Electromagnetic drive blood pump

Abstract

A magnetic drive system (102) includes a drive shaft (110) coupled to an impeller (106), a driven magnet assembly (140) coupled to at least one of the drive shaft (110) and the impeller (106), and a drive coil assembly (114) configured to drive the driven magnet assembly (140). A blood pump (100) is also disclosed and includes a pump housing and the magnetic drive system (102) disposed therein.

Description

[0001] Cross-references to Related Literature

[0002] This application claims priority to provisional application No. 62 / 964,102, filed January 21, 2020, the entirety of which is incorporated herein by reference. TECHNICAL FIELD

[0003] The present disclosure relates to percutaneous circulatory support devices. More particularly, the present disclosure relates to motors and bearings used in percutaneous circulatory support devices. BACKGROUND

[0004] Percutaneous circulatory support devices, such as blood pumps, are generally easier to implant and provide greater benefit if they can be made as small as possible without sacrificing functionality. Typically, a motor mounted in a motor housing drives an impeller mounted in a separate impeller housing. SUMMARY

[0005] In Example 1, a magnetic drive system of a blood pump, the magnetic drive system comprising a drive shaft coupled to an impeller and configured to rotate with the impeller; a driven magnet assembly coupled to at least one of the drive shaft and the impeller; and a drive coil assembly surrounding the driven magnet assembly and configured to drive the driven magnet assembly.

[0006] In Example 2, the magnetic drive system of Example 1, the driven magnet assembly is coupled to the drive shaft proximal of the impeller.

[0007] In Example 3, the magnetic drive system of either of Examples 1 or 2, the drive coil assembly comprises a coil housing and a plurality of coil windings disposed within the coil housing.

[0008] In Example 4, the magnetic drive system of Example 3, the coil housing is disposed within a pump housing and surrounds the driven magnet assembly.

[0009] In Example 5, the magnetic drive system of any of Examples 1-4, the driven magnet assembly comprises a permanent magnet disposed within a magnet housing.

[0010] In Example 6, a blood pump comprising a pump housing; an impeller disposed within the pump housing; a drive shaft disposed within the pump housing, coupled to the impeller, and configured to rotate with the impeller; a driven magnet assembly disposed within the pump housing and coupled to at least one of the drive shaft and the impeller; and a drive coil assembly disposed within the pump housing and surrounding the driven magnet assembly, and configured to drive the driven magnet assembly.

[0011] In Example 7, the blood pump of Example 6, the driven magnet assembly is coupled to the drive shaft proximal of the impeller.

[0012] In Example 8, the blood pump of Example 6 or 7, the drive coil assembly includes a coil housing and a plurality of coil windings disposed within the coil housing, the coil housing disposed within the pump housing and surrounding the driven magnet assembly.

[0013] In Example 9, the blood pump of any of Examples 6-8, the driven magnet assembly includes a permanent magnet disposed within a magnet housing.

[0014] In Example 10, the blood pump of any of Examples 6-9, further comprising a proximal bearing assembly, the proximal end of the drive shaft rotatably retained by the proximal bearing assembly.

[0015] In Example 11, the blood pump of Example 10, the proximal bearing assembly includes a first bearing portion including a distally facing bearing surface having a recess defined therein, and a second bearing portion including a proximally facing bearing surface, the first bearing portion and the second bearing portion configured to be coupled together to form a cavity configured to retain the proximal end of the drive shaft.

[0016] In Example 12, the blood pump of Example 10, the proximal bearing assembly includes a first bearing portion including a distally facing bearing surface, a second bearing portion including a proximally facing bearing surface, and a third bearing portion including a radially facing bearing surface, the first bearing portion, the second bearing portion, and the third bearing portion configured to be coupled together to form a cavity configured to retain the proximal end of the drive shaft.

[0017] In Example 13, the blood pump of Example 11 or 12, the first bearing portion and the second bearing portion are configured to be press fit together, adhered together, or fastened together.

[0018] In Example 14, the blood pump of any of Examples 10-13, the first bearing portion has a first aperture defined therethrough, the second bearing portion has a second aperture defined therethrough, the first aperture and the second aperture configured to align when the first bearing portion and the second bearing portion are coupled so that an electrical conductor can be disposed through the first aperture and the second aperture, the electrical conductor electrically coupling the power source with the drive coil assembly.

