Blood pumps

Abstract

To provide improved blood pumps.SOLUTION: A blood flow assist system can include: an impeller assembly including an impeller shaft and an impeller on the impeller shaft; and a primary flow pathway disposed along an exterior surface of the impeller. The system can include a rotor assembly at a proximal portion of the impeller shaft. A secondary flow pathway can be disposed along a lumen of the impeller shaft. During operation of the blood flow assist system, blood can be pumped proximally along the primary flow pathway and the secondary flow pathway. The system can include a sleeve bearing distal to the impeller. The system can include a drive unit having a distal end disposed distal to a proximal end of the second impeller. The drive unit comprises a drive magnet and a drive bearing between the drive magnet and the impeller assembly.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] The present invention relates to an improved blood pump. [Background technology]

[0002] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Patent Application No. 62 / 943,062, filed December 3, 2019, and U.S. Provisional Patent Application No. 62 / 947,740, filed December 13, 2019, the entire contents of each of which are incorporated herein by reference in their entirety for all purposes. Any application for which a foreign or domestic priority claim is identified in an Application Data Sheet filed with this application is incorporated herein by reference under 37 CFR 1.57.

[0003] In the field of cardiac assist devices and mechanical circulatory assistance, blood pumps are used to assist the heart in circulating blood through the body. Implantable impeller pumps constitute one common class of blood pumps used.

[0004] Impeller pumps use bearings to constrain the impeller both radially and axially, but connect it to the rest of the pump in a way that allows it to rotate freely. Sleeve bearings (or journal bearings) are a common type of bearing that provide radial containment. Conical bearings provide both axial and radial containment. Both sleeve and conical bearings also have improved pressure-velocity characteristics (due to their two-dimensional bearing interface) as opposed to bearings that rely on point or line contact.

[0005] Blood pumps also typically include a structure that provides a torque coupling between the motor and the pump impeller. Common variations of this design element are direct torque coupling and magnetic torque coupling. Summary of the Invention

[0006] There continues to be a need for improved blood pumps.

[0007] One major difficulty with blood pumps is the susceptibility of the blood to the conditions created by the pump. Common problems include thrombosis and hemolysis, especially with bearings that have areas where blood can stagnate and clot.

[0008] Important factors in the design and evaluation of blood pumps include enhancing fluid flow to and from the bearing region, forming a lubricating fluid layer within the bearing region, maintaining pressure-volume characteristics of the bearing interface within preferred ranges, and minimizing forces on the blood that may cause thrombosis or hemolysis.

[0009] In one embodiment, a modular bearing system for blood pumps is provided that allows for different combinations of bearing design elements with unique novel advantages. The first bearing is a sleeve bearing (or equivalently, a journal bearing) that is uniquely designed to allow flow through the pump with minimal blockage. The other is a conical bearing. In some embodiments, one or more of these bearing designs can be used. In other embodiments, either bearing design can be used with an additional bearing design. In other embodiments, two bearing designs can be used together in a configuration that provides additional advantages.

[0010] The sleeve bearings can have modified geometries to reduce thrombosis. A variety of low thrombosis sleeve geometries are contemplated. The sleeve bearings can include additional features (e.g., thrust rings) that provide a degree of axial containment as well as radial containment.

[0011] The conical bearings described herein have a modified geometry that promotes thorough cleaning of the bearing surface by blood, which can be promoted by enhanced blood supply to the bearing area, enhanced removal of blood from the bearing area, or some combination thereof.

[0012] Sleeve bearings and conical bearings can have certain features that support their use in combination and provide inherent advantages that flow from these combinations.

[0013] In some embodiments, a blood flow assist system is disclosed. In some embodiments, the system consists essentially of an impeller assembly comprising a rotor assembly and an impeller coupled to the rotor assembly, the rotor assembly comprising a first curved bearing surface (e.g., a concave bearing surface) and a drive unit proximal to the impeller assembly, the drive unit comprising a drive magnet and a drive bearing between the drive magnet and the impeller assembly, the drive bearing comprising a second curved bearing surface (e.g., a convex bearing surface) shaped to mate with (e.g., fit within) the first curved bearing surface. In some embodiments, the first curved bearing surface comprises a fluid port. In some embodiments, the second bearing surface comprises a void (e.g., a central hollow) and one or more channels extending radially outward from the void. The void can be in fluid communication with the fluid port to direct blood radially outward along at least one channel. In some embodiments, the convex bearing surface has a distal end disposed distal to a proximal end of the rotor assembly. In some embodiments, the convex bearing surface includes a plurality of distally projecting segments, the plurality of distally projecting segments being circumferentially spaced apart to define at least one channel between adjacent segments.

[0014] In various illustrated embodiments, the rotor assembly can include a concave bearing surface and the drive bearing can include a convex bearing surface. However, it should be understood that in each embodiment disclosed herein, the rotor assembly can alternatively include a convex bearing surface and the drive bearing can include a concave bearing surface, with the convex bearing surface mating with (e.g., fitting within) the concave bearing surface. Furthermore, in embodiments in which the rotor assembly includes a convex bearing surface, the multiple segments can extend proximally (e.g., as opposed to extending distally) and can be circumferentially spaced to define at least one channel between adjacent segments.

[0015] In some embodiments, the rotor assembly includes an impeller shaft and a rotor magnet coupled to the impeller shaft, the impeller disposed on the impeller shaft. In some embodiments, the impeller assembly includes a second impeller disposed on the impeller shaft spaced proximally from the impeller along the impeller shaft. The flange can extend non-parallel from a proximal end portion of the impeller shaft, the second impeller including a plurality of vanes disposed on a generally proximally facing surface of the flange.

[0016] In some embodiments, the impeller is configured to pump blood along a first flow path along an outer surface of the impeller, and a majority of the blood flowing along the first flow path is directed along a longitudinal axis of the blood flow assistance system. In some embodiments, the system includes a second flow path through a lumen of the impeller shaft, and the second impeller is configured to direct blood from the second flow path radially outward relative to the longitudinal axis. In some embodiments, the inclined cavity extends inward and distally relative to a generally proximal-facing surface of the flange. In some embodiments, the drive unit comprises a convex member dimensioned to fit within the inclined cavity. In some embodiments, the system includes a sleeve bearing disposed about the impeller shaft at a location distal to the impeller. In some embodiments, in a cross section perpendicular to the axis of rotation of the impeller, the support surface of the sleeve bearing is disposed around only a portion of the circumference of the impeller shaft at the selected axial position, such that as the impeller shaft rotates about the axis of rotation, an outer surface of the impeller shaft at the selected axial position is cyclically exposed to blood during operation of the blood flow assist system. In some embodiments, the system includes a pump housing, and the impeller assembly is disposed at least partially within the pump housing. In some embodiments, the pump housing includes an outlet, and the outlet is disposed proximal to the impeller. In some embodiments, the second impeller is disposed proximal to a distal end of the outlet. In some embodiments, the system includes a support structure coupled to or formed with the pump housing, the support structure comprising struts configured to contact a vessel wall to maintain spacing of the pump housing from a vessel wall in which the pump housing is disposed. In some embodiments, the blood flow assist system comprises a percutaneous pump configured for percutaneous insertion into a treatment location within a patient's body. The motor can be mechanically coupled with a drive magnet and a power line connected to the motor, the power line extending proximally from the motor.

[0017] In some embodiments, a method of operating a blood flow assist system is disclosed that may include, or consist essentially of, delivering an impeller assembly percutaneously to a treatment location within a patient's blood vessel, the impeller assembly comprising a rotor assembly and an impeller coupled to the rotor assembly, the rotor assembly comprising a concave bearing surface, the blood flow assist system comprising a drive unit proximal to the impeller assembly, the drive unit comprising a drive magnet and a drive bearing between the drive magnet and the impeller assembly, the drive bearing comprising a convex bearing surface that fits within the concave bearing surface, the convex bearing surface comprising a plurality of distally projecting segments, the plurality of distally projecting segments being circumferentially spaced apart to define at least one channel between adjacent segments, pumping blood longitudinally along a length of the impeller assembly and radially outwardly through the at least one channel, and removing the impeller assembly from the patient. In some embodiments, the method includes directing blood radially outward between a drive unit and a second impeller disposed proximal to the impeller, the drive unit having a distal end disposed distal to the proximal end of the second impeller. In some embodiments, the method includes providing a relative motion between the impeller assembly and a sheath to cause the plurality of struts to self-expand radially outwardly to engage a wall of the blood vessel. In some embodiments, providing an opposite relative motion between the impeller assembly and the sheath to cause the plurality of struts to collapse within the sheath. In some embodiments, the rotor assembly includes an impeller shaft on which the impeller is disposed and a sleeve bearing disposed about the impeller shaft distal to the impeller, the method includes periodically exposing an outer surface of the impeller shaft to blood at a selected axial position. In some embodiments, the method includes providing electrical current to a motor via a power line, the motor operably connected to the impeller assembly, the power line extending outside the patient's body.

[0018] In some embodiments, a method of manufacturing a blood flow assist system is disclosed. In some embodiments, the method includes, or consists essentially of, providing an impeller assembly comprising a rotor assembly and an impeller coupled to the rotor assembly, the rotor assembly including a concave bearing surface, and providing a drive unit proximal to the impeller assembly, the drive unit including a drive magnet and a drive bearing between the drive magnet and the impeller assembly, the drive bearing including a convex bearing surface shaped to fit within the concave bearing surface, the convex bearing surface having a distal end disposed distal to the proximal end of the rotor assembly.

[0019] In some embodiments, providing the drive unit includes forming a plurality of distally projecting segments on the convex bearing surface, the plurality of distally projecting segments being circumferentially spaced to define at least one channel between adjacent segments. In some embodiments, the method includes disposing the impeller at least partially within the pump housing. In some embodiments, the method includes providing a support structure coupled to or formed with the pump housing, the support structure comprising struts configured to contact a vessel wall to maintain spacing of the pump housing from a vessel wall in which the pump housing is disposed. In some embodiments, the method includes providing a motor proximal to the impeller, the motor configured to impart rotation to the impeller. In some embodiments, the method includes connecting the motor to a power line extending proximally to the motor.

[0020] In some embodiments, a blood flow assist system is disclosed. In some embodiments, the blood flow assist system includes or consists essentially of an impeller assembly including an impeller shaft, a first impeller disposed on the impeller shaft, a second impeller disposed on the impeller shaft spaced proximally from the first impeller along the impeller shaft, and a drive unit configured to impart rotation to the impeller shaft, the drive unit having a distal end disposed distal to a proximal end of the second impeller. In some embodiments, the first impeller is configured to pump blood along a first flow path along an outer surface of the first impeller, and a majority of the blood flowing along the first flow path is directed along a longitudinal axis of the blood flow assist system. In some embodiments, the system includes a fairing disposed around the impeller shaft between the first impeller and the second impeller, and the first flow path is disposed along an angled outer surface of the fairing. In some embodiments, the system includes a second flow path through a lumen of the impeller shaft, and the second impeller is configured to direct blood from the second flow path radially outward relative to the longitudinal axis. In some embodiments, during operation of the blood flow assistance system, blood pumped along the second flow path flows between a proximal end portion of the impeller shaft and a distal end of the drive unit.

[0021] In some embodiments, the drive unit includes a drive magnet and a drive bearing between the drive magnet and the impeller assembly, the drive bearing includes a convex bearing surface having a plurality of distally projecting segments, the plurality of distally projecting segments being circumferentially spaced to define at least one channel between adjacent segments, and the secondary flow path includes at least one channel. In some embodiments, the system includes a flange extending non-parallel from a proximal end portion of the impeller shaft, the second impeller disposed with a plurality of vanes on a generally proximally facing surface of the flange. In some embodiments, the system includes an inclined cavity extending inwardly and distally relative to the generally proximally facing surface of the flange. In some embodiments, the drive unit includes a convex member dimensioned to fit within the inclined cavity. In some embodiments, the system includes a rotor magnet coupled to the impeller shaft, the rotor magnet disposed adjacent to a distally facing surface of the flange. In some embodiments, the system includes a sleeve bearing disposed about the impeller shaft at a location distal to the first impeller. In some embodiments, in a cross section perpendicular to the axis of rotation of the first impeller, the support surface of the sleeve bearing is disposed around only a portion of the circumference of the impeller shaft at the selected axial location, such that as the impeller shaft rotates about the axis of rotation, an outer surface of the impeller shaft at the selected axial location is cyclically exposed to blood during operation of the blood flow assist system. In some embodiments, the system includes a pump housing, and the impeller assembly is disposed at least partially within the pump housing. In some embodiments, the pump housing includes an outlet, and the outlet is disposed proximal to the first impeller. In some embodiments, the second impeller is disposed proximal to a distal end of the outlet. In some embodiments, the system includes a support structure coupled to or formed with the pump housing, the support structure comprising struts configured to contact a vessel wall to maintain spacing of the pump housing from a vessel wall in which the pump housing is disposed.In some embodiments, the first impeller comprises a plurality of axially aligned blades extending outwardly. In some embodiments, the kit includes a blood flow assist system comprising a motor assembly configured to impart rotation to the first impeller and the second impeller, and a power line electrically connected to the motor assembly. The kit can include a console configured to electrically connect to the power line. In some embodiments, the impeller shaft, the second impeller, and the flange form an integral rotor core, and the first impeller is attached to the impeller shaft. In some embodiments, the impeller shaft, the first impeller, the second impeller, and the flange form a unitary body.

[0022] In some embodiments, a blood pump is disclosed. In some embodiments, the blood pump includes or consists essentially of a primary impeller, a flow tube passing through the primary impeller, a rotatable part including a secondary impeller, a conical opening, and a flow tube, and a drive unit sealed by a drive unit cover, the drive unit cover including a conical member that conforms to the contour of the conical opening and fits inside the conical opening. In some embodiments, the drive unit includes a magnet sealed within the drive unit cover. In some embodiments, the drive unit includes a motor, and the magnet is rotatable by the motor. In some embodiments, the secondary impeller includes a plurality of vanes.

[0023] In some embodiments, a method of operating a blood flow assist system is disclosed. In some embodiments, the method includes or consists essentially of: delivering an impeller assembly percutaneously to a treatment location within a blood vessel of a patient, the impeller assembly comprising an impeller shaft, a first impeller disposed on the impeller shaft, and a second impeller disposed on the impeller shaft proximally spaced from the first impeller along the impeller shaft; pumping blood along a first flow path and a second flow path, the first flow path being disposed along an outer surface of the first impeller, a majority of blood flowing along the first flow path being directed along a longitudinal axis of the blood flow assist system, and the second flow path being disposed through a lumen of the impeller shaft, the second impeller directing blood from the second flow path radially outward relative to the longitudinal axis; and removing the blood flow assist system from the patient. In some embodiments, the method includes directing blood radially outward between the second impeller and a drive unit, the drive unit having a distal end disposed distal to the proximal end of the second impeller. In some embodiments, the method includes providing a relative motion between the impeller assembly and a sheath to cause the plurality of struts to self-expand radially outward to engage a wall of the blood vessel. In some embodiments, the method includes providing an opposing relative motion between the impeller assembly and the sheath to cause the plurality of struts to collapse within the sheath. In some embodiments, a sleeve bearing is disposed about the impeller shaft distal to the first impeller, and the method includes periodically exposing an outer surface of the impeller shaft to blood at a selected axial location. In some embodiments, the method includes providing electrical current to a motor via a power line, the motor operably connected to the impeller assembly, the power line extending outside the patient's body.

