the second fluid port(s) 25. In embodiments that access the treatment location through the left subclavian artery, the second fluid port(s) 25 can serve as the inlet(s) to the pump 2, and the first port 27 can serve as the outlet of the pump 2.

[0082] When the treatment procedure is complete, the pump 2 can be removed from the patient. For example, in some embodiments, the pump can be withdrawn proximally (and / or the sheath 28 can be advanced distally) such that a distal edge of the sheath 28 engages with a radially-outer facing surface 43 of the struts 19. In some embodiments, the distal edge of the sheath 28 can engage with the knees of the struts. Thedistal edge of the sheath 28 can impart radially-inward forces to the radi ally-outer facing surface 43 e.g., at approximately the location of the knees) to cause the struts 19 to collapse and be drawn inside the sheath 28. Relative motion opposite to that used for deploying the pump 2 can be provided between the sheath 28 and the pump 2 (e.g., between the sheath 28 and the impeller assembly 4 and pump housing 35) to collapse the struts 19 into the sheath 28 in the collapsed configuration. In some embodiments, the pump 2 can be withdrawn from the sheath 28 with the sheath 28 in the patient’s body, and the sheath 28 can be subsequently used for another procedure or removed. In other embodiments, the sheath 28 and the pump 2 can be removed together from the patient’s body.

[0083] The foregoing description includes embodiments in which a proximal end of a drive shaft 51 is located in the drive unit 9. The proximal end of the drive shaft 51 and the motor 30 are disposed within the body in use. FIG. 1J shows another embodiment in which a motor 30A is disposed outside the body in use. An elongate, flexible shaft 51’ is coupled at a distal end with the drive magnet 17. The shaft 51’ extends through an elongate body 20’ and is or can be coupled at a proximal end thereof with a motor 30A. The motor 30A can be larger than the motor 30 since it need not be disposed within the profile of the sheath 28. The elongate body 20’ may have one or more lumens. The shaft 51’ may extend through the central lumen 55. One or more outer lumens 56a may be provided to flow a fluid into the system to lubricate and / or cool the shaft 51’. Rotation of the proximal end of the shaft 51’ by the motor 30a results in rotation of the entire length of the shaft 51’ through the elongate body 20’ and also results in rotation of the drive magnet 17. Rotation of the drive magnet 17 causes rotation of one or more magnets in the impeller 6 to create flow through the pump 2 by virtue of magnetic attraction of these magnets across the distal drive unit cover. In other embodiments, the shaft 51’ can be directly mechanically coupled to the impeller 6 such that rotation does not depend on magnetic coupling. One or more shaft rotation supports 54A can be provided within a distal housing 29A to support a distal portion of the shaft 51’. The elongate body 20’ and / or the shaft 51’ can comprise a tether to control or to aid in control of the position of the pump, e.g., to counter thrust forces of the impeller 6 to reduce or minimize movement of the pump 2 in operation.

[0084] Additional details of the pump 2 and related components shown in FIGS. 1A-1H may be found throughout U.S. Patent Nos. 11,324,940 and 11,471,665, the entirecontents of each of which are incorporated by reference herein in their entirety and for all purposes.II. EXAMPLES OF DRIVE BEARINGS

[0085] As shown in FIGS. 1A and 1C, the drive unit 9 can comprise a drive magnet 17 and a drive bearing 18 between the drive magnet 17 and the impeller assembly 4. The drive bearing 18 can provide a magnetic coupling and a fluid bearing interface between the drive magnet 17 and a rotor assembly that comprises the driven or rotor magnet (not shown) and an integrated rotor core 8 that includes the impeller shaft 5 and a secondary impeller 7. In various embodiments, the drive bearing 18 can comprise a segmented cone bearing. Cone bearings can comprise a convex (e g., generally conical) shaped member 45 seated inside a generally concave (e.g., conical) opening 32 or cavity of the rotor assembly. The concave opening 32 can serve as a concave bearing surface sized and shaped to mate with the convex member 45. The concave opening 32 can comprise an angled concave cavity sized to receive the convex member 45. The drive unit 9 can comprise a convex member sized to fit within the angled cavity of the concave opening 32.

[0086] The bearing interface region of this bearing design can be formed by the matching surfaces of the conical or convex member 45 and the conical or concave opening 32 and the space between them. A cone bearing can provide both axial and radial confinement. The axial confinement from a single cone bearing can be in one direction only. Cone bearings with steep slopes provide relatively more radial confinement, and cone bearings with shallower slopes provide relatively more axial confinement. In some embodiments, the conical shaped member 45 can be modified to reduce hemolysis and / or clotting. In some embodiments, the conical member 45 can be truncated by a cylinder coaxial to the axis of the cone (or axis of rotation) to remove base portions of the cone. In some embodiments, the conical member 45 can be truncated by a plane perpendicular to the axis of the cone (creating a frustrum or a frustoconical surface). In other embodiments, the conical member 45 can be truncated by both a cylinder and a cone. In some embodiments, the surface of the conical opening 32 may be modified in a similar manner in conjunction with the conical member 45 or instead of the conical member 45. One or the other or both of the surfaces of the conical member 45 and conical opening 32 may also be modified by holes, gaps, channels, grooves, bumps, ridges, and / or projections. Each of the surfaces of theconical member 45 and conical opening 32 may also be formed as part of other components of the pump with any overall shape.

[0087] Given the general possibility of holes, grooves, channels, or gaps in either the conical member 45 and / or conical opening 32, either of their surfaces comprise of a plurality of separate bearing surfaces in the plane of the generally conical shape defining the member 45 or opening 32. In such a manner the opening 32 and / or the conical member 45 of the bearing pair may be formed by a plurality of separate surfaces or a segmented surface. The plurality of separate surfaces or the segmented surface that make up either the conical member 45 or conical opening 32 of the bearing pair may extend from the same component or part, or may extend from distinct components or parts. Grooves and gaps in either the conical member 45 and / or conical opening 32 may be created by removing material from a single generally conical surface or by using a plurality of separate surfaces.

[0088] In some embodiments of a modified cone bearing, the conical member 45 of the bearing pair can comprise a convex bearing surface having a segmented frustoconical shape formed from a plurality of distally-extending segments 33 (FIGS. 2A-2D). The distally-extending segments 33 can extend distally from the drive unit cover 11. The segments 33 can be spaced apart circumferentially to define at least one channel 34 between adjacent segments 33. Three segments 33 are shown in FIGS 2A-2D, but any suitable number of segments 33 may be utilized. As shown, the segments 33 can be separate components arising from a common part with gaps or channels 34 between them, but the segments 33 may also be separated by shallow or deep grooves. The gaps, grooves or channels 34 may follow any path. In the illustrated embodiment, the channel(s) 34 extend radially outward from a central recess or hollow 31 (also referred to herein as a void) at a location proximal a proximal end portion 5B of the impeller shaft 5. In some embodiments, the width and depth of any groove or channel 34 may vary along its path. In some embodiments, two or more channels 34 may join or separate. In certain embodiments, two or more channels 34 may join to form the central hollow area 31 coaxial with the axis of the conical surfaces and / or with the longitudinal axis of rotation L. In some embodiments, the conical opening 32 of the bearing pair can be a continuous (e.g., no gaps, channels, or grooves), generally conical surface. The relative angles of the cone bearings e.g., the segments 33) and spacing between segments 33 can be selected to provide a desired flowprofile through the channel(s) 34 described herein. For example, increased spacing between the segments 33 can provide increased flow through the channels 34. Together, the segmented conical member 45 of the drive bearing 18 with channels 34 between the segments 33 and the continuous conical opening 32 can serve as a “segmented cone bearing”.

[0089] The channels 34 between the segments 33 allow interrupted contact between bearing surfaces. This interrupted contact provides, without limitation, benefits for reduced hemolysis. For example, in embodiments in which the conical opening 32 is part of the rotating member (e.g., the impeller shaft 5), the channels 34 between the segments 33 can ensure that at least one point throughout the length or height of the conical opening 32 on the rotating member 5 is intermittently exposed by the conical opening 32 and not continuously covered by the bearing pair. This design promotes exchange of a lubricating layer blood over the entire bearing interface. The channels 34 also generate pressure changes that contribute to lubricating layer formation and dispersal as described above for the sleeve bearing 15, 15 A, 15B.