[0019] In Example 15, the blood pump of any of Examples 10-14, the distal end of the drive shaft is not retained by the distal bearing assembly.

[0020] In Example 16, a magnetic drive system of a blood pump, the magnetic drive system comprising a drive shaft coupled to an impeller and configured to rotate with the impeller; a driven magnet assembly coupled to at least one of the drive shaft and the impeller; and a drive coil assembly electrically coupled to a power source, surrounding the driven magnet assembly, and configured to drive the driven magnet assembly.

[0021] In Example 17, the magnetic drive system of Example 16, the driven magnet assembly is coupled to the drive shaft proximal of the impeller.

[0022] In Example 18, the magnetic drive system of Example 16, the drive coil assembly includes a coil housing and a plurality of coil windings disposed within the coil housing.

[0023] In Example 19, the magnetic drive system of Example 18, the coil housing is disposed within the pump housing and surrounds the driven magnet assembly.

[0024] In Example 20, the magnetic drive system of Example 16, the driven magnet assembly includes a permanent magnet disposed within a magnet housing.

[0025] In Example 21, a blood pump comprising a pump housing; an impeller disposed within the pump housing; a drive shaft disposed within the pump housing, coupled to the impeller, and configured to rotate with the impeller; a driven magnet assembly disposed within the pump housing and coupled to at least one of the drive shaft and the impeller; and a drive coil assembly disposed within the pump housing, electrically coupled to a power source, surrounding the driven magnet assembly, and configured to drive the driven magnet assembly.

[0026] In Example 22, the blood pump of Example 21, the driven magnet assembly is coupled to the drive shaft proximal of the impeller.

[0027] In Example 23, the blood pump of Example 21, the drive coil assembly includes a coil housing and a plurality of coil windings disposed within the coil housing, the coil housing is disposed within the pump housing and surrounds the driven magnet assembly.

[0028] In Example 24, the blood pump of Example 21, the driven magnet assembly includes a permanent magnet disposed within a magnet housing.

[0029] In Example 25, the blood pump of Example 21, further comprising a proximal bearing assembly, a proximal end of the drive shaft is rotatably held by the proximal bearing assembly.

[0030] In Example 26, the blood pump of Example 25, the proximal bearing assembly includes a first bearing portion including a distally facing bearing surface having a recess defined therein; and a second bearing portion including a proximally facing bearing surface, the first bearing portion and the second bearing portion are configured to be coupled together to form a cavity configured to hold the proximal end of the drive shaft.

[0031] In Example 27, the blood pump of Example 25, the proximal bearing assembly includes a first bearing portion including a distally facing bearing surface; a second bearing portion including a proximally facing bearing surface; and a third bearing portion including a radially facing bearing surface, the first bearing portion, the second bearing portion, and the third bearing portion are configured to be coupled together to form a cavity configured to hold the proximal end of the drive shaft.

[0032] In Example 28, the blood pump of Example 27, the first bearing portion and the second bearing portion are configured to press-fit together, adhere together, or fasten together.

[0033] In Example 29, the blood pump of Example 27, the first bearing portion has a first bore defined therethrough, the second bearing portion has a second bore defined therethrough, the first bore and the second bore are configured to align when the first bearing portion and the second bearing portion are coupled so that an electrical conductor can be disposed through the first and second bores, the electrical conductor electrically coupling the power source with the drive coil assembly.

[0034] In Example 30, the blood pump of Example 25, the distal end of the drive shaft is not retained by the distal bearing assembly.

[0035] In Example 31, a blood pump, comprising a pump housing; an impeller disposed within the pump housing; a drive shaft disposed within the pump housing, coupled with the impeller, and configured to rotate with the impeller; a driven magnet assembly disposed within the pump housing and coupled with at least one of the drive shaft and the impeller; a drive coil assembly disposed within the pump housing, electrically coupled with the motor, surrounding the driven magnet assembly, and configured to drive the driven magnet assembly; and a proximal bearing assembly, a proximal end of the drive shaft is rotatably retained by the proximal bearing assembly, the proximal bearing assembly comprising a first bearing portion comprising a distally facing bearing surface; and a second bearing portion comprising a proximally facing bearing surface, the first bearing portion and the second bearing portion are configured to couple together to form a chamber configured to retain the proximal end of the drive shaft.

[0036] In Example 32, the blood pump of Example 31, the driven magnet assembly is coupled to the drive shaft proximally of the impeller.