[0024] In some embodiments, a method of manufacturing a blood flow assist system is disclosed. In some embodiments, the method includes or consists essentially of: mounting a first impeller to an impeller shaft, where a flange is disposed at a proximal end of the impeller shaft, and providing a second impeller spaced proximally from the first impeller along the impeller shaft, where the second impeller is disposed on a proximally facing surface of the flange. In some embodiments, the method includes disposing the first impeller and the second impeller at least partially within a pump housing. In some embodiments, the method includes providing a support structure coupled to or formed with the pump housing, the support structure comprising a convex contact pad configured to contact a vessel wall to maintain spacing of the pump housing from a vessel wall in which the pump housing is disposed. In some embodiments, the method includes providing a motor proximal to the second impeller, where the motor is configured to impart rotation to the impeller shaft. In some embodiments, the method includes connecting the motor to a power line extending proximally relative to the motor, the motor sized for insertion into a patient's vasculature, and the power line configured to extend through the vasculature to a location outside the patient's body.

[0025] In some embodiments, a blood flow assist system is provided. In some embodiments, the system includes or consists essentially of an impeller (or a first impeller), a lumen extending through the first impeller along a longitudinal axis of the first impeller, a primary flow path along an outer surface of the first impeller, and a secondary flow path along the lumen. In some embodiments, the system includes an impeller assembly comprising an impeller shaft, the impeller disposed on the impeller shaft, the impeller shaft including a lumen extending from a distal end of the impeller shaft to a proximal end of the impeller shaft. In some embodiments, a drive unit is provided configured to impart rotation to the impeller shaft and the impeller, at least a portion of the drive unit being disposed proximal to the proximal end of the impeller shaft. In one embodiment, during operation of the blood flow assist system, blood is pumped proximally along the primary flow path and the secondary flow path. In some embodiments, the blood flow assist system includes a pump housing. In one embodiment, a primary flow path is also provided, disposed between an outer surface of the first impeller and the pump housing. For example, the primary flow path can be disposed between (and extending from) a radially outermost surface of the first impeller and an inner wall of the pump housing. In one embodiment, during operation of the blood flow assist system, blood pumped along the secondary flow path flows between a proximal end of the impeller shaft and the drive unit. In one embodiment, the drive unit comprises a drive magnet and a drive bearing between the drive magnet and the impeller assembly, the drive bearing comprising a convex bearing surface having a plurality of distally projecting segments, the plurality of distally projecting segments being circumferentially spaced apart to define at least one channel between adjacent segments, and the secondary flow path comprises at least one channel. In some embodiments, the second impeller is disposed on the impeller shaft proximally spaced apart from the first impeller along the impeller shaft. The blood flow assist system can include a flange at a proximal end of the impeller shaft, and the second impeller is disposed on a proximally-facing surface of the flange. In some embodiments, the impeller shaft, the second impeller, and the flange form an integral rotor core, and the first impeller is attached to the impeller shaft.In some embodiments, the impeller shaft, the first impeller, the second impeller, and the flange form a single body. In some embodiments, during operation of the blood flow assist system, blood pumped along the secondary flow path flows between a proximal end of the impeller shaft and the drive unit. In some embodiments, the kit can include a blood flow assist system further including a motor assembly configured to impart rotation to the impeller and a power line electrically connected to the motor assembly. The kit can include a console configured to electrically connect to the power line.

[0026] In some embodiments, a blood flow assist system is disclosed. In some embodiments, the blood flow assist system includes or consists essentially of a pump housing, an impeller assembly disposed within the pump housing, the impeller assembly comprising an impeller shaft and an impeller on the impeller shaft, the impeller shaft configured to rotate about an axis of rotation, and a sleeve bearing disposed around the impeller shaft distal to the impeller. In some embodiments, the sleeve bearing has an inner support structure supporting the impeller shaft, an outer support structure coupled to or formed with the pump housing, and a connecting structure extending radially between the inner support structure and the outer support structure. In some embodiments, the inner support structure comprises a distal boundary, the distal boundary being inclined with respect to the axis of rotation such that in a cross section taken perpendicular to the axis of rotation, only a portion of the distal boundary is disposed around the impeller shaft at a selected axial position along the axis of rotation, and as the impeller shaft rotates about the axis of rotation, an outer surface of the impeller shaft at the selected axial position is periodically exposed to blood during operation of the blood flow assist system. In some embodiments, in a cross section perpendicular to the axis of rotation, the support surface of the sleeve bearing is disposed only partially around the circumference of the impeller shaft at a selected axial position along the axis of rotation, such that as the impeller shaft rotates about the axis of rotation, an outer surface of the impeller shaft at the selected axial position is periodically exposed to blood during operation of the blood flow assist system. In some embodiments, at all axial positions along the axis of rotation along the length of the sleeve bearing, the support surface of the sleeve bearing is disposed only partially around the circumference of the impeller shaft. In some embodiments, at axial positions along the axis of rotation, the support surface of the sleeve bearing is disposed only partially around the circumference of the impeller shaft.In some embodiments, the system includes a drive unit configured to impart rotation to the impeller shaft, the drive unit including a drive magnet and a drive bearing between the drive magnet and the impeller assembly, the drive bearing including a convex bearing surface and a plurality of distally projecting segments extending from the convex bearing surface, the plurality of distally projecting segments circumferentially spaced apart to define at least one channel between adjacent segments.

[0027] In some embodiments, the support surface comprises a crenulated surface as shown in a side view of the sleeve bearing. In some embodiments, the support surface is disposed completely around the circumference of the impeller shaft at a second axial location along the axis of rotation. In some embodiments, the system includes a pump housing, the impeller assembly is disposed within the pump housing. In some embodiments, the system includes a support structure coupled with the pump housing, the support structure comprising struts configured to contact a vessel wall to maintain spacing of the pump housing from the vessel wall in which the pump housing is disposed. In some embodiments, the impeller is configured to pump blood along a first flow path along an outer surface of the impeller, and a majority of the blood flowing along the first flow path is directed along the axis of rotation. In some embodiments, the system includes a second impeller disposed on the impeller shaft spaced proximally from the impeller along the impeller shaft, the second impeller configured to direct blood from a second flow path within a lumen of the impeller shaft radially outward relative to the axis of rotation. In some embodiments, the system includes a flange extending non-parallel from a proximal end portion of the impeller shaft, and the second impeller is disposed on a generally proximally facing surface of the flange. In some embodiments, the kit includes a blood flow assist system including a motor assembly configured to impart rotation to the impeller and a power line electrically connected to the motor assembly. The kit can include a console configured to electrically connect to the power line.

[0028] In some embodiments, a blood pump is disclosed. In some embodiments, the blood pump includes or consists essentially of a pump rotor comprising a rotating member including a primary impeller and a flow tube that rotates the primary impeller about a rotation axis, and a sleeve bearing that fits around the pump rotor, the sleeve bearing comprising a bearing interface edge that is non-perpendicular to the rotation axis. In some embodiments, the bearing interface edge comprises a non-circular sleeve edge that ensures that no point on the rotating member remains aligned with the sleeve edge during rotation of the rotating member. In some embodiments, the sleeve bearing exposes at least one point on the rotating member over the entire height of the sleeve bearing such that the surface of the rotating member is covered by the sleeve bearing for only a portion of the rotation. In some embodiments, the bearing interface edge comprises an ellipse. In some embodiments, the bearing interface edge varies sinusoidally.

[0029] In some embodiments, a method of operating a blood flow assist system is disclosed. In some embodiments, the method includes or consists essentially of: delivering an impeller assembly percutaneously to a treatment location within a blood vessel of a patient, the impeller assembly being disposed within a pump housing, the impeller assembly including an impeller shaft and an impeller on the impeller shaft, the impeller shaft being configured to rotate about an axis of rotation, and a sleeve bearing being disposed about the impeller shaft; pumping blood through the blood flow assist system such that an outer surface of the impeller shaft is periodically exposed to blood at selected axial positions; and removing the impeller assembly from the patient. In some embodiments, at the selected axial positions along the axis of rotation, a support surface of the sleeve bearing is disposed only partially around an outer circumference of the impeller shaft. In some embodiments, the method includes directing blood longitudinally along a length of the impeller assembly and radially outward between a drive unit disposed proximal to the impeller and a second impeller, the drive unit having a distal end disposed distal to a proximal end of the second impeller. In some embodiments, the method includes retracting the sheath to cause the plurality of struts to self-expand radially outwardly to engage a wall of the blood vessel.

[0030] In some embodiments, a method of manufacturing a blood flow assist system is disclosed. In some embodiments, the method includes or consists essentially of: disposing an impeller assembly disposed within a pump housing, the impeller assembly comprising an impeller shaft and an impeller on the impeller shaft, the impeller shaft configured to rotate about an axis of rotation; and disposing a sleeve bearing around the impeller shaft, where at an axial position along the axis of rotation, a support surface of the sleeve bearing is disposed only partially around an outer circumference of the impeller shaft. In some embodiments, the method includes providing a drive unit proximal to the impeller assembly, the drive unit comprising a drive magnet and a drive bearing between the drive magnet and the impeller assembly, the drive bearing comprising a convex bearing surface shaped to fit within the concave bearing surface. In some embodiments, providing the drive unit includes forming a plurality of distally projecting segments in the convex bearing surface, the plurality of distally projecting segments being circumferentially spaced apart to define at least one channel between adjacent segments. In some embodiments, the method includes providing a support structure coupled to or formed with the pump housing, the support structure comprising struts configured to contact a vessel wall to maintain spacing of the pump housing from a vessel wall in which the pump housing is disposed. In some embodiments, the method includes providing a motor proximal to the impeller, the motor configured to impart rotation to the impeller. In some embodiments, the method includes connecting the motor to a power line extending proximally to the motor.

[0031] In some embodiments, a blood flow assist system is disclosed comprising an impeller shaft, an impeller on the impeller shaft, a primary flow path disposed along an outer surface of the impeller, a rotor assembly at a proximal portion of the impeller shaft, the rotor assembly comprising a concave bearing surface, a flange disposed about the concave bearing surface, a rotor magnet supported by the impeller shaft, and a second impeller disposed on a proximal-facing surface of the flange, the secondary flow path being disposed along a lumen of the impeller shaft, during operation of the blood flow assist system, blood is pumped proximally along the primary and secondary flow paths, and a sleeve bearing disposed distal to the impeller, the sleeve bearing being configured to rotate around the outer surface of the impeller shaft at selected axial positions during rotation of the impeller shaft. The blood flow assist system may include, or consist essentially of, a sleeve bearing disposed about the impeller shaft such that a surface of the impeller shaft is periodically exposed to blood during operation of the blood flow assist system, and a drive unit having a distal end disposed distal to a proximal end of the second impeller, the drive unit comprising a drive magnet and a drive bearing between the drive magnet and the impeller assembly, the drive bearing comprising a convex bearing surface shaped to fit within the concave bearing surface and a plurality of distally projecting segments, the plurality of distally projecting segments being circumferentially spaced to define at least one channel between adjacent segments, the drive unit configured to cause the drive magnet to impart rotation to the rotor magnet and the impeller shaft. In some embodiments, the kit includes a blood flow assist system comprising a motor assembly configured to impart rotation to the impeller and a power line electrically connected to the motor assembly. The kit may include a console configured to electrically connect to the power line. In some embodiments, the blood flow assist system includes a percutaneous pump configured for percutaneous insertion into a treatment location within a patient's body.

[0032] In some embodiments, a blood flow assist system is disclosed. In some embodiments, the blood flow assist system includes or consists essentially of a pump configured for percutaneous insertion into a treatment location on a patient, an elongate body extending proximally from the pump, and a retrieval mechanism between a proximal curved portion of the pump and the elongate body, the retrieval mechanism comprising an enlarged portion and a neck portion between the enlarged portion and the proximal curved portion of the pump. In some embodiments, the enlarged portion comprises a first curved portion having a first radius of curvature and a second curved portion having a second radius of curvature different from the first radius of curvature. In some embodiments, a first plane extending parallel to a longitudinal axis of the blood flow assist system and intersecting the first curved portion defines a first angle between the proximal curved portion and the first curved portion, and a second plane extending parallel to the longitudinal axis and intersecting the second curved portion defines a second angle between the proximal curved portion and the second curved portion, the second angle being different from the first angle. In some embodiments, the upset portion comprises a plurality of lobes extending radially outward. In some embodiments, the pump comprises a pump head and a motor housing coupled to the pump head, a proximal end portion of the motor housing comprising a proximal curve. In some embodiments, the pump head comprises a pump housing and an impeller within the pump housing, the motor housing including a motor operably coupled to the impeller. In some embodiments, the neck portion comprises a first depth at a first circumferential location of the retrieval mechanism and a second depth less than the first depth at a second circumferential location of the retrieval mechanism spaced from the first circumferential location. [Brief description of the drawings]

[0033] These and other features, aspects, and advantages are described below with reference to the drawings, which are for illustrative purposes and should not be construed as limiting the scope of the embodiments in any way. Furthermore, various features of different disclosed embodiments can be combined to form additional embodiments that are part of this disclosure. In the drawings, like reference characters indicate corresponding features consistently throughout like embodiments. Each of the figures will now be briefly described.

[0034] [Figure 1A] 1 is a schematic perspective, partially exploded view of a blood flow assist system according to various embodiments. FIG.

[0035] [Figure 1B] FIG. 1B is a schematic perspective view of a pump in the distal portion of the blood flow assist system of FIG. 1A.

[0036] [Figure 1C] FIG. 1C is a schematic perspective, partially exploded view of the pump of FIG.

[0037] [Figure 1D] FIG. 1 is a schematic side view of a pump disposed in a folded configuration within a delivery sheath.

[0038] [Figure 1E] FIG. 13 is a schematic perspective view of a retrieval mechanism used to remove the pump, according to some embodiments.

[0039] [Figure 2A] FIG. 1 is a schematic perspective view of a modified sleeve bearing disposed about an impeller shaft distal to the impeller of an impeller assembly;

[0040] [Figure 2B] FIG. 2B is a schematic front plan view of the sleeve bearing of FIG. 2A.

[0041] [Figure 2C] FIG. 2C is a schematic side perspective view of the sleeve bearing of FIG. 2B.

[0042] [Figure 2D] FIG. 2B is a schematic front plan view of the sleeve bearing and impeller assembly of FIG. 2A.

[0043] [Figure 2E] FIG. 2E is a schematic cross-sectional side view of the impeller assembly and sleeve bearing of FIG. 2D.