[0090] In some embodiments, additional features may promote blood flow through the central hollow 31 and channels 34 of the segmented cone bearing. In some embodiments blood may flow in through the channels 34 and exit via the central hollow 31. In other embodiments blood may flow into the central hollow 31 (e.g., from the secondary flow pathway 3B of the impeller shaft 5) and exit via the channels 34. This net flow of blood through the central hollow 31 and channels 34 may serve to ensure the volume of blood in the channels 34 and central hollow 31 is constantly flowing to provide a source of fresh blood for lubricating layer exchange, to carry away heat, and / or to reduce the time that blood is exposed to conditions within the bearing region that may increase the potential for hemolysis or thrombus formation. Accordingly, in various embodiments, a concave bearing surface (which can comprise or be defined by the concave opening 32) can include a fluid port to deliver blood proximally along the second flow pathway 3B. The convex bearing surface (which can comprise the convex member 45) can including a void (e.g., the central hollow 31), which can be disposed on the longitudinal axis L. The one or more channels 34 can extend radially outward from the void or central hollow 31. The void can be in fluid communication with the fluid port (e.g., an interface between the flow tube 5 and the conical opening 32) so as to direct blood radially outward along at least one channel 34.

[0091] As shown in FIG. 5 A, the segments 33 of the convex member 45 can be shaped to fit within the concave bearing surface comprising the concave opening 32. In some embodiments, as shown in FIGS. 4A-4B, a direct secondary flow pathway 3B (for example through the flow tube of the impeller shaft 5 shown in FIGS. 4B-4D and 5B) may provide proximally-flowing blood into the central hollow 31. In some embodiments a secondary or second impeller 7 may be used to drive the secondary flow of blood through the bearing region, e.g., through the second flow pathway 3B, the central hollow 32, and radially outwardly through the channel(s) 34. The primary impeller 6 of the pump and / or the additional secondary impeller 7 may assist in drawing the blood proximally and directing the blood radially outwardly along the channel(s) 34. FIGS. 4A-4D show the secondary impeller 7 that draws blood out through the channels 34 of the segmented cone bearing. As explained herein, the secondary impeller 7 and impeller shaft 5 can form an integrated rotor core. The secondary impeller 7 can have a plurality of vanes 10 as explained herein to assist in directing blood radially outward through the channel(s) 34 of the drive bearing 18.

[0092] Keeping the segmented cone bearing elements or segments 33 near the central longitudinal axis L of the pump can have several advantages. For example, in the illustrated embodiment, the bearing elements 33 can be more directly exposed to the blood flow from the flow tube of the impeller shaft 5 along the second flow pathway 3B. Further, the bearing elements 33 can have a smaller radius where the linear speed of the rotating member is lower. Placing the bearing elements or segments 33 near the axis L of the pump allows the vanes 10 of the secondary impeller 7 to be placed at a greater radius where the linear speed of the rotating member or shaft 5 is higher.

[0093] FIG. 2D shows an embodiment in which the channels 34 between the segments 33 follow a curved path from the central hollow 31. The channels 34 can be configured to increase flow and reduce shear forces on the blood. In some embodiments, the depth of the channels 34 may be varied to form a central flow diverter 31a as shown in, e.g., FIG. 2E. The flow diverter 31a may comprise a distally-extending projection (e.g.sa cylindrical projection, a conical projection, a pyramidal projection, etc.) disposed in a central region of the bearing between the segments 33. In the illustrated embodiment, the flow diverter 31a can comprise a symmetrical flow diverter. The flow diverter 31a may aid blood coming from the flow tube or lumen of the shaft 5 to transition from axial flow to radial flowto exit through the channels 34. The flow diverter may optionally be manufactured as one or more separate pieces that are then attached in the central hollow 31 and / or channels 34. In some embodiments, the flow diverter 31a may comprise a generally right cylindrical shape extending distally from the bearing 18. In other embodiments, the flow diverter 31a can have a tapered, for example, conical, profile.

[0094] The interface between the segments 33 of the conical member 45 and concave, e.g., conical, opening 32 of the segmented cone bearing can be lubricated by blood. Depending on geometry, materials used, and operating conditions, this lubrication may be hydrodynamic lubrication, elastohydrodynamic lubrication, boundary lubrication, or mixed lubrication. The channels 34 between the segments 33 of the conical member 45 of the bearing pair may promote fluid exchange so that a portion of the blood that makes up the lubricating layer between a region of the conical opening 32 of the bearing pair over one segment 33 of the conical member of the bearing pair is replaced by fresh blood in the lubricating layer that forms between that same region of the conical opening 32 of the bearing pair and the next segment 33 of the conical member of the bearing pair during rotation. The width and depth of the channels 34 can be altered to encourage this exchange. In various embodiments, the height and lateral spacing of the segments 33 can be selected to provide a desired channel depth and width. For example, a width of the channels 34 can be in a range of 0.02” to 0.06”, in a range of 0.03” to 0.05”, or in a range of 0.035” to 0.045” (for example, about 0.04” in some embodiments). The surfaces of the segments 33 of conical member of the bearing pair along the channels 34 form the leading and trailing edges (as seen by a region of the conical opening 32 of the bearing pair) of the segments 33 of the conical member of the bearing pair. The distance of the leading and trailing edges from the conical opening 32 may also be modified to encourage fluid exchange. For example, the edges may be beveled or rounded or the distance of the leading and trailing edges may taper away or towards the surface of the conical opening 32.

[0095] The surfaces of the segments 33 of the conical member 45 of the bearing pair may also be modified to diverge from a perfect conical surface to promote formation of a lubricating layer. For example, one or more surfaces of the segments 33 of the conical member 45 of the bearing pair may be shaped so the normal distance to the surface of the conical opening 32 of the bearing pair decreases from the leading edge to the trailing edge.Such a surface contour may encourage creation of fluid wedges between the segments 33 of the conical member 45 and the conical opening 32 of the bearing pair for improved lubrication. In another embodiment, the surfaces of the segments 33 of the conical member 45 and conical opening 32 of the bearing pair may be smooth and well matched to allow a relatively thin lubricating layer of relatively uniform thickness to form. It should be appreciated that although conical member 45 and conical opening 32 are described as having a generally conical shape in some embodiments, the member 45 and opening 32 may generally be considered convex member 45 and concave opening 32. The shapes of the convex member and the concave opening 32 may be any suitable mating shapes.

[0096] The flow of blood driven by the secondary impeller 7 from the central hollow 31 through the channels 34 provides fresh blood for exchange of the lubricating layers and carries away heat in the bearing region. Both functions are important to reducing the potential for thrombus formation in the segmented cone bearing.

[0097] The segments 33 of the conical member 45 of the bearing pair and the conical opening 32 of the bearing pair may each be made of any suitable blood compatible bearing material. As a non-limiting example, the segments 33 of the conical member of the bearing pair may be made out of titanium or stainless steel and / or the conical opening 32 of the bearing pair may be made out of PEEK or polyethylene.

[0098] By making one side of the bearing pair relatively hard and the other side of the bearing pair relatively soft, the bearing pair may initially undergo boundary or mixed lubrication where surface asperities are worn to the point where the surfaces of the conical member and conical opening are smooth and well-matched enough for hydrodynamic or elastohydrodynamic lubrication to dominate. Having one side of the bearing pair be relatively softer may increase the range over which elastohydrodynamic lubrication is present. In some embodiments, the continuous, conical opening 32 of the bearing pair will be softer and the segmented, conical member of the bearing pair will be harder. This arrangement may help preserve special geometric features of the segments 33 on the conical member of the bearing pair. In some embodiments, the continuous, conical opening 32 of the bearing pair will be harder and the segmented, conical member 45 of the bearing pair will be softer. This arrangement may help preserve the surface of the opening 32 as a surface of rotation about the longitudinal axis L. In other variations the conical opening 32 and theconical member 45 can be of similar or even the same hardness which can provide the advantage of dimensional and shape stability throughout the operation of the pump 2.

[0099] In cases where hydrodynamic lubrication dominates, the normal distance between the segments 33 on the conical member of the bearing pair and the conical opening 32 of the bearing pair may be small enough to exclude red blood cells. In these cases, exchange of the lubricating layer may be less important as long as heat is still transferred away. Given sufficient exclusion of red blood cells, a continuous (e.g., without channels or grooves) conical member 45 of the bearing pair may still demonstrate low potential for thrombus formation as long as heat can be transferred away quickly enough. In some embodiments, this may be accomplished by eliminating or covering the channels 34 to form a continuous conical surface. Blood flow through the covered channels 34 may transfer sufficient heat from the bearing pair.

[0100] The segmented bearing embodiments described above provide an additional advantage of enhancing the flexibility of the portion of the pump 2 in the vicinity of the pump head 50. The impeller assembly 4 can be coupled with the drive unit 9 in a manner that permits some motion between the impeller assembly 4 and the cover 11. For example, the pump 2 may be delivered through tortuous or curving vasculature or may be inserted from outside the patient to inside a blood vessel in tight bends. The impeller assembly 4 can tip toward one or more of the segments 33 and away from one or more segments at the conical opening 32 such that proximal end face of the impeller assembly is at a non-parallel angle to the distal face of the cover 11. The motion may be significant compared to a mounting of the impeller assembly 4 on a shaft rotatably supported in a drive unit. The tipping of the impeller assembly 4 can occur with a flexing of the shroud 16, which may be flexed in high bending stress maneuvers. In some embodiments, the shroud 16 is made of an elastic material, such as nitinol, such that the pump head 50 can flex and elastically return to an undeflected state without elongation.

