Blood pump

Abstract

The blood flow assist system may include an impeller assembly including an impeller shaft and an impeller on the impeller shaft, and a primary flow path disposed along an outer surface of the impeller. The system may include a rotor assembly at a proximal portion of the impeller shaft. The secondary flow path may be disposed along a lumen of the impeller shaft. During operation of the blood flow assist system, blood may be pumped proximally along the primary flow path and the secondary flow path. The system may include a sleeve bearing distal to the impeller. The system may include a drive unit having a distal end disposed distal to the proximal end of the second impeller. The drive unit includes a drive magnet and a drive bearing between the drive magnet and the impeller assembly.

Description

Technical Field

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

Background Art

[0002] (Cross - reference to related applications) This application claims priority to U.S. Provisional Patent Application No. 62 / 943,062, filed on December 3, 2019, and U.S. Provisional Patent Application No. 62 / 947,740, filed on December 13, 2019, the entire contents of each of which are hereby incorporated by reference in their entirety for all purposes. Any application in which a foreign or domestic priority claim is identified in the application data sheet filed together with this application is hereby incorporated by reference in this specification under 37 C.F.R. 1.57.

[0003] In the field of heart assist devices and mechanical circulatory support, 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 while connecting the impeller to the rest of the pump so that the impeller rotates freely. Sleeve bearings (or journal bearings) are a common type of bearing that provides radial confinement. Tapered bearings provide confinement in both the axial and radial directions. Both sleeve bearings and tapered bearings also have improved pressure - velocity characteristics (due to their two - dimensional bearing interfaces) 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 a motor and a pump impeller. Common variations of this design element are direct torque coupling and magnetic torque coupling.

Summary of the Invention

[0006] There is a continuing need for improved blood pumps.

[0007] One of the main difficulties of blood pumps is the susceptibility of blood to the conditions created by the pump. Common problems include thrombus and hemolysis due to bearings, especially in areas where the blood may stagnate and clot.

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

[0009] In one embodiment, a modular bearing system for a blood pump is provided that allows 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 occlusion. Another is a conical bearing. In some embodiments, one or more of these bearing designs can be used. In other embodiments, any bearing design can be used in combination with additional bearing designs. In other embodiments, the two bearing designs can be used together in a configuration that provides additional advantages.

[0010] The sleeve bearing can have a modified shape to reduce thrombosis. Various low - thrombosis sleeve shapes are contemplated. The sleeve bearing can include additional features (e.g., a thrust ring) that provide some degree of axial confinement as well as radial confinement.

[0011] The conical bearing described in the present disclosure has a modified shape that facilitates complete washing of the bearing surface by the blood. Complete washing of the bearing surface can be facilitated by enhancing the supply of blood to the bearing region, enhancing the removal of blood from the bearing region, or some combination of these.

[0012] The sleeve bearing and the conical bearing can have specific features that support the use of their combinations and provide the unique advantages resulting from these combinations.

[0013] In some embodiments, a blood flow assistance 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 fit (e.g., fit inside) the first curved bearing surface. In some embodiments, the first curved bearing surface includes a fluid port. In some embodiments, the second bearing surface includes 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 of the channels. In some embodiments, the convex bearing surface has a distal end disposed distal to the proximal end of the rotor assembly. In some embodiments, the convex bearing surface includes a plurality of segments protruding in the distal direction, the plurality of segments protruding in the distal direction 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, in each embodiment disclosed herein, the rotor assembly may alternatively include a convex bearing surface, the drive bearing can include a concave bearing surface, and it should be understood that the convex bearing surface mates (e.g., fits inside) with the concave bearing surface. Further, in embodiments where the rotor assembly includes a convex bearing surface, the plurality of segments may extend proximally (e.g., as opposed to extending in the distal direction), and can be circumferentially spaced apart 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, and the impeller is disposed on the impeller shaft. In some embodiments, the impeller assembly includes a second impeller disposed on the impeller shaft and spaced proximally from the impeller along the impeller shaft. The flange can extend non-parallel from the proximal end portion of the impeller shaft, and the second impeller includes a plurality of vanes disposed on a surface that faces generally proximally of the flange.

[0016] In some embodiments, the impeller is configured to pump blood along a first flow path along the outer surface of the impeller, and most of the blood flowing along the first flow path is directed along the longitudinal axis of the blood flow assistance system. In some embodiments, the system includes a second flow path through the lumen of the impeller shaft, and the second impeller is configured to direct blood radially outward from the second flow path with respect to the longitudinal axis. In some embodiments, the inclined cavity extends inwardly and distally with respect to the surface facing substantially proximal to the flange. In some embodiments, the drive unit includes a convex member sized to fit within the inclined cavity. In some embodiments, the system includes a sleeve bearing disposed around the impeller shaft at a distal position of 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 a selected axial position, such that as the impeller shaft rotates about the axis of rotation, the outer surface of the impeller shaft at the selected axial position is cyclically exposed to blood during operation of the blood flow assistance 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 disposed proximal to the impeller. In some embodiments, the second impeller is disposed proximal to the 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 including struts configured to contact the vessel wall to maintain the spacing of the pump housing from the vessel wall in which the pump housing is disposed. In some embodiments, the blood flow assistance system includes a percutaneous pump configured for percutaneous insertion to a treatment location within a patient's body. The motor can be mechanically coupled to the drive magnet and the power line connected to the motor, and the power line extends proximally from the motor.

[0017] In some embodiments, a method of operating a blood flow assistance system is disclosed. The method includes percutaneously delivering an impeller assembly to a treatment location within a patient's blood vessel, the impeller assembly including a rotor assembly and an impeller coupled to the rotor assembly, the rotor assembly including a concave bearing surface, the blood flow assistance system including 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 that fits within the concave bearing surface, the convex bearing surface including a plurality of segments projecting in a distal direction, the plurality of segments projecting in the distal direction being circumferentially spaced apart to define at least one channel between adjacent segments; pumping blood longitudinally along the length of the impeller assembly and radially outward through at least one channel; and removing the impeller assembly from the patient, and can include or consist essentially of these. In some embodiments, the method includes directing blood radially outward between the 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 relative movement between the impeller assembly and a sheath to self-expand a plurality of struts radially outward to engage the wall of the blood vessel. In some embodiments, opposite relative movement is provided between the impeller assembly and the sheath to fold a plurality of struts within the sheath. In some embodiments, the rotor assembly includes an impeller shaft on which the impeller is disposed and a sleeve bearing disposed around the impeller shaft distal to the 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 supplying current to a motor via power lines, the motor being operably connected to the impeller assembly, the power lines extending outside the patient's body.

[0018] In some embodiments, a method of manufacturing a blood flow assistance system is disclosed. In some embodiments, the method includes providing an impeller assembly comprising a rotor assembly and an impeller coupled to the rotor assembly, wherein the rotor assembly includes a concave bearing surface; 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 having 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; and including or consisting essentially of these steps.

[0019] In some embodiments, providing the drive unit includes forming a plurality of segments projecting in a distal direction on the convex bearing surface, the plurality of segments projecting in the distal direction being circumferentially spaced apart so as to define at least one channel between adjacent segments. In some embodiments, the method includes at least partially disposing the impeller 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 including struts configured to contact a blood vessel wall to maintain a spacing of the pump housing from the blood vessel wall in which the pump housing is disposed. In some embodiments, the method includes providing a motor proximal to the impeller, the motor being 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 assistance system is disclosed. In some embodiments, the blood flow assistance system includes, or consists essentially of, an impeller assembly comprising an impeller shaft, a first impeller disposed on the impeller shaft, and a second impeller disposed on the impeller shaft and spaced proximally from the first impeller along the impeller shaft, and a drive unit configured to impart rotation to the impeller shaft and having a distal end disposed distally of the 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 most of the blood flowing along the first flow path is directed along the longitudinal axis of the blood flow assistance 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 inclined outer surface of the fairing. In some embodiments, the system includes a second flow path passing through the lumen of the impeller shaft, and the second impeller is configured to direct blood radially outward from the second flow path with respect to the longitudinal axis. In some embodiments, during operation of the blood flow assistance system, the blood pumped along the second flow path flows between the proximal end portion of the impeller shaft and the distal end of the drive unit.

[0021] In some embodiments, 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 segments projecting in the distal direction, the plurality of segments projecting in the distal direction being circumferentially spaced so as to define at least one channel between adjacent segments, and the secondary flow path comprising at least one channel. 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 with a plurality of vanes on a surface facing generally proximal to the flange. In some embodiments, the system includes an inclined cavity extending inwardly and distally relative to a surface facing generally proximal to the flange. In some embodiments, the drive unit comprises a convex member sized to fit within the inclined cavity. In some embodiments, the system includes a rotor magnet coupled to the impeller shaft, the rotor magnet being disposed adjacent to a surface facing distally to the flange. In some embodiments, the system includes a sleeve bearing disposed around the impeller shaft at a distal position of 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 a selected axial position, such that when the impeller shaft rotates about the axis of rotation, the outer surface of the impeller shaft at the selected axial position is cyclically exposed to blood during operation of the blood flow assistance 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 disposed proximal to the first impeller. In some embodiments, the second impeller is disposed proximal to the 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 the blood vessel wall to maintain a spacing of the pump housing from the blood vessel wall in which the pump housing is disposed.In some embodiments, the first impeller comprises a plurality of axially aligned blades that extend outwardly. In some embodiments, the kit includes a blood flow assistance 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 a one-piece 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.