[0044] [Figure 2F] 1 is a schematic cross-sectional side view of a non-overlapping sleeve assembly according to another embodiment.

[0045] [Figure 2G] FIG. 1 is a schematic perspective view of a sleeve bearing having a small sawtooth pattern.

[0046] [Figure 2H] FIG. 2C is a schematic plan view of the sinusoidal pattern of the sleeve bearing of FIG. 2G.

[0047] [Figure 3A] 1 is a schematic perspective view of a drive bearing according to various embodiments; FIG.

[0048] [Figure 3B] FIG. 3B is a front end view of the drive bearing of FIG. 3A.

[0049] [Figure 3C] FIG. 3B is a side view of the drive bearing of FIG. 3A.

[0050] [Figure 3D] FIG. 13 is a schematic front view of a drive bearing according to another embodiment.

[0051] [Figure 3E] FIG. 13 is a schematic front view of a drive bearing according to another embodiment.

[0052] [Figure 4A] FIG. 1 is a schematic perspective view of a one-piece rotor core including an impeller shaft with a flow tube and a secondary impeller.

[0053] [Figure 4B] FIG. 4B is a schematic perspective view of a proximal portion of the unitary rotor core of FIG. 4A.

[0054] [Figure 4C] FIG. 4C is a cross-sectional view taken along the longitudinal axis of the rotor core of FIG. 4B.

[0055] [Figure 4D] FIG. 4D is a schematic proximal end view of the unitary rotor core of FIG. 4C.

[0056] [Figure 5A] FIG. 1 is a schematic perspective exploded view of a segmented conical bearing including a proximal portion of a one-piece rotor core and a drive bearing.

[0057] [Figure 5B] FIG. 13 is a cross-sectional distal end view of the secondary impeller and drive bearing.

[0058] [Figure 6] 1 is a schematic perspective exploded view of a blood flow assistance system according to various embodiments. FIG.

[0059] [Figure 7] 1 is a schematic cross-sectional side view of a pump according to various embodiments.

[0060] [Figure 8A] 1 is a schematic cross-sectional side view of a motor housing according to various embodiments.

[0061] [Figure 8B] FIG. 2 is a schematic perspective view of a motor and a motor mounting support.

[0062] [Figure 8C] FIG. 2 is a schematic perspective view of a distal end of a power line for supplying power to a motor.

[0063] [Figure 8D] FIG. 2 is a schematic perspective view of a proximal end portion of a power line.

[0064] [Figure 9A] 1 is a schematic cross-sectional side view of primary and secondary flow paths through a pump in accordance with various embodiments. [Figure 9B] 1 is a schematic cross-sectional side view of primary and secondary flow paths through a pump in accordance with various embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0065] Referring now to the drawings, the elements depicted are not necessarily drawn to scale, and like or similar elements are designated by the same reference numerals throughout the several views. Referring generally to the drawings, it will be understood that the illustrations are for illustrating certain embodiments of the present disclosure and are not intended to be limiting thereto. It will be understood that while most of the terms used herein are recognizable to those skilled in the art, unless expressly defined, the terms should be interpreted to adopt the meaning currently accepted by those skilled in the art.

[0066] I. Overview of the Blood Flow Support System Various embodiments disclosed herein relate to a blood flow assist system 1 configured to provide circulatory support to a patient, as shown in FIGS. 1A-1D. The system 1 can be sized for intravascular delivery to a treatment location within the patient's circulatory system, for example, a location within the patient's descending aorta. As shown in FIG. 1A, the system 1 can have a proximal end 21 having a connector 23 configured to connect to an external control system, for example, a console (not shown). The connector 23 can provide electrical communication between the control system and a power line 20 extending distally from the connector 23 and the proximal end 21 along a longitudinal axis L. The power line 20 can comprise an elongated body that electrically and mechanically connects to a pump 2 at or near a distal end 22 of the blood flow assist system 1, the distal end 22 being spaced apart from the proximal end 21 along the longitudinal axis L.

[0067] The pump 2 can include a pump head 50 including a pump housing 35 connected to a drive unit 9 including a motor housing 29. A retrieval mechanism 48 can be provided at a proximal end portion of the pump 2. In some embodiments, the retrieval mechanism can be coupled to a distal end of the power line 20 between the power line 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, clamp, hook, etc.) with the retrieval mechanism 48 and withdrawing the pump 2 from the patient. For example, the retrieval mechanism 48 can include a neck portion 49 (e.g., a reduced diameter portion) at a proximal curved portion 51c of the motor housing 29 and an enlarged diameter portion disposed proximal to the neck portion 49. The enlarged diameter portion can include a first curved portion 51a and a second curved portion 51b as shown in FIG. 1E. The first and second curved portions 51a, 51b can include convex surfaces, 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. 1E, the first curved portion 51a can have a larger radius of curvature than the second curved portion 51b. In some embodiments, the first curved portion 51a can be disposed on either side of the retrieval mechanism 48. 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 line 20. The neck portion 49 can have a first depth at a first circumferential position of the retrieval mechanism 48 and a second depth at a second circumferential position of the retrieval mechanism 48 spaced from the first circumferential position that is less than the first depth.

[0068] Beneficially, as shown in FIG. 1E, one or more first planes P1 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 (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 (almost monotonically decreasing) geometric transition between the proximal curved portion 51c of the motor housing 29 and the power line 20, which can provide smooth blood flow and reduce the risk of thrombosis. The second curved portion 51b can function as a lobe extending radially outward, e.g., radially outward from the first curved portion 51a. The second curved portion 51b can be used to engage a retrieval device or snare to remove the pump 2 from the anatomy. Some cross sections through the longitudinal axis of the retrieval mechanism 48 can include 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 mechanism 48 can include a non-substantial local minimum or no local minimum. In the illustrated embodiment, there are two first curved portions 51a that can function as a dual lobe retrieval mechanism. In other embodiments, more or fewer lobes can be provided to allow pump retrieval while ensuring a smooth flow transition between the motor housing 29 and the power lines 20.

[0069] As shown in FIGS. 1B-1C and 1E, the neck portion 49 can be disposed between the curved portions 51a, 51b and the proximal convex surface 51c of the motor housing 29. In the illustrated embodiment, the retrieval mechanism 48 can be coupled to or integrally formed with the motor housing 29. In other arrangements, the retrieval mechanism 48 can be disposed at other locations on the pump 2. As shown, the retrieval mechanism 48 can be symmetrically and sequentially disposed about the longitudinal axis L. In other configurations, the retrieval mechanism 48 can include multiple distinct surfaces spaced circumferentially and / or longitudinally.

[0070] In the illustrated embodiment, the motor housing 29 (and motor) may be part of the pump 2 and may be located inside the vasculature of the patient during use. However, in other embodiments, the motor housing 29 (and motor) may be located outside the patient and a drive cable may be connected to the impeller 6.

[0071] As shown in FIGS. 1A-1C, the drive unit 9 can be configured to impart rotation to the impeller assembly 4 disposed within the pump housing 35 of the pump head 50. As described herein, the drive unit 9 can include a drive magnet 17 and a motor 30 disposed within a motor housing 29 covered by a distal drive unit cover 11 (see FIGS. 6-8A). The drive unit cover 11 can be formed by or coupled to a drive bearing 18. The drive magnet 17 can be magnetically coupled to a corresponding driven or rotor magnet 12 (see FIG. 7) of the impeller assembly 4 disposed within a shroud 16 proximal to the impeller 6. A power line 20 can extend from the treatment location outside the patient's body and can provide power (e.g., current) and / or control to the motor 30. Thus, in some embodiments, the rotating drive shaft does not extend outside the patient's body. As described herein, the power lines 20 can excite the motor 12, which can rotate the drive magnet 17 about a longitudinal axis L, which can serve as, be aligned with, or correspond to the axis of rotation. Rotation of the drive magnet 17 can impart rotation of the rotor magnet 12 and the primary or first impeller 6 of the impeller assembly 4 about the longitudinal axis L. For example, as described herein, the rotor magnet 12 can rotate the impeller shaft 5 (which can serve as a flow tube), which in turn can rotate the first impeller 6 to pump blood. In other embodiments, the drive unit 9 can include a stator or other fixed magnetic device. The stator or other magnetic device can be energized, for example, with alternating current, to impart rotation to the rotor magnet 12. In the illustrated embodiment, the impeller 6 can have one or more 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 may have a plurality (e.g., two) axially aligned blades 40 extending radially outward from a common hub and having a common length along the longitudinal axis L.The curvature and / or overall profile can be selected to improve flow rate and reduce shear stress. Those skilled in the art will appreciate that other designs for the first impeller 5 may be suitable.

[0072] As shown in FIGS. 1A-1C, the impeller assembly 4 can be disposed within 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, can include a base 36 coupled with the sleeve bearing 15 and / or the shroud 16. In some embodiments, the base 36, the sleeve bearing 15, and / or the shroud 16 can be welded to one another. The base 36, the sleeve bearing 15, and the shroud 16 of the support structure or localization system can cooperate to at least partially define a pump housing 35, as shown in FIGS. 1A and 1C. The localization system can include a plurality of self-expanding struts 19 having convex contact pads 24 configured to contact a vessel wall to maintain spacing of the pump housing 35 from the vessel wall in which the pump housing 35 is disposed. In Figures 1A-1C, the struts 19 of the localization system are shown in an expanded deployed configuration, with the contact pads 24 extending radially outward to a position where the contact pads 24 contact the blood vessel wall, and within which the pump 2 is positioned to at least partially control, e.g., fix, the position and / or orientation of the pump 2 during operation of the system 1.

[0073] The first fluid port 27 can be provided distal to the impeller assembly 4 at the distal end of the pump housing 35. The shroud 16 can include a proximal ring 26 coupled to 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) to the proximal ring 26. As shown in FIG. 1C, the second fluid ports 25 can include openings formed between axially extending members 60 extending along the longitudinal axis L between the proximal ring 26 and the cylindrical section 59 of the shroud 16. In some embodiments, the axially extending members 60 (also referred to as pillars) can be shaped to function 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 or curved to match the profile of the impeller blades 40. 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 may comprise an inlet port through which blood enters. In such embodiments, the impeller assembly 4 may draw blood into the first fluid port 27 and may expel blood from the pump 2 via the second fluid port 25, which may function as an outlet port. However, in other embodiments, the direction of blood flow may be reversed, in which case the second fluid port 25 may function as a fluid inlet and the first fluid port 27 may function as a fluid outlet.

[0074] Beneficially, the blood flow assist system 1 can be delivered percutaneously to a treatment location on a patient. FIG. 1D shows the pump 2 disposed within an elongated sheath 28. As shown, the struts 19 are held in a folded configuration by the inner wall of the sheath 28. In the folded configuration, the struts 19 can be compressed to a diameter or major transverse dimension in one or more locations that is approximately the same as (or slightly smaller than) the diameter of the shroud 16. The patient can be prepared for the procedure in a catheter lab in standard fashion, and the femoral artery can be exposed. The sheath 28 (or a dilator structure within the sheath 28) can be passed over a guidewire and positioned at the treatment location, for example, in the descending aorta. After the sheath 28 is positioned, the pump 2 can be advanced within the sheath 28, and the pump 2 can be positioned in the mid-thoracic aorta approximately 4 cm below the takeoff of the left subclavian artery. In other embodiments, the pump 2 and the sheath 28 can be advanced together to the treatment location. Placing the pump 2 in this position can beneficially allow for adequate cardiac assistance as well as increased perfusion of other organs such as the kidneys. Once in the treatment position, relative motion can be provided between the sheath 28 and the pump head (e.g., the sheath 28 can be retracted relative to the pump 2 or the pump 2 can be advanced from the sheath 28). The struts 19 of the localization system can self-expand radially outward along the radial axis R due to stored strain energy to the deployed and expanded configuration shown in Figures 1A-1C. The convex contact pads 24 can engage the vessel wall to stabilize (e.g., anchor) the pump 2 within the patient's vasculature. Once secured in the treatment position, the clinician can engage the control system to activate the motor 30 to rotate the impeller assembly 4 to pump blood.

[0075] Thus, in some embodiments, the pump 2 can be inserted into the femoral artery and advanced to a desired treatment location within the descending aorta. In such a configuration, the pump 2 can be positioned such that the distal end 22 is upstream of the impeller 6, e.g., the distally located first fluid port 27 is upstream of the second fluid port 25. In embodiments accessing a treatment location via the femoral artery, the first fluid port 27 can serve as an inlet to the pump 2 and the second port 25 can serve as an outlet for the pump 2. However, in other embodiments, the pump 2 can be inserted percutaneously through the left subclavian artery and advanced to a desired treatment location within the descending aorta. In such a configuration, the pump 2 can be positioned such that the distal end 22 of the system 1 is downstream of the impeller 6, e.g., the distally located first fluid port 27 is downstream of the second fluid port 25. In an embodiment in which the treatment location is accessed via the left subclavian artery, the second fluid port 25 can function as an inlet to the pump 2 and the first port 27 can function as an outlet for the pump 2.

[0076] Once the procedure is complete, the pump 2 can be removed from the patient. An opposite relative motion 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) than that used to deploy the pump 2 to collapse the struts 19 within the sheath 28 in a collapsed configuration. In some embodiments, the pump 2 can be withdrawn from the sheath 28 with the sheath 28 inside the patient's body, and then the sheath 28 can be removed. In other embodiments, the sheath 28 and the pump 2 can be removed together from the patient's body.

[0077] II. Modified Sleeve Bearing As mentioned above, in some embodiments, the sleeve bearing 15 can support the distal end portion 5A of the impeller shaft 5, which can support the first impeller 6 and can also function as a flow tube. The design can generally be described in terms of the central axis of rotation of the impeller assembly 4 being oriented along the longitudinal axis L of the system 1, e.g., in some cases vertically for purposes of description. As used herein, the proximal and distal ends (or ends) of components may be axially spaced apart along the longitudinal axis L of the system 1. Thus, the sleeve bearing 15 can be described interchangeably in terms of an associated length or height extending along the longitudinal axis L. Generally, a rotating member (such as a shaft or tube, such as the impeller shaft 5 shown and described herein) that rotates inside a tubular sleeve or bearing has a bearing surface that is cylindrically shaped as an open right cylinder. This standard bearing design has circular proximal and distal edges (e.g., upper and lower interface edges) that are perpendicular to the longitudinal axis L of the rotating member or shaft, and a cylindrical bearing surface between the edges that is covered by the bearing body and remains unexposed. In addition, there is a circular set of points where the rotating member (e.g., shaft 5) and the bearing contact one another, which may be referred to herein as the bearing interface or interface edge. In other words, any point on this circle on the rotating member will always be aligned perpendicularly with the edge of the sleeve. This condition has been shown to promote clot formation at the sleeve edge. This clot can grow to form a complete ring around the sleeve edge, thereby preventing proper operation.