[0101] The secondary impeller 7 can be disposed proximal the impeller 6. In some embodiments, as shown in FIGS. 4A-5B, the secondary impeller 7 can comprise a flange 47 extending non-parallel e.g., radially outward along the radial axis R) from the proximal end portion 5B of the impeller shaft 5 and a plurality of vanes 10 on a proximally- facing surface of the flange 47. The flange 47 can extend non-parallel and radially outwardfrom the impeller shaft 5. In some embodiments, the flange 47 may not extend radially beyond the shroud 16. In some embodiments, the flange 47 may not extend radially beyond an adjacent portion of the impeller assembly 4, e.g., may not extend radially beyond an integrated streamlined fairing 13, discussed below. In some of these embodiments, the flange 47 can comprise a section of the combined rotor surface that lies in a plane perpendicular to the longitudinal axis L. As shown in FIGS. 4A-4C and 5A, the vanes 10 can extend proximally from the flange 47 and can have a curved profile circumferentially about the longitudinal axis L. The vanes 10 can be disposed in the space between the proximal face of the flange 47 and the distal end of the drive unit 9. The concave opening 32 can comprise an angled cavity extending inwardly and distally relative to the generally proximally-facing surface of the flange 47. The rotor magnet can be disposed adjacent a distally-facing surface of the flange 47. Each of the vanes 10 can have an inner end 10a disposed at or near the concave opening 32 and an outer end 10b extending radially and circumferentially outward from the inner end 10a along the flange 47. The flange 47 can be coupled to or formed with the proximal end of the impeller shaft 5. In some embodiments, for example, the flange 47 can be monolithically formed with (e.g., seamlessly formed with) the impeller shaft 5. In other embodiments, the flange 47 and impeller shaft 5 can be separate components that are mechanically connected to one another (e.g., welded or otherwise coupled). In some embodiments, the vanes 10 can be monolithically formed with the proximally-facing surface of the flange 47. In other embodiments, the vanes 10 can be mechanically connected to the proximally-facing surface of the flange 47.

[0102] As shown in FIG. 4D, the vanes 10 can extend circumferentially about the longitudinal axis L in a manner such that adjacent vanes 10 circumferentially overlap. For example, the radially outer end 10b of one vane can circumferentially overlap with, and be disposed radially outward from, the radially inner end 10a of an adjacent vane. The vanes 10 can be prevented from contacting the drive unit 9 by the thrust bearing aspect of the segmented cone bearing. As the impeller assembly 4 rotates, the vanes 10 can pump blood radially out of the channels 34 in the segmented cone bearing and thereby increase net flow through the flow tube of the impeller shaft 5 and segmented cone bearing. As shown, blood can exit the flow tube of the impeller shaft 5 at a location proximal the primary impeller 6 and be driven radially out of the channels 34 by the vanes 10. In the illustrated embodiment,five (5) vanes 10 are used, but it should be appreciated that fewer than five or more than five vanes 10 can be used.

[0103] As shown in FIGS. 4A, 4C, and 5 A, the secondary impeller 7 can have a proximal end 52 at a proximal edge of the vanes 10. Further as shown in FIGS. 2A and 2C, the drive unit 9 can have a distal end 53 at a distal end of the distally-projecting segments 33. As explained above, the distally projecting convex segments 33 can be received within the concave opening 32 of the rotor assembly 46. When the convex segments 33 are mated within the concave opening 32, the distal end of the drive unit 9 is distal the proximal end of the second impeller 7 (e.g., distal the proximal-most end of the rotor assembly).

[0104] FIGS 2F and 2G illustrate additional examples of drive units 18A, 18B, according to various embodiments. Unless otherwise noted, components of FIGS. 2F-2G may be the same as or generally similar to like-numbered components of FIGS. 2A-2E. As above, the bearings 18 A, 18B can include a plurality of distally-projecting segments 33 extending from a base 606 of the drive bearing 18A or 18B, the plurality of distally- projecting segments 33 spaced apart circumferentially to define at least one channel 34 between adjacent segments 33. As shown, the drive bearing 18A or 18B can comprise a curved and / or ramped surface 605 angled distally (and radially inwardly) from the base 606 and defining a portion of the at least one channel 34, e.g., the ramped surface 605 may converge inwardly. The ramped or curved surface 605, when considered in combination with the opposing features on the secondary impeller 7, can effectively create a converging or diverging channel 34 for blood egress. The converging or diverging channels 34 may function in multiple planes simultaneously if desired. Furthermore, the boundaries of the projections 33 can be varied to control the mean flow vector defining the exiting blood flow. The channel 34 can be defined as desired to vary the degree of flow vector and channeling desired. Further, the distally-extending projections 33 can extend distal the curved or ramped surface 605. Beneficially, the curved or ramped surface 605 can assist in guiding the flow of blood out of the secondary impeller 7.

[0105] FIGS. 2H-2K illustrate additional bearing portions of drive units 18C, 18D and 18E. The bearing portions of these embodiments can be integrated into a blood flow assist system similar to any of those disclosed herein. The blood flow assist system can include an impeller unit, which can be the impeller assembly 4 or any other impellercomponent disclosed herein. As discussed above, the impeller assembly 4 has an impeller 6 disposed about a central tubular body, e.g., an impeller shaft 5. The impeller assembly 4 can have a concave bearing surface, e.g., at the conical opening 32. See FIGS. 4A-5A. The opening 32 can be connected to a secondary flow pathway 3B through the shaft 5 as seen in FIG. 4C.

[0106] When the system 1 is assembled, the conical opening 32 can be placed over the bearing portion of drive unit 18C such that the flow in the secondary flow pathway 3B can flow over bearing surfaces 33C of the bearing portion of the drive unit 18C. This can be achieved by making the opening formed between upper edges of the bearing surface 33C smaller than the diameter of the flow pathway 3B. The surfaces 33C can be configured to at least partially fit within the concave bearing surface at the conical opening 32. The surfaces 33C are formed on a plurality of, e.g., three, spaced apart members 33C’ that extend from a base of the drive bearing (not shown but see FIG. 2G). Similar to the structure of FIG. 2G, the members 33C’ can extend from the drive unit cover 11, e.g., from a transverse surface of the cover 11 or from a surface that extends perpendicularly to the direction of a longitudinal axis of the pathway 3B. The plurality of spaced apart members 33C’ are spaced apart circumferentially along a length thereof to define at least one channel (e.g., channel 34 as in FIG. 2D) between adjacent members 33C’. The bearing surface 33C of the bearing portion projects circumferentially from a top portion of the members 33C’ at least partially over the at least one channel 34. The bearing surfaces 33C can provide an overhang portion that extends circumferentially beyond at least one side surface of a corresponding member of the plurality of spaced apart members 33C’. The overhang can be similar to eaves on a house, extending over the portion of the channel 34. In some cases, the bearing surface 33C overhangs radially outward relative to a radially outward surface of a corresponding member of the plurality of spaced apart members 33C’. The bearing surface 33C can be flush with a radially outward surface of a corresponding member of the plurality of spaced apart members 33C’ while overhanging the channel 34 circumferentially. The bearing surfaces 33C can comprise a plurality of overhang portions, each overhang portion having a circumferential edge 33C” spaced apart from a circumferential edge 33C” of an adjacent overhang portion. The increased bearing surface area of the bearing portion of FIG. 2H reduces pressure between the bearing pair including the bearing surfaces 33C and the surface at the conicalopening 32. The increased area advantageously does not restrict flow from the flow pathway 3B through the opening in the bearing portion of FIG. 2H and through the channel(s) 34.

[0107] FIG. 21 illustrates another embodiment similar to that of FIG. 2H, the description of which can be applied to that of FIG. 21. In FIG. 21, spaced apart members 33D’ support an annular portion 33D coupled with at least two members of the plurality of spaced apart members. The annular portion 33D extends over the at least one channel 34. The annular portion 33D can be a continuous frustoconical bearing surface in one embodiment. The increased bearing surface area of the bearing portion of FIG. 21 further reduces pressure between of the bearing pair including the bearing surface 33D and the surface at the conical opening 32. The increased area advantageously does not restrict flow from the flow pathway 3B through the opening in the bearing portion of FIG. 21 and through the channel(s) 34.

