Magnetic propulsion and bearings for hemodynamic support pumps.

Abstract

Various aspects of the present disclosure are directed to devices, systems, and methods that may include a blood pump. The blood pump may include a magnetic field source and an impeller assembly. The impeller assembly includes an impeller and a driven magnet. The driven magnet is longitudinally offset and distally disposed relative to the magnetic field source, the driven magnet being rotatable and longitudinally constrained by the magnetic field source. The driven magnet includes a distal side, the distal side facing the impeller. The blood pump further includes a bearing assembly near the distal side of the driven magnet.

Description

[Technical field]

[0001] The present disclosure relates to percutaneous circulatory assist devices. More particularly, the present disclosure relates to bearing assemblies and magnetic drive systems for use in percutaneous circulatory assist devices. [Background technology]

[0002] Percutaneous circulatory assist devices, such as blood pumps, can provide temporary support for hours or months of use in patients with compromised cardiac function or output. Magnetically driven pumps offer an improvement over existing technology because they provide easier therapy management, easier patient mobility, and improved device durability. Wear at the bearing surfaces can limit device life, and mechanical interaction with blood at the bearing surfaces can lead to hemolysis or other health complications. Blood contact with magnetic surfaces can also result in corrosion of components. Additionally, blood pump performance and blood flow can be affected by component imbalance and insufficient magnetic torque generation and transmission between device components. Summary of the Invention

[0003] In Example 1, the blood pump comprises a magnetic field source, an impeller assembly including a longitudinal axis, an impeller and a driven magnet, the driven magnet being longitudinally offset and distally positioned relative to the magnetic field source, the driven magnet being rotatable and longitudinally restrained by the magnetic field source, the driven magnet having a distal side facing the impeller, and a bearing assembly near the distal side of the driven magnet.

[0004] In Example 2, the blood pump of Example 1 further comprises an impeller assembly housing, the bearing assembly being in contact with the impeller assembly housing, and the impeller assembly housing rotatably supporting the impeller assembly via the bearing assembly.

[0005] In Example 3, the blood pump of Example 2, wherein the impeller assembly housing includes a recess that receives the bearing assembly. In Example 4, the blood pump of any one of Examples 1-3, wherein the distance between the magnetic field source and the driven magnet is less than 0.030 inches (0.762 mm).

[0006] In Example 5, the blood pump of any one of Examples 1-4, wherein the impeller assembly has a center of mass, and the bearing assembly is longitudinally aligned with the center of mass of the impeller assembly.

[0007] In Example 6, the blood pump of any one of Examples 1-5, wherein no portion of the bearing assembly is disposed between the driven magnet and the magnetic field source. In Example 7, the blood pump of any one of Examples 2 to 6, wherein the impeller assembly housing does not include a bearing assembly disposed at a distal end of the impeller.

[0008] In Example 8, a blood pump described in any one of Examples 1 to 7, wherein the impeller assembly is rotatable about the longitudinal axis and the bearing assembly is disposed radially outward relative to the longitudinal axis.

[0009] In Example 9, the blood pump of any one of Examples 2-8, wherein the impeller assembly further includes a shaft, and the bearing assembly contacts the shaft and the impeller assembly housing.

[0010] In Example 10, the blood pump of any one of Examples 2 to 9, wherein the bearing assembly includes a first bearing in contact with the shaft and the impeller assembly housing, and a second bearing in contact with the first bearing and the impeller.

[0011] In Example 11, a blood pump includes a magnetic field source, an impeller assembly including a longitudinal axis, an impeller, and a driven magnet, wherein the driven magnet is longitudinally offset and distally positioned relative to the magnetic field source, the driven magnet being rotatable and longitudinally restrained by the magnetic field source, and a bearing assembly coupled to the impeller assembly, wherein no portion of the bearing assembly is positioned between the driven magnet and the magnetic field source.

[0012] In Example 12, the blood pump of Example 11 further comprises an impeller assembly housing, the bearing assembly contacting the impeller assembly housing, and the impeller assembly housing rotatably supporting the impeller assembly via the bearing assembly.

[0013] In Example 13, the blood pump of Example 12, wherein the impeller assembly housing includes a recess that receives the bearing assembly. In Example 14, the blood pump of any one of Examples 12 to 13, wherein the bearing assembly includes a first bearing in contact with the shaft and the impeller assembly housing, and a second bearing in contact with the first bearing and the impeller.