[0078] The modified sleeve bearing 15 design described herein has a novel design to reduce or prevent thrombus formation during operation. With reference to FIGS. 2A-2E, one embodiment of such a sleeve bearing 15 is shown. The sleeve bearing 15 can comprise an inner support structure including an inner sleeve 37 that supports the distal portion 5A of the impeller shaft 5. The inner sleeve 37 can be mechanically coupled to the first impeller 6, for example, by a thrust ring bearing 14 (see FIG. 6), in some embodiments. In one embodiment, the thrust bearing 14 can be laser welded to the inner sleeve 37. In other embodiments, there may be no thrust bearing 14 between the first impeller 6 and the inner sleeve 37. The sleeve bearing 15 can further comprise an outer support structure including an outer annular or cylindrical member, sometimes referred to herein as an outer sleeve or outer bearing carrier 38, connected to the shroud 16. The outer sleeve or bearing carrier 38 can comprise a small radially outer portion of the sleeve bearing 15. The connecting structure 39 may extend radially between the inner sleeve 37 and the outer bearing carrier 38 to connect the inner sleeve 37 and the outer bearing carrier 38. In a variation, the connecting structure 39 may be directly coupled to the shroud 16. In one embodiment, the outer bearing carrier 38 may be omitted. The outer bearing carrier 38 may be integral to or part of the shroud 16 such that the structure is monolithic and not an assembly of multiple parts. In other variations, the connecting structure 39 may be indirectly coupled to the shroud 16 via a structure other than the annular member or bearing carrier 38.

[0079] As described herein, the pump 2 may have a primary or first flow path 3A. Blood may flow along the first flow path 3A between the outer bearing carrier 38 and the inner sleeve 37 and along the outer surface of the first impeller 6. A majority of the blood flow through the pump 2 (e.g., a majority of the momentum of the total blood flow) may flow along the primary or first flow path 3A. The first flow path 3A may extend radially between the rotating first impeller 6 and the stationary pump housing 35. Thus, blood may flow on the rotating outermost surface of the first impeller 6 between the first impeller 6 and the stationary inner wall of the pump housing 35. The pump 2 may also have a secondary or second flow path 3B along the lumen of the impeller shaft 5, which may function as a flow tube as described herein. A portion of the total blood flow may flow along the secondary flow path 3B. For example, in some embodiments, the volumetric flow rate of blood along the secondary flow path 3B can be in the range of 0.5% to 10% of the volumetric flow rate of blood along the primary flow path 3A, in the range of 1% to 5% of the volumetric flow rate of blood along the primary flow path 3A, or in the range of 2% to 3% of the volumetric flow rate of blood along the primary flow path 3A.

[0080] As shown in FIGS. 2A, 2C, and 2E, the inner sleeve 37 can have a bearing interface 41 extending between a proximal edge 37B (or "lower edge" when viewed vertically) and a distal edge 37A (or "upper edge" when viewed vertically) spaced apart from the proximal edge 37B along the longitudinal axis L. The sleeve bearing 15 can be shaped such that one or more of the bearing interfaces 41 and / or mating edges (37A, 37B) of the inner sleeve 37 are not perpendicular to the axis of rotation or longitudinal axis L of the sleeve bearing 15. In one embodiment, the bearing interface 41 can include edges 37A, 37B that form an inclined or tapered ellipse relative to the longitudinal axis L of the sleeve bearing 15 (FIGS. 2A-2E). In another embodiment, as described below, the bearing surface 41 can be sinusoidally varying to form a crenulated edge (see FIG. 2F). These or other shapes resulting in non-circular sleeve edges 37A, 37B ensure that there is no point on the rotating member or impeller shaft 5 that remains aligned with the sleeve edges 37A, 37B during rotation of the rotating member (e.g., shaft 5), thereby minimizing the possibility of thrombus formation. Whereas in conventional designs the entire right cylinder remains covered, the modified sleeve bearing 15 exposes at least one point on the rotating member or shaft 5 over the entire length of the sleeve bearing 15 (or height, if the sleeve bearing is viewed as vertically oriented), so that the rotating member-bearing interface 41 is covered by the sleeve bearing for only a portion of the rotation. Thus, the interface bearing surface 41 can have a better exchange of a lubricating layer of blood than conventional designs.

[0081] Thus, in some embodiments, the distal edge 37A can include the distal boundary of the inner sleeve 37. The distal boundary (e.g., the distal edge 37A) can be inclined with respect to the axis of rotation (aligned with the longitudinal axis L) such that, in a cross section perpendicular to the axis of rotation, only a portion of the distal boundary (e.g., the distal edge 37A) is disposed around the impeller shaft 5 at a selected axial position L along the axis of rotation. In some embodiments, only a portion of the proximal boundary can be disposed around the impeller shaft 5 at a selected axial position along the axis of rotation. For example, as shown in FIG. 2E, the bearing interface 41 can have exposed axial regions 42A, 42B that include axial positions where the outer surface 5′ (see FIG. 2A) of the impeller shaft 5 is periodically exposed to blood flowing along the first flow path 3A. In the exposed axial regions 42A, 42B, the bearing interface 41 is disposed around only a portion of the circumference (e.g., circumference) of the impeller shaft 5. Thus, as the impeller shaft 5 rotates about its axis of rotation (aligned with the longitudinal axis L), the outer surface of the impeller shaft 5 at selected axial locations within the exposed axial regions 42A, 42B is periodically exposed to the blood flow in the first pathway 3A during operation of the blood flow assistance system 1.

[0082] In some embodiments, such as shown in FIGS. 2A-2E, the inner sleeve 37 may partially axially overlap along the longitudinal axis L. As shown in FIG. 2E, for example, in an exemplary overlapping cross-sectional plane 43, the bearing surface 41 of the inner sleeve 37 may be disposed completely around the outer surface of the impeller shaft 5 such that the outer surface 5′ of the shaft 5 at that overlapping cross-sectional plane 43 is not exposed to blood flow in the first passageway 3A. For example, in some embodiments, the sleeve bearing 15 may have a length along the longitudinal axis L. The inner sleeve 37 may partially overlap by an amount ranging from 1% to 50% of the length of the sleeve bearing 15, ranging from 5% to 50% of the length of the sleeve bearing 15, ranging from 10% to 50% of the length of the sleeve bearing 15, ranging from 20% to 40% of the length of the sleeve bearing 15, or ranging from 25% to 35% of the length of the sleeve bearing 15 (e.g., in some embodiments, about 30% of the length of the sleeve bearing 15).

[0083] In other embodiments, as shown in FIG. 2F, the sleeve bearing 15A can include a non-overlapping inner sleeve 37 such that no point on the outer surface 5′ of the impeller shaft 5 remains covered by the bearing interface 41 during rotation of the impeller shaft 37. In FIG. 2F, all axial positions along the length of the inner sleeve 37 include exposed axial regions 42, such that the bearing surface 41 of the inner sleeve 37 is only partially disposed around the circumference of the impeller shaft 5 at all axial positions along the length of the inner sleeve 37. For example, the edges 37A, 37B can include non-circular edges that ensure that no point on the rotating member or shaft 5 remains aligned with the sleeve edges 37A, 37B throughout the entire rotation of the rotating member or shaft 5. Thus, the sleeve bearing 15A can expose at least one point on the rotating member or shaft 5 over the entire length (or height) of the sleeve bearing 15A such that the outer surface 5′ of the shaft 5 is covered by the inner sleeve 37 for only a portion of the rotation.

[0084] Thus, in some embodiments, the bearing edges 37A, 37B are shaped such that the maximum length (or height) of the lower or proximal edge 37B exceeds the minimum length (or height) of the upper or distal edge 37A at one or more locations (FIGS. 2E and 3F) around the circumference of the inner sleeve 37. In these embodiments, there is at least one point on the bearing interface 41 throughout the length (or height) of the bearing interface 41 that is exposed and not covered by the inner sleeve 37 of the sleeve bearing 15, 15A. In other words, the sleeve bearing 15, 15A does not cover 360° of the rotating member or shaft 5 throughout the entire length or height of the bearing interface area 41. This interrupted contact of the disclosed embodiments promotes the exchange of a lubricating layer of blood throughout the bearing interface 41 and does not allow blood to stagnate or become trapped.

[0085] In some embodiments, the inclination or taper of the sleeve edges 37A, 37B relative to the longitudinal axis L (and axis of rotation) can also create or enhance hydrodynamic forces that contribute to proper bearing operation and reduce contact and wear of the bearing components. As one non-limiting example, fluid near the surface of a particular spot on the rotating member (e.g., shaft 5) can experience increases and decreases in pressure as it travels under and out of the inner sleeve 37. These pressure changes contribute to the formation and distribution of a lubricant layer.

[0086] The interface between the sleeve bearing 15, 15A and the rotating member (e.g., shaft 5) is lubricated by blood. Depending on the geometry, materials used, and operating conditions, this lubrication can be hydrodynamic, elastohydrodynamic, boundary, or mixed. Various exposures of the rotating member surface and / or various edge profiles of the sleeve support edges 37A, 37B can be designed to help promote fluid wedging to improve lubrication. As a non-limiting example, viscous drag from a surface patch of the rotating member or shaft 5 can increase fluid pressure above the sleeve edges 37A, 37B as they rotate beneath it. In some embodiments, the cross section of the inner bearing surface 41 of the sleeve 37 can be optionally non-circular to aid in the generation of wedge pressure, for example, by varying the wall thickness of the inner sleeve 37. The sleeve edge profile of the edges 37A, 37B can be angled or rounded to enhance this pressure generation.

[0087] 2G and 2H show another example of a sleeve bearing 15B having a non-overlapping design. The sleeve bearing 15B comprises a crenulated bearing in which the bearing interfaces 41 are arranged in a repeating, wavy, or possibly sinusoidal pattern 44 about the longitudinal axis L. The sinusoidal pattern 44 can have alternating exposed gaps around the circumference of the impeller shaft 5 during rotation such that all axial positions along the length of the sleeve bearing 15B are periodically exposed to blood flow during operation of the system 1. FIG. 2G shows that the inner sleeve 37′ can have a wavy pattern with multiple (e.g., two) distal peaks 61 and multiple (e.g., two) proximal peaks 62. For example, as shown in FIG. 2G, the peaks 61, 62 can be substantially flat with an arcuate portion 64 extending between the peaks 61, 62. The gaps 63 between the arcuate portions 64 can provide periodic exposure of the shaft 5 to blood flow. Thus, during rotation, the shaft 5 can transition from being covered by the arcuate portion 64 to being uncovered and exposed through the gap 63. In other variations, there can be more than two peaks in the wavy pattern of the sleeve 37'. FIG. 2H shows an inner sleeve 37'' with another crenellated structure, for example having a sinusoidal pattern with curved peaks 61, 62. In some configurations, the use of curved peaks 61, 61 (as opposed to sharp or flat peaks) can advantageously allow for a smoother flow profile.

[0088] The rotating member 5 and the sleeve bearings 15, 15A, 15B, respectively, can be made of any suitable blood-compatible material. As a non-limiting example, the rotating member (e.g., impeller shaft 5) may comprise a flow tube made of a biocompatible polymer, e.g., PEEK or polyethylene, and / or the sleeve bearings 15, 15A, 15B may be made of a metal, e.g., titanium or stainless steel. Making the rotating member or shaft 5 as a plastic tube can expand the range in which elastohydrodynamic lubrication exists. For example, the use of a material that allows for elastic deformation of the material during operation can provide an improved pressure profile.

[0089] III. Modified Conical Bearings As shown in FIGS. 1A, 1C and 6, the drive unit 9 can include 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, the driven or rotor magnet 12, and the rotor assembly 46 including the integral rotor core 8 including the impeller shaft 5 and the secondary impeller 7, as shown in FIG. 6. In various embodiments, the drive bearing 18 can include a segmented conical bearing. The conical bearing can include a convex (e.g., generally conical) member 45 that seats inside a generally concave (e.g., conical) opening 32 or cavity in the rotor assembly 46. The concave opening 32 can function as a concave bearing surface sized and shaped to mate with the convex member 45. The concave opening 32 can include a sloped concave cavity sized to receive the convex member 45. The drive unit 9 may comprise a convex member sized to fit within the angled cavity of the recessed opening 32 .

[0090] The bearing interface area of ​​this bearing design can be formed by the mating surfaces of the conical or convex member 45 and the conical or concave opening 32 and the space between them. The conical bearing can provide both axial and radial containment. The axial restriction from a single conical bearing can be in only one direction. A steep conical bearing provides relatively greater radial containment and a shallow conical bearing provides relatively greater axial containment. In some embodiments, the conical 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 with the axis (or axis of rotation) of the cone to remove the base of the cone. In some embodiments, the conical member 45 can be truncated by a plane perpendicular to the axis of the cone (forming a frustum or frustum-shaped 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 can be modified in a similar manner along with or instead of the conical member 45. One or the other or both of the surfaces of the conical member 45 and the conical opening 32 may also be modified with holes, gaps, channels, grooves, bumps, ridges, and / or protrusions. Each of the surfaces of the conical member 45 and the conical opening 32 may also be formed as part of another component of the pump having any overall shape.

[0091] Given the general possibility of holes, grooves, channels, or gaps in either the conical member 45 and / or the conical opening 32, any of those surfaces may comprise a plurality of separate bearing surfaces within the generally conical plane that defines the member 45 or the opening 32. In this manner, the opening 32 and / or the conical member 45 of the bearing pair may be formed by a plurality of separate or segmented surfaces. The multiple separate or segmented surfaces that make up either the conical member 45 or the conical opening 32 of the bearing pair may extend from the same component or part, or may extend from separate components or parts. The grooves and gaps in either the conical member 45 and / or the conical opening 32 may be formed by removing material from a single generally conical surface, or by using a plurality of separate surfaces.

[0092] In some embodiments of the modified conical bearing, the conical member 45 of the bearing pair can include a convex bearing surface having a segmented frustoconical shape formed from a plurality of distally extending segments 33 (FIGS. 3A-3D). The distally extending segments 33 can extend distally from the drive unit cover 11. The segments 33 can be circumferentially spaced to define at least one channel 34 between adjacent segments 33. Although three segments 33 are shown in FIGS. 3A-3D, any suitable number of segments 33 can be utilized. As shown, the segments 33 can be separate components arising from a common part having gaps or channels 34 therebetween, although the segments 33 may also be separated by shallow or deep grooves. The gaps, grooves, or channels 34 can follow any path. In the illustrated embodiment, the channels 34 extend radially outward from a central recess or hollow 31 (also referred to herein as a void) at a location proximal to the 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 a central hollow region 31 coaxial with the axis of the conical surface and / or the longitudinal axis of rotation L. In some embodiments, the conical opening 32 of the bearing pair may be a continuous (e.g., no gaps, channels, or grooves), approximately conical surface. The relative angles of the conical bearings (e.g., segments 33) and the spacing between the segments 33 may be selected to provide a desired flow profile through the channels 34 described herein. For example, increasing the spacing between the segments 33 may increase the flow through the channels 34. Together, the segmented conical member 45 of the drive bearing 18 having the channels 34 between the segments 33 and the continuous conical opening 32 can function as a "segmented conical bearing."