[0108] FIGS. 2J and 2K illustrate another embodiment similar to that of FIG. 21, the description of which can be applied to that of FIGS. 2J and 2K. The bearing portions of drive unit 18E can be formed from a solid member. The solid member can be a cylindrical member. The cylindrical member can have a conical, e.g., a frustoconical end portion 33E. Flow pathways can be formed through the solid member. For example, a central hole 33E” can be drilled through the solid member, e.g., from the end with the conical portion to the opposite end forming a through-hole. Additional holes can be drilled through the solid member to form channels 34 similar to the channels described above. The channels can extend along axes perpendicular to the central hole 33E”. There can be any number of channels 34 formed in this manner, e.g., two, three, four or more than four channels. There can be four channels formed on two axes, e.g., at 12 and 6 o’clock and at 3 and 9 o’clock as viewed from the side opposite to the frustoconical end portion 33E. In other embodiments, the channels may extend along axes non-parallel to the central hole 33E” by a nonperpendicular angle.III. ADDITIONAL EXAMPLES OF MODULAR DRIVE BEARINGS

[0109] FIGS. 3A-3J illustrate additional examples of drive bearings 118, 118A, 118B, 118C, 118D, 118E for a medical device, such as a blood flow assist system. The drive bearings 118, 118A, 118B, 118C, 118D, 118E can be shaped or dimensioned in a manner similar to any of the drive bearings 18-18E shown in FIGS. 2A-2K. The drive bearings 118,118A, 118B, 1 18C, 118D, 118E can also function and interact with other components of the blood flow assist systems as disclosed herein. For example, the drive bearings 118, 118A, 118B, 118C, 118D, 118E can interact with any of the driven units disclosed herein, including, e.g., a rotor assembly that comprises a driven or rotor magnet and the integrated rotor core 8 that includes the impeller shaft 5 and the secondary impeller 7. The embodiments of FIGS. 3A-3J may be used in combination with all of the other embodiments disclosed herein.

[0110] In the drive bearings 18-18E described herein, the bearing can be part of the drive unit 9, which can comprise a weldable material, such as titanium or another metal. For example, the drive unit cover 11 can be welded to a portion of the motor housing 29 to form a sealed cavity in which the drive magnet 17 is disposed. However, forming the drive unit 9 by welding may limit the material sets available for use in the bearing 18-18E to a weldable material, such as a metal. Utilizing a weldable material may also, in some instances, limit the shapeability of the bearing. It can be desirable to have the ability to utilize different types of materials and / or shapes for the drive bearing 18-18E and / or for the material forming a sidewall 141 of cavity 32 of the secondary impeller 7 (see FIG. 16B). For example, it may be desirable to utilize a polymer for a portion of the drive bearing 18-18E, and a metal for the 141 sidewall of cavity 32, or vice versa. Additionally or alternatively, it may be desirable to utilize a polymer both the drive bearing 18-18E and the sidewall 141 of cavity 32. Accordingly, various embodiments disclosed herein enable the use of different material sets so that the bearing or sidewall of the cavity 32 can be chosen to hard or soft, or to have any suitable material properties for the application. Additionally or alternatively, it can be beneficial to utilize different materials for the drive bearing and for the support structure (e.g., housing) to which it is coupled.[0U1] In addition, some drive bearings may utilize a construction method in which an interface between the bearing and a support structure has a strain tensor that is continuous across the interface. In such bearings, the strain induced across the interface between the bearing and the support structure on which the bearing is coupled may continuously change across the interface. For example, bearings that are molded (e.g., injection molded) or adhered (e.g., with an adhesive such as a glue) to the support structure may have a strain profile in which the strain continuously changes in a transition regionincluding the bearing, the interface, and the support structure. In US 2018 / 0228953 to Siess, for example, a stationary bearing surface and a rotating bearing surface are disclosed. See Siess, U

[0023] , In Siess, inserts, such as ceramic inserts, can be insert molded or bonded to an inner blade surface contacting a pin surface in order to increase bearing life. Siess, T|

[0023] , However, the use of insert molding or adhesive bonding techniques creates a continuous strain tensor across the interface between the bearing and the underlying support structure. Similarly, the use of a welding technique to form a welded joint between the bearing and the support structure (e.g., between the drive unit cover 11 with bearing 18-18E and the motor housing 29) also creates a continuous strain tensor across the interface. One disadvantage of creating a continuous strain sensor is that doing so can lead to for example, micromotions at the interface that can cause misalignments between adjacent components during assembly and / or during operation.

[0112] Accordingly, various embodiments herein relate to modular drive bearings 118-118E in which a strain tensor across an interface between the drive bearing and a support structure (e.g., a housing) is discontinuous. For example, in some embodiments, the discontinuous strain tensor can change abruptly across a boundary between two or more components (e.g., across the interface between the drive bearing and support structure). The disclosed embodiments can beneficially enable the use of different materials for the bearing 118-118E and sidewall 141 of the cavity in the driven unit, and can also provide for reduced misalignments between components during assembly and / or operation. FIG. 3A is a schematic perspective view of a portion of a drive unit 109 including a modular drive bearing 118 according to one embodiment. FIG. 3B is a schematic cross-sectional view of the modular drive bearing 118 of FIG. 3 A. As shown in FIGS. 3A-3B, the illustrated drive unit portion 109 can be integrated to and / or coupled with a motor housing (not shown) as explained above, and can be configured to impart rotation to a driven unit (which, as explained above can comprise an impeller). The drive unit 109 can comprise a housing 119 configured to impart rotation to the driven unit and the drive bearing 118 that is physically separate from the housing 119. The housing can comprise a first recess 153 in which a drive magnet 17 is disposed. The drive magnet may be generally similar to or the same as the drive magnet 17 described herein. The housing 19 can further comprise a second recess 151at an end portion of the housing 19 and a wall 152 that separates the first recess 153 from the second recess 151.

[0113] As shown in FIG. 3B, the housing 119 can have an outside surface 142 disposed on an exterior of the housing 119, e.g., outside of the first recess 153 in the interior of the housing 119. As shown in FIGS. 3A-3B, the outside surface 142 can extend about an outer periphery of the housing 119 and onto and exterior side of the wall 152 within the second recess 151. An interface 150 can be disposed along the outside surface 142 of the housing 119 and along a connecting portion 143 of the drive bearing 119. As shown, the connecting portion 143 of the drive bearing 118 can be disposed inside the second recess 151 of the housing 119. A mechanical connection can be formed between the housing 119 and the connecting portion 143 of the drive bearing 119 along the interface 150. As explained herein, in various embodiments, a strain tensor across the interface 150 is discontinuous.

[0114] In FIGS. 3A-3B, the drive bearing 118 can comprise a planar surface 144 at an upper surface of the connecting portion 150 of the drive bearing 118, a vertical surface 145 extending non-parallel (e.g., substantially perpendicular to) the planar surface 144, a conical shaped member 145 extending from the vertical surface 145, and a second planar surface 146 enclosing the conical shaped member 145. The conical shaped member 145 can serve as a convex bearing member as explained above in connection with, e.g., FIGS. 2A-2E. For example, as explained herein, the conical shaped member 145 can extend into the conical opening 32 of the secondary impeller 7. Rotation of a motor (e.g., motor 30) can impart rotation of the drive magnet 17 within the first cavity 153, which in turn can impart rotation to the driven magnet (which can be similar to or the same as driven or rotor magnet described above) and the impeller. Thus, the drive bearing 118 of FIG. 3 A can comprise a continuous conical bearing (e.g., an unsegmented frustoconical bearing) in which the planar surface 144, the vertical surface 147, the conical shaped member 145, and the second planar surface 146 are continuous. Other shapes for the bearing 118 may be suitable.

[0115] Beneficially, the drive bearing 118 can be connected to the housing 119 along the interface 150 by way of an interference fit between the drive bearing 118 and the housing 119. For example, in the illustrated embodiment, the interference fit along the interface 150 comprises a friction fit in which a friction-enhancing element (e.g., an O-ring 117) is disposed between the connecting portion 143 of the bearing 118 and the outsidesurface 142 of the housing 1 19. In FIG. 3B, the lateral dimension of the connecting portion 143 of the drive bearing 118 can be approximately the same as, or slightly smaller than, the lateral dimension of the second recess 151. The O-ring 117 can provide a frictional force against the outer surface 142 that induces a discontinuous strain tensor across the interface 150. In other embodiments, the interference fit along the interface 150 can comprise a press fit. In such an embodiment that utilizes a press fit, the nominal lateral dimension of the connecting portion 143 of the drive bearing 118 can be slightly larger than the lateral dimension of the second recess 151 before the connecting portion 143 is inserted into the second recess 151. Utilizing a press fit between the connecting portion 143 and the outside surface 142 of the housing 119 can impart a laterally outward force on the housing 119 that induces a discontinuous strain bearing across the interface 150.