[0037] In Example 33, the blood pump of Example 31, the drive coil assembly comprises a coil housing and a plurality of coil windings disposed within the coil housing.

[0038] In Example 34, the blood pump of Example 33, the coil housing is disposed within the pump housing and surrounds the driven magnet assembly.

[0039] In Example 35, the blood pump of Example 34, the driven magnet assembly comprises a permanent magnet disposed within a magnet housing.

[0040] While several embodiments have been disclosed, numerous other embodiments will be apparent to those skilled in the art in view of the detailed description provided herein, which shows and describes only example embodiments of the current inventive subject matter. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature rather than restrictive. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1A cross-sectional side view depicting a portion of an illustrative percutaneous mechanical circulatory support device (also referred to herein interchangeably as a "blood pump") in accordance with embodiments of the subject matter disclosed herein.

[0042] Figure 2A A perspective view of a proximal bearing assembly holding a drive shaft in accordance with embodiments of the subject matter herein.

[0043] Figure 2B A perspective view of a proximal bearing assembly holding a drive shaft in accordance with embodiments of the subject matter herein. Figure 2A A side view of a proximal bearing assembly and drive shaft in accordance with embodiments of the subject matter herein.

[0044] Figure 2C A cross-sectional side view of the proximal bearing assembly and drive shaft depicted in Figure 2A and 2B A cross-sectional side view of the proximal bearing assembly and drive shaft depicted in

[0045] While the subject matter of the present disclosure can be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. However, it should be understood that the subject matter described herein is not intended to be limited to the particular embodiments described. Rather, the intention is to cover all modifications, equivalents and alternatives falling within the scope of the subject matter disclosed and defined by the appended claims. DETAILED DESCRIPTION

[0046] Embodiments of the subject matter disclosed herein include a blood pump and bearing design that can facilitate reducing the form factor of a mechanical circulatory assist device by providing a compact electromagnetic drive system. In embodiments, a metal coil is implanted in a sealed housing. An electronic controller alternately adjusts the current of the coil to change the polarity of the electromagnetic field, thereby driving a permanent magnet coupled to an impeller. The permanent magnet is a strong magnet that can be encapsulated in some kind of housing to eliminate the risk of corrosion of the magnet or the need for a coating of the magnet. The rotational motion of the magnet drives the impeller to rotate to provide forward flow of blood and supply arterial blood pressure to ensure adequate perfusion of the patient's organs. The permanent magnet is incorporated on a drive shaft. The drive shaft is placed in a bearing assembly where the proximal end of the shaft is held in a chamber defined in a proximal bearing assembly. This enables the shaft to rotate at the speed required to pump blood while keeping the shaft and impeller concentric within the housing to maintain the clearance of the blades from the tip. The assembly of the bearing is strictly controlled to the inside / outside diameter tolerance between the shaft and the bearing so that the degrees of freedom are minimized to obtain a good bearing fit that prevents blood from entering the bearing, reducing the risk of hemolysis and thrombosis.

[0047] The forward flow of blood on the coil housing serves as a means of heat dissipation from the electromagnetic coil. Given that air is a poor conductor of heat and can cause heat buildup within the coil housing, which could limit motor performance if left unaddressed, measures can be taken to reduce thermal resistance from the electromagnetic coil to the outside of the housing by minimizing the amount of air within the coil housing. For example, the coil assembly within the housing can be optimized for heat transfer through tolerant assembly features to minimize air gaps introduced between components. The coil can also be coated with atomic layer deposition of ceramic to achieve a tight fit within the housing, minimizing gaps between assembled components and thus optimizing heat conduction without the risk of electrical short circuits. Furthermore, the coil housing can be coated with a non-electrolytic, highly thermally conductive liquid to increase heat transfer from the electromagnetic coil to the outside of the coil housing. Optimizing heat conduction to drive heat away from the electromagnet coil can increase torque output for devices of similar size or reduce the required coil size, which facilitates easier delivery and optimized positioning of the device. Additionally, by eliminating a separate motor housing and motor, and instead using a coil with a magnet that drives an impeller in turn, the length required to house such components in existing devices can be significantly reduced.