[0093] The channels 34 between the segments 33 allow interrupted contact between the bearing surfaces, similar to the interrupted contact described above for the modified sleeve bearings 15, 15A, 15B. This interrupted contact provides the same, but not limited to, benefits of a segmented conical bearing as those provided for the modified sleeve bearings 15, 15A, 15B. For example, in an embodiment in which the conical opening 32 is part of a rotating member (e.g., 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 the exchange of lubricant layer blood throughout the bearing interface. The channels 34 also generate pressure changes that contribute to the formation and dispersion of the lubricant layer, as described above for the sleeve bearings 15, 15A, 15B.

[0094] In some embodiments, additional features can facilitate blood flow through the central hollow 31 and channels 34 of the segmented conical bearing. In some embodiments, blood can flow in through the channels 34 and out through the central hollow 31. In other embodiments, blood can flow into the central hollow 31 (e.g., from the secondary flow path 3B of the impeller shaft 5) and out through the channels 34. This net flow of blood through the central hollow 31 and channels 34 can help ensure that the volume of blood in the channels 34 and central hollow 31 is constantly flowing to provide a source of fresh blood for lubricant layer replacement, carry away heat, and / or reduce the time blood is exposed to conditions in the bearing region that may increase the likelihood of hemolysis or thrombus formation. Thus, in various embodiments, the concave bearing surface (which can include or be defined by the concave opening 32) can include a fluid port for delivering blood proximally along the secondary flow path 3B. The convex bearing surface (which may include convex member 45) may include a void (e.g., central hollow 31) that may be disposed on the longitudinal axis L. One or more channels 34 may extend radially outward from the void or central hollow 31. The void may be in fluid communication with a fluid port (e.g., the interface between the flow tube 5 and the conical opening 32) to direct blood radially outward along the at least one channel 34.

[0095] As shown in FIG. 5A, the segments 33 of the convex member 45 can be shaped to fit within a concave bearing surface that includes a concave opening 32. In some embodiments, as shown in FIGS. 4A-5B, a direct secondary flow path 3B (e.g., through the flow tube of the impeller shaft 5 shown in FIGS. 4B-4D and 5B) can provide blood flowing proximally to the central hollow 31. In some embodiments, a secondary or second impeller 7 can be used to drive a secondary flow of blood through the bearing region, e.g., a second flow path 3B, through the central hollow 32, and radially outward through the channel 34. The pump's primary impeller 6 and / or additional secondary impellers 7 can help draw blood proximally and direct blood radially outward along the channel 34. FIGS. 4A-4D show a secondary impeller 7 drawing blood through the channel 34 of a segmented conical bearing. As described herein, the secondary impeller 7 and the impeller shaft 5 can form an integral rotor core 8. The secondary impeller 7 may have a number of vanes 10 that help direct blood radially outward through the channels 34 of the drive bearing 18, as described herein.

[0096] Keeping the segmented conical bearing element or segment 33 close to the central longitudinal axis L of the pump can have several advantages. For example, in the illustrated embodiment, the bearing element 33 can be directly exposed to blood flow from the flow tube of the impeller shaft 5 along the second flow path 3B. Additionally, the bearing element 33 can have a smaller radius when the linear velocity of the rotating member is lower. Locating the bearing element or segment 33 close to the axis L of the pump allows the vanes 10 of the secondary impeller 7 to be located at a larger radius where the linear velocity of the rotating member or shaft 5 is higher.

[0097] FIG. 3D illustrates 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 can be modified to form a central flow diverter 31a, for example, as shown in FIG. 3E. The flow diverter 31a can comprise a distally extending protrusion (e.g., a cylindrical protrusion, a conical protrusion, a pyramidal protrusion, etc.) located in a central region of the bearing between the segments 33. In the illustrated embodiment, the flow diverter 31a can include a symmetric flow diverter. The flow diverter 31a can help blood coming from the flow tube or lumen of the shaft 5 transition from axial to radial flow as it exits through the channels 34. The flow diverter may optionally be manufactured as one or more separate pieces that are attached to the central hollow 31 and / or the channels 34. In some embodiments, the flow diverter 31a can comprise a generally right-angled cylindrical shape extending distally from the bearing 18. In other embodiments, the flow diverter 31a may have a tapered, for example conical, profile.

[0098] The interface between the segment 33 of the conical member 45 and the concave, e.g., conical opening 32 of the segmented conical bearing can be lubricated by blood. Depending on the geometry, the material used, and the operating conditions, this lubrication can be hydrodynamic, elastohydrodynamic, boundary, or mixed. The channels 34 between the segments 33 of the conical member 45 of the bearing pair can facilitate fluid exchange such that a portion of the blood constituting the lubricating layer between the region of the conical opening 32 of the bearing pair on one segment 33 of the conical member of the bearing pair is replaced by fresh blood in the lubricating layer formed 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 varied to facilitate this exchange. In various embodiments, the height and lateral spacing of the segments 33 can be selected to provide the desired channel depth and width. For example, the width of the channel 34 can be in the range of 0.02 inches to 0.06 inches, in the range of 0.03 inches to 0.05 inches, or in the range of 0.035 inches to 0.045 inches (e.g., about 0.04 inches in some embodiments). The surface of the conical member segment 33 of the bearing pair along the channel 34 forms the leading and trailing edges of the conical member segment 33 of the bearing pair (as seen by the area of ​​the conical opening 32 of the bearing pair). The distance of the leading and trailing edges from the conical opening 32 can also be varied to promote fluid exchange. For example, the edges can be beveled or rounded, or the distance of the leading and trailing edges can taper away from or towards the surface of the conical opening 32.

[0099] The surfaces of the segments 33 of the conical members 45 of the bearing pair may also be modified to diverge from a perfect conical surface to promote the formation of a lubricating layer. For example, one or more surfaces of the segments 33 of the conical members 45 of the bearing pair may be shaped such that the vertical 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 promote the formation of a fluid wedge between the segments 33 of the conical members 45 and the conical opening 32 of the bearing pair to improve lubrication. In another embodiment, the surfaces of the segments 33 of the conical members 45 and the conical opening 32 of the bearing pair may be smooth and well matched to allow for the formation of a relatively thin lubricating layer of relatively uniform thickness. Although the conical members 45 and the conical opening 32 are described as having a generally conical shape in some embodiments, it should be understood that the members 45 and the openings 32 may be generally considered to be convex members 45 and concave openings 32. The shapes of the convex members and the concave openings 32 may be any suitable mating shapes.

[0100] The flow of blood driven from the central hollow 31 through the channels 34 by the secondary impeller 7 provides fresh blood for replacement of the lubricant layer and carries away heat within the bearing area. Both functions are important to reduce the possibility of blood clot formation in segmented conical bearings.

[0101] The segments 33 of the conical member 45 of the bearing pair and the conical opening 32 of the bearing pair can each be made from any suitable blood-compatible bearing material. As non-limiting examples, the segments 33 of the conical member of the bearing pair may be made from titanium or stainless steel and / or the conical opening 32 of the bearing pair may be made from PEEK or polyethylene.

[0102] By making one side of the bearing pair relatively hard and the other side of the bearing pair relatively soft, the bearing pair can initially undergo boundary or mixed lubrication, where surface asperities wear to the point where the surfaces of the conical member and the conical opening are smooth and match well enough for hydrodynamic or elastohydrodynamic lubrication to dominate. Making one side of the bearing pair relatively soft can expand the range where elastohydrodynamic lubrication exists. In some embodiments, the continuous conical opening 32 of the bearing pair is softer and the segmented conical member of the bearing pair is harder. This configuration can help preserve the special geometric characteristics of the segments 33 on the conical member of the bearing pair. In some embodiments, the continuous conical opening 32 of the bearing pair is harder and the segmented conical member 45 of the bearing pair is softer. This configuration can help preserve the surface of the opening 32 as a surface of revolution about the longitudinal axis L. In other variations, the conical opening 32 and the conical member 45 may have similar or even the same hardness, which may provide the advantage of dimensional and shape stability throughout operation of the pump 2.

[0103] In cases where hydrodynamic lubrication dominates, the normal distance between the segment 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, replacement of the lubricating layer may not be of great importance as long as heat can still be transferred. Assuming that red blood cells are sufficiently excluded, a continuous (e.g., no channels or grooves) conical member 45 of the bearing pair may still exhibit a low likelihood of thrombus formation as long as heat can be transferred quickly enough. In some embodiments, this can be achieved by excluding or coating the channels 34 to form a continuous conical surface. Blood flow through the coated channels 34 can transfer sufficient heat away from the bearing pair.

[0104] The segmented bearing embodiment described above provides the additional benefit of increasing the flexibility of the portion of the pump 2 in the vicinity of the pump head 50. The impeller assembly 4 can be coupled to the drive unit 9 to allow some movement between the impeller assembly 4 and the cover 11. For example, the pump 2 may be delivered through a tortuous or curved vasculature or may be abruptly inserted inside a blood vessel from outside the patient. The impeller assembly 4 can be tilted toward or away from one or more of the segments 33 at the conical opening 32 such that the proximal end face of the impeller assembly is at a non-parallel angle to the distal face of the cover 11. The movement can be significant relative to the mounting of the impeller assembly 4 on a shaft rotatably supported in the drive unit. The tilting of the impeller assembly 4 can be caused by bending of the shroud 16, which can be bent in high bending stress operations. In some embodiments, the shroud 16 is made of an elastic material, such as Nitinol, allowing the pump head 50 to bend and elastically return to an undeflected state without stretching.

[0105] IV. Impeller shaft with flow tube through primary impeller 4A-5B and 7 show how the flow tubes of the impeller shaft 5 can be routed through the primary impeller 6. This allows for a compact pump rotor assembly 46 in which the primary flow path 3A and the secondary flow path 3B are separate and flow in the same direction through the system 1, as shown in FIGS. 9A-9B. Having the two flow paths 3A, 3B in the same direction minimizes or reduces the possibility of blood recirculating through the pump. In some embodiments, the primary impeller 6 can also have a thrust ring 14 or thrust surface designed to limit axial motion in the upstream or distal direction by contacting a corresponding thrust ring or thrust surface of the sleeve bearing 15. The primary impeller 6 can have features described in U.S. Patent Application Publication No. 2017 / 0087288, incorporated herein by reference.

[0106] V. Secondary impeller As described herein, the secondary impeller 7 can be disposed proximal to the primary impeller 6. In some embodiments, as shown in FIGS. 4A-7, the secondary impeller 7 can comprise a flange 47 extending non-parallel (e.g., radially outward along the radial axis R) from a 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 outward from 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, for example, may not extend radially beyond an integral streamlined fairing 13, described below. In some of these embodiments, the flange 47 can comprise a portion of the combined rotor surface that is in a plane perpendicular to the longitudinal axis L. As shown in FIGS. 4A-4C and 5A, the vanes 10 may extend proximally from the flange 47 and may have a circumferentially curved profile about the longitudinal axis L. The vanes 10 may be disposed in a space between a proximal face of the flange 47 and a distal end of the drive unit 9. The recessed opening 32 may comprise an inclined cavity extending inwardly and distally relative to a generally proximally facing surface of the flange 47. The rotor magnets 12 may be disposed adjacent to a distally facing surface of the flange 47. Each of the vanes 10 may have an inner end 10a disposed at or near the recessed opening 32 and an outer end 10b extending radially and circumferentially outwardly from the inner end 10a along the flange 47. The flange 47 may be coupled to or formed at a proximal end of the impeller shaft 5. In some embodiments, for example, the flange 47 may be integrally formed with (e.g., seamlessly formed with) the impeller shaft 5. In other embodiments, the flange 47 and the impeller shaft 5 may be separate components that are mechanically connected (e.g., welded or otherwise bonded) to one another. In some embodiments, the vane 10 may be monolithically formed with the proximally-facing surface of the flange 47.In other embodiments, the vane 10 may be mechanically connected to the proximal facing surface of the flange 47 .

[0107] As shown in FIG. 4D, the vanes 10 can extend circumferentially about the longitudinal axis L such that adjacent vanes 10 overlap circumferentially. For example, the radially outer end 10b of one vane can overlap circumferentially with the radially inner end 10a of an adjacent vane and be disposed radially outward. The vanes 10 can be prevented from contacting the drive unit 9 by the thrust bearing aspect of the segmented conical bearing. As the impeller assembly 4 rotates, the vanes 10 can pump blood radially out of the channel 34 of the segmented conical bearing, thereby increasing the net flow through the impeller shaft 5 and the flow tube of the segmented conical bearing. As shown, blood can exit the flow tube of the impeller shaft 5 at a location proximal to the primary impeller 6 and be pushed radially out of the channel 34 by the vanes 10. In the illustrated embodiment, five vanes 10 are used, but it should be understood that less than five or more than five vanes 10 can be used.

[0108] As shown in Figures 4A, 4C, and 5A, the secondary impeller 7 can have a proximal end 52 at a proximal edge of the vane 10. Additionally, as shown in Figures 3A and 3C, the drive unit 9 can have a distal end 53 at a distal end of the distally projecting segment 33. As discussed above, the distally projecting convex segment 33 can be received within the concave opening 32 of the rotor assembly 46. When the convex segment 33 is fitted within the concave opening 32, the distal end 53 of the drive unit 9 is distal to the proximal end 52 of the second impeller 7 (e.g., the distal end closest to the proximal end of the rotor assembly 46), as shown, for example, in Figure 7.

[0109] VI. Integrated rotor core As described herein, in some embodiments, the flow tube of the impeller shaft 5, the recessed openings 32 of the segmented conical bearing, and the secondary impeller 7 can be integrated into one piece as a one-piece rotor core 8. Advantages of this approach include, but are not limited to, simpler assembly (as described below) and minimization or reduction of joints between the pieces (particularly on the inner surface of the flow tube of the shaft 5). Beneficially, the primary impeller 6 can be disposed (e.g., mounted and fixed (e.g., welded or glued)) on the impeller shaft 5, providing a compact design.

[0110] Thus, in various embodiments, the primary impeller 6 and the impeller shaft 5 may be separate components with the impeller 6 mechanically connected to the impeller shaft 5. In other embodiments, the primary impeller 6 and the impeller shaft 5 may comprise an integral or monolithic structure (e.g., a molded or cast structure). Such an integral or monolithic structure may be formed without seams or joints between the components of the integral or monolithic structure. Similarly, the secondary impeller 7 may be disposed (e.g., mechanically secured) at a proximal end of the impeller shaft 5. In some embodiments, the secondary impeller 7 may be monolithically formed with the impeller shaft 5 to form a single component (e.g., molded, cast, etc.). In other embodiments, the secondary impeller 7 and the impeller shaft 5 may comprise separate components. In some embodiments, the primary impeller 6, the secondary impeller 7 (including the flange 47), and the impeller shaft 5 may form a single or monolithic component or body. In some embodiments, for example, the primary impeller 6, secondary impeller 7, and impeller shaft 5 can be injection molded onto the rotor magnet 12. When the secondary impeller 5 is molded onto the magnet 12, the surface on which the secondary impeller 6 is disposed can be considered a flange extending radially outward from a lumen formed in a central portion of the molded part. Beneficially, as discussed above, the integral rotor core 8 can form a compact structure. Rotation of the drive magnet 17 can impart rotation to the rotor magnet 12, which is also disposed (e.g., mechanically connected or attached) on the impeller shaft 5. Rotation of the rotor magnet 12 can impart a common rotation to the impeller shaft 5, the primary impeller 6, and the secondary impeller 7.