[0116] Accordingly, in the embodiment of FIGS.3A-3B, the connection between the connecting portion 143 of the drive bearing 118 and the outside surface 142 of the housing can exert forces on the housing 119 and / or bearing 118 that induces a strain tensor that is discontinuous across the interface 150. Accordingly, the drive bearing 118 can be mechanically connected to the housing 118 without an intervening adhesive such that the drive bearing 118 is not bonded or adhered to the housing 118 which as explained above, creates a continuous strain tensor across the interface. Rather, the bearing 118 can be secured to the housing 119 with an interference fit (e.g., a friction fit or a press fit). Moreover, in the illustrated embodiment, the drive bearing 118 is not molded into or over the housing 119, which as explained above, creates a continuous strain tensor across the interface.

[0117] Beneficially, the use of an interference fit in which the strain tensor is discontinuous across the interface 150 can improve the alignment of the bearing 118 with other components during assembly and / or operation. Moreover, the embodiment of FIGS. 3A-3B can enable the use of a modular bearing 118 in which different material sets can be used for the bearing 118 and housing 119, and / or for the bearing 118 and sidewall 141 of the cavity 32. Materials that cannot be easily or reliably attached to each other by gluing or welding can be used as the bearing 118 and sidewall 141. For example, in some embodiments, the bearing 118 and the housing 119 can comprise different materials. In some embodiments, the bearing 118 can comprise a metal, and the housing 119 can comprisea polymer. In other embodiments, the bearing 118 can comprise a polymer, and the housing 119 can comprise a metal. In still other embodiments, both the bearing 118 and the housing 119 can comprise a metal. In other embodiments, both the bearing 118 and the housing 119 can comprise a polymer. In some embodiments, the bearing 118 and the sidewall 141 can comprise different materials; in other embodiments, the bearing 118 and the sidewall 141 can comprise the same material. In some embodiments, the bearing 118 can comprise a polymer, and the sidewall 141 can comprise a metal. In other embodiments, the bearing 118 can comprise a metal, and the sidewall 141 can comprise a polymer. In other embodiments, the sidewall 141 and the bearing 118 can comprise a metal. In other embodiments, the sidewall 141 and the bearing 118 can comprise a polymer.

[0118] FIG. 3C is a schematic top perspective view of a modular drive bearing 118A according to another embodiment, in which the drive bearing comprises a segmented cone bearing. FIG. 3D is a schematic bottom perspective view of the modular drive bearing 118A of FIG. 3C. FIG. 3E is a schematic cross-sectional view of the modular drive bearing 118A of FIG. 3C. Unless otherwise noted, the components of FIGS. 3C-3E may be the same as or generally similar to like numbered components in FIGS. 3A-3B, with the reference numeral appended with the letter “A.” The drive magnet 17 is not illustrated in FIGs. 3D-3E for ease of illustration, but it should be appreciated that the drive magnet 17 can be disposed in the first recess 153 A as explained herein.

[0119] For example, as with the drive bearing 118 of FIGS. 3A-3B, the drive bearing 118A of FIGS. 3C-3E can comprise a conical shaped member 145A configured to engage with the driven element (e.g., the sidewall 141 of cavity 32 of the secondary impeller 7). However, unlike the embodiment of FIGS. 3A-3B, in FIGS. 3C-3E, the drive bearing 118A can comprise a segmented cone bearing in which the conical shape member 145A includes a plurality of distally-extending segments 133 A extending distally from the planar surface 144A. The segments 133A can be spaced apart circumferentially to define at least one channel 134A between adjacent segments 133A. Three segments 133A are shown in FIGS 3C-3E, but any suitable number of segments 133A may be utilized. The gaps, grooves or channels 134A between adjacent segments 133A may follow any path. In the illustrated embodiment, the channel(s) 134A extend radially outward from a central recess or hollow 131 A (also referred to herein as a void) at a location proximal a proximal end portion 5B ofthe impeller shaft 5. In some embodiments, the width and depth of any groove or channel 134A may vary along its path. In some embodiments, two or more channels 134A may join or separate. In certain embodiments, two or more channels 134A may join to form the central hollow area 131 A coaxial with the axis of the conical surfaces and / or with the longitudinal axis of rotation L. In some embodiments, the conical opening 32 of the bearing pair can be a continuous (e.g., no gaps, channels, or grooves), generally conical surface. The relative angles of the cone bearings (e.g., the segments 133A) and spacing between segments 133A can be selected to provide a desired flow profile through the channel(s) 134A described herein. For example, increased spacing between the segments 133A can provide increased flow through the channels 134A. Together, the segmented conical member 145A of the drive bearing 118A with channels 134A between the segments 133A and the continuous conical opening 32 can serve as a segmented cone bearing. Additional details of the geometry of the segmented cone bearing may be generally similar to or the same as the segmented cone bearing described herein in connection with, e.g., FIGS. 2A-2G.

[0120] Unlike the embodiment of FIGS. 2A-2G, however, the drive bearing 118A can be coupled to the housing 119A by way of an interference fit. As with the embodiment of FIGS. 3A-3B, the drive bearing 118A can be connected to the outside surface 142A of the housing 119A by way of a friction fit using O-ring 117A. In other embodiments, the interference fit can comprise a press fit as explained above. Beneficially, as explained herein, the embodiment of FIGS. 3C-3E can utilize a connection between the bearing 118A and housing 119A that does not use an adhesive and that does not utilize a mold process. The strain tensor induced across the interface 150A can be discontinuous as explained above. The bearing 118A can be made of a different material or the same material as the housing 119A. The bearing 118A can be made of a different material or the same material as the sidewall 141 of the cavity 23.

[0121] FIG. 3F is a schematic top perspective view of a modular drive bearing 118B according to another embodiment, in which the drive bearing 118B utilizes a cover 160B to retain the drive bearing 118B in the second recess 15 IB of the housing 119B. FIG. 3G is a schematic cross-sectional view of the modular drive bearing 118B of FIG. 3F. The drive magnet 17 is not illustrated in FIGs. 3F-3G for ease of illustration, but it should be appreciated that the drive magnet 17 can be disposed in the first recess 153B as explainedherein. Unless otherwise noted, the components of FIGS. 3F-3G may be the same as or generally similar to like numbered components in FIGS. 3A-3B, with the reference numeral appended with the letter “B ” For example, as with the embodiment of FIGS. 3A-3B, the bearing 118B can comprise a conical member 145B, which can be continuous (as is shown in FIGS. 3A-3B and 3F-3G) or segmented (as shown in FIGS. 3C-3E). Unlike the embodiments of FIGS. 3A-3E, however, in FIGS. 3F-3G, the drive bearing 118B can be positioned in the second cavity 15 IB and secured in the cavity 15 IB with a cover 160B. In some embodiments, the cover 160B can be connected to the housing 119B over the second recess 15 IB to retain the drive bearing 118B in the second recess 15 IB. As shown, the cover 160B can comprise an opening 161B, with a portion (e.g., at least the conical member 145B) of the drive bearing 118B extending through the opening 16 IB. In some embodiments, the cover 160B is adhered or welded to the housing 119B.

[0122] In the embodiment of FIGS. 3F-3G, the bearing 118B may be fit into the second recess 15 IB by way of an interference fit (e.g., a friction fit or press fit) as explained above in connection with FIGS. 3A-3E. In other embodiments, the bearing 118B may not be connected to the housing 119B by an interference fit, but may instead be secured within the recess 15 IB only by the cover 160B. In either implementation, the strain tensor across the interface 150B may be discontinuous, which can improve alignment between the bearing 118B and other components during assembly and / or operation. For example, during assembly and / or operation, the bearing 118B may be able to self-align with other components due to lateral freedom of movement, such that the cover 160B can retain the bearing 118B in the cavity 15 IB but may allow lateral movement such that the bearing 118B can align with, e.g., the conical opening 32. Such a configuration is also an example of a discontinuous strain tensor across the interface 150B.

[0123] FIG. 3H is a schematic cross-sectional view of a drive unit 109C having a modular drive bearing 118C, according to another embodiment, in which the drive bearing 118C is connected to a projection 170C of a housing 119C. The drive magnet 17 is not illustrated in FIG. 3H for ease of illustration, but it should be appreciated that the drive magnet 17 can be disposed in the first recess 153C as explained herein. Unless otherwise noted, the components of FIG. 3H may be the same as or generally similar to like numbered components in FIGS. 3A-3G, with the reference numeral appended with the letter “C ” Forexample, as with the embodiment of FIGS. 3A-3B, the bearing 1 18C can comprise a conical member 145C, which can be continuous (as is shown in FIGS. 3A-3B and 3F-3G) or segmented (as shown in FIGS. 3C-3E). Unlike the embodiments of FIGS. 3A-3G, however, in FIG. 3H, the housing 119C can comprise a projection 170C extending upwardly or distally from the wall 152C of the housing 119C. In FIG. 3H, the drive bearing 118C can have a cavity 171C that is disposed over the projection 170C. An inner surface of the cavity 171C can be connected to the projection 170C along an interface 150C by way of an interference fit, c. ., press fit or friction fit. As above, a strain tensor induced across the interface 150C can be discontinuous.