[0048] Figure 1 A cross-sectional side view of a portion of an illustrative percutaneous mechanical circulatory support device 100 (which may also be interchangeably referred to herein as a "blood pump") according to an embodiment of the subject matter disclosed herein is shown. Figure 1 As shown, the circulation support device 100 includes a magnetic drive system 102 disposed within a pump housing 104. The magnetic drive system 102 is configured to drive an impeller 106 to provide blood flow through the device 100. The impeller 106 is disposed within the pump housing 104, which includes a plurality of outlet holes 108 defined therein.

[0049] like Figure 1 As shown, the magnetic drive system 102 includes a drive shaft 110 coupled to and configured to rotate with an impeller 106. As shown, the drive shaft 110 is at least partially disposed within the impeller 106. In embodiments, the drive shaft 110 may be made of any number of different rigid materials, such as steel, titanium alloy, cobalt-chromium alloy, nitinol, high-strength ceramics, and / or similar materials. A driven magnet assembly 112 is coupled to at least one of the drive shaft 110 and the impeller 106. In embodiments, for example, the driven magnet assembly 112 may be coupled to the drive shaft 110 proximal to the impeller 106. In other embodiments, the driven magnet assembly 112 may be directly coupled to the impeller 106, while in some embodiments, the driven magnet assembly 112 may be coupled to both the drive shaft 110 and the impeller 106. The magnetic drive system 102 includes a drive coil assembly 114 electrically coupled to a power source (not shown). The magnetic drive coil assembly 114 surrounds the driven magnet assembly 112 and is configured to drive the driven magnet assembly 112.

[0050] The drive coil assembly 114 includes a coil housing 116 and a number of coil windings 118A disposed within the coil housing 116. The electromagnetic field can be generated by copper, graphene, or other high thermal conductivity material in a coiled configuration. The drive coil assembly 114 can include any number of coil windings 118A arranged in any number of configurations within the coil housing 116. In embodiments, the coil housing 116 can actually include multiple independent housings. The coil housing 116 is disposed within the pump housing 104 and can circumferentially or longitudinally surround the driven magnet assembly 112. As shown, in embodiments, the driven magnet assembly 112 can include a permanent magnet 140 disposed within a magnet housing 142, which can be hermetically sealed.

[0051] A controller (not shown) is operably coupled to the drive coil assembly 114 via electrical conductors 118B and is configured to control the drive coil assembly 114. In embodiments, the controller can be disposed within the pump housing 104, or in other embodiments, can be disposed outside the housing 104 (e.g., in a catheter handle, a separate housing, etc.). In embodiments, the controller can include multiple components, one or more of which can be disposed within the housing 104. Depending on the embodiment, the controller can be, include, or incorporate one or more field-programmable gate arrays (FPGAs), one or more programmable logic devices (PLDs), one or more complex PLDs (CPLDs), one or more custom application-specific integrated circuits (ASICs), one or more special-purpose processors (e.g., microprocessors), one or more central processing units (CPUs), software, hardware, firmware, or any combination of these and / or other components. Although the controller is referred to in the singular herein, the controller can be implemented in multiple instances, distributed across multiple computing devices, instantiated within multiple virtual machines, etc.

[0052] As shown, the impeller 106 is held in orientation by a drive shaft 110, which is held at a proximal end 120 by a proximal bearing assembly 122 and at a distal end 124 by a distal bearing assembly 126. Depending on the embodiment, the proximal bearing assembly 122 and the distal bearing assembly 126 can include different types of bearings. Depending on the embodiment, the proximal bearing assembly 122 and / or the distal bearing assembly 126 can include lubrication, while in other embodiments, one and / or the other can not include lubrication. In embodiments, the drive shaft 110 can be held rigidly enough by the proximal bearing assembly 122 such that a distal bearing assembly is not needed, in which case the drive shaft 110 is not held in place by a distal bearing assembly.

[0053] As Figure 1As shown, the proximal bearing assembly 122 can include a first bearing portion 128 and a second bearing portion 130 configured to couple together to form a cavity 132 configured to hold the proximal end 120 of the drive shaft 110. According to embodiments, the first bearing portion 128 and the second bearing portion 130 can be configured to press fit together, couple using interlocking slots, couple using an adhesive, couple using a pin, couple using a fastener, and / or the like. In embodiments, a hole 134 is defined through the proximal bearing assembly 122. The conductor 118B passes through the hole 134 to electrically connect the coil winding 118A with a power source. The proximal bearing assembly 122 can be configured to seal a conduit 136 from blood.