[0111] VII. Exemplary Assembled Blood Flow Assist Systems 7 and 8A-8D show exemplary schematic diagrams of various features of the blood flow assistance system 1 described herein. The features described above can also be combined in other ways.

[0112] As shown in FIGS. 7 and 8A, the system 1 includes a drive unit 9 having a motor 30 that may be sealed within a motor housing 29. A drive magnet 17 may be rotatable by the motor 30 via a motor shaft 51. The motor 30 may be electrically connected to a power line 20. As shown in FIGS. 8A and 8C, the power line 20 may include an insulator having a central lumen 55 and multiple (e.g., three) outer lumens 56A-56C extending along the length of the power line 20. The outer lumens 56A-56C may be sized and shaped to receive corresponding electrodes or wires (not shown) for providing power to the motor 30. For example, the lumens 56A-56C may receive a hot electrode or wire, a neutral electrode or wire, and a ground electrode or wire, respectively. The electrodes may extend through corresponding openings 57A-57C in a motor mounting support 54 configured to support the motor 30. The central lumen 55 can be sized and shaped to receive an elongated stiffening member or guidewire (not shown). The stiffening member or guidewire can be inserted into the central lumen 55 to help guide the pump 2 to a treatment location. As shown in FIG. 8D, the connector 23 near the proximal end 21 of the system 1 can have electrical contacts 58A-58C electrically connected to electrodes in corresponding outer lumens 56A-56C. The contacts 58A-58C can comprise rings spaced apart by insulating material and can be configured to electrically connect to corresponding electrical components in a control system or console (not shown).

[0113] The drive magnet 17 can be sealed within the drive unit 9 by the drive unit cover 11, which can also have features that function as bearing components (e.g., distally projecting segments 33). In some embodiments, the top distal portion of the cover 11 can provide the segments 33 that form the conical members 45 of the segmented conical bearing described in this disclosure. The corresponding conical openings 32 of this bearing pair can be incorporated into the rotatable part (integral rotor core 8) that includes the secondary impeller 7 and the flow tube or impeller shaft 5. The convex members 45 match the contour and fit inside the concave openings 32 of the rotatable part. The channels 34 of the segmented conical bearing provide a fluid passage for blood that enters the bearing area through the flow tube 5 and is pushed out of the bearing area by the secondary impeller 7. A lubricating layer of blood between the bearing surface of the integral rotor core 8 and the matching surface of the conical segments 33 provides lubrication, reduces wear, and facilitates relative motion of the two components. Depending on the geometry, rotational speed, and materials that make up the interface, this can be hydrodynamic, elastohydrodynamic, boundary, or mixed lubrication.

[0114] The rotor magnets 12 of the rotor assembly 46 can be disposed on the integral rotor core 8 in close proximity to the drive unit 9, thereby allowing the integral rotor core 8 to be magnetically coupled to the drive unit 9 and rotated as desired. A first or primary impeller 6 with an integral streamlined fairing 13 can be disposed over the rotor magnets 12 and joined to the integral rotor core 8 to at least partially form the pump rotor assembly 46. A three-piece construction (integral rotor core 8, magnets, and primary impeller 6 with integrated fairing) can have advantages as previously described with respect to ease of construction and compact design. In some embodiments, the portion of the primary impeller 6 that contacts the flow tube 5 can be shaped to function as a thrust pad or to mate with a separate thrust ring 14 that contacts a matching thrust pad on a sleeve bearing 15 that fits around the flow tube 5. The rotor magnets 12 and primary impeller 6 with fairing 13 can be secured to the integral rotor core 8 such that the components rotate together.

[0115] Alternatively, the pump rotor can be assembled from three or more parts. In an alternative embodiment, the primary impeller 6 and the fairing 13 are separate parts. This can allow the primary impeller 6 and the fairing 13 to be made from different materials. Alternatively, the rotor magnets 12 may be coated to be suitable for blood contact and may not be covered by the fairing 13, but rather bonded directly to the primary impeller 6. Such a configuration can allow the use of larger diameter magnets (with corresponding higher torque coupling) for the same pump rotor diameter than would be possible with magnets inside the fairing.

[0116] In another alternative embodiment, a separate ring 14 can be added around the flow tube 5 above the primary impeller 6. This separate ring acts as a thrust interface that mates with the thrust face of the sleeve bearing. The separate ring can be made from a different material than the flow tube 5 or the primary impeller 6.

[0117] The flow tube of the impeller shaft 5 of the pump rotor may fit inside a fixed (non-rotating) sleeve bearing 15 (FIG. 7). As described above, the sleeve bearing 15 may provide radial containment of the impeller assembly 4 and the rotor assembly 46. The bearing interface comprises the outer surface of the impeller shaft 5 and the inner surface of the sleeve bearing 15. The sleeve bearing 15 may have a modified shape as described above that reduces or minimizes continuous coverage of the outer surface of the impeller shaft 5, thereby reducing the possibility of thrombosis. The sleeve bearing 15 may also optionally provide a thrust bearing surface that interfaces with any thrust bearing surface of the primary impeller 6 or any thrust ring 14.

[0118] An outer bearing carrier 38 of the sleeve bearing 15 may be attached to a shroud 16 that fits around the impeller assembly 4 and is attached to the drive unit cover 11 of the drive unit 9. The connecting structure 39 may include an arm or multiple arms that may be attached directly to the shroud 16 or to a ring attached to the shroud 16 to improve the stiffness and circularity of the shroud 16.

[0119] The shroud 16 may comprise a tube having an inlet end and an outlet end. The shroud 16 may be disposed over various internal components that make up the pump rotor (e.g., impeller assembly 4 and rotor assembly 46). The outlet end of the shroud 16 may be secured to the drive unit cover 11 of the drive unit 9. The inlet side of the shroud 16 may be open to form an inlet port 27. A front bearing is disposed within the inlet port of the shroud 16 as described above. The outlet side of the shroud 16 has an opening 25 in the surface of the shroud (the outlet port) that provides an outlet for the fluid driven by the primary impeller 6 and secondary impeller 7.

[0120] Although some drawings of the system are shown without struts for clarity, the pump may include struts or any other fixation means for securing the pump to the circulatory system, as shown in U.S. Pat. Nos. 8,012,079 and 9,572,915 and U.S. Patent Application Publication No. 2017 / 0087288.

[0121] VIII.Operation As shown in Figures 9A and 9B, various embodiments of pump 2 provide two flow paths 3A, 3B as described herein. The first flow path 3A (red in Figures 9A-9B) is driven by a primary impeller 6 that draws fluid through an inlet port 27 of the shroud 16 and directs fluid out an outlet port 25 of the shroud 16. The second flow path 3B (yellow in Figures 9A and blue in Figures 9B) is driven by a secondary impeller 7 that draws fluid through an internal secondary flow path 3B, e.g., a lumen or flow tube of the impeller shaft 5. The internal flow path passes through a flow tube of the shaft 5 of the integral rotor core 8. When the fluid reaches the proximal end 5B of the shaft 5, a portion of the fluid passes through a channel 34 between the conical segments 33 and a smaller portion passes between the matching conical surfaces of the bearing interface (e.g., between the convex member 45 and the concave opening or cavity 32). The fluid may be driven radially outward by the vanes 10 of the secondary impeller 7. Notably, in the embodiment shown, flow from both flow paths may be directed from the inlet 27 to the outlet 25. In other embodiments, the flow of blood may be reversed, as described herein.

[0122] It will be apparent to one skilled in the art that the fluid flowing through the secondary flow path, particularly the fluid layer between the matching conical bearing interfaces, acts as a lubrication layer between the rotor assembly 46 and the fixed segments 33 of the segmented conical bearing. Additionally, the matching conical surfaces of the segmented conical bearing can provide both axial and radial containment of the pump assembly 46.

[0123] IX. Advantages Various embodiments disclosed herein may have several inherent advantages. Many of these advantages are described herein, but they are not an exhaustive list. The following are merely additional, non-limiting examples of advantages, one or more of which may apply to a particular embodiment.

[0124] a. The bearing elements (eg, sleeve bearings 15, 15A, 15B and / or segmented conical bearings) may have surface area contact rather than point or line contact.

[0125] b. The secondary flow along the second pathway 3B may be in the same direction as the primary flow path 3A to reduce or minimize potential recirculation of blood.

[0126] c. The flow tube or shaft 5, the conical opening 32 of the segmented conical bearing, and the secondary impeller 7 may be advantageously integrated into a one-piece rotor core 8.

[0127] d. The attractive force of the magnetic coupling utilizes a one-way thrust bearing to support the outer rotor. No thrust bearing may be used to prevent movement of the pump rotor 8 away from the drive unit 9.

[0128] The embodiments described herein are included to demonstrate certain aspects of the disclosure. It should be understood by those skilled in the art that the embodiments described herein merely represent non-limiting embodiments of the disclosure. In light of the present disclosure, those skilled in the art should understand that many variations can be made to the specific embodiments described, including various combinations of different elements, components, steps, features, etc. of the described embodiments, and still obtain the same or similar results without departing from the spirit and scope of the present disclosure. From the foregoing description, those skilled in the art can easily ascertain the essential features of the present disclosure, and can make various modifications and changes to adapt the present disclosure to various applications and conditions without departing from the spirit and scope thereof. The above-described embodiments are intended to be illustrative only and should not be construed as limiting the scope of the present disclosure.

[0129] Conditional language such as "can," "could," "might," or "may," unless otherwise specified or understood otherwise within the context in which it is used, is generally intended to convey that certain embodiments include certain features, elements, and / or steps, while other embodiments do not. Thus, such conditional language generally does not imply that the features, elements, and / or steps are in any way required for one or more embodiments.

[0130] Terms such as "comprising," "including," "having," and the like are synonymous and are used in an inclusive, open-ended manner and do not exclude additional elements, features, acts, operations, etc. Also, the term "or" is used in an inclusive (not exclusive) sense, e.g., when used to connect a list of elements, the term "or" may mean one, some, or all of the elements in the list. Additionally, the articles "a," "an," and "the," as used in this application and the appended claims, should be construed to mean "one or more" or "at least one," unless otherwise specified.

[0131] Ranges disclosed herein also encompass any and all overlaps, subranges, and combinations thereof. Phrases such as "up to," "at least," "greater than," "less than," "between," and the like, include the recited numbers. Numbers preceded by terms such as "about" or "approximately" are inclusive of the recited numbers and should be interpreted in the context (e.g., as precisely as reasonably possible under the circumstances, e.g., ±5%, ±10%, ±15%, etc.). For example, "about 1" includes "1." Phrases preceded by terms such as "substantially," "generally," and the like, are inclusive of the recited numbers and should be interpreted in the context (e.g., as precisely as reasonably possible under the circumstances). For example, "approximately spherical" includes "spherical." Unless otherwise specified, all measurements are made at standard conditions, including temperature and pressure.

[0132] 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 encompass A, B, C, A and B, A and C, B and C, and A, B and C. Conjunctions such as the phrase "at least one of X, Y, and Z" are otherwise understood in the context in which they are generally used to convey that an item, term, etc. can be at least one of X, Y, or Z, unless otherwise noted. Thus, such conjunctions are not generally intended to imply that a particular embodiment requires at least one of X, at least one of Y, and at least one of Z, respectively, to be present.

[0133] While specific embodiments and examples have been described herein, it should be emphasized that many variations and modifications can be made to the humeral head assembly shown and described in this disclosure, and that the elements can be differently combined and / or changed to form yet other embodiments or acceptable examples. All such modifications and variations are intended to be within the scope of the present disclosure. A wide variety of designs and approaches are possible. No feature, structure, or step disclosed herein is essential or critical.

[0134] Some embodiments are described in conjunction with the accompanying drawings. However, it should be understood that the drawings are not drawn to scale. Distances, angles, etc. are merely illustrative and do not necessarily bear precise relationship to the actual dimensions and layout of the illustrated devices. Components can be added, removed, and / or rearranged. Furthermore, any particular features, aspects, methods, properties, characteristics, qualities, attributes, elements, etc. disclosed herein in connection with various embodiments can be used in all other embodiments described herein. Furthermore, it will be recognized that any method described herein can be implemented using any device suitable for performing the recited steps.

[0135] For the purpose of this disclosure, certain aspects, advantages, and novel features are described herein. It should be understood that not all such advantages can necessarily be achieved according to any particular embodiment. Thus, for example, a person skilled in the art will recognize that the present disclosure can be embodied or implemented to achieve one advantage or group of advantages as taught herein, without necessarily achieving other advantages as may be taught or suggested herein.

[0136] Furthermore, while exemplary embodiments are described herein, it will be understood by those skilled in the art that the scope of the present invention extends beyond the specifically disclosed embodiments to any and all embodiments having equivalent elements, modifications, omissions, combinations or subcombinations, adaptations and / or substitutions of certain features and aspects of the embodiments (e.g., of aspects across various embodiments), and uses of the present invention as would be understood by those skilled in the art based on this disclosure. Any limitations in the claims should be fairly interpreted based on the language used in the claims, and not limited during prosecution of the examples or applications described herein, and the examples should be interpreted as non-exclusive. Furthermore, the operations of the disclosed processes and methods can be modified in any manner, including rearranging operations and / or inserting additional operations and / or deleting operations. Accordingly, it is intended that the specification and examples be considered as exemplary only, with a true scope and spirit being indicated by the full scope of the claims and their equivalents.

Claims

1. 1. A blood flow assist system comprising: an impeller assembly comprising: a rotor assembly; and an impeller coupled to the rotor assembly, the rotor assembly including a concave bearing surface, an impeller shaft, and a rotor magnet coupled to the impeller shaft, the impeller disposed on the impeller shaft; a drive unit proximate to the impeller assembly, the drive unit including a drive magnet and a drive bearing between the drive magnet and the impeller assembly, the drive bearing having a convex bearing surface shaped to fit within the concave bearing surface, the convex bearing surface including a plurality of distally projecting segments, the plurality of distally projecting segments being circumferentially spaced apart to define at least one channel between adjacent segments, the at least one channel extending outwardly from a gap; and a sleeve bearing disposed about the impeller shaft distal to the impeller; Equipped with in a cross section perpendicular to the axis of rotation of the impeller shaft, the support surface of the sleeve bearing is disposed about only a portion of the circumference of the impeller shaft at a selected axial position, whereby as the impeller shaft rotates about the axis of rotation, an outer surface of the impeller shaft at the selected axial position is periodically exposed to blood during operation of the blood flow assist system; Blood flow support system.