[0124] FIG. 31 is a schematic perspective view of a portion of a drive unit 109D including a modular drive bearing 118D according to another embodiment. The drive magnet 17 is not illustrated in FIG. 31 for ease of illustration, but it should be appreciated that the drive magnet 17 can be disposed in the first recess 153D as explained herein. Unless otherwise noted, the components of FIG. 31 may be the same as or generally similar to like numbered components in FIGS. 3A-3H, with the reference numeral appended with the letter “D.” Unlike the embodiments of FIGS. 3A-3H, in FIG. 31, the wall 152D does not extend entirely across the first recess 153D. Rather, in FIG. 31, the wall 152D extends only partially across a width of the first cavity 153D (and partially across a width of the bearing 118D). The wall 152D can accordingly serve as a ledge or shelf upon which the bearing 118D can be disposed. As shown, a gap 153D’ can be provided in the wall 152D such that the wall 152D extends around the gap 153D’). Beneficially, the gap 153D’ can enable portions of the magnet (which may be positioned in the recess 153D) to be positioned closer to the drive bearing 118D. For example, a portion of the magnet can extend into the gap 153D’ in various embodiments.

[0125] FIG. 3J is a schematic perspective view of a portion of a drive unit 109E including a modular drive bearing 118E according to another embodiment. Unless otherwise noted, the components of FIG. 3 J may be the same as or generally similar to like numbered components in FIGS. 3A-3I, with the reference numeral appended with the letter “E.” Unlike the embodiment of FIG. 31, in the embodiment of FIG. 3 J, the wall 153-153D can be omitted, such that the first recess 153E can be open to (e.g., exposed to) the bearing 118E. Thus, in FIG. 3 J, the drive magnet (not shown) can be positioned in the recess 153E directlyadjacent to the bearing 1 18E without an intervening wall, which can improve the magnetic performance of the drive unit 109E.

[0126] Embodiments described herein are included to demonstrate particular aspects of the present disclosure. It should be appreciated by those of ordinary skill in the art that the embodiments described herein merely represent exemplary embodiments (e.g., nonlimiting examples) of the disclosure. Those of ordinary skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments described, including various combinations of the different elements, components, steps, features, or the like of the embodiments described, and still obtain a like or similar result without departing from the spirit and scope of the present disclosure. From the foregoing description, one of ordinary skill in the art can easily ascertain the essential characteristics of this disclosure, and without departing from the spirit and scope thereof, can make various changes and modifications to adapt the disclosure to various usages and conditions. The embodiments described hereinabove are meant to be illustrative only and should not be taken as limiting of the scope of the disclosure.

[0127] Prior work is detailed in U.S. Pat. No. 8,012,079 and U.S. Pat. Pub. No. 2017 / 0087288 , which are both fully incorporated by reference herein.

[0128] Conditional language, such as “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements, and / or steps. Thus, such conditional language is not generally intended to imply that features, elements, and / or steps are in any way required for one or more embodiments.

[0129] The terms “comprising,” “including,” “having,” and the like are synonymous and are used inclusively, in an open-ended fashion, and do not exclude additional elements, features, acts, operations, and so forth. Also, the term “or” is used in its inclusive sense (and not in its exclusive sense) so that when used, for example, to connect a list of elements, the term “or” means one, some, or all of the elements in the list. In addition, the articles “a,” “an,” and “the” as used in this application and the appended claims are to be construed to mean “one or more” or “at least one” unless specified otherwise.

[0130] The ranges disclosed herein also encompass any and all overlap, subranges, and combinations thereof. Language such as “up to,” “at least,” “greater than,” “less than,” “between,” and the like includes the number recited. Numbers preceded by a term such as “about” or “approximately” include the recited numbers and should be interpreted based on the circumstances (e.g., as accurate as reasonably possible under the circumstances, for example ±5%, ±10%, ±15%, etc.). For example, “about 1” includes “1.” Phrases preceded by a term such as “substantially,” “generally,” and the like include the recited phrase and should be interpreted based on the circumstances (e.g., as much as reasonably possible under the circumstances). For example, “substantially spherical” includes “spherical.” Unless stated otherwise, all measurements are at standard conditions including temperature and pressure.

[0131] As used herein, a phrase referring to “at least one of’ a list of items refers to any combination of those items, including single members. As an example, “at least one of: A, B, or C” is intended to cover: A, B, C, A and B, A and C, B and C, and A, B, and C. Conjunctive language such as the phrase “at least one of X, Y and Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be at least one of X, Y or Z. Thus, such conjunctive language is not generally intended to imply that certain embodiments require at least one of X, at least one of Y and at least one of Z to each be present.

[0132] Although certain embodiments and examples have been described herein, it should be emphasized that many variations and modifications may be made to the humeral head assembly shown and described in the present disclosure, the elements of which are to be understood as being differently combined and / or modified to form still further embodiments or acceptable examples. All such modifications and variations are intended to be included herein within the scope of this disclosure. A wide variety of designs and approaches are possible. No feature, structure, or step disclosed herein is essential or indispensable.

[0133] Some embodiments have been described in connection with the accompanying drawings. However, it should be understood that the figures are not drawn to scale. Distances, angles, etc. are merely illustrative and do not necessarily bear an exact relationship to actual dimensions and layout of the devices illustrated. Components can be added, removed, and / or rearranged. Further, the disclosure herein of any particular feature,aspect, method, property, characteristic, quality, attribute, element, or the like in connection with various embodiments can be used in all other embodiments set forth herein. Additionally, it will be recognized that any methods described herein may be practiced using any device suitable for performing the recited steps.

[0134] For purposes of this disclosure, certain aspects, advantages, and novel features are described herein. It is to be understood that not necessarily all such advantages may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the disclosure may be embodied or carried out in a manner that achieves one advantage or a group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein.

[0135] Moreover, while illustrative embodiments have been described herein, it will be understood by those skilled in the art that the scope of the inventions extends beyond the specifically disclosed embodiments to any and all embodiments having equivalent elements, modifications, omissions, combinations or sub-combinations of the specific features and aspects of the embodiments (e.g., of aspects across various embodiments), adaptations and / or alterations, and uses of the inventions as would be appreciated by those in the art based on the present disclosure. The limitations in the claims are to be interpreted fairly based on the language employed in the claims and not limited to the examples described in the present specification or during the prosecution of the application, which examples are to be construed as non-exclusive. Further, the actions of the disclosed processes and methods may be modified in any manner, including by reordering actions and / or inserting additional actions and / or deleting actions. It is intended, therefore, that the specification and examples be considered as illustrative only, with a true scope and spirit being indicated by the claims and their full scope of equivalents.

Claims

WHAT IS CLAIMED IS:

1. A blood flow assist system comprising: a driven unit comprising an impeller that is rotatable about a longitudinal axis of the blood flow assist system; a drive unit configured to impart rotation to the driven unit, the drive unit comprising: a housing configured to support a drive magnet; and a drive bearing separate from the housing; and an interface disposed along a surface of the housing and along a connecting portion of the drive bearing, a mechanical connection formed between the housing and the drive bearing along the interface; wherein a strain tensor across the interface is discontinuous.

2. The system of Claim 1, wherein the surface comprises an outside surface of the housing.

3. The system of Claim 1, wherein the housing comprises a first recess, the system further comprising a drive magnet disposed in the first recess.

4. The system of Claim 3, wherein the surface of the housing comprises a second recess at an end portion of the drive unit, the connecting portion of the drive bearing disposed in the second recess.

5. The system of Claim 4, wherein the first and second recesses are separated by a wall.

6. The system of any one of Claims 1 to 5, wherein the interface comprises an interference fit between the drive bearing and the housing.

7. The system of Claim 6, wherein the interference fit comprises a friction fit, including a friction-enhancing element along the interface.

8. The system of Claim 7, wherein the friction-enhancing element comprises an O-ring disposed in a gap between the drive bearing and the housing.

9. The system of Claim 6, wherein the interference fit comprises a press fit.

10. The system of Claim 4, wherein the drive unit comprises a cover connected to the housing over the second recess to retain the drive bearing in the second recess.11 . The system of Claim 10, wherein the cover comprises an opening, a portion of the drive bearing extending through the opening.

12. The system of Claim 10 or 11, wherein the cover is welded to the housing.

13. The system of any one of Claims 1 to 4, wherein the drive bearing comprises a first material, and wherein the housing comprises a second material different from the first material.

14. The system of Claim 13, wherein the first material is a polymer and the second material is a metal.

15. The system of Claim 1, wherein the housing comprises a projection, the drive bearing having a cavity that is disposed over the projection.