[0022] In some embodiments, a blood pump is disclosed. In some embodiments, the blood pump includes a primary impeller, a flow tube through which the primary impeller is fed, a rotatable component including a secondary impeller, a conical opening, and the flow tube, and a drive unit sealed by a drive unit cover, the drive unit cover including a conical member that matches 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 assistance system is disclosed. In some embodiments, the method comprises percutaneously delivering an impeller assembly to a treatment location within a patient's blood vessel, the impeller assembly comprising an impeller shaft, a first impeller disposed on the impeller shaft, and a second impeller disposed on the impeller shaft and spaced proximally 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 and most of the blood flowing along the first flow path being directed along a longitudinal axis of the blood flow assistance system, the second flow path being disposed through a lumen of the impeller shaft and the second impeller directing blood radially outwardly from the second flow path relative to the longitudinal axis; and removing the blood flow assistance system from the patient, or consisting essentially thereof. In some embodiments, the method comprises directing blood radially outwardly between the second impeller and a drive unit, the drive unit having a distal end disposed distally of a proximal end of the second impeller. In some embodiments, the method comprises providing relative movement between the impeller assembly and a sheath to self-expand a plurality of struts radially outwardly to engage the vessel wall. In some embodiments, the method comprises providing opposite relative movement between the impeller assembly and the sheath to collapse a plurality of struts within the sheath. In some embodiments, a sleeve bearing is disposed around the impeller shaft distal to the first impeller, and the method comprises periodically exposing an outer surface of the impeller shaft to blood at a selected axial location. In some embodiments, the method comprises supplying current to a motor via a power line, the motor being operably connected to the impeller assembly and 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 comprises or consists essentially of attaching a first impeller to an impeller shaft such that a flange is disposed at a proximal end of the impeller shaft; providing a second impeller proximally spaced from the first impeller along the impeller shaft such that the second impeller is disposed on a surface facing proximally of the flange; in some embodiments, the method comprises at least partially disposing the first impeller and the second impeller within a pump housing; in some embodiments, the method comprises providing a support structure coupled to or formed with the pump housing, the support structure comprising a convex contact pad configured to contact a blood vessel wall to maintain a spacing of the pump housing from the blood vessel wall in which the pump housing is disposed; in some embodiments, the method comprises providing a motor proximal to the second impeller, the motor being configured to impart rotation to the impeller shaft; in some embodiments, the method comprises connecting the motor to a power line extending proximally relative to the motor, the motor being sized to be inserted into a patient's vasculature and the power line being configured to extend through the vasculature to a location outside the patient's body.

[0025] In some embodiments, a blood flow assistance 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 the longitudinal axis of the first impeller, a primary flow path along the outer surface of the first impeller, and a secondary flow path along the lumen. In some embodiments, the system includes an impeller assembly having an impeller shaft, the impeller is disposed on the impeller shaft, and the impeller shaft includes a lumen extending from the distal end of the impeller shaft to the proximal end of the impeller shaft. In some embodiments, a drive unit configured to impart rotation to the impeller shaft and the impeller is provided, and at least a portion of the drive unit is disposed proximal to the proximal end of the impeller shaft. In one embodiment, during operation of the blood flow assistance system, blood is pumped proximally along the primary flow path and the secondary flow path. In some embodiments, the blood flow assistance system includes a pump housing. In one embodiment, the primary flow path is disposed between the outer surface of the first impeller and the pump housing and is also provided. For example, the primary flow path can be disposed (and extend from) between the radially outermost surface of the first impeller and the inner wall of the pump housing. In one embodiment, during operation of the blood flow assistance system, the blood pumped along the secondary flow path flows between the proximal end of the impeller shaft and the drive unit. In one embodiment, 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 segments protruding in the distal direction, the plurality of segments protruding in the distal direction are circumferentially spaced apart to define at least one channel between adjacent segments, and the secondary flow path includes at least one channel. In some embodiments, a second impeller is disposed on the impeller shaft proximal to and spaced from the first impeller along the impeller shaft. The blood flow assistance system can include a flange at the proximal end of the impeller shaft, and the second impeller is disposed on a surface facing proximal to the flange. In some embodiments, the impeller shaft, the second impeller, and the flange form a one-piece 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 assistance system, the blood pumped along the secondary flow path flows between the proximal end of the impeller shaft and the drive unit. In some embodiments, the kit can include a blood flow assistance 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 assistance system is disclosed. In some embodiments, the blood flow assistance system includes a pump housing and 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 being configured to rotate about a rotation axis, the impeller assembly, and a sleeve bearing disposed around the impeller shaft distal to the impeller, or consisting essentially of them. In some embodiments, the sleeve bearing has an inner support structure that supports the impeller shaft, an outer support structure coupled to or formed with the pump housing, and a connection structure that extends radially between the inner support structure and the outer support structure. In some embodiments, the inner support structure has a distal boundary, and the distal boundary is inclined with respect to the rotation axis such that in a cross-section taken perpendicular to the rotation axis, only a portion of the distal boundary is disposed around the impeller shaft at a selected axial position along the rotation axis. When the impeller shaft rotates about the rotation axis, the outer surface of the impeller shaft at the selected axial position is periodically exposed to blood during operation of the blood flow assistance system. In some embodiments, in a cross-section perpendicular to the rotation axis, the support surface of the sleeve bearing is disposed around only a portion of the periphery of the impeller shaft at a selected axial position along the rotation axis, whereby when the impeller shaft rotates about the rotation axis, the outer surface of the impeller shaft at the selected axial position is periodically exposed to blood during operation of the blood flow assistance system. In some embodiments, at all axial positions along the rotation axis along the length of the sleeve bearing, the support surface of the sleeve bearing is disposed only partially around the outer periphery of the impeller shaft. In some embodiments, at an axial position along the rotation axis, the support surface of the sleeve bearing is disposed only partially around the outer periphery 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 segments projecting distally from the convex bearing surface, the plurality of segments projecting distally being circumferentially spaced apart so as to define at least one channel between adjacent segments.

[0027] In some embodiments, the support surface comprises a small circular sawtooth surface as shown in the side view of the sleeve bearing. In some embodiments, the support surface is disposed completely around the outer circumference of the impeller shaft at a second axial position along the axis of rotation. In some embodiments, the system includes a pump housing, and the impeller assembly is disposed within the pump housing. In some embodiments, the system includes a support structure coupled to the pump housing, the support structure comprising struts configured to contact the blood vessel wall to maintain a spacing of the pump housing from the blood 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 the outer surface of the impeller, and most 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 proximally spaced from the impeller along the impeller shaft, the second impeller being configured to direct blood radially outward from the second flow path within the lumen of the impeller shaft with respect to the axis of rotation. In some embodiments, the system includes a flange extending non-parallel to the proximal end portion of the impeller shaft, and the second impeller is disposed on a surface facing generally proximally of the flange. In some embodiments, the kit includes a blood flow assistance system comprising 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 comprises a pump rotor having a rotating member including a primary impeller and a flow conduit that rotates the primary impeller about a rotational axis, and a sleeve bearing that fits around the pump rotor and has a bearing interface edge that is non-perpendicular to the rotational axis, or consists essentially of these. In some embodiments, the bearing interface edge comprises a non-circular sleeve edge that ensures that there is no point on the rotating member that 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 full height of the sleeve bearing such that the surface of the rotating member is covered by the sleeve bearing only for a portion of the rotation. In some embodiments, the bearing interface edge includes an ellipse. In some embodiments, the bearing interface edge varies sinusoidally.

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

[0030] In some embodiments, a method of manufacturing a blood flow assistance system is disclosed. In some embodiments, the method comprises disposing an impeller assembly within a pump housing, the impeller assembly comprising an impeller shaft and an impeller on the impeller shaft, the impeller shaft being configured to rotate about a rotational axis; and disposing a sleeve bearing about the impeller shaft, wherein at an axial position along the rotational axis, the support surface of the sleeve bearing is disposed only partially around the 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 a concave bearing surface. In some embodiments, providing the drive unit includes forming a plurality of segments projecting in a distal direction on the convex bearing surface, the plurality of segments projecting in the distal direction 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 blood vessel wall to maintain a spacing of the pump housing from the blood vessel wall in which the pump housing is disposed. In some embodiments, the method includes providing a motor proximal to the impeller, the motor being 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. The system includes an impeller shaft, an impeller on the impeller shaft, a primary flow path disposed along an outer surface of the impeller, and a rotor assembly at a proximal portion of the impeller shaft, the rotor assembly including a concave bearing surface, a flange disposed around the concave bearing surface, a rotor magnet supported by the impeller shaft, and a second impeller disposed on a surface facing proximal to the flange. The impeller assembly further includes a secondary flow path disposed along a lumen of the impeller shaft, and during operation of the blood flow assist system, blood is pumped proximally along the primary and secondary flow paths. A sleeve bearing is disposed distal to the impeller and is disposed around the impeller shaft such that an outer surface of the impeller shaft at a selected axial position is periodically exposed to blood during operation of the blood flow assist system as the impeller shaft rotates. A drive unit has a distal end disposed distal to a proximal end of the second impeller, 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 and a plurality of segments projecting in a distal direction, the plurality of segments projecting in the distal direction being circumferentially spaced apart to define at least one channel between adjacent segments, and the drive unit being configured to impart rotation to the drive magnet, the rotor magnet, and the impeller shaft. In some embodiments, the kit can include or consist essentially of 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. 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 assistance system is disclosed. In some embodiments, the blood flow assistance system includes, or consists essentially of, a pump configured for percutaneous insertion into a treatment location of a patient, an elongate body extending proximally from the pump, and a recovery mechanism between a proximal curvature of the pump and the elongate body, the recovery mechanism including a diameter-expanded portion and a neck portion between the diameter-expanded portion and the proximal curvature of the pump. In some embodiments, the diameter-expanded portion includes 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 the longitudinal axis of the blood flow assistance system and intersecting the first curved portion defines a first angle between the proximal curvature and the first curved portion, and a second plane extending parallel to the longitudinal axis of the blood flow assistance system and intersecting the second curved portion defines a second angle between the proximal curvature and the second curved portion, the second angle being different from the first angle. In some embodiments, the diameter-expanded portion includes a plurality of lobes extending radially outward. In some embodiments, the pump includes a pump head and a motor housing coupled to the pump head, and a proximal end portion of the motor housing includes the proximal curvature. In some embodiments, the pump head includes a pump housing and an impeller within the pump housing, and the motor housing includes a motor operably coupled to the impeller. In some embodiments, the neck portion includes a first depth at a first circumferential position of the recovery mechanism and a second depth smaller than the first depth at a second circumferential position of the recovery mechanism spaced from the first circumferential position.

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 only and should in no way be construed as limiting the scope of the embodiments. Furthermore, various features of the different disclosed embodiments can be combined to form additional embodiments that are part of this disclosure. In the drawings, like reference numerals consistently denote corresponding features throughout like embodiments. A brief description of each drawing is provided below.

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Best Mode for Carrying Out the Invention

[0065] Referring now to the drawings, the elements shown are not necessarily drawn to scale, and like or similar elements are designated by the same reference numeral throughout several views. Generally referring to the drawings, it will be understood that the illustrations are for the purpose of describing particular embodiments of the present disclosure and are not intended to be limiting. Most of the terms used herein will be recognizable to those skilled in the art, but where not explicitly defined, the terms should be construed to adopt the meaning currently accepted by those skilled in the art.

[0066] I. Overview of the Blood Flow Assistance System The various embodiments disclosed herein relate to a blood flow assistance 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, such as 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, such as a console (not shown). The connector 23 can provide electrical communication between the control system and a power line 20 that extends distally along the longitudinal axis L from the connector 23 and the proximal end 21. The power line 20 can comprise an elongate body that electrically and mechanically connects to the pump 2 at or near the distal end 22 of the blood flow assistance system 1, and the distal end 22 is spaced from the proximal end 21 along the longitudinal axis L.