2. a distal end of the drive unit disposed distal to a proximal end of the rotor assembly; 10. The blood flow assist system of claim 1.

3. the impeller is a first impeller, and the impeller assembly includes a second impeller disposed on the impeller shaft proximally spaced from the first impeller along the impeller shaft.

10. The blood flow assist system of claim 1.

4. a flange extending non-parallel from a proximal end portion of the impeller shaft, the second impeller including a plurality of vanes disposed on a generally proximally-facing surface of the flange; 4. The blood flow assist system of claim 3.

5. the first impeller is configured to pump blood along a first flow path along an outer surface of the first impeller, and a majority of the blood flowing along the first flow path is directed along a longitudinal axis of the blood flow assistance system.

5. The blood flow assist system of claim 4.

6. a second flow path through a lumen of the impeller shaft, the second impeller being configured to direct blood from the second flow path radially outward relative to the longitudinal axis.

6. The blood flow assist system of claim 5.

7. a sloped cavity extending inwardly and distally relative to the generally proximally-facing surface of the flange; 5. The blood flow assist system of claim 4.

8. the drive unit includes a convex member dimensioned to fit within the inclined cavity; 8. The blood flow assist system of claim 7.

9. a pump housing, the impeller assembly being at least partially disposed within the pump housing.

10. The blood flow assist system of claim 1.

10. the pump housing including at least one outlet disposed proximate to the impeller; 10. The blood flow assist system of claim 9.

11. the impeller is a first impeller, and the blood flow assist system further includes a second impeller disposed proximal to a distal end of the at least one outlet.

11. The blood flow assist system of claim 10.

12. a support structure coupled to or formed with the pump housing, the support structure including struts configured to contact a vessel wall to maintain spacing of the pump housing from a vessel wall in which the pump housing is disposed.

11. The blood flow assist system of claim 10.

13. configured as a percutaneous pump for percutaneous insertion into a treatment location within a patient's body; 10. The blood flow assist system of claim 1.

14. a motor mechanically coupled to the drive magnet and a power line connected to the motor and extending proximally from the motor.

14. The blood flow assist system of claim 13.

15. 1. A blood flow assist system comprising: an impeller assembly including a rotor assembly and an impeller coupled to the rotor assembly, the rotor assembly including a concave bearing surface, an impeller shaft, and a rotor magnet coupled to the impeller shaft, the impeller being disposed on the impeller shaft; a drive unit proximate to the impeller assembly, the drive unit including a drive magnet and a drive bearing between the drive magnet and the impeller assembly, the drive bearing including a convex bearing surface shaped to fit within the concave bearing surface, the convex bearing surface having a distal end disposed distal to a proximal end of the rotor assembly, the convex bearing including a segmented bearing including at least one channel extending outwardly from a central hollow; a sleeve bearing disposed about the impeller shaft at a location distal to the impeller, wherein in a cross section perpendicular to the axis of rotation of the impeller, a support surface of the sleeve bearing is disposed about only a portion of the circumference of the impeller shaft at a selected axial position, such that as the impeller shaft rotates about the axis of rotation, an outer surface of the impeller shaft at the selected axial position is periodically exposed to blood during operation of the blood flow assist system; A blood flow assist system comprising:

16. the convex bearing surface comprises a plurality of distally projecting segments, the plurality of distally projecting segments being circumferentially spaced apart to define at least one channel between adjacent segments; 16. The blood flow assist system of claim 15.

17. the impeller is a first impeller, the impeller assembly comprises a second impeller disposed on the impeller shaft spaced proximally from the first impeller along the impeller shaft, the blood flow assist system further comprises a flange extending non-parallel from a proximal end portion of the impeller shaft, the second impeller comprising a plurality of vanes disposed on a generally proximally facing surface of the flange.

16. The blood flow assist system of claim 15.

18. the first impeller is configured to pump blood along a first flow path along an outer surface of the first impeller, a majority of the blood flowing along the first flow path being directed along a longitudinal axis of the blood flow assistance system, the blood flow assistance system further comprising a second flow path through a lumen of the impeller shaft, the second impeller being configured to direct blood from the second flow path radially outward relative to the longitudinal axis.

20. The blood flow assist system of claim 17.

19. A kit comprising:

16. A blood flow assist system according to claim 15, a motor assembly configured to impart rotation to the impeller; a power line electrically connected to the motor assembly; and a console configured to electrically connect to the power line.

20. 1. A blood flow assist system comprising: A pump housing; an impeller assembly disposed within the pump housing, the impeller assembly including an impeller shaft and an impeller on the impeller shaft, the impeller shaft configured to rotate about an axis of rotation; a sleeve bearing disposed about the impeller shaft, the sleeve bearing having an inner support structure supporting the impeller shaft, an outer support structure coupled to or formed with the pump housing, and a connecting structure extending radially between the inner support structure and the outer support structure; Equipped with in a cross section perpendicular to the axis of rotation, the support surface of the sleeve bearing is disposed about only a portion of the circumference of the impeller shaft at a selected axial position along the axis of rotation, such that as the impeller shaft rotates about the axis of rotation, an outer surface of the impeller shaft at the selected axial position is periodically exposed to blood during operation of the blood flow assist system; the inner support structure includes a distal boundary that is angled relative to the axis of rotation; Blood flow support system.

21. and a drive unit configured to impart rotation to the impeller shaft, the drive unit comprising a drive magnet and a drive bearing between the drive magnet and the impeller assembly, the drive bearing including a convex bearing surface and a plurality of distally projecting segments extending from the convex bearing surface, the plurality of distally projecting segments being circumferentially spaced apart to define at least one channel between adjacent segments.

21. The blood flow assist system of claim 20.

22. A kit comprising:

22. A blood flow assist system according to claim 21, a motor assembly configured to impart rotation to the impeller; a power line electrically connected to the motor assembly; and a console configured to electrically connect to the power line.

23. 1. A blood flow assist system comprising: A pump housing; an impeller assembly disposed within the pump housing, the impeller assembly including an impeller shaft and an impeller on the impeller shaft, the impeller shaft configured to rotate about an axis of rotation; a sleeve bearing disposed about the impeller shaft, the sleeve bearing having an inner support structure supporting the impeller shaft, an outer support structure coupled to or formed with the pump housing, and a connecting structure extending radially between the inner support structure and the outer support structure; Equipped with in a cross section perpendicular to the axis of rotation, the support surface of the sleeve bearing is disposed about only a portion of the circumference of the impeller shaft at a selected axial position along the axis of rotation, such that as the impeller shaft rotates about the axis of rotation, an outer surface of the impeller shaft at the selected axial position is periodically exposed to blood during operation of the blood flow assist system; the inner support structure includes a distal boundary that is angled relative to the axis of rotation; Blood flow support system.

24. the support surface of the sleeve bearing is only partially disposed around the outer periphery of the impeller shaft at all axial positions along the axis of rotation along the length of the sleeve bearing.

24. The blood flow assist system of claim 23.

25. in a cross section perpendicular to the axis of rotation, only a portion of the distal boundary is disposed about the impeller shaft at the selected axial position, such that as the impeller shaft rotates about the axis of rotation, an outer surface of the impeller shaft at the selected axial position is periodically exposed to blood during operation of the blood flow assist system.

24. The blood flow assist system of claim 23.

26. and a drive unit configured to impart rotation to the impeller shaft, the drive unit comprising a drive magnet and a drive bearing between the drive magnet and the impeller assembly, the drive bearing including a convex bearing surface and a plurality of distally projecting segments extending from the convex bearing surface, the plurality of distally projecting segments being circumferentially spaced apart to define at least one channel between adjacent segments.

24. The blood flow assist system of claim 23.

27. A kit comprising:

24. A blood flow assist system according to claim 23, a motor assembly configured to impart rotation to the impeller; a power line electrically connected to the motor assembly; and a console configured to electrically connect to the power line.

28. 1. A blood flow assist system comprising: an impeller assembly disposed within the pump housing, the impeller assembly including an impeller shaft and an impeller on the impeller shaft, the impeller shaft configured to rotate about an axis of rotation; a sleeve bearing disposed around the impeller shaft, the sleeve bearing having an inner support structure supporting the impeller shaft, the inner support structure including a boundary inclined with respect to the axis of rotation; Equipped with At an axial position along the axis of rotation, the support surface of the sleeve bearing is disposed only partially around the outer periphery of the impeller shaft. Blood flow support system.

29. as the impeller shaft rotates about the axis of rotation, an outer surface of the impeller shaft at the axial location is periodically exposed to blood during operation of the blood flow assist system.

30. The blood flow assist system of claim 28.

30. the support surface of the sleeve bearing is only partially disposed around the outer periphery of the impeller shaft at all axial positions along the axis of rotation along the length of the sleeve bearing.

30. The blood flow assist system of claim 28.

31. the axial location is a first axial location, and the support surface is disposed completely around the circumference of the impeller shaft at a second axial location along the axis of rotation.

30. The blood flow assist system of claim 28.

32. the sleeve bearing having an outer support structure coupled to or formed with the pump housing and a connecting structure extending radially between the inner support structure and the outer support structure; 30. The blood flow assist system of claim 28.

33. the boundary includes a distal boundary that is inclined such that, in a cross section perpendicular to the axis of rotation, only a portion of the distal boundary is disposed about the impeller shaft at the axial location, such that as the impeller shaft rotates about the axis of rotation, an outer surface of the impeller shaft at the axial location is periodically exposed to blood during operation of the blood flow assist system.

33. The blood flow assist system of claim 32.

34. a support structure coupled to the pump housing, the support structure comprising struts configured to contact a vessel wall to maintain spacing of the pump housing from a vessel wall in which the pump housing is disposed.

24. The blood flow assist system of claim 23.

35. The impeller is configured to pump blood along a first flow path along an outer surface of the impeller, and a majority of the blood flowing along the first flow path is directed along the axis of rotation.

30. The blood flow assist system of claim 28.

36. a second impeller disposed on the impeller shaft spaced proximally from the impeller along the impeller shaft, the second impeller configured to direct blood from a second flow passage within a lumen of the impeller shaft radially outward relative to the axis of rotation.

36. The blood flow assist system of claim 35.

37. a flange extending non-parallel from a proximal end portion of the impeller shaft, the second impeller being disposed on a generally proximally-facing surface of the flange.

37. A blood flow assist system as claimed in claim 36.

38. a drive unit configured to impart rotation to the impeller shaft; 30. The blood flow assist system of claim 28.

39. the drive unit comprises a drive magnet and a drive bearing between the drive magnet and the impeller assembly, the drive bearing comprising a convex bearing surface having a plurality of distally projecting segments, the plurality of distally projecting segments being circumferentially spaced apart to define at least one channel between adjacent segments; 39. A blood flow assist system as claimed in claim 38.

40. A kit comprising:

29. A blood flow assist system according to claim 28, a motor assembly configured to impart rotation to the impeller; a power line electrically connected to the motor assembly; and a console configured to electrically connect to the power line.

41. 1. A blood pump comprising: A pump rotor including a primary impeller and a rotating member including a flow pipe that rotates around a rotation axis together with the primary impeller; a sleeve bearing fitted around the flow pipe, the sleeve bearing having a non-circular bearing interface edge that is non-perpendicular to the axis of rotation, the non-circular bearing interface edge being inclined relative to the axis of rotation; A blood pump comprising:

42. the bearing interface edge comprises a non-circular sleeve edge, the sleeve edge ensuring that no point exists on the rotating member that remains aligned with the sleeve edge during rotation of the rotating member; 42. The blood pump of claim 41.

43. the sleeve bearing exposes at least one point on the rotating member over the entire height of the sleeve bearing such that a surface of the rotating member is covered by the sleeve bearing for only a portion of the rotation; 42. The blood pump of claim 41.

44. The pump further includes a pump housing, the pump rotor being disposed within the pump housing.

42. The blood pump of claim 41.

45. 1. A blood flow assist system comprising: an impeller assembly disposed within the pump housing, the impeller assembly including an impeller shaft and an impeller on the impeller shaft, the impeller shaft configured to rotate about an axis of rotation; a sleeve bearing disposed around the impeller shaft; Equipped with At an axial position along the axis of rotation, the support surface of the sleeve bearing is disposed only partially around an outer periphery of the impeller shaft; the support surface of the sleeve bearing is disposed only partially around the outer periphery of the impeller shaft at all axial positions along the axis of rotation along a length of the sleeve bearing; the support surface comprises a crenulated surface as shown in a side view of the sleeve bearing; Blood flow support system.

46. and a support structure coupled to the pump housing, the support structure comprising struts configured to contact a vessel wall to maintain a spacing of the pump housing from a vessel wall in which the pump housing is disposed.

45. The blood pump of claim 44.

47. 1. A blood pump comprising: A pump rotor including a primary impeller and a rotating member including a flow pipe that rotates around a rotation axis together with the primary impeller; a sleeve bearing fitted around the flow pipe, the sleeve bearing having a bearing interface edge that is non-perpendicular to the axis of rotation; Equipped with the bearing interface edge varies sinusoidally; Blood pump.

48. a pump housing, the pump rotor disposed within the pump housing, and a support structure coupled to the pump housing, the support structure including struts configured to contact a vessel wall to maintain a spacing of the pump housing from a vessel wall in which the pump housing is disposed.

48. The blood pump of claim 47.

49. 1. A blood flow assist system comprising: an impeller assembly including a rotor assembly and an impeller coupled to the rotor assembly, the rotor assembly including a concave bearing surface, the impeller configured to rotate about an axis of rotation; a drive unit proximate to the impeller assembly, the drive unit including a drive magnet and a drive bearing between the drive magnet and the impeller assembly, the drive bearing including a convex bearing surface shaped to fit within the concave bearing surface, the convex bearing surface including a plurality of segments extending distally of the drive unit, the plurality of segments being circumferentially spaced apart to define at least one channel between adjacent segments, the at least one channel extending radially outward from a central hollow, the axis of rotation passing through the central hollow; Equipped with rotation of the impeller generates a proximal flow of blood within the central cavity along the axis of rotation and a radial flow of blood from within the central cavity outwardly through the at least one channel. Blood flow support system.

50. a distal end of the drive unit disposed distal to a proximal end of the rotor assembly; 50. A blood flow assist system as claimed in claim 49.

51. the rotor assembly comprises an impeller shaft and a rotor magnet coupled to the impeller shaft, the impeller being disposed on the impeller shaft; 50. A blood flow assist system as claimed in claim 49.

52. the impeller is a first impeller, and the impeller assembly includes a second impeller disposed on the impeller shaft proximally spaced from the first impeller along the impeller shaft.

52. A blood flow assist system as claimed in claim 51.

53. a flange extending non-parallel from a proximal end portion of the impeller shaft, the second impeller including a plurality of vanes disposed on a generally proximally-facing surface of the flange; 53. A blood flow assist system as claimed in claim 52.

54. the first impeller is configured to pump blood along a first flow path along an outer surface of the first impeller, and a majority of the blood flowing along the first flow path is directed along a longitudinal axis of the blood flow assistance system.