16. The system of any one of Claims 1 to 4, wherein the housing and the drive bearing are composed of the same material.

17. The system of Claim 1, further comprising a drive magnet, wherein the driven unit comprises a rotor assembly coupled with the impeller, the rotor assembly comprising a concave bearing surface and a rotor magnet configured to magnetically coupled with the drive magnet.

18. The system of Claim 17, wherein the drive bearing comprises a first material and the concave bearing surface comprises a second material that is different from the first material.

19. The system of Claim 18, wherein the first material is a polymer and the second material is a metal.

20. The system of any one of Claims 17 to 19, wherein the drive bearing comprises a convex drive bearing shaped to fit within the concave bearing surface.

21. The system of Claim 20, wherein the convex drive bearing comprises a plurality of distally-projecting segments spaced apart circumferentially to define at least one channel between adjacent segments, the at least one channel extending outwardly from a central hollow.

22. The system of Claim 21, wherein the rotor assembly includes a second impeller disposed on a proximally-facing surface of the rotor assembly.

23. The system of Claim 22, wherein a first flow pathway is disposed along an exterior surface of the first impeller and a second flow pathway is disposed along a lumenextending through the impeller, the central hollow and at least one channel in fluid communication with the second flow pathway.

24. The system of any one of Claims 17 to 19, further comprising a pump housing, the impeller disposed in the pump housing.

25. The system of Claim 24, further comprising a plurality of struts coupled to or formed with the pump housing, the plurality of struts extending outwardly from the pump housing and configured to engage a blood vessel wall during operation of the blood flow assist system.

26. A blood flow assist system comprising: a driven unit comprising an impeller that is rotatable about an axis of rotation; and a drive unit configured to impart rotation to the driven unit, the drive unit comprising: a housing supporting a drive magnet; and a drive bearing connected to the housing by way of an interference fit.

27. The system of Claim 26, wherein the housing comprises a first recess, the system further comprising a drive magnet disposed in the first recess.

28. The system of Claim 27, wherein the housing comprises a second recess at an end portion of the drive unit, a connecting portion of the drive bearing disposed in the second recess, the first and second recesses separated by a wall.

29. The system of Claim 26, wherein the interference fit comprises a friction fit, including a friction-enhancing element along the interface.

30. The system of Claim 29, wherein the friction-enhancing element comprises an O-ring disposed in a gap between the drive bearing and the housing.

31. The system of Claim 26, wherein the interference fit comprises a press fit.

32. The system of any one of Claims 26 to 31, wherein the drive bearing comprises a first material, and wherein the housing comprises a second material different from the first material.

33. The system of Claim 32, wherein the first material is a polymer and the second material is a metal.

34. The system of Claim 26, wherein the housing comprises a projection, the drive bearing having a cavity that is disposed over the projection.

35. The system of any one of Claims 26 to 31, wherein the housing and the drive bearing are composed of the same material.

36. The system of Claim 26, further comprising a drive magnet, wherein the driven unit comprises a rotor assembly coupled with the impeller, the rotor assembly comprising a concave bearing surface and a rotor magnet configured to magnetically coupled with the drive magnet.

37. The system of Claim 36, wherein the drive bearing comprises a first material and the concave bearing surface comprises a second material that is different from the first material.

38. The system of Claim 37, wherein the first material is a polymer and the second material is a metal.

39. The system of any one of Claims 36 to 38, wherein the drive bearing comprises a convex drive bearing shaped to fit within the concave bearing surface.

40. The system of Claim 39, wherein the convex drive bearing comprises a plurality of distally-projecting segments spaced apart circumferentially to define at least one channel between adjacent segments, the at least one channel extending outwardly from a central hollow.

41. A blood flow assist system comprising: a driven unit comprising an impeller that is rotatable about a longitudinal axis of the blood flow assist system; and a drive unit configured to impart rotation to the driven unit, the drive unit comprising: a housing including a first recess configured to receive one or more drive components; a drive bearing disposed in a second recess of the housing; and a cover disposed over the second recess and connected to the housing to retain the drive bearing in the second recess.

42. The system of Claim 41, wherein the cover comprises an opening, a portion of the drive bearing extending through the opening.-SO-43. The system of Claim 41 or 42, wherein the cover is welded to the housing.

44. The system of any one of Claims 41 to 43, wherein the drive bearing comprises a first material, and wherein the housing comprises a second material different from the first material.

45. The system of Claim 44, wherein the first material is a polymer and the second material is a metal.

46. The system of any one of Claims 41 to 43, wherein the housing and the drive bearing are composed of the same material.

47. The system of any one of Claims 41 to 46, further comprising a drive magnet, wherein the driven unit comprises a rotor assembly coupled with the impeller, the rotor assembly comprising a concave bearing surface and a rotor magnet configured to magnetically coupled with the drive magnet.

48. The system of Claim 47, wherein the drive bearing comprises a first material and the concave bearing surface comprises a second material that is different from the first material.

49. The system of Claim 48, wherein the first material is a polymer and the second material is a metal.

50. The system of any one of Claims 47 to 49, wherein the drive bearing comprises a convex drive bearing shaped to fit within the concave bearing surface.

51. The system of Claim 50, wherein the convex drive bearing comprises a plurality of distally-projecting segments spaced apart circumferentially to define at least one channel between adjacent segments, the at least one channel extending outwardly from a central hollow.

52. A medical system comprising: a rotatable medical device; a drive unit configured to impart rotation to the rotatable medical device, the drive unit comprising: a housing; and a drive bearing separate from the housing and mechanically connected to a portion of the housing along an interface; andan interface disposed along a surface of the housing and along a connecting portion of the drive bearing, a mechanical connection formed between the housing and the drive bearing along the interface, wherein a strain tensor across the interface is discontinuous.

53. The medical system of Claim 52, wherein the surface comprises an outside surface of the housing.

54. The system of Claim 52 or 53, wherein the housing comprises a first recess, the system further comprising a drive magnet disposed in the first recess.

55. The system of Claim 54, wherein the surface of the housing comprises a second recess at an end portion of the drive unit, the connecting portion of the drive bearing disposed in the second recess.

56. The system of Claim 55, wherein the first and second recesses are separated by a wall.

57. The system of any one of Claims 52 to 56, wherein the interface comprises an interference fit between the drive bearing and the housing.

58. The system of Claim 57, wherein the interference fit comprises a friction fit, including a friction-enhancing element along the interface.

59. The system of Claim 58, wherein the friction-enhancing element comprises an O-ring disposed in a gap between the drive bearing and the housing.

60. The system of Claim 57, wherein the interference fit comprises a press fit.

61. The system of Claim 55, wherein the drive unit comprises a cover connected to the housing over the second recess to retain the drive bearing in the second recess.

62. The system of Claim 61, wherein the cover comprises an opening, a portion of the drive bearing extending through the opening.

63. The system of Claim 61 or 62, wherein the cover is welded to the housing.

64. The system of any one of Claims 52 to 63, wherein the drive bearing comprises a first material, and wherein the housing comprises a second material different from the first material.

65. The system of Claim 64, wherein the first material is a polymer and the second material is a metal.

66. The system of Claim 52, wherein the housing comprises a projection, the drive bearing having a cavity that is disposed over the projection.

67. The system of any one of Claims 52 to 63, wherein the housing and the drive bearing are composed of the same material.

68. The system of any one of Claims 52 to 67, wherein the rotatable medical device comprises a blood flow assist system including a driven unit comprising an impeller that is rotatable about a longitudinal axis of the blood flow assist system.

69. The system of Claim 68, further comprising a drive magnet, wherein the driven unit comprises a rotor assembly coupled with the impeller, the rotor assembly comprising a concave bearing surface and a rotor magnet configured to magnetically coupled with the drive magnet.

70. The system of Claim 69, wherein the drive bearing comprises a first material and the concave bearing surface comprises a second material that is different from the first material.

71. The system of Claim 70, wherein the first material is a polymer and the second material is a metal.

72. The system of any one of Claims 69 to 71, wherein the drive bearing comprises a convex drive bearing shaped to fit within the concave bearing surface.

73. The system of Claim 72, wherein the convex drive bearing comprises a plurality of distally-projecting segments spaced apart circumferentially to define at least one channel between adjacent segments, the at least one channel extending outwardly from a central hollow.

74. The system of Claim 73, wherein the rotor assembly includes a second impeller disposed on a proximally-facing surface of the rotor assembly.

75. The system of Claim 74, wherein a first flow pathway is disposed along an exterior surface of the first impeller and a second flow pathway is disposed along a lumen extending through the impeller, the central hollow and at least one channel in fluid communication with the second flow pathway.

76. The system of any one of Claims 69 to 75, further comprising a pump housing, the impeller disposed in the pump housing.