[0067] The pump 2 can include a pump head 50 that includes a pump housing 35 connected to a drive unit 9 that includes a motor housing 29. A recovery mechanism 48 can be provided at the proximal end portion of the pump 2. In some embodiments, the recovery mechanism can be coupled to the distal end of the power line 20 between the power line 20 and the motor housing 29. After the procedure, the clinician can remove the pump 2 from the patient by engaging a tool (e.g., a snare, clamp, hook, etc.) with the recovery mechanism 48 and pulling the pump 2 out of the patient. For example, the recovery mechanism 48 can include a neck portion 49 (e.g., a reduced diameter portion) at the 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 both sides of the recovery mechanism 48. The second curved portion 51b can be disposed around the first curved portion 51a and can have a surface facing radially outward and a convex surface facing proximally that is 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 recovery mechanism 48 and a second depth that is less than the first depth at a second circumferential position of the recovery mechanism 48 spaced from the first circumferential position.

[0068] Advantageously, 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 smooth continuous (substantially monotonically decreasing) geometric transition between the proximal curved portion 51c of the motor housing 29 and the power line 20, thereby providing smooth blood flow and reducing the risk of thrombosis. The second curved portion 51b can function as a lobe extending radially outward, for example, radially outward of 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 anatomical structure. Some cross-sections through the longitudinal axis of the retrieval mechanism 48 can include a substantial neck portion (e.g., a minimum value of 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 minimum value or no minimum value. In the illustrated embodiment, there are two first curved portions 51a that can function as a double-lobe retrieval mechanism. In other embodiments, more or fewer lobes can be provided to enable pump retrieval while ensuring a smooth flow transition between the motor housing 29 and the power line 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 recovery mechanism 48 can be coupled to or integrally formed with the motor housing 29. In other arrangements, the recovery mechanism 48 can be disposed at other locations of the pump 2. As shown, the recovery mechanism 48 can be symmetrically and continuously disposed about the longitudinal axis L. In other configurations, the recovery mechanism 48 can include a plurality of discrete surfaces spaced circumferentially and / or longitudinally apart.

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

[0071] As shown in FIGS. 1A - 1C, the drive unit 9 can be configured to impart rotation to an impeller assembly 4 disposed within a pump housing 35 of a pump head 50. As described herein, the drive unit 9 can include a drive magnet 17 and a motor 30 (see FIGS. 6 - 8A) disposed within a motor housing 29 covered by a distal drive unit cover 11. 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 proximal shroud 16 of the impeller 6. Power lines 20 can extend from a treatment position outside the patient's body and can provide power (e.g., current) and / or control to the motor 30. Thus, in some embodiments, the rotational drive shaft does not extend outside the patient's body. As described herein, the power lines 20 can energize the motor 12, thereby rotating the drive magnet 17 about a longitudinal axis L, which can function as, be aligned with, or correspond to a rotation axis. Rotation of the drive magnet 17 can impart rotation to 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 an impeller shaft 5 (which can function 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 stationary magnetic device. The stator or other magnetic device can be energized, for example, with an 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 transversely crosses the longitudinal axis L in the radial direction. For example, the first impeller 6 can have a plurality (e.g., two) of 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 and reduce shear stress. One of ordinary skill in the art will understand that other designs of the first impeller 5 may be appropriate.

[0072] As shown in FIGS. 1A - 1C, the impeller assembly 4 can be disposed within the shroud 16. The impeller shaft 5 can be supported at its distal end by a sleeve bearing 15 connected to the distal portion of the shroud 16. A support structure, such as a positioning system, can include a base 36 coupled to 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 each other. The base 36, the sleeve bearing 15, and the shroud 16 of the support structure or positioning system can cooperate to at least partially define the pump housing 35, as shown in FIGS. 1A and 1C. The positioning system can include a plurality of self - expanding struts 19 having convex contact pads 24 configured to contact the blood vessel wall to maintain the spacing of the pump housing 35 from the blood vessel wall in which the pump housing 35 is disposed. In FIGS. 1A - 1C, the struts 19 of the positioning system are shown in an expanded deployed configuration, and the contact pads 24 extend radially outwardly to a position where the contact pads 24 contact the blood vessel wall, in which the pump 2 is arranged 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 port 25 can include an opening formed between axial extension members 60 that extend 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 member 60 (also referred to as a pillar) can be shaped to function as a vane that can shape or direct the flow of blood through the second fluid port 25. For example, in various embodiments, the axially extending member 60 can be inclined or curved to match the profile of the impeller blade 40. In other embodiments, the axially extending member 60 may not be inclined to match the blade 40. In some embodiments, the first fluid port 27 can include an inlet port through which blood flows. In such embodiments, the impeller assembly 4 can draw blood into the first fluid port 27 and discharge the blood from the pump 2 through the second fluid port 25 that can 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] Advantageously, the blood flow assistance system 1 can be delivered percutaneously to the treatment location of the patient. FIG. 1D shows the pump 2 disposed within the elongate sheath 28. As shown, the struts 19 are held in a configuration folded by the inner wall of the sheath 28. In the folded configuration, the struts 19 can be compressed in diameter or major transverse dimension at one or more locations that are approximately the same as (or slightly smaller than) the diameter of the shroud 16. The patient can be prepared for the procedure in a standard manner in a catheterization laboratory, and the femoral artery can be exposed. The sheath 28 (or an introducer structure within the sheath 28) can be passed over a guide wire and disposed at the treatment location, for example, within the descending aorta. After the sheath 28 is disposed, the pump 2 can be advanced within the sheath 28, and the pump 2 is disposed in the central 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. Disposing the pump 2 at this location can advantageously enable sufficient cardiac assistance and increased perfusion of other organs such as the kidneys. Once at the treatment location, relative movement 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 positioning system can self-expand radially outward along the radial axis R due to the stored strain energy to the deployed and expanded configurations shown in FIGS. 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 location, the clinician can engage the control system to activate the motor 30 and 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 arranged such that the distal end 22 is upstream of the impeller 6, for example, such that a first fluid port 27 located distally is upstream of a second fluid port 25. In embodiments accessing the treatment location via the femoral artery, the first fluid port 27 can function as an inlet to the pump 2, and the second port 25 can function as an outlet of the pump 2. However, in other embodiments, the pump 2 can be percutaneously inserted 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 arranged such that the distal end 22 of the system 1 is downstream of the impeller 6, for example, such that a first fluid port 27 arranged distally is downstream of a second fluid port 25. In embodiments accessing the treatment location 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 of the pump 2.

[0076] When the treatment procedure is completed, the pump 2 can be removed from the patient. To fold the struts 19 into the sheath 28 in the folded configuration, a relative movement opposite to that used to deploy the pump 2 can be provided between the sheath 28 and the pump 2 (e.g., between the sheath 28 and the impeller assembly 4 and the pump housing 35). In some embodiments, the pump 2 can be withdrawn from the sheath 28 together with the sheath 28 within 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 described above, in some embodiments, the sleeve bearing 15 can support the first impeller 6 and can support the distal end portion 5A of the impeller shaft 5 that also functions as a flow tube. The design can generally be described from the perspective that the rotational central axis of the impeller assembly 4 is along the longitudinal axis L of the system 1, for example, vertically oriented for illustrative purposes in some cases. As used herein, the proximal and distal ends (or ends) of a component may be axially spaced along the longitudinal axis L of the system 1. Thus, the sleeve bearing 15 can be described as being replaceable with respect to the associated length or height extending along the longitudinal axis L. Generally, a rotating member (such as a shaft or tube like the impeller shaft 5 illustrated and described herein) that rotates inside a tubular sleeve or bearing has a cylindrical bearing surface as an open right cylinder. This standard bearing design has circular proximal and distal edges (e.g., upper and lower interface edges) perpendicular to the longitudinal axis L of the rotating member or rotating shaft, and a cylindrical bearing surface between the edges that remains covered by the bearing body and is not exposed. Further, there is a circular set of points where the rotating member (e.g., shaft 5) and the bearing contact each other, 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 is always aligned perpendicular to the edge of the sleeve. This condition has been shown to promote thrombus formation at the sleeve edge. This thrombus can grow to form a complete ring around the sleeve edge, thereby interfering with proper operation.

[0078] The design of the modified sleeve bearing 15 described herein has a novel design for reducing or preventing thrombosis during operation. Referring to FIGS. 2A-2E, an 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, in some embodiments, by, for example, a thrust ring bearing 14 (see FIG. 6). In one embodiment, the thrust bearing 14 can be laser welded to the inner sleeve 37. In other embodiments, the thrust bearing 14 may be absent between the first impeller 6 and the inner sleeve 37. The sleeve bearing 15 can further comprise an outer support structure including an outer sleeve or outer bearing carrier 38, also sometimes referred to herein as an outer annular or cylindrical member, connected to the shroud 16. The outer sleeve or bearing carrier 38 can comprise a small radially outer portion of the sleeve bearing 15. A connection structure 39 can 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 variant, the connection structure 39 can be directly coupled to the shroud 16. In one embodiment, the outer bearing carrier 38 can be omitted. The outer bearing carrier 38 can be integrated with the shroud 16 or made a part of the shroud such that the structure is a monolithic structure and not an assembly of multiple parts. In other variants, the connection structure 39 can 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 can have a primary flow path or a first flow path 3A. Blood can 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. Most of the blood flow through the pump 2 (e.g., most of the momentum of the total blood flow) can flow along the primary flow path or the first flow path 3A. The first flow path 3A can extend radially between the rotating first impeller 6 and the stationary pump housing 35. Thus, blood can flow on the outermost rotating surface of the first impeller 6 between the first impeller 6 and the stationary inner wall of the pump housing 35. The pump 2 can also have a secondary or second flow path 3B along the lumen of the impeller shaft 5, which can function as a flow tube as described herein. A portion of the total blood flow can 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 range from 0.5% to 10% of the volumetric flow rate of blood along the primary flow path 3A, from 1% to 5% of the volumetric flow rate of blood along the primary flow path 3A, or from 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 that extends between a proximal edge 37B (or “lower edge” when viewed vertically) and a distal edge 37A (or “upper edge” when viewed vertically) spaced from the proximal edge 37B along the longitudinal axis L. The sleeve bearing 15 can be shaped such that one or more bearing interfaces 41 and / or joining edges (37A, 37B) of the inner sleeve 37 are not perpendicular to the axis of rotation or the longitudinal axis L of the sleeve bearing 15. In one embodiment, the bearing interface 41 can comprise edges 37A, 37B that form an inclined or tapered ellipse with respect to the longitudinal axis L of the sleeve bearing 15 (FIGS. 2A-2E). In another embodiment, as described below, the bearing surface 41 can vary sinusoidally to form a small circular sawtooth edge (see FIG. 2F). These or other shapes that result in non-circular sleeve edges 37A, 37B ensure that there is no point on the rotating member (e.g., shaft 5) that remains aligned with the sleeve edges 37A, 37B during rotation of the rotating member, thereby minimizing the potential for thrombus formation. In a conventional design, the entire straight cylindrical portion remains covered, but 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 when the sleeve bearing appears to be vertically oriented), such that the rotating member bearing interface 41 is covered by the sleeve bearing only for a portion of the rotation. Thus, the interface bearing surface 41 can have a better exchange of the blood lubricating layer than conventional designs.