[0014] In Example 15, the blood pump of any one of Examples 11-14, wherein the bearing assembly includes a magnetic bearing containing a driven magnet. In Example 16, a blood pump includes an impeller assembly housing, a magnetic field source coupled to the impeller assembly housing, an impeller assembly within the impeller assembly housing and including a longitudinal axis, an impeller, and a driven magnet, the driven magnet being longitudinally offset and distally disposed relative to the magnetic field source, the driven magnet being rotatable and longitudinally restrained by the magnetic field source, the driven magnet having a distal side facing the impeller, and a bearing assembly within the impeller assembly housing and in contact therewith and near the distal side of the driven magnet.

[0015] In Example 17, the blood pump of Example 16, wherein the impeller assembly housing includes a recess that receives the bearing assembly. In Example 18, the blood pump of Example 16, wherein the distance between the magnetic field source and the driven magnet is less than 0.030 inches (0.762 mm).

[0016] In Example 19, the blood pump of Example 16, wherein the impeller assembly has a center of mass, and the bearing assembly is longitudinally aligned with the center of mass of the impeller assembly. In Example 20, the blood pump of Example 16, wherein no portion of the bearing assembly is disposed between the driven magnet and the magnetic field source.

[0017] In Example 21, the blood pump of Example 16, wherein the impeller assembly housing does not include a bearing assembly disposed at a distal end of the impeller. In Example 22, the blood pump of Example 16, wherein the impeller assembly is rotatable about the longitudinal axis and the bearing assembly is disposed radially outward relative to the longitudinal axis.

[0018] In Example 23, the blood pump of Example 16, wherein the impeller assembly further includes a shaft, and the bearing assembly contacts the shaft and the impeller assembly housing.

[0019] In Example 24, the blood pump of Example 23, wherein the bearing assembly includes a first bearing in contact with the shaft and the impeller assembly housing, and a second bearing in contact with the first bearing and the impeller.

[0020] In Example 25, the blood pump of Example 23, wherein the shaft is coupled to the impeller and is rotatable therewith. In Example 26, a blood pump includes an impeller assembly housing, a magnetic field source coupled to the impeller assembly housing, an impeller assembly within the impeller assembly housing and including a longitudinal axis, an impeller, and a driven magnet, wherein the driven magnet is longitudinally offset and distally positioned relative to the magnetic field source and is rotatable by the magnetic field source, and a bearing assembly within the impeller assembly housing, in contact therewith, and coupled to the impeller assembly, wherein no portion of the bearing assembly is positioned between the driven magnet and the magnetic field source.

[0021] In Example 27, the blood pump of Example 26, wherein the impeller assembly further comprises a shaft. In Example 28, the blood pump of Example 27, wherein the bearing assembly contacts the shaft and the impeller assembly housing.

[0022] In Example 29, the blood pump of Example 27, wherein the shaft is coupled to the impeller and is rotatable with the impeller. In Example 30, the blood pump of Example 26, wherein the impeller assembly housing includes a recess that receives the bearing assembly.

[0023] In Example 31, the blood pump of Example 26, wherein the bearing assembly includes a magnetic bearing containing a driven magnet. In Example 32, the blood pump of Example 26, wherein the impeller assembly housing does not include a bearing assembly disposed at the distal end of the impeller.

[0024] In Example 33, a method of assembling a blood pump includes coupling an impeller assembly to a bearing assembly so that the bearing assembly is near a distal side of a driven magnet and the distal side of the driven magnet faces an impeller of the impeller assembly, and coupling the bearing assembly to the impeller assembly housing so that the bearing assembly contacts the impeller assembly housing and the driven magnet is longitudinally offset and positioned distally relative to a magnetic field source.

[0025] In Example 34, the method of Example 33, wherein coupling the impeller assembly to the bearing assembly comprises contacting a shaft of the impeller assembly with the bearing assembly.

[0026] In Example 35, the method of Example 33, wherein coupling the bearing assembly to the impeller assembly housing includes disposing the bearing assembly within a recess in the impeller assembly housing.

[0027] While multiple embodiments are disclosed, still other embodiments will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. [Brief description of the drawings]