54. A blood flow assist system as claimed in claim 53.

55. a second flow path through a lumen of the impeller shaft, the second impeller being configured to direct blood from the second flow path radially outward relative to the longitudinal axis.

55. A blood flow assist system as claimed in claim 54.

56. a sloped cavity extending inwardly and distally relative to the generally proximally-facing surface of the flange; 54. A blood flow assist system as claimed in claim 53.

57. the drive unit comprises a convex member dimensioned to fit within the inclined cavity; 57. A blood flow assist system as claimed in claim 56.

58. a sleeve bearing disposed about the impeller shaft distal to the impeller.

52. A blood flow assist system as claimed in claim 51.

59. in a cross section perpendicular to the axis of rotation of the impeller, the support surface of the sleeve bearing is disposed about only a portion of the circumference of the impeller shaft at a selected axial position, whereby as the impeller shaft rotates about the axis of rotation, an outer surface of the impeller shaft at the selected axial position is periodically exposed to blood during operation of the blood flow assist system; 59. A blood flow assist system as claimed in claim 58.

60. a pump housing, the impeller assembly being at least partially disposed within the pump housing.

50. A blood flow assist system as claimed in claim 49.

61. the pump housing including at least one outlet disposed proximate to the impeller; 61. A blood flow assist system as claimed in claim 60.

62. the second impeller is disposed proximal to a distal end of the at least one outlet.

62. A blood flow assist system as claimed in claim 61.

63. a support structure coupled to or formed with the pump housing, the support structure comprising struts configured to contact a vessel wall to maintain a spacing of the pump housing from a vessel wall in which the pump housing is disposed.

62. A blood flow assist system as claimed in claim 61.

64. the blood flow assist system being configured as a percutaneous pump for percutaneous insertion into a treatment location within a patient's body; 50. A blood flow assist system as claimed in claim 49.

65. the at least one channel includes a plurality of channels, the plurality of channels joining to form the central hollow, the plurality of segments extending from a distal surface of the drive unit, and flow through the central hollow being directed radially outward from the axis of rotation through the plurality of channels by the distal surface of the drive unit; 50. A blood flow assist system as claimed in claim 49.

66. 1. A blood flow assist system comprising: an impeller assembly including a rotor assembly and an impeller coupled to the rotor assembly, the rotor assembly including a first curved bearing surface including a fluid port, the impeller configured to rotate about an axis of rotation; a drive unit proximate to the impeller assembly, the drive unit comprising: a drive magnet; and a drive bearing between the drive magnet and the impeller assembly, the drive bearing comprising a second curved bearing surface shaped to mate with the first curved bearing surface, the second curved bearing surface including a central hollow and one or more channels extending radially outward from the central hollow, the central hollow in fluid communication with the fluid port to direct blood radially outward along at least one channel, the central hollow being coaxial with the axis of rotation; Equipped with rotation of the impeller generates a proximal flow of blood within the central cavity along the axis of rotation and a radial flow of blood outwardly from the central cavity through the at least one channel. Blood flow support system.

67. the first curved bearing surface comprises a concave bearing surface and the second curved bearing surface comprises a convex bearing surface shaped to fit within the concave bearing surface.

67. A blood flow assist system as claimed in claim 66.

68. the convex bearing surface comprises a plurality of distally projecting segments, the plurality of distally projecting segments being circumferentially spaced apart to define the at least one channel between adjacent segments.

68. A blood flow assist system as claimed in claim 67.

69. the impeller is a first impeller and the impeller assembly includes a second impeller spaced proximally from the first impeller.

67. A blood flow assist system as claimed in claim 66.

70. the first impeller is configured to pump blood along a first flow path along an outer surface of the first impeller, a majority of the blood flowing along the first flow path being directed along a longitudinal axis of the blood flow assistance system, the blood flow assistance system further comprising a second flow path through a lumen of the first impeller, the lumen being in fluid communication with the fluid port, and the second impeller is configured to direct blood from the fluid port and the second flow path radially outward relative to the longitudinal axis and through the at least one channel.

70. A blood flow assist system as claimed in claim 69.

71. the one or more channels include a plurality of channels, the plurality of channels joining together to form the central cavity; 67. A blood flow assist system as claimed in claim 66.

72. 1. A blood flow assist system comprising: an impeller assembly including a rotor assembly and an impeller coupled to the rotor assembly, the rotor assembly including a concave bearing surface, the impeller configured to rotate about an axis of rotation; a drive unit proximate to the impeller assembly, the drive unit comprising: a drive magnet; and a drive bearing between the drive magnet and the impeller assembly, the drive bearing comprising a convex bearing surface shaped to fit within the concave bearing surface, the convex bearing surface having a distal end disposed distal to a proximal end of the rotor assembly, the convex bearing surface comprising a segmented bearing including a plurality of segments projecting distally from a surface of the drive unit and at least one channel extending outwardly from a central hollow, the rotational axis extending through the central hollow; Equipped with rotation of the impeller generates a proximal flow of blood along the axis of rotation within the central hollow, blood in the proximal flow of blood being directed radially outward from the central hollow by the surface of the drive unit through the at least one channel. Blood flow support system.

73. the segments of the plurality of segments being circumferentially spaced apart to define the at least one channel between adjacent segments; 73. A blood flow assist system as claimed in claim 72.

74. the rotor assembly comprises an impeller shaft and a rotor magnet coupled to the impeller shaft, the impeller being disposed on the impeller shaft; 73. A blood flow assist system as claimed in claim 72.

75. the impeller is a first impeller, the impeller assembly comprises a second impeller disposed on the impeller shaft spaced proximally from the first impeller along the impeller shaft, the blood flow assist system further comprises a flange extending non-parallel from a proximal end portion of the impeller shaft, the second impeller comprising a plurality of vanes disposed on a generally proximally facing surface of the flange.

75. A blood flow assist system as claimed in claim 74.

76. the first impeller is configured to pump blood along a first flow path along an outer surface of the first impeller, a majority of the blood flowing along the first flow path being directed along a longitudinal axis of the blood flow assistance system, the blood flow assistance system further comprising a second flow path through a lumen of the impeller shaft, the second impeller being configured to direct blood from the second flow path radially outward relative to the longitudinal axis.

76. A blood flow assist system as claimed in claim 75.

77. the at least one channel includes a plurality of channels, the plurality of channels joining together to form the central cavity; 73. A blood flow assist system as claimed in claim 72.

78. A kit comprising:

74. A blood flow assist system according to claim 73, a motor assembly configured to impart rotation to the impeller; a power line electrically connected to the motor assembly; and a console configured to electrically connect to the power line.

79. 1. A blood flow assist system comprising: an impeller assembly; The impeller assembly includes: A rotatable member; a first impeller separate from the rotatable member and in contact with an outer surface of the rotatable member, the first impeller configured to pump blood along a first flow path along an outer surface of the first impeller, such that a majority of the blood flowing along the first flow path is directed along a longitudinal axis of the blood flow assistance system; a second impeller disposed on the rotatable member spaced proximally from the first impeller along the rotatable member, the second impeller configured to direct blood from a second flow passage within a lumen of the rotatable member radially outward relative to the longitudinal axis, the second impeller disposed on a generally proximally-facing surface of the rotatable member; Including, Blood flow support system.

80. a drive unit configured to impart rotation to the rotatable member, the drive unit having a distal end disposed distal to a proximal end of the second impeller, the drive unit comprising a drive magnet, the blood flow assist system further comprising a drive bearing between the drive magnet and the impeller assembly, the drive bearing comprising a convex bearing surface having a plurality of distally projecting segments, the plurality of distally projecting segments being circumferentially spaced apart to define at least one channel between adjacent segments, and the second flow path including the at least one channel.

80. A blood flow assist system as claimed in claim 79.

81. a sleeve bearing disposed about the rotatable member at a location distal to the first impeller, wherein in a cross section perpendicular to an axis of rotation of the first impeller, a bearing surface of the sleeve bearing is disposed about only a portion of the circumference of the rotatable member at a selected axial position, such that as the rotatable member rotates about the axis of rotation, an outer surface of the rotatable member at the selected axial position is periodically exposed to blood during operation of the blood flow assist system.

80. A blood flow assist system as claimed in claim 79.

82. a pump housing, the impeller assembly being at least partially disposed within the pump housing.

80. A blood flow assist system as claimed in claim 79.

83. a support structure coupled to the pump housing, the support structure comprising struts configured to contact a vessel wall to maintain spacing of the pump housing from a vessel wall in which the pump housing is disposed.

83. A blood flow assist system as claimed in claim 82.

84. the rotatable member further comprises an impeller shaft and a flange extending radially outward from the impeller shaft, the impeller shaft, the second impeller, and the flange forming an integral rotor core, and the first impeller is attached to the impeller shaft.

80. A blood flow assist system as claimed in claim 79.

85. the rotatable member, the first impeller, and the second impeller form a unitary body.

80. A blood flow assist system as claimed in claim 79.

86. A kit comprising:

80. A blood flow assist system according to claim 79, a motor assembly configured to impart rotation to the first impeller and the second impeller; a power line electrically connected to the motor assembly; and a console configured to electrically connect to the power line.

87. the rotatable member is free of any obstruction within the lumen that would restrict blood flow within the second flow path; 80. A blood flow assist system as claimed in claim 79.

88. the rotatable member further comprises an impeller shaft and a flange extending radially outward from the impeller shaft, an inner circumferential surface of the first impeller being disposed on an outer circumferential surface of the impeller shaft, and the flange extending radially beyond the outer circumferential surface of the impeller shaft.

80. A blood flow assist system as claimed in claim 79.

89. 1. A blood flow assist system comprising:

1. An impeller assembly comprising: an impeller shaft including a circular right cylinder defining a lumen of constant inner diameter extending proximally from a distal end; a first impeller extending outwardly from the impeller shaft; a second impeller disposed on the impeller shaft spaced proximally from the first impeller along the impeller shaft; an impeller assembly comprising: a drive unit configured to impart rotation to the impeller shaft, the drive unit having a distal end disposed distal to the proximal end of the second impeller within a recessed opening in a proximal end portion of the impeller shaft, the recessed opening being defined in a conical surface extending from a proximal end of the constant inner diameter lumen; Equipped with Blood flow support system.

90. the first impeller is configured to pump blood along a first flow path along an outer surface of the first impeller, and a majority of the blood flowing along the first flow path is directed along a longitudinal axis of the blood flow assistance system.

90. The blood flow assist system of claim 89.

91. and a fairing disposed about the impeller shaft between the first impeller and the second impeller, the first flow passage being disposed along an angled outer surface of the fairing.

90. The blood flow assist system of claim 89.

92. a second flow path through a lumen of the impeller shaft, the second impeller being configured to direct blood from the second flow path radially outward relative to the longitudinal axis.

90. The blood flow assist system of claim 89.

93. During operation of the blood flow assist system, blood pumped along the second flow path flows between a proximal end portion of the impeller shaft and the distal end of the drive unit.

93. A blood flow assist system as claimed in claim 92.

94. the drive unit comprises a drive magnet and a drive bearing between the drive magnet and the impeller assembly, the drive bearing comprising a convex bearing surface having a plurality of distally projecting segments, the plurality of distally projecting segments being circumferentially spaced apart to define at least one channel between adjacent segments, and the second flow path includes the at least one channel.

94. A blood flow assist system as claimed in claim 93.

95. a flange extending non-parallel from a proximal end portion of the impeller shaft, the second impeller being disposed with a plurality of vanes on a generally proximally facing surface of the flange.

90. The blood flow assist system of claim 89.

96. the conical opening extends inwardly and distally relative to the generally proximally-facing surface of the flange, and the drive unit includes a convex member dimensioned to fit within the conical opening.

96. A blood flow assist system as claimed in claim 95.

97. and a rotor magnet coupled to the impeller shaft, the rotor magnet being disposed adjacent a distal-facing surface of the flange.

96. A blood flow assist system as claimed in claim 95.

98. a sleeve bearing disposed about the impeller shaft at a location distal to the first impeller, wherein in a cross section perpendicular to the axis of rotation of the first impeller, a support surface of the sleeve bearing is disposed about only a portion of the circumference of the impeller shaft at a selected axial location, such that as the impeller shaft rotates about the axis of rotation, an outer surface of the impeller shaft at the selected axial location is periodically exposed to blood during operation of the blood flow assist system.

90. The blood flow assist system of claim 89.

99. a pump housing, the impeller assembly being at least partially disposed within the pump housing, the pump housing including an outlet, the outlet being disposed proximate to the first impeller.

90. The blood flow assist system of claim 89.

100. the second impeller is disposed proximal to a distal end of the outlet.

100. A blood flow assist system as claimed in claim 99.

101. a pump housing and a support structure coupled to or formed with the pump housing, the impeller assembly being at least partially disposed within the pump housing, the support structure including struts configured to contact a vessel wall to maintain a spacing of the pump housing from a vessel wall in which the pump housing is disposed.

100. A blood flow assist system as claimed in claim 99.

102. the first impeller including a plurality of outwardly extending, axially aligned blades; 90. The blood flow assist system of claim 89.

103. 1. A blood flow assist system comprising: a rotatable member having an outer surface and an inner surface extending along a longitudinal axis of the blood flow assist system; a first impeller having an inner surface disposed on the outer surface of the rotatable member; a second impeller disposed on the rotatable member and spaced proximally from the first impeller along the rotatable member; Equipped with the second impeller is disposed on a proximally facing surface of the rotatable member, the proximally facing surface extending radially beyond the outer surface of the rotatable member on which the first impeller is disposed. Blood flow support system.

104. the first impeller is configured to pump blood along a first flow path along an outer surface of the first impeller, a majority of the blood flowing along the first flow path being directed along a longitudinal axis of the blood flow assistance system, the blood flow assistance system further including a second flow path through a lumen of the rotatable member, the second impeller configured to direct blood from the second flow path radially outward relative to the longitudinal axis.

104. A blood flow assist system as described in claim 103.

105. and a drive unit configured to impart rotation to the rotatable member, the drive unit having a distal end disposed distal to a proximal end of the second impeller, the drive unit comprising a drive magnet and a drive bearing between the drive magnet and the second impeller, the drive bearing comprising a convex bearing surface having a plurality of distally projecting segments, the plurality of distally projecting segments being circumferentially spaced apart to define at least one channel between adjacent segments.

104. A blood flow assist system as described in claim 103.

106. and a drive unit bearing including a segmented convex bearing surface, the rotatable member including a conical opening disposed between the inner surface and the proximally-facing surface of the rotatable member, the conical opening configured to receive the segmented convex bearing surface.

104. A blood flow assist system as described in claim 103.

107. the distal end of the drive unit is disposed proximal to a proximal end of the first impeller.

107. A blood flow assist system as described in claim 106.

108. the segmented convex bearing includes a central hollow configured to receive blood flowing along the inner surface of the rotatable member within an internal flow passage, and the second impeller drives blood radially outward from the central hollow between adjacent segments of the segmented convex bearing.

107. A blood flow assist system as described in claim 106.

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