[0081] Accordingly, in some embodiments, the distal edge 37A can include the distal boundary of the inner sleeve 37. The distal boundary (e.g., 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., 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 at which the outer surface 5' of the impeller shaft 5 (see FIG. 2A) is periodically exposed to the blood flowing along the first flow path 3A. In the exposed axial regions 42A, 42B, the bearing interface 41 is disposed only on a portion of the perimeter (e.g., circumference) around the impeller shaft 5. Thus, as the impeller shaft 5 rotates about the axis of rotation (aligned with the longitudinal axis L), the outer surface of the impeller shaft 5 at selected axial positions within the exposed axial regions 42A, 42B is periodically exposed to the blood flow within the first path 3A during operation of the blood flow assistance system 1.

[0082] In some embodiments as shown in FIGS. 2A - 2E, the inner sleeve 37 may be partially axially overlapped 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 in that overlapping cross - sectional plane 43 is not exposed to the blood flow within the first path 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 in the range of 1% to 50% of the length of the sleeve bearing 15, in the range of 5% to 50% of the length of the sleeve bearing 15, in the range of 10% to 50% of the length of the sleeve bearing 15, in the range of 20% to 40% of the length of the sleeve bearing 15, or in the range of 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 there are no points on the outer surface 5' of the impeller shaft 5 that remain 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 an exposed axial region 42, whereby the bearing surface 41 of the inner sleeve 37 is disposed only partially 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 there are no points on the rotating member or shaft 5 that remain aligned with the sleeve edges 37A, 37B throughout the 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] Accordingly, 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 positions around the circumference of the inner sleeve 37 (Figs. 2E and 3F). In these embodiments, there is at least one point on the bearing interface 41 over the entire length (or height) of the bearing interface 41 that is exposed and not covered by the inner sleeve 37 of the sleeve bearings 15, 15A. In other words, the sleeve bearings 15, 15A do not cover 360° of the rotating member or shaft 5 over the entire length or height of the bearing interface region 41. This interrupted contact of the disclosed embodiments facilitates the exchange of the lubricating layer of blood across the entire bearing interface 41 and does not allow the blood to stagnate or become trapped.

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

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

[0087] Figures 2G and 2H show another example of a sleeve bearing 15B having a non-overlapping design. The sleeve bearing 15B comprises a small serrated bearing in which the bearing interface 41 is arranged in a repeating, wavy, or in some cases a sinusoidal pattern 44 around the longitudinal axis L. The sinusoidal pattern 44 can have gaps that are alternately exposed around the impeller shaft 5 during rotation such that all axial positions along the length of the sleeve bearing 15B are periodically exposed to the blood flow during operation of the system 1. FIG. 2G shows that the inner sleeve 37' can have a wavy pattern having a plurality (e.g., two) of distal peaks 61 and a plurality (e.g., two) of proximal peaks 62. For example, as shown in FIG. 2G, the peaks 61, 62 can be substantially flat having an arcuate portion 64 extending between the peaks 61, 62. The gap 63 between the arcuate portions 64 can provide for periodic exposure of the shaft 5 to the blood flow. Thus, during rotation, the shaft 5 can transition from a state covered by the arcuate portion 64 to a state not covered and exposed through the gap 63. In other variations, the wavy pattern of the sleeve 37' can have more than three peaks. FIG. 2H shows an inner sleeve 37'' having another small serrated structure having a sinusoidal pattern with, for example, curved peaks 61, 62. In some configurations, the use of curved peaks 61, 61 (as opposed to sharp or flat peaks) can advantageously enable a smoother flow profile.

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

[0089] III. Modified Conical Bearing 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, as shown in FIG. 6, can provide a magnetic coupling and a fluid bearing interface between the drive magnet 17, a driven or rotor magnet 12, and a rotor assembly 46 that includes an impeller shaft 5 and an integral rotor core 8 that includes a secondary impeller 7. 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 of 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 an inclined concave cavity sized to receive the convex member 45. The drive unit 9 can include a convex member sized to fit within the inclined cavity of the concave opening 32.

[0090] The bearing interface region of this bearing design can be formed by the mating surfaces of a conical or convex member 45 and a conical or concave opening 32 and the space therebetween. A conical bearing can provide confinement in both the axial and radial directions. The axial restraint from a single conical bearing can be in one direction only. A steep taper conical bearing provides a relatively large radial confinement, and a shallow taper conical bearing provides a relatively large axial confinement. In some embodiments, the conical member 45 can be modified to reduce hemolysis and / or coagulation. In some embodiments, the conical member 45 can be cut away by a cylinder coaxial with the axis of the cone (or the axis of rotation) to remove the base of the cone. In some embodiments, the conical member 45 can be cut away 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 cut away by both a cylinder and a cone. In some embodiments, the surface of the conical opening 32 can be modified in a similar manner, either 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 by 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 a pump having any overall shape.

[0091] Considering the general possibility that there are holes, grooves, channels, or gaps in either the conical member 45 and / or the conical opening 32, any of their surfaces consists of a plurality of distinct bearing surfaces within the generally conical plane that defines the member 45 or the opening 32. In this way, the opening 32 and / or the conical member 45 of the bearing pair may be formed by a plurality of distinct surfaces or segmented surfaces. The plurality of distinct surfaces 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 distinct components or parts. The grooves and gaps in either the conical member 45 and / or the conical opening 32 can be formed by removing material from a single generally conical surface or by using a plurality of distinct surfaces.

[0092] In some embodiments of the modified conical bearing, the conical members 45 of the bearing pair can comprise a segmented frustoconical shaped convex bearing surface formed from a plurality of segments 33 (Figs. 3A-3D) extending in the distal direction. The segments 33 extending in the distal direction can extend distally from the drive unit cover 11. The segments 33 can be circumferentially spaced so as 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 resulting from a common part having a gap or channel 34 therebetween, although the segments 33 can also be separated by shallow or deep grooves. The gap, groove, or channel 34 can follow any path. In the illustrated embodiment, the channel 34 extends radially outward from a central recess or void 31 (also referred to herein as a void) at a proximal location of the proximal end portion 5B of the impeller shaft 5. In some embodiments, the width and depth of any groove or channel 34 can vary along its path. In some embodiments, two or more channels 34 can join or separate. In certain embodiments, two or more channels 34 can 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 openings 32 of the bearing pair can be a continuous (e.g., no gaps, channels, or grooves), generally conical surface. The relative angles of the conical bearings (e.g., segments 33) and the spacing between segments 33 can be selected to provide a desired flow profile through the channels 34 described herein. For example, increasing the spacing between segments 33 can increase the flow through the channels 34. Together, the segmented conical member 45 of the drive bearing 18 having channels 34 between the segments 33 and the continuous conical opening 32 can function as a "segmented conical bearing".

[0093] The channel 34 between the segments 33 allows for interrupted contact between bearing surfaces, similar to the interrupted contact described above for the modified sleeve bearings 15, 15A, 15B. This interrupted contact provides, among other things, the advantages of a segmented conical bearing similar to that provided by the modified sleeve bearings 15, 15A, 15B. For example, in embodiments where the conical opening 32 is part of a rotating member (e.g., the impeller shaft 5), the channel 34 between the segments 33 can ensure that at least one point along the entire 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 lubricating layer fluid across the bearing interface. The channel 34 also generates pressure changes that contribute to the formation and dispersion of the lubricating layer, as described above for the sleeve bearings 15, 15A, 15B.

[0094] In some embodiments, additional features can promote blood flow through the central lumen 31 and channels 34 of the segmented conical bearing. In some embodiments, blood can flow into the channels 34 and out through the central lumen 31. In other embodiments, blood can flow into the central lumen 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 lumen 31 and channels 34 ensures that the volume of blood within the channels 34 and central lumen 31 is constantly flowing, provides a source of fresh blood for lubricant layer replacement, carries away heat, and / or can serve to shorten the time that blood is exposed to conditions within the bearing region that may increase the likelihood of hemolysis or thrombosis. 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 second flow path 3B. The convex bearing surface (which can include the convex member 45) can include a void (e.g., the central lumen 31) that can be disposed on the longitudinal axis L. One or more channels 34 can extend radially outward from the void or central lumen 31. The void can be in fluid communication with a fluid port (e.g., the interface between the distribution tube 5 and the conical opening 32) so as to direct blood radially outward along at least one channel 34.

[0095] As shown in FIG. 5A, the segment 33 of the convex member 45 can be shaped to fit within a concave bearing surface that includes the concave opening 32. In some embodiments, as shown in FIGS. 4A-5B, the direct secondary flow path 3B can provide blood that flows proximally to the central lumen 31 (e.g., through the flow tubes of the impeller shaft 5 shown in FIGS. 4B-4D and 5B). In some embodiments, a secondary or second impeller 7 is used to drive a secondary flow of blood through the bearing region, e.g., through the second flow path 3B, through the central lumen 32, and radially outward through the channel 34. The primary impeller 6 and / or additional secondary impellers 7 of the pump can help draw blood proximally and direct the blood radially outward along the channel 34. FIGS. 4A-4D show a secondary impeller 7 that draws blood out 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 can have a plurality of vanes 10 that help direct blood radially outward through the channel 34 of the drive bearing 18, as described herein.

[0096] Holding the segmented conical bearing element or segment 33 near 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 by the blood flow from the flow tubes of the impeller shaft 5 along the second flow path 3B. Further, the bearing element 33 can have a smaller radius when the linear velocity of the rotating member is lower. Placing the bearing element or segment 33 near the axis L of the pump allows the vanes 10 of the secondary impeller 7 to be placed at a larger radius where the linear velocity of the rotating member or shaft 5 is higher.