[0054] Figure 1 The illustrative circulatory support device 100 shown in FIG. 1 is not meant to imply any limitation on the scope of use or functionality of embodiments of the present disclosure. The illustrative circulatory support device 100 should also not be interpreted as having any dependency or requirement related to any individual components or combination of components illustrated therein. Furthermore, in embodiments, Figure 1 The various components depicted in FIG. 1 can be integrated with various ones of the other components depicted therein (and / or components not illustrated), all of which are considered to be within the scope of the present disclosure.

[0055] As noted above, with regard to Figure 1 Embodiments of blood pumps include a proximal bearing assembly configured to hold a drive shaft in place and seal a conduit from blood while allowing an electrical conductor to pass to a coil winding. In embodiments, the proximal bearing assembly can include three or more bearing portions. For example, Figure 2A is a perspective view of a proximal bearing assembly 200 holding a drive shaft 202 according to embodiments of the subject matter disclosed herein; Figure 2B is a perspective view of a proximal bearing assembly 200 holding a drive shaft 202 according to embodiments of the subject matter disclosed herein; Figure 2A is a side view of the proximal bearing assembly 200 and the drive shaft 202 of Figure 2C is a cross-sectional side view of the proximal bearing assembly 200 and the drive shaft 202 described in FIGS. 1-4 according to embodiments of the subject matter disclosed herein. According to embodiments, the circulatory support device and / or any number of various components thereof can be identical or similar to the respective components of the circulatory support device 100 depicted in FIG. 1. Figure 2A and Figure 2B is a cross-sectional side view of the proximal bearing assembly 200 and the drive shaft 202 described in FIGS. 1-4 according to embodiments of the subject matter disclosed herein. According to embodiments, the circulatory support device and / or any number of various components thereof can be identical or similar to the respective components of the circulatory support device 100 depicted in FIG. 1. Figure 1

[0056] As noted above, with regard to Figures 2A-2C ​As shown, the proximal bearing assembly 200 can include a first bearing portion 204 having a distally facing bearing surface 206, a second bearing portion 208 having a proximally facing bearing surface 210, and a third bearing portion 212 having a radially facing bearing surface 214. As shown, the first bearing portion 204, the second bearing portion 208, and the third bearing portion 212 are configured to be coupled together with the third bearing portion 212 disposed between the first bearing portion 204 and the second bearing portion 208. When coupled together, the bearing portions 204, 208, and 212 form a cavity 216 that is configured to retain a proximal end 218 of the drive shaft 202. For example, as shown, the proximal end 218 of the drive shaft 202 can be formed as a disc that is configured to fit within the cavity 216 within the bearing assembly 200. In embodiments, as shown, the proximal end 218 of the drive shaft 202 can include a ball or other at least partially circular shape that is configured to be retained within the cavity 216. The head of the drive shaft 202 can include internal grooves to create pressure as the head is rotated, reducing the friction and torque required to operate the pump. Figure 1

[0057] The bearing portions 204, 208, and 212 can be coupled together using any number of different coupling techniques and / or mechanisms. For example, in embodiments, the bearing portions 204, 208, and 212 can be pressed together and secured by one or more pins 220, as shown. In embodiments, the bearing portions 204, 208, and 212 can be glued together, fastened together with one or more fasteners, and / or the like. The proximal bearing assembly can be attached to the impeller housing by laser welding, reflow soldering, or adhesive application, and / or the like. Figures 2A-2C

[0058] In addition, in embodiments, holes can be provided through the proximal bearing assembly 200 to facilitate connection of the coil windings to a power source. For example, the first bearing portion 204 can include a first hole 222 defined therethrough, the second bearing portion 208 can include a second hole 224 defined therethrough, and the third bearing portion 212 can include a third hole 226 defined therethrough, such that the first hole 222, the second hole 224, and the third hole 226 are configured to align when the first bearing portion 204 and the second bearing portion 208 are coupled so that an electrical conductor can be disposed through the holes 222, 224, and 226, where the electrical conductor electrically couples the power source to the drive coil assembly. In embodiments, the proximal bearing assembly can include only two bearing portions, in which case each bearing portion can include one or more holes corresponding to one or more holes in the other bearing portion.