[0028] [Figure 1A] 1 shows a side cross-sectional view of a portion of an exemplary percutaneous mechanical circulatory assist device (also referred to herein interchangeably as a "blood pump") in accordance with an embodiment of the subject matter disclosed herein. [Figure 1B] 1 shows a cross-sectional view of an exemplary embodiment of a percutaneous mechanical circulatory assist device in accordance with an embodiment of the subject matter disclosed herein. [Figure 1C] 1B shows a perspective view of a portion of the exemplary percutaneous mechanical circulatory assist device of FIG. 1A, according to an embodiment of the subject matter disclosed herein. [Figure 1D]1 shows a side view of a portion of an exemplary embodiment of a percutaneous mechanical circulatory assist device in accordance with an embodiment of the subject matter disclosed herein. [Figure 2A] 1 shows a side cross-sectional view of a circulatory assist device according to an embodiment of the subject matter disclosed herein. [Figure 2B] 2B shows a perspective view of a portion of the exemplary percutaneous mechanical circulatory assist device shown in FIG. 2A, according to an embodiment of the subject matter disclosed herein. [Figure 3A] 1 illustrates a perspective view of an embodiment of a bearing assembly in accordance with an embodiment of the subject matter disclosed herein. [Figure 3B] 3B illustrates a cross-sectional side view of the bearing assembly shown in FIG. 3A according to an embodiment of the subject matter disclosed herein. [Figure 4] 1 shows a cross-sectional view of another embodiment of an exemplary percutaneous mechanical circulatory assist device in accordance with embodiments of the subject matter disclosed herein. [Diagram 5] 1 shows a cross-sectional view of yet another embodiment of an exemplary percutaneous mechanical circulatory assist device, in accordance with embodiments of the subject matter disclosed herein.

[0029] While the disclosed subject matter is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention, however, is not to limit the subject matter disclosed herein to the specific embodiments described. On the contrary, the disclosure is intended to cover all modifications, equivalents, and alternatives falling within the scope of the subject matter disclosed herein as defined by the appended claims.

[0030] As used herein, "about" and "approximately" refer to terms of values ​​(e.g., magnitudes, measurements, and / or other degrees of qualitative and / or quantitative observations of tangible (e.g., products, inventory, etc.) and / or intangible (e.g., data, electronic representations of currency, accounts, information, portions of things (e.g., percentages, proportions), calculations, data models, dynamic system models, algorithms, parameters, etc.) and / or characteristics (e.g., dimensions, measurements, attributes, components, etc.) and / or ranges thereof) that are used herein to refer to values, configurations, orientations, and / or characteristics that are equal to (or the same as) the stated value, configuration, orientation, and / or other characteristic, or that are reasonably close to (or the same as) the stated value, configuration, orientation, and / or other characteristic. may be used interchangeably to refer to values, configurations, orientations, and / or other characteristics, but may vary by reasonably small amounts as understood and readily ascertained by those skilled in the art due to measurement error, differences in measurement and / or manufacturing equipment calibration, human error in reading and / or setting measurements, adjustments to optimize operational and / or structural parameters with respect to other measurements (measurements relative to other things), specific implementation scenarios, imprecise adjustments and / or manipulations of things by humans, computing devices and / or machines, settings, and / or measurements, system tolerances, control loops, machine learning, predicted variations (e.g., statistically non-significant variations, random variations, system and / or model instability, etc.), and / or preferences, etc. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Embodiments of the subject matter disclosed herein include blood pump and bearing designs that may facilitate a reduction in the number of bearing surfaces and a reduction in the number or size of magnets incorporated into a percutaneous circulatory assist device. Reducing the number of bearing surfaces in a blood pump may provide numerous advantages, including reducing the likelihood of hemolysis and other health complications. Embodiments of the subject matter disclosed herein include blood pump and bearing designs that improve magnetic torque transfer, which can be used to increase blood flow, reduce the risk of magnet corrosion, and improve the durability of the blood pump. In addition, embodiments disclosed herein provide improved stability and efficiency of blood pump components for improved therapeutic performance.

[0032] FIG. 1A illustrates a side cross-sectional view of a portion of an exemplary percutaneous mechanical circulatory assist device 100 (also referred to herein interchangeably as a "blood pump") according to an embodiment of the subject matter disclosed herein. The blood pump 100 includes a magnetic drive housing 104 that includes a magnetic field source 101. The magnetic field source 101 is configured to generate magnetic field variations to drive rotation of an impeller 114 to provide blood flow through the blood pump 100. In the embodiment illustrated in FIG. 1A, the magnetic field source 101 includes a permanent drive magnet 118 rotating on a motor 102, which is configured to cause rotation of a permanent driven magnet 116 coupled to the impeller 114 to provide blood flow through the blood pump 100. In alternative embodiments, the drive magnet 118 may be replaced by any type of magnetic rotor. For example, as illustrated in FIG. 1B and described below, the magnetic field source may include a series of electromagnetic coils configured to cause rotation of a permanent driven magnet coupled to the impeller to provide blood flow through the blood pump 100. In other alternative embodiments, the magnetic field source may include a stator and a motor for generating the magnetic field.