[0097] Figure 3D shows an embodiment in which the channels 34 between 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, for example, a central diverter 31a as shown in Figure 3E. The diverter 31a can comprise a distally extending projection (e.g., a cylindrical projection, a conical projection, a pyramidal projection, etc.) disposed in the central region of the bearing between segments 33. In the illustrated embodiment, the diverter 31a can include a symmetric diverter. The diverter 31a can assist in transitioning the blood coming from the flow tube or lumen of the shaft 5 from an axial flow to a radial flow so that it exits through the channels 34. The diverter may optionally be manufactured as one or more separate components attached to the central hollow 31 and / or the channels 34. In some embodiments, the diverter 31a can have a generally right-angled cylindrical shape extending distally from the bearing 18. In other embodiments, the diverter 31a can have a tapered, e.g., 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 shape, the materials used, and the operating conditions, this lubrication can be hydrodynamic lubrication, elastohydrodynamic lubrication, boundary lubrication, or mixed lubrication. The channel 34 between the segments 33 of the conical member 45 of the bearing pair facilitates fluid exchange such that a portion of the blood that forms a lubricating layer between the regions 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 channel 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 range from 0.02 inches to 0.06 inches, from 0.03 inches to 0.05 inches, or from 0.035 inches to 0.045 inches (e.g., about 0.04 inches in some embodiments). The surface of the segment 33 of the conical member of the bearing pair along the channel 34 forms the front and rear edges (as viewed by the region of the conical opening 32 of the bearing pair) of the segment 33 of the conical member of the bearing pair. The distance of the front and rear edges from the conical opening 32 can also be varied to facilitate fluid exchange. For example, the edges can be inclined or rounded, or the distance of the front and rear edges can taper away from or towards the surface of the conical opening 32.

[0099] The surface of the segment 33 of the conical member 45 of the bearing pair may also be modified to branch from the complete conical surface to facilitate the formation of a lubricating layer. For example, one or more surfaces of the segment 33 of the conical member 45 of the bearing pair can be shaped such that the perpendicular distance to the surface of the conical opening 32 of the bearing pair decreases from the front edge to the rear edge. Such a surface profile can promote the formation of a fluid wedge between the segment 33 of the conical member 45 and the conical opening 32 of the bearing pair to improve lubrication. In another embodiment, the surfaces of the segment 33 of the conical member 45 and the conical opening 32 of the bearing pair may be smooth and well - mated to allow the formation of a relatively thin lubricating layer of relatively uniform thickness. The conical member 45 and the conical opening 32 are described as having a generally conical shape in some embodiments, but it should be understood that the member 45 and the opening 32 can generally be considered as a convex member 45 and a concave opening 32. The shapes of the convex member and the concave opening 32 may be any suitable mating shape.

[0100] The blood flow driven by the secondary impeller 7 from the central hollow 31 through the channel 34 provides fresh blood for the exchange of the lubricating layer and carries away the heat within the bearing region. Both functions are important for reducing the likelihood of thrombus formation in the segmented conical bearing.

[0101] The segment 33 of the conical member 45 of the bearing pair and the conical opening 32 of the bearing pair can each be made of any suitable blood - compatible bearing material. As non - limiting examples, the segment 33 of the conical member of the bearing pair may be made of titanium or stainless steel, and / or the conical opening 32 of the bearing pair may be made of 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 first undergo boundary or mixed lubrication, where the surface asperities wear until the surfaces of the conical member and the conical opening are smooth and well - adapted enough to govern hydrodynamic or elastohydrodynamic lubrication. 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 maintain the special geometric features of the segments 33 on the conical member of the bearing pair. In some embodiments, the continuous conical opening 32 of the bearing pair 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 rotating surface centered about the longitudinal axis L. In other variations, the conical opening 32 and the conical member 45 can have similar or even the same hardness that can provide advantages in dimensional and shape stability throughout the operation of the pump 2.

[0103] When hydrodynamic lubrication is dominant, 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, as long as heat is still being transferred, the exchange of the lubricating layer may not be very important. Assuming that red blood cells are sufficiently excluded, the continuous (e.g., without channels or grooves) conical member 45 of the bearing pair can still show a low likelihood of thrombus formation as long as heat can be transferred sufficiently quickly. In some embodiments, this can be achieved by eliminating or coating the channels 34 to form a continuous conical surface. The blood flow through the coated channels 34 can transfer sufficient heat from the bearing pair.

[0104] The above-described embodiments of the segmented bearing provide the additional advantage 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 for some movement between the impeller assembly 4 and the cover 11. For example, the pump 2 may be delivered through a tortuous or curved vascular structure or may be abruptly inserted from outside the patient into the inside of a blood vessel. The impeller assembly 4 can be inclined 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 with respect to the distal face of the cover 11. The movement can be important compared to the attachment of the impeller assembly 4 onto a shaft rotatably supported within the drive unit. The inclination of the impeller assembly 4 can be caused by the bending of the shroud 16 that can be bent in a high bending stress operation. In some embodiments, the shroud 16 is made of an elastic material such as nitinol and can elastically return to a state where the pump head 50 is bent and not deflected without stretching.

[0105] IV. Impeller Shaft Having a Flow Tube Passing Through a Primary Impeller Figures 4A-5B and 7 show how the flow tube of the impeller shaft 5 can be routed through the primary impeller 6. This allows for a compact pump rotor assembly 46 where 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 Figures 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 a thrust surface designed to limit axial movement 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 the features described in U.S. Patent Application Publication No. 2017 / 0087288, which is 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 include a flange 47 that extends non-parallel (e.g., radially outward along the radial axis R) from the proximal end portion 5B of the impeller shaft 5, and a plurality of vanes 10 on a surface facing proximal to 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, e.g., may not extend radially beyond the integral streamlined fairing 13 described below. In some of these embodiments, the flange 47 can include 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 can extend proximally from the flange 47 and can have a profile that curves circumferentially about the longitudinal axis L. The vanes 10 can be disposed in a space between the proximal surface of the flange 47 and the distal end of the drive unit 9. The concave opening 32 can include an inclined cavity that extends inwardly and distally with respect to a surface facing generally proximal to the flange 47. The rotor magnet 12 can be disposed adjacent to a surface facing distal to the flange 47. Each of the vanes 10 can have an inner end portion 10a disposed in or near the concave opening 32, and an outer end portion 10b that extends radially and circumferentially outward from the inner end portion 10a along the flange 47. The flange 47 can be coupled or formed at the proximal end of the impeller shaft 5. In some embodiments, e.g., the flange 47 can be formed integrally (e.g., seamlessly formed therewith) with the impeller shaft 5. In other embodiments, the flange 47 and the impeller shaft 5 may be separate components that are mechanically connected to each other (e.g., joined by welding or other means). In some embodiments, the vanes 10 can be formed monolithically with the surface facing proximal to the flange 47.In other embodiments, the vane 10 can be mechanically connected to the surface facing proximal to the flange 47.

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

[0108] As shown in FIGS. 4A, 4C, and 5A, the secondary impeller 7 can have a proximal end 52 at the proximal edge of the vane 10. Further, as shown in FIGS. 3A and 3C, the drive unit 9 can have a distal end 53 at the distal end of the segment 33 that projects in the distal direction. As described above, the convex segment 33 that projects in the distal direction 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 on the proximal end side of the rotor assembly 46), as shown, for example, in FIG. 7.

[0109] VI. Integrated Rotor Core As described herein, in some embodiments, the flow tube of the impeller shaft 5, the concave opening 32 of the segmented conical bearing, and the secondary impeller 7 can be integrated into one part as an integral rotor core 8. The advantages of this approach include, but are not limited to, simpler assembly (as described below) and minimization or reduction of joints between components (particularly on the inner surface of the flow tube of the shaft 5). Advantageously, the primary impeller 6 can be disposed (e.g., mounted and fixed, e.g., welded or adhered) on the impeller shaft 5, providing a compact design.

[0110] Accordingly, 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 can be formed without seams or joints between the components of the integral or monolithic structure. Similarly, the secondary impeller 7 can be disposed (e.g., mechanically fixed) at the proximal end of the impeller shaft 5. In some embodiments, the secondary impeller 7 can be formed monolithically with the impeller shaft 5 so as to form a single component (e.g., molded, cast, etc.). In other embodiments, the secondary impeller 7 and the impeller shaft 5 can comprise separate components. In some embodiments, the primary impeller 6, the secondary impeller 7 (including the flange 47), and the impeller shaft 5 can form a single or monolithic component or body. In some embodiments, for example, the primary impeller 6, the secondary impeller 7, and the 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 that extends radially outward from a lumen formed in the central portion of the molded part. Advantageously, as described above, the integral rotor core 8 can form a compact structure. The rotation of the drive magnet 17 can impart rotation to the rotor magnet 12, and the rotor magnet 12 is also disposed (e.g., mechanically connected or attached) on the impeller shaft 5. The 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 Assistance System Figures 7 and 8A - 8D show exemplary schematic views 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 can be sealed within a motor housing 29. The drive magnet 17 can be rotated by the motor 30 via a motor shaft 51. The motor 30 can be electrically connected to a power line 20. As shown in FIGS. 8A and 8C, the power line 20 can include an insulator having a central lumen 55 and a plurality (e.g., three) of outer lumens 56A - 56C extending along the length of the power line 20. The outer lumens 56A - 56C can be sized and shaped to receive corresponding electrodes or electrical wires (not shown) for supplying power to the motor 30. For example, the lumens 56A - 56C can each receive a high - temperature electrode or wire, a neutral electrode or wire, and a ground electrode or wire, respectively. The electrodes can 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 elongate reinforcement member or guide wire (not shown). The reinforcement member or guide wire can be inserted into the central lumen 55 to assist in guiding the pump 2 to a treatment position. As shown in FIG. 8D, a connector 23 near the proximal end 21 of the system 1 can have electrical contacts 58A - 58C electrically connected to the electrodes within the corresponding outer lumens 56A - 56C. The contacts 58A - 58C can include rings spaced apart by an insulating material and can be configured to be electrically connected to corresponding electrical components within a control system or console (not shown).

[0113] The drive magnet 17 can be encapsulated within the drive unit 9 by a drive unit cover 11 that can also have features that function as bearing components (e.g., segments 33 that project distally). In some embodiments, the top distal portion of the cover 11 can provide 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 a rotatable component (integral rotor core 8) that includes the secondary impeller 7 and a flow tube or impeller shaft 5. The convex member 45 conforms to the contour and fits inside the concave opening 32 of the rotatable component. The channels 34 of the segmented conical bearing enter the bearing region through the flow tube 5 and provide a fluid passage for blood that is pushed out of the bearing region by the secondary impeller 7. The lubricating layer of blood between the bearing surface of the integral rotor core 8 and the mating surface of the conical segment 33 provides lubrication, reduces wear, and facilitates the relative movement of the two components. Depending on the shape, rotational speed, and materials that make up the interface, this can be hydrodynamic, elastohydrodynamic, boundary, or mixed lubrication.