77. The system of Claim 76, further comprising a plurality of struts coupled to or formed with the pump housing, the plurality of struts extending outwardly from the pump housing and configured to engage a blood vessel wall during operation of the blood flow assist system.

78. A drive unit for a medical device, the drive unit comprising: a housing enclosing a recess configured to retain one or more drive unit components; and a drive bearing having a first end with a bearing surface and a second end disposed between the bearing surface and the recess of the housing, the drive bearing separate from the housing and mechanically connected to a portion of the housing along an interface, wherein a strain tensor across the interface is discontinuous.

79. The drive unit of Claim 78, wherein the interface is disposed along a surface of the housing and along a connecting portion of the drive bearing, a mechanical connection formed between the housing and the drive bearing along the interface.

80. The drive unit of Claim 79, wherein the surface comprises an outside surface of the housing.

81. The drive unit of any one of Claims 78 to 80, further comprising a drive magnet disposed in the recess.

82. The drive unit of Claim 79, wherein the surface of the housing comprises a second recess, the connecting portion of the drive bearing disposed in the second recess.

83. The drive unit of Claim 82, wherein the recess and the second recess are separated by a wall.

84. The drive unit of any one of Claims 78 to 83, wherein the interface comprises an interference fit between the drive bearing and the housing.

85. The drive unit of Claim 84, wherein the interference fit comprises a friction fit, including a friction-enhancing element along the interface.

86. The drive unit of Claim 85, wherein the friction-enhancing element comprises an O-ring disposed in a gap between the drive bearing and the housing.

87. The drive unit of Claim 84, wherein the interference fit comprises a press fit.

88. The drive unit of any one of Claims 82 to 83, further comprising a cover connected to the housing over the second recess to retain the drive bearing in the second recess.

89. The drive unit of Claim 88, wherein the cover comprises an opening, a portion of the drive bearing extending through the opening.

90. The drive unit of Claim 88 or 89, wherein the cover is welded to the housing.

91. The drive unit of any one of Claims 78 to 90, wherein the drive bearing comprises a first material, and wherein the housing comprises a second material different from the first material.

92. The drive unit of Claim 91, wherein the first material is a polymer and the second material is a metal.

93. The drive unit of Claim 78, wherein the housing comprises a projection, the drive bearing having a cavity that is disposed over the projection.

94. The drive unit of any one of Claims 78 to 90, wherein the housing and the drive bearing are composed of the same material.

95. A drive unit for a medical device, the drive unit comprising: a housing; a drive bearing connected to the housing by way of an interference fit.

96. The drive unit of Claim 95, wherein the interference fit comprises a friction fit, including a friction-enhancing element along the interface.

97. The drive unit of Claim 96, wherein the friction-enhancing element comprises an O-ring disposed in a gap between the drive bearing and the housing.

98. The drive unit of Claim 95, wherein the interference fit comprises a press fit.

99. The drive unit of any one of Claims 95 to 98, wherein the drive bearing component comprises a first material, and wherein the housing comprises a second material different from the first material.

100. The drive unit of Claim 99, wherein the first material is a polymer and the second material is a metal.

101. The drive unit of any one of Claims 95 to 98, wherein the housing and the drive bearing component are composed of the same material.

102. A drive unit for a medical device, the drive unit comprising:a housing having an outside surface defining a recess; a drive bearing component having a portion disposed in the recess of the housing; and a cover disposed over at least part of the recess to retain the drive bearing component in the second recess.

103. The drive unit of Claim 102, wherein the cover comprises an opening, a portion of the drive bearing component extending through the opening.

104. The drive unit of Claim 102 or 103, wherein the cover is welded to the housing.

105. The drive unit of any one of Claims 102 to 104, wherein the drive bearing component comprises a first material, and wherein the housing comprises a second material different from the first material.

106. The drive unit of Claim 105, wherein the first material is a polymer and the second material is a metal.

107. The drive unit of any one of Claims 102 to 104, wherein the housing and the drive bearing component are composed of the same material.

108. A blood flow assist system comprising: a driven unit comprising: an impeller assembly comprising a rotor assembly, a first impeller coupled with the rotor assembly, and a second impeller disposed on a proximally-facing surface of the rotor assembly, the impeller assembly rotatable about a longitudinal axis of the blood flow assist system, the rotor assembly comprising a rotor magnet and a concave bearing surface, wherein a first flow pathway is disposed along an exterior surface of the first impeller and a second flow pathway is disposed along a lumen extending through the first impeller; and a drive unit configured to impart rotation to the driven unit, the drive unit comprising: a housing enclosing a drive magnet disposed therein, the drive magnet magnetically coupled with the rotor magnet; anda convex drive bearing separate from the housing and shaped to fit within the concave bearing surface, the convex drive bearing comprising a plurality of distally-projecting segments spaced apart circumferentially to define at least one channel between adjacent segments, the at least one channel in fluid communication with the second flow pathway, the convex drive bearing mechanically connected to a portion of the housing along an interface, wherein a strain tensor across the interface is discontinuous.

109. The blood flow assist system of Claim 108, wherein the interface comprises an interference fit between the drive bearing and the housing.

110. The blood flow assist system of Claim 109, wherein the interference fit comprises a friction fit, including a friction-enhancing element along the interface.

111. The blood flow assist system of Claim 110, wherein the friction-enhancing element comprises an O-ring disposed in a gap between the drive bearing and the housing.

112. The blood flow assist system of Claim 109, wherein the interference fit comprises a press fit.

113. The blood flow assist system of Claims 108, further comprising a cover connected to the housing to retain the drive bearing in a recess.

114. The blood flow assist system of Claim 113, wherein the cover comprises an opening, a portion of the drive bearing extending through the opening.

115. The blood flow assist system of Claim 108, wherein the housing comprises a projection, the drive bearing having a cavity that is disposed over the projection.

116. A blood flow assist system comprising: a driven unit comprising: an impeller assembly comprising a rotor assembly and an impeller coupled with the rotor assembly and rotatable about a longitudinal axis of the blood flow assist system, the rotor assembly comprising a rotor magnet and a concave bearing surface; and a drive unit configured to impart rotation to the driven unit, the drive unit comprising: a housing enclosing one or more drive components; anda convex drive bearing component shaped to fit within the concave bearing surface, the convex drive bearing component comprising a plurality of distally-projecting segments spaced apart circumferentially to define at least one channel between adjacent segments, the convex drive bearing component coupled with a portion of the housing along an interface, wherein a strain tensor across the interface is discontinuous.

117. The blood flow assist system of Claim 116, wherein the interface comprises an interference fit between the drive bearing and the housing.

118. The blood flow assist system of Claim 117, wherein the interference fit comprises a friction fit, including a friction-enhancing element along the interface.

119. The blood flow assist system of Claim 118, wherein the friction-enhancing element comprises an O-ring disposed in a gap between the drive bearing and the housing.

120. The blood flow assist system of Claim 117, wherein the interference fit comprises a press fit.

121. The blood flow assist system of Claims 116, further comprising a cover connected to the housing to retain the drive bearing in a recess.

122. The blood flow assist system of Claim 121, wherein the cover comprises an opening, a portion of the drive bearing extending through the opening.

123. The blood flow assist system of Claim 116, wherein the housing comprises a projection, the drive bearing having a cavity that is disposed over the projection.

124. A method of manufacturing a drive unit for a medical device, the method comprising: providing a housing having a recess configured to enclose a drive component; and mechanically connecting a bearing to the housing along an interface such that a strain tensor across the interface is discontinuous.

125. The method of Claim 124, wherein mechanically connecting comprises forming an interference fit between the bearing and the housing.

126. The method of Claim 125, wherein forming an interference fit comprises providing a friction-enhancing element along the interface to form a friction fit.

127. The method of Claim 126, wherein providing the friction-enhancing element comprises disposing an O-ring in a gap between the bearing and the housing.

128. The method of Claim 124, wherein mechanically connecting comprises providing a cover connected to the housing to retain the bearing in a second recess.

129. The blood flow assist system of Claim 128, wherein the cover comprises an opening, a portion of the bearing extending through the opening.

130. The blood flow assist system of Claim 124, wherein the housing comprises a projection, and wherein mechanically connecting comprise disposing a cavity of the bearing over the projection.

131. A method comprising: delivering a pump to a treatment location in a blood vessel of a patient, the pump comprising a driven unit including a rotatable impeller; and imparting rotation to the driven unit by way of a drive unit to cause the impeller to rotate, the drive unit comprising a housing configured to support a drive magnet, and a drive bearing separate from the housing, an interface disposed along a surface of the housing and along a connecting portion of the drive bearing, a mechanical connection formed between the housing and the drive bearing along the interface, wherein a strain tensor across the interface is discontinuous.

132. The method of Claim 131, further comprising expanding a support structure connected to the pump to position the pump in the blood vessel.

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