[0033] A controller (not shown) is operatively coupled to the motor 102 and configured to regulate the motor 102. The controller may be disposed within the magnetic drive housing 104 in embodiments, or may be disposed outside the magnetic drive housing 104 (e.g., in a catheter handle, a separate housing, etc.) in other embodiments. In embodiments, the controller may include multiple components, one or more of which may be disposed within the magnetic drive housing 104. According to embodiments, the controller may be, include, or be included in 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 dedicated processors (e.g., microprocessors), one or more central processing units (CPUs), software, hardware, firmware, or any combination of these and / or other components. Although a controller is referred to in the singular herein, the controller may be executed in multiple instances, may be distributed across multiple computing devices, may be instantiated within multiple virtual machines, and / or the like.

[0034] 1A, impeller assembly 106 is disposed within impeller assembly housing 108, which includes an inlet opening (not shown) defined therein and a number of outlet openings 107. A longitudinal axis 142 extends through impeller assembly 106. According to embodiments, magnetic drive housing 104 and impeller assembly housing 108 may be integral with one another. In other embodiments, magnetic drive housing 104 and impeller assembly housing 108 may be separate components configured to be removably or permanently coupled together.

[0035] In FIG. 1A, the impeller assembly 106 includes an impeller 114 and a driven magnet 116 coupled to the impeller 114. The driven magnet 116 has a proximal side 120 and a distal side 122. The driven magnet 116 may be coupled distally to the impeller 114 as shown in FIG. 1A. The driven magnet 116 and the impeller 114 may be coupled in a variety of ways, including the use of adhesives, mechanical coupling, or an interference fit. The driven magnet 116 may be any type of magnetic rotor capable of being driven by a drive magnet 118. When a magnetic field is applied to the driven magnet 116 by the drive magnet 118, the driven magnet 116 rotates, causing the impeller assembly 106 to rotate. The rotation of the impeller 114 causes blood flow through the blood pump 100.

[0036] 1A , the driven magnet 116 and the impeller 114 may be coupled via a drive shaft 112 that is coupled to the impeller 114 and configured to rotate with the impeller 114. The driven magnet 116 may be coupled to the drive shaft 112 and the impeller 114 in a variety of ways, including the use of adhesives, mechanical bonding, or an interference fit. The drive shaft 112 may be at least partially disposed within the impeller 114. The drive shaft 112 may also be at least partially surrounded by the driven magnet 116. The drive shaft 112 may be made from any number of different rigid materials, such as, for example, steel, titanium alloy, cobalt chrome alloy, nitinol, high strength ceramic, and / or the like.

[0037] 1B illustrates an alternative embodiment of the magnetic field source 101 including a stator electromagnetic drive coil assembly 136 electrically coupled to a power source (not shown). In such an embodiment, the drive coil assembly 136 may be axially aligned or may circumferentially surround the driven magnet 116 and is configured to drive the driven magnet 116. The drive coil assembly 136 includes a ferromagnetic core 138 and several coil windings 140. The electromagnetic field may be generated from copper, graphene, or other highly conductive materials in a coiled configuration. The drive coil assembly 136 may include any number of coil windings 140 arranged in any number of configurations within the magnetic drive housing 104. As shown, the drive coil assembly 136 is disposed within the magnetic drive housing 104 and may be axially aligned or may circumferentially surround the driven magnet 116. The magnetic drive housing 104 and impeller assembly housing 108 are integrated in the illustrated embodiment and contain the magnetic field source 101 and the impeller assembly 106 which includes a driven magnet 116 .

[0038] As shown in Figure 1A, the impeller assembly 106, including the driven magnet 116, is retained within the impeller assembly housing 108 by a bearing assembly 124. According to an embodiment, the bearing assembly 124 may be located near a distal side 122 of the driven magnet 116. Figure 1C is a perspective view of the driven magnet 116, magnet bearing 126, and impeller 114, according to an embodiment of the subject matter disclosed herein.

[0039] Various embodiments of bearing assemblies for use in blood pumps are described herein. For example, as shown in FIG. 1A, the bearing assembly 124 can include a magnet bearing 126 and a housing bearing 128. According to embodiments, the bearing assembly 124 can include different types of bearings. The bearing assembly 124 can also include a lubricant, while in other embodiments, the bearing assembly 124 can be lubricant-free. As shown, the bearing assembly 124 has a proximal side 130 that contacts the distal shoulder 110 of the driven magnet 116. As shown, the housing bearing 128 includes a proximal inner lip 129 that contacts the magnet bearing 126. The proximal inner lip 129 supports thrust loads and prevents the driven magnet 116 from bottoming out against the proximal end 134 of the impeller assembly housing 108.