[0114] The rotor magnet 12 of the rotor assembly 46 can be arranged on the integral rotor core 8 so as to be close to the drive unit 9, whereby the integral rotor core 8 is magnetically coupled to the drive unit 9 and can be rotated as desired. The first or primary impeller 6 having an integral streamlined fairing 13 is arranged on the rotor magnet 12 and joined to the integral rotor core 8 to at least partially form the pump rotor assembly 46. The three-part structure (the integral rotor core 8, the magnet, and the primary impeller 6 in which the fairing is integrated) can have advantages as described above in relation to ease of construction and compact design. In some embodiments, the portion of the primary impeller 6 that contacts the flow pipe 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 pipe 5. The rotor magnet 12 and the primary impeller 6 having the fairing 13 may be fixed to the integral rotor core 8 so 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 enable the primary impeller 6 and the fairing 13 to be made from different materials. Alternatively, the rotor magnet 12 may be coated to be suitable for blood contact, may not be covered by the fairing 13, but rather may be joined directly to the primary impeller 6. Such a configuration can enable the use of a magnet of a larger diameter (having a correspondingly higher torque coupling) at the same pump rotor diameter than is possible with a magnet inside the fairing.

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

[0117] The flow pipe of the impeller shaft 5 of the pump rotor can be fitted inside a fixed (non-rotating) sleeve bearing 15 (Figure 7). As described above, the sleeve bearing 15 can provide radial confinement 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 can have a modified shape as described above that reduces or minimizes continuous coating of the outer surface of the impeller shaft 5, thereby reducing the likelihood of thrombosis. The sleeve bearing 15 can also optionally provide a thrust bearing surface that engages any thrust bearing surface of the primary impeller 6 or any thrust ring 14.

[0118] The outer bearing carrier 38 of the sleeve bearing 15 can be fitted around the impeller assembly 4 and attached to a shroud 16 that is attached to the drive unit cover 11 of the drive unit 9. The connection structure 39 can include an arm or a plurality of arms that can be attached directly to the shroud 16 or attached to a ring attached to the shroud 16 to improve the rigidity and roundness of the shroud 16.

[0119] The shroud 16 can comprise a tube having an inlet end and an outlet end. The shroud 16 can be disposed over various internal components that make up the pump rotor (e.g., the impeller assembly 4 and the rotor assembly 46). The outlet end of the shroud 16 can be fixed to the drive unit cover 11 of the drive unit 9. The inlet side of the shroud 16 can be open to form an inlet port 27. The 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 on the surface of the shroud (outlet port) that provides an outlet for the fluid driven by the primary impeller 6 and the secondary impeller 7.

[0120] For clarity, some of the drawings of the system are shown without struts, but the pump can include struts or any other fixing means for fixing the pump to the circulation system, as shown in U.S. Patent No. 8,012,079, U.S. Patent No. 9,572,915, and U.S. Patent Application Publication No. 2017 / 0087288.

[0121] VIII. Operation As shown in FIGS. 9A and 9B, various embodiments of the pump 2 provide two flow paths 3A, 3B as described herein. The first flow path 3A (red in FIGS. 9A - 9B) draws fluid through the inlet port 27 of the shroud 16 and is driven by the primary impeller 6 that directs the fluid from the outlet port 25 of the shroud 16. The second flow path 3B (yellow in FIG. 9A and blue in FIG. 9B) is driven by the secondary impeller 7, which draws fluid through an internal secondary flow path 3B, such as the lumen or flow tube of the impeller shaft 5. The internal flow path passes through the 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 the channel 34 between the conical segments 33 and at a reduced rate through the space between the mating conical surfaces of the bearing interface (e.g., between the convex member 45 and the concave opening or cavity 32). The fluid can be driven radially outward by the vanes 10 of the secondary impeller 7. In particular, in the illustrated embodiment, the flow from both flow paths can be directed from the inlet 27 to the outlet 25. In other embodiments, as described herein, the blood flow can be reversed.

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

[0123] IX. Advantages The various embodiments disclosed herein can have several unique 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 be applicable to a particular embodiment.

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

[0125] b. The secondary flow along the second path 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 openings 32 of the segmented conical bearings, and the secondary impeller 7 can be advantageously integrated into the integral rotor core 8.

[0127] d. The attractive force of the magnetic coupling utilizes a one-way thrust bearing to support the outer rotor. A thrust bearing may not 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 specific aspects of the present disclosure. It should be understood by those skilled in the art that the embodiments described herein merely represent non-limiting embodiments of the present disclosure. Those skilled in the art can make many modifications to the specific embodiments described, including various combinations of different elements, components, steps, features, etc. of the described embodiments, and still obtain similar or analogous results without departing from the spirit and scope of the present disclosure. From the foregoing description, those skilled in the art can readily identify the essential features of the present disclosure and make various modifications and changes to adapt the present disclosure to various applications and conditions without departing from its spirit and scope. The above-described embodiments are intended for illustration only and should not be construed as limiting the scope of the present disclosure.

[0129] Conditional language such as "can," "could," "might," or "may" generally intends to convey that a particular embodiment includes a particular feature, element, and / or step, but other embodiments do not, unless otherwise specified or understood in the context in which it is used. Thus, such conditional language generally does not imply that a feature, element, and / or step is required in any form in one or more embodiments.

[0130] Terms such as "comprising", "including", "having", etc. are synonyms 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 sense (not an exclusive sense), for example, when used to connect a list of elements, the term "or" means one, some, or all of the elements in the list. Further, the articles "a", "an", and "the" used in this application and the appended claims should be interpreted to mean "one or more" or "at least one" unless otherwise specified.

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

[0132] As used herein, the phrase "at least one of" in a list of items refers to any combination of those items, including a single member. By way of example, "at least one of A, B, or C" is intended to include A, B, C, A and B, A and C, B and C, and A, B, and C. Connective phrases such as "at least one of X, Y, and Z" are understood in other senses in the context generally used to convey that items, terms, etc. can be at least one of X, Y, or Z, unless otherwise specified. Thus, such connective phrases are generally not intended to mean that a particular embodiment requires at least one of X, at least one of Y, and at least one of Z to each exist.

[0133] Although 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 its elements can be combined and / or altered differently to form further alternative embodiments or acceptable examples. All such changes and modifications are intended to be included within the scope of this disclosure. A wide variety of designs and techniques are possible. The features, structures, or steps disclosed herein are not essential or indispensable.

[0134] Some embodiments are described in connection 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 have an exact relationship to the actual dimensions and layout of the devices shown. Components can be added, removed, and / or rearranged. Further, the disclosure herein of any particular features, aspects, methods, properties, characteristics, qualities, attributes, elements, etc. related to various embodiments can be used in all other embodiments described herein. Additionally, it will be recognized that any method described herein can be implemented using any device suitable for performing the recited steps.

[0135] For purposes 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 in accordance with any particular embodiment. Thus, for example, one skilled in the art will recognize that the disclosure can be embodied or implemented to achieve one advantage or group of advantages as taught herein without necessarily achieving other advantages that can be taught or suggested herein.

[0136] Furthermore, while exemplary embodiments are described herein, the scope of the present invention extends beyond the specifically disclosed embodiments to include equivalent elements, modifications, omissions, combinations, or sub-combinations of particular features and aspects of the embodiments (e.g., aspects across various embodiments), adaptations and / or alternatives, and any and all embodiments having the use of the present invention as would be understood by one of ordinary skill in the art based on the present disclosure. Limitations in the claims are to be fairly construed based on the language employed in the claims and are not limited to the examples described herein or during the prosecution of the application, and the examples are to be construed as non-exclusive. Additionally, the operations of the disclosed processes and methods can be changed in any manner, including reordering the operations, and / or inserting additional operations, and / or deleting operations. Accordingly, the specification and examples are to be considered exemplary only, and the true scope and spirit are intended to be indicated by the claims and the full scope of their equivalents.

Claims

1. A blood flow assist system, comprising an impeller assembly including a rotor assembly and an impeller coupled to the rotor assembly, wherein the rotor assembly includes a concave bearing surface, an impeller shaft, and a rotor magnet coupled to the impeller shaft, and the impeller is disposed on the impeller shaft; an impeller assembly, 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 having a convex bearing surface shaped to fit within the concave bearing surface, the convex bearing surface including a plurality of segments protruding in a distal direction, the plurality of segments protruding in the distal direction being circumferentially spaced apart to define at least one channel between adjacent segments, the at least one channel extending outward from a void; a drive unit, a sleeve bearing disposed around the impeller shaft at a distal position of the impeller; and in a cross-section perpendicular to the axis of rotation of the impeller shaft, a support surface of the sleeve bearing is disposed around only a portion of the outer circumference of the impeller shaft at a selected axial position, such that when 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.

2. A distal end of the drive unit is disposed distal to a proximal end of the rotor assembly. The blood flow assist system according to Claim 1.

3. The impeller is a first impeller, and the impeller assembly includes a second impeller disposed on the impeller shaft proximal to and spaced apart from the first impeller along the impeller shaft. The blood flow assist system according to Claim 1.

4. Further comprising 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 surface facing generally proximal to the flange. The blood flow assist system according to 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 most of the blood flowing along the first flow path is directed along a longitudinal axis of the blood flow assistance system. The blood flow assistance system according to claim 4.

6. Further comprising a second flow path through a lumen of the impeller shaft, the second impeller being configured to direct blood radially outward from the second flow path with respect to the longitudinal axis. The blood flow assistance system according to claim 5.

7. Further comprising an inclined cavity extending inwardly and distally with respect to a surface of the flange that faces substantially proximally. The blood flow assistance system according to claim 4.

8. The drive unit includes a convex member sized to fit within the inclined cavity. The blood flow assistance system according to claim 7.

9. Further comprising a pump housing, the impeller assembly being at least partially disposed within the pump housing. The blood flow assistance system according to claim 1.

10. The pump housing includes at least one outlet disposed proximally to the impeller. The blood flow assistance system according to claim 9.

11. The impeller is a first impeller, and the blood flow assistance system further includes a second impeller disposed proximally to a distal end of the at least one outlet. The blood flow assistance system according to claim 10.

12. Further comprising a support structure coupled to or formed with the pump housing, the support structure including struts configured to contact a blood vessel wall to maintain a spacing of the pump housing from the blood vessel wall in which the pump housing is disposed. The blood flow assistance system according to claim 10.