[0059] Figures 2A-2C ​​The illustrative proximal bearing assembly 200 and drive shaft 202 shown in the figures are not intended to suggest any limitation as to the scope of use or functionality of embodiments of the present disclosure. Neither should the illustrative proximal bearing assembly 200 and drive shaft 202 be interpreted as having any dependency or requirement related to any single component or combination of components illustrated therein. Additionally, in embodiments, Figures 2A-2C Various components depicted in the figures can be integrated with various components of other components depicted therein (and / or components not illustrated), all of which are considered to be within the scope of the present disclosure.

[0060] Various modifications and additions can be made to the exemplary embodiments discussed without departing from the scope of the present disclosure. For example, while the embodiments described above refer to particular features, the scope of the present disclosure also includes embodiments that do not include all of these features. Thus, embodiments of the present disclosure can include, but are not limited to, some, all, or none of the features described above. Accordingly, the scope of the present disclosure is intended to embrace all such alternatives, modifications, and variations as can be included within the scope of the claims, now or in the future, together with all equivalents thereof.

Claims

1. A magnetic drive system of a blood pump, the magnetic drive system comprising: a drive shaft coupled to an impeller and configured to rotate with the impeller; a driven magnet assembly coupled to at least one of the drive shaft and the impeller; a drive coil assembly surrounding the driven magnet assembly and configured to drive the driven magnet assembly; and a proximal bearing assembly, wherein a proximal end of the drive shaft is rotatably held by the proximal bearing assembly; wherein the proximal bearing assembly comprises: a first bearing portion comprising a distally facing bearing surface having a recess defined therein; and a second bearing portion comprising a proximally facing bearing surface, wherein the first bearing portion and the second bearing portion are configured to be coupled together to form a cavity configured to hold a proximal end of the drive shaft.

2. The magnetic drive system of claim 1, wherein the driven magnet assembly is coupled to the drive shaft proximally of the impeller.

3. The magnetic drive system of claim 1 or 2, the drive coil assembly comprising a coil housing and a plurality of coil windings disposed within the coil housing.

4. The magnetic drive system of claim 3, wherein the coil housing is disposed within a pump housing and surrounds the driven magnet assembly.

5. The magnetic drive system of claim 1, wherein the driven magnet assembly comprises a permanent magnet disposed within a magnet housing.

6. A blood pump, comprising: a pump housing; an impeller disposed within the pump housing; a drive shaft disposed within the pump housing, coupled to the impeller, and configured to rotate with the impeller; a driven magnet assembly disposed within the pump housing and coupled to at least one of the drive shaft and the impeller; a drive coil assembly disposed within the pump housing and surrounding the driven magnet assembly, and the drive coil assembly is configured to drive the driven magnet assembly; and a proximal bearing assembly, wherein a proximal end of the drive shaft is rotatably held by the proximal bearing assembly; wherein the proximal bearing assembly comprises: a first bearing portion comprising a distally facing bearing surface having a recess defined therein; and a second bearing portion comprising a proximally facing bearing surface, wherein the first bearing portion and the second bearing portion are configured to be coupled together to form a cavity configured to hold a proximal end of the drive shaft.

7. The blood pump of claim 6, wherein the driven magnet assembly is coupled to the drive shaft proximally of the impeller.

8. The blood pump of claim 6 or 7, the drive coil assembly comprising a coil housing and a plurality of coil windings disposed within the coil housing, wherein the coil housing is disposed within the pump housing and surrounds the driven magnet assembly.

9. The blood pump of claim 6 or 7, wherein the driven magnet assembly comprises a permanent magnet disposed within a magnet housing. ​ ​ ​ 10. The blood pump of claim 6, the proximal bearing assembly comprising: a first bearing portion comprising a distally facing bearing surface; a second bearing portion comprising a proximally facing bearing surface; and a third bearing portion comprising a radially facing bearing surface, wherein the first bearing portion, the second bearing portion, and the third bearing portion are configured to be coupled together to form a cavity configured to hold a proximal end of the drive shaft.

11. The blood pump of claim 6 or 10, wherein the first bearing portion and the second bearing portion are configured to be press fit together, adhered together, or fastened together.

12. The blood pump of claim 6 or 10, the first bearing portion having a first hole defined therethrough, the second bearing portion having a second hole defined therethrough, wherein the first hole and the second hole are configured to align when the first bearing portion and the second bearing portion are coupled so that an electrical conductor can be disposed through the first hole and the second hole, wherein the electrical conductor electrically couples a power source with the drive coil assembly.

13. The blood pump of claim 6, wherein a distal end of the drive shaft is not held by a distal bearing assembly. ​

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