[0040] 1A, the bearing assembly 124, including the magnet bearing 126 and the housing bearing 128, is located longitudinally near the center of mass of the impeller assembly 106. Mounting the magnet bearing 126 near the distal side 122 of the driven magnet 116 allows the bearing assembly 124 to be located near the center of mass of the impeller assembly 106. The bearing assembly 124 is optimized when the magnet bearing 126 and the housing bearing 128 are aligned with the center of mass of the impeller assembly 106. Locating the bearing assembly 124 longitudinally near the center of mass of the impeller assembly 106 improves radial restraint of the impeller assembly 106 and protects against eccentric movement of the impeller 114, as compared to bearing assemblies that rely on bearing assemblies both proximal and distal to the impeller assembly 106. The location of the bearing assembly 124 may be offset from the center of mass of the impeller assembly 106 by approximately 0.050 inches (1.27 mm) based on practical considerations of component assembly, but is optimized when located longitudinally as close as possible to the center of mass of the impeller assembly 106. The bearing assembly 124 is also configured to use a force parallel to the longitudinal axis of the impeller assembly 106 to oppose a magnetic coupling axial force and prevent the driven magnet 116 from bottoming out against the proximal end 134 of the impeller assembly housing 108, thereby providing axial restraint for the impeller assembly 106.

[0041] The center of mass of the impeller assembly 106 is dependent on both the design and material selection of the driven magnet 116, impeller 114, drive shaft 112, and any other materials used to assemble the components together. Suitable magnetic materials that may be used for the driven magnet 116, including neodymium iron boron and samarium cobalt, have densities five to six times greater than polymers such as polyetheretherketone (PEEK) that may be used for the impeller 114. The driven magnet 116 will therefore likely comprise more than 50 percent of the total mass of the impeller assembly 106. The driven magnet 116 may have a reduced diameter portion, such as a distal shoulder 110, to facilitate fastening of the magnetic bearing 126 to the driven magnet 116.

[0042] As shown in FIG. 1A, a cavity 132 is formed by the proximal side 130 of the bearing assembly 124, the impeller assembly housing 108, and the driven magnet 116. In an embodiment, the size of the driven magnet 116 can be reduced to increase the spacing between the driven magnet 116 and the impeller assembly housing 108. The size of the cavity 132 can then be increased. Increasing the size of the cavity 132 reduces the shear stress acting on the blood in the cavity 132. The reduced shear stress is associated with reduced hemolysis and reduced platelet activation, which can result in a reduced rate of clot formation. In some embodiments, a liquid may be disposed in the cavity 132. The liquid may be any type of hydrophobic lubricant suitable for use in a blood pump. For example, in an embodiment, but not intended to limit the disclosure, the liquid may be a biocompatible oil or modified silicone lubricant, such as, for example, modified polydimethylsiloxane (PDMS). In other embodiments, the liquid may be an oil-based lubricant, a synthetic oil, a carbon-based lubricant, or the like. Advantages of using liquid in cavity 132 include reducing the possibility of air embolism, limiting exposure of blood to driven magnet 116 to reduce hemolysis associated with driven magnet 116, reducing the risk of clot formation and corrosion on the driven magnet through less blood contact, and reducing hemolysis associated with bearing assembly 124 through lubrication of bearings 126, 128. In other embodiments, cavity 132 may remain empty. In other embodiments, as shown in FIG. 1D, cavity 132 may be exposed to blood flow to promote constant blood circulation around driven magnet 116, which may be beneficial in preventing thrombosis.

[0043] The blood pump shown in Figures 1A and 1B may be assembled as follows: The bearing assembly 124 may be assembled by separately mounting the magnet bearing 126 and the housing bearing 128. The housing bearing 128 may be secured to the impeller assembly housing 108 by press-fitting, adhesive, mechanical bonding, sintering, welding, or any method known to those skilled in the art. Outside the impeller assembly housing 108, the impeller assembly 106 including the driven magnet 116 may be coupled to the magnet bearing 126, which is secured to the driven magnet 116 by press-fitting, adhesive, mechanical bonding, sintering, welding, or any method known to those skilled in the art. The impeller assembly 106 including the driven magnet 116 and the coupled magnet bearing 126 may be collectively referred to as the impeller-magnet bearing assembly 144. The impeller-magnet bearing assembly 144 may then be placed in the impeller assembly housing 108 such that the magnet bearing 126 mates with the housing bearing 128. In one embodiment, the outer diameter of the driven magnet 116 may be uniform and of a smaller diameter than the inner diameter of the impeller assembly housing 108 and housing bearing 128 combination such that the impeller-magnet-bearing assembly 144 fits within the combination of the housing bearing 128 and impeller assembly housing 108. In other embodiments, as shown in FIGS. 