13. Configured as a percutaneous pump for percutaneous insertion into a treatment location within a patient's body. The blood flow assistance system according to claim 1.

14. Further comprising a motor mechanically coupled to the drive magnet and a power line connected to the motor and extending proximally from the motor. The blood flow assistance system according to claim 13.

15. A blood flow assistance system, An impeller assembly including a rotor assembly and an impeller coupled to the rotor assembly, wherein the rotor assembly includes a concave bearing surface, an impeller shaft, and a rotor magnet coupled to the impeller shaft, and the impeller is disposed on the impeller shaft. 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 having 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, the convex bearing surface including a segmented bearing including at least one channel extending outward from a central hollow. A sleeve bearing disposed around the impeller shaft at a distal position of the impeller, wherein in a cross-section perpendicular to the rotation axis of the impeller, a support surface of the sleeve bearing is disposed around only a portion of the outer circumference of the impeller shaft at a selected axial position, such that when the impeller shaft rotates around the rotation axis, an outer surface of the impeller shaft at the selected axial position is periodically exposed to blood during operation of the blood flow assistance system. A blood flow assistance system comprising.

16. The convex bearing surface includes a plurality of segments protruding in the distal direction, and the plurality of segments protruding in the distal direction are circumferentially spaced apart to define at least one channel between adjacent segments. The blood flow assistance system according to claim 15.

17. The impeller is a first impeller, the impeller assembly includes a second impeller disposed on the impeller shaft proximal to and spaced apart from the first impeller along the impeller shaft, the blood flow assistance system further includes a flange extending non-parallel to a proximal end portion of the impeller shaft, and the second impeller includes a plurality of vanes disposed on a surface facing substantially proximal to the flange. The blood flow assistance system according to claim 15.

18. The first impeller is configured to pump blood along a first flow path along the outer surface of the first impeller, and most of the blood flowing along the first flow path is directed along the longitudinal axis of the blood flow assistance system. The blood flow assistance system further includes a second flow path passing through the lumen of the impeller shaft, and the second impeller is configured to direct blood radially outward from the second flow path with respect to the longitudinal axis. The blood flow assistance system according to claim 17. **Claim 19** A kit comprising: the blood flow assistance 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 be electrically connected to the power line. **Claim 20** A blood flow assistance 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 being configured to rotate about a rotation axis, a sleeve bearing disposed around the impeller shaft, the sleeve bearing having an inner support structure that supports the impeller shaft, an outer support structure coupled to the pump housing or formed with the pump housing, and a connection structure extending radially between the inner support structure and the outer support structure, wherein in a cross-section perpendicular to the rotation axis, the support surface of the sleeve bearing is disposed around only a portion of the outer circumference of the impeller shaft at a selected axial position along the rotation axis, such that when the impeller shaft rotates about the rotation axis, an outer surface of the impeller shaft at the selected axial position is periodically exposed to blood during operation of the blood flow assistance system, and the inner support structure includes a distal boundary that is inclined with respect to the rotation axis. The blood flow assistance system. **Claim 21** ​ The blood flow assistance system further includes 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 segments projecting in a distal direction extending from the convex bearing surface, the plurality of segments projecting in the distal direction being circumferentially spaced apart so as to define at least one channel between adjacent segments. The blood flow assistance system according to claim 20.

22. A kit comprising the blood flow assistance 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 be electrically connected to the power line.

23. A blood flow assistance system comprising a pump housing, an impeller assembly disposed within the pump housing and comprising an impeller shaft and an impeller on the impeller shaft, the impeller shaft being configured to rotate about a rotation axis, a sleeve bearing disposed around the impeller shaft and having an inner support structure for supporting the impeller shaft, an outer support structure coupled to the pump housing or formed with the pump housing, and a radially extending connection structure between the inner support structure and the outer support structure, wherein in a cross-section perpendicular to the rotation axis, the support surface of the sleeve bearing is disposed around only a part of the outer periphery of the impeller shaft at a selected axial position along the rotation axis, such that when the impeller shaft rotates about the rotation axis, the outer surface of the impeller shaft at the selected axial position is periodically exposed to blood during operation of the blood flow assistance system. The inner support structure includes a distal boundary inclined with respect to the rotation axis. Blood flow assistance system.

24. At all axial positions along the rotation axis along the length of the sleeve bearing, the support surface of the sleeve bearing is disposed only partially around the outer periphery of the impeller shaft. The blood flow assistance system according to claim 23.

25. In a cross-section perpendicular to the rotation axis, only a part of the distal boundary is arranged around the impeller shaft at the selected axial position, so that when the impeller shaft rotates around the rotation axis, the outer surface of the impeller shaft at the selected axial position is periodically exposed to blood during the operation of the blood flow assistance system. The blood flow assistance system according to claim 23.

26. Further comprising 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 comprising a convex bearing surface and a plurality of segments protruding distally from the convex bearing surface, the plurality of segments protruding distally being circumferentially spaced apart so as to define at least one channel between adjacent segments. The blood flow assistance system according to claim 23.

27. A kit comprising: The blood flow assistance 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 be electrically connected to the power line.

28. A blood flow assistance system comprising: 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 being configured to rotate about a rotation axis, a sleeve bearing disposed around the impeller shaft, the sleeve bearing having an inner support structure for supporting the impeller shaft, the inner support structure including a boundary inclined with respect to the rotation axis, comprising: At an axial position along the rotation axis, the support surface of the sleeve bearing is disposed only partially around the outer periphery of the impeller shaft. Blood flow assistance system.

29. When the impeller shaft rotates around the rotation axis, the outer surface of the impeller shaft at the axial position is periodically exposed to blood during the operation of the blood flow assistance system. The blood flow assistance system according to claim 28.

30. At all axial positions along the rotational axis along the length of the sleeve bearing, the support surface of the sleeve bearing is disposed only partially around the outer periphery of the impeller shaft. The blood flow assisting system according to claim 28.

31. The axial position is a first axial position, and the support surface is disposed completely around the outer periphery of the impeller shaft at a second axial position along the rotational axis. The blood flow assisting system according to claim 28.

32. The sleeve bearing has 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. The blood flow assisting system according to claim 28.

33. The boundary is a distal boundary, and in a cross-section perpendicular to the rotational axis, includes a distal boundary that is inclined such that only a part of the distal boundary is disposed around the impeller shaft at the axial position, whereby when the impeller shaft rotates around the rotational axis, the outer surface of the impeller shaft at the axial position is periodically exposed to blood during operation of the blood flow assisting system. The blood flow assisting system according to claim 32.

34. Further comprising a support structure coupled to the pump housing, the support structure including struts configured to contact the blood vessel wall to maintain the spacing of the pump housing from the blood vessel wall in which the pump housing is disposed. The blood flow assisting system according to claim 23.

35. The impeller is configured to pump blood along a first flow path along the outer surface of the impeller, and most of the blood flowing along the first flow path is directed along the rotational axis. The blood flow assisting system according to claim 28.

36. Further comprising a second impeller disposed on the impeller shaft proximally spaced from the impeller along the impeller shaft, the second impeller configured to direct blood radially outward from the second flow path within the lumen of the impeller shaft with respect to the rotational axis. The blood flow assisting system according to claim 35.

37. Further comprising a flange extending non-parallel from the proximal end portion of the impeller shaft, the second impeller being disposed on a surface facing generally proximally of the flange. The blood flow assistance system according to claim 36.

38. Further comprising a drive unit configured to impart rotation to the impeller shaft, The blood flow assistance system according to claim 28.

39. The drive unit includes a drive magnet and a drive bearing between the drive magnet and the impeller assembly, the drive bearing having a convex bearing surface with a plurality of segments protruding in the distal direction, and the plurality of segments protruding in the distal direction being circumferentially spaced apart so as to define at least one channel between adjacent segments. The blood flow assistance system according to claim 38.

40. A kit, Comprising the blood flow assistance system according to claim 28, A motor assembly configured to impart rotation to the impeller, Power lines electrically connected to the motor assembly, And a console configured to be electrically connected to the power lines.

41. The sleeve bearing has a non-circular bearing interface edge that is non-perpendicular to the rotation axis, and the non-circular bearing interface edge is inclined with respect to the rotation axis. The blood flow assistance system according to claim 1.

42. The bearing interface edge includes a non-circular sleeve edge, and the sleeve edge ensures that there is no point on the impeller shaft that remains aligned with the sleeve edge during rotation of the impeller shaft. The blood pump according to claim 41.

43. The sleeve bearing exposes at least one point on the impeller shaft over the entire height of the sleeve bearing such that the surface of the impeller shaft is covered by the sleeve bearing only for a part of the rotation. The blood pump according to claim 41.

44. Further comprising a pump housing, and the rotor assembly is disposed within the pump housing. The blood pump according to claim 41.

45. A blood flow assistance system, 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 being configured to rotate about a rotation axis, A sleeve bearing disposed around the impeller shaft, Comprising. At an axial position along the rotation axis, the support surface of the sleeve bearing is arranged only partially around the outer periphery of the impeller shaft. At all axial positions along the rotation axis along the length of the sleeve bearing, the support surface of the sleeve bearing is arranged only partially around the outer periphery of the impeller shaft. The support surface comprises a small circular sawtooth surface. Blood flow assistance system.

46. Further comprising a support structure coupled to the pump housing, the support structure comprising struts configured to contact the blood vessel wall to maintain the spacing of the pump housing from the blood vessel wall in which the pump housing is disposed. The blood pump according to claim 45.

47. The sleeve bearing comprises a bearing interface edge that is non-perpendicular to the rotation axis. The bearing interface edge varies in a sinusoidal wave shape. The blood flow assistance system according to claim 1.

48. A pump housing, further comprising a pump housing in which the rotor assembly is disposed therein, and a support structure coupled to the pump housing, the support structure comprising struts configured to contact the blood vessel wall to maintain the spacing of the pump housing from the blood vessel wall in which the pump housing is disposed. The blood pump according to claim 47.

49. A blood flow assistance system, An impeller assembly including a rotor assembly and an impeller coupled to the rotor assembly, the rotor assembly having a concave bearing surface, the impeller being configured to rotate about a rotation axis, the impeller assembly; A drive unit proximal to the impeller assembly, comprising 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 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 rotation axis passing through the central hollow, the drive unit; Comprising Rotation of the impeller generates a proximal flow of blood along the rotation axis within the central hollow and a radial flow of blood outward from the central hollow through the at least one channel. Blood flow assistance system.

50. The distal end of the drive unit is disposed distal to the proximal end of the rotor assembly. The blood flow assistance system according to claim 49.

51. The rotor assembly includes an impeller shaft and a rotor magnet coupled to the impeller shaft, and the impeller is disposed on the impeller shaft. The blood flow assistance system according to 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. The blood flow assistance system according to claim 51.

53. The impeller shaft further includes a flange extending non-parallel from a proximal end portion of the impeller shaft, and the second impeller includes a plurality of vanes disposed on a surface substantially facing proximally of the flange. The blood flow assistance system according to 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 most of the blood flowing along the first flow path is directed along a longitudinal axis of the blood flow assistance system. The blood flow assistance system according to claim 53.

55. The impeller shaft further includes a second flow path passing through a lumen of the impeller shaft, and the second impeller is configured to direct blood radially outward from the second flow path with respect to the longitudinal axis. The blood flow assistance system according to claim 54.

56. The flange further includes an inclined cavity extending inwardly and distally with respect to the surface substantially facing proximally of the flange. The blood flow assistance system according to claim 53.

57. The drive unit includes a convex member sized to fit within the inclined cavity. The blood flow assistance system according to claim 56.

58. The impeller further includes a sleeve bearing disposed around the impeller shaft at a distal position of the impeller. The blood flow assistance system according to claim 51.

59. In a cross-section perpendicular to the rotation axis of the impeller, the support surface of the sleeve bearing is arranged around only a part of the outer periphery of the impeller shaft at a selected axial position, so that when the impeller shaft rotates around the rotation axis, the outer surface of the impeller shaft at the selected axial position is periodically exposed to blood during the operation of the blood flow assistance system. The blood flow assistance system according to claim 58.

60. Further comprising a pump housing, wherein the impeller assembly is at least partially disposed within the pump housing. The blood flow assistance system according to claim 49.

61. The pump housing includes at least one outlet disposed proximal to the impeller. The blood flow assistance system according to claim 60.

62. A second impeller is disposed proximal to the distal end of the at least one outlet. The blood flow assistance system according to claim 61.

63. Further comprising a support structure coupled to or formed with the pump housing, the support structure comprising struts configured to contact the blood vessel wall to maintain the spacing of the pump housing from the blood vessel wall in which the pump housing is disposed. The blood flow assistance system according to claim 61.

64. The blood flow assistance system is configured as a percutaneous pump for percutaneous insertion into a treatment location within a patient's body. The blood flow assistance system according to claim 49.

65. The at least one channel includes a plurality of channels, the plurality of channels combine to form the central hollow, the plurality of segments extend from the distal surface of the drive unit, and the flow through the central hollow is directed radially outward from the rotation axis through the plurality of channels by the distal surface of the drive unit. The blood flow assistance system according to claim 49.

66. A blood flow assistance system, An impeller assembly including a rotor assembly and an impeller coupled to the rotor assembly, the rotor assembly comprising a first curved bearing surface including a fluid port, the impeller being configured to rotate about a rotation axis. A drive unit proximal to the impeller assembly, comprising a drive magnet and a drive bearing between the drive magnet and the impeller assembly, the drive bearing having a second curved bearing surface shaped to fit 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 being in fluid communication with the fluid port so as to direct blood radially outward along at least one channel, the central hollow being coaxial with the rotation axis, a drive unit, comprising, wherein rotation of the impeller generates a proximal flow of blood along the rotation axis within the central hollow and a radial flow of blood outward from the central hollow through the at least one channel, a blood flow assistance system.

67. wherein 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, The blood flow assistance system according to claim 66.

68. wherein the convex bearing surface comprises a plurality of segments protruding in the distal direction, and the plurality of segments protruding in the distal direction are circumferentially spaced apart so as to define the at least one channel between adjacent segments, The blood flow assistance system according to claim 67.

69. wherein the impeller is a first impeller and the impeller assembly comprises a second impeller spaced proximally from the first impeller, The blood flow assistance system according to claim 66.

70. wherein the first impeller is configured to pump blood along a first flow path along an outer surface of the first impeller, most 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 being configured to direct blood from the fluid port and the second flow path radially outward with respect to the longitudinal axis and through the at least one channel, The blood flow assistance system according to claim 69.

71. wherein the one or more channels include a plurality of channels, and the plurality of channels combine to form the central hollow, The blood flow assistance system according to claim 66.

72. A blood flow assistance system, An impeller assembly including a rotor assembly and an impeller coupled to the rotor assembly, wherein the rotor assembly has a concave bearing surface and the impeller is configured to rotate about a rotation axis. A drive unit proximal to the impeller assembly, comprising 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 having a distal end disposed distally of the proximal end of the rotor assembly, the convex bearing surface comprising a plurality of segments protruding distally from the surface of the drive unit and at least one channel extending outwardly from a central hollow, the rotation axis extending through the central hollow. Comprising Rotation of the impeller generates a proximal flow of blood along the rotation axis within the central hollow, and blood in the proximal flow of blood is radially outwardly guided from the central hollow by the surface of the drive unit through the at least one channel. Blood flow assistance system.

73. Segments of the plurality of segments are circumferentially spaced apart to define the at least one channel between adjacent segments. The blood flow assistance system according to claim 72.

74. The rotor assembly comprises an impeller shaft and a rotor magnet coupled to the impeller shaft, and the impeller is disposed on the impeller shaft. The blood flow assistance system according to claim 72.

75. The impeller is a first impeller, the impeller assembly comprises a second impeller disposed on the impeller shaft proximally spaced from the first impeller along the impeller shaft, the blood flow assistance system further comprises a flange extending non-parallel to the proximal end portion of the impeller shaft, and the second impeller comprises a plurality of vanes disposed on a surface facing generally proximally of the flange. The blood flow assistance system according to claim 74.

76. The first impeller is configured to pump blood along a first flow path along an outer surface of the first impeller, and most of the blood flowing along the first flow path is directed along a longitudinal axis of the blood flow assistance system. The blood flow assistance system further includes a second flow path passing through a lumen of the impeller shaft, and the second impeller is configured to direct blood radially outward from the second flow path with respect to the longitudinal axis. The blood flow assistance system according to claim 75.

77. The at least one channel includes a plurality of channels, and the plurality of channels combine to form the central hollow. The blood flow assistance system according to claim 72.

78. A kit, comprising the blood flow assistance 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 be electrically connected to the power line.

79. A blood flow assistance system, comprising an impeller assembly, wherein the impeller assembly includes a rotatable member, a first impeller that is separate from the rotatable member and contacts an outer surface of the rotatable member. The first impeller is configured to pump blood along a first flow path along an outer surface of the first impeller, and most 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 and spaced proximally from the first impeller along the rotatable member. The second impeller is configured to direct blood radially outward from a second flow path within a lumen of the rotatable member with respect to the longitudinal axis, and the second impeller is disposed on a surface that generally faces proximally of the rotatable member. including a blood flow assistance system.

80. The blood flow assistance system further comprises a drive unit configured to impart rotation to the rotatable member, the drive unit having a distal end disposed distally of the proximal end of the second impeller, the drive unit comprising a drive magnet, the blood flow assistance 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 segments protruding in the distal direction, the plurality of segments protruding in the distal direction being circumferentially spaced apart so as to define at least one channel between adjacent segments, the second flow path including the at least one channel. The blood flow assistance system according to claim 79.

81. The blood flow assistance system further comprises a sleeve bearing disposed around the rotatable member at a position distal to the first impeller, and in a cross-section perpendicular to the axis of rotation of the first impeller, the bearing surface of the sleeve bearing is disposed around only a part of the outer periphery of the rotatable member at a selected axial position, such that when the rotatable member rotates about the axis of rotation, the outer surface of the rotatable member at the selected axial position is periodically exposed to blood during operation of the blood flow assistance system. The blood flow assistance system according to claim 79.

82. The blood flow assistance system further comprises a pump housing, and the impeller assembly is disposed at least partially within the pump housing. The blood flow assistance system according to claim 79.

83. The blood flow assistance system further comprises a support structure coupled to the pump housing, the support structure comprising struts configured to contact the blood vessel wall to maintain the spacing of the pump housing from the blood vessel wall in which the pump housing is disposed. The blood flow assistance system according to 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. The blood flow assistance system according to claim 79.

85. The rotatable member, the first impeller, and the second impeller form a single body. The blood flow assistance system according to claim 79.

86. A kit comprising: The blood flow assistance 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; A kit further comprising a console configured to be electrically connected to the power line. **Claim 87** The rotatable member further includes an impeller shaft and a flange extending radially outward from the impeller shaft, an inner circumferential surface of the first impeller is disposed on an outer circumferential surface of the impeller shaft, and the flange extends radially beyond the outer circumferential surface of the impeller shaft. The blood flow assistance system according to claim 79. **Claim 88** A blood flow assistance system, comprising: A rotatable member having an outer surface and an inner surface extending along a longitudinal axis of the blood flow assistance 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; wherein the second impeller is disposed on a surface facing the proximal side of the rotatable member, and the surface facing the proximal side extends radially beyond the outer surface of the rotatable member on which the first impeller is disposed. Blood flow assistance system. **Claim 89** The first impeller is configured to pump blood along a first flow path along an outer surface of the first impeller, most of the blood flowing along the first flow path is directed along a longitudinal axis of the blood flow assistance system, the blood flow assistance system further includes a second flow path passing through a lumen of the rotatable member, and the second impeller is configured to direct blood radially outward from the second flow path with respect to the longitudinal axis. The blood flow assistance system according to claim 88. **Claim 90** The blood flow assistance system according to claim 88, further comprising a drive unit configured to impart rotation to the rotatable member, the drive unit having a distal end disposed distally of a proximal end of the second impeller, the drive unit including a drive magnet and a drive bearing between the drive magnet and the second impeller, the drive bearing having a convex bearing surface with a plurality of segments protruding in a distal direction, the plurality of segments protruding in the distal direction being circumferentially spaced apart so as to define at least one channel between adjacent segments. The blood flow assistance system according to claim 88. **Claim 91** Further comprising a drive unit bearing including a segmented convex bearing surface, wherein the rotatable member comprises a conical opening disposed between the inner surface of the rotatable member and the surface facing the proximal side, and the conical opening is configured to receive the segmented convex bearing surface. The blood flow assistance system according to claim 88.

92. The distal end of the drive unit bearing is disposed proximal to the proximal end of the first impeller. The blood flow assistance system according to claim 91.

93. The segmented convex bearing surface includes a central hollow configured to receive blood flowing along the inner surface of the rotatable member within an internal flow path, and the second impeller drives blood radially outward from the central hollow between adjacent segments of the segmented convex bearing surface. The blood flow assistance system according to claim 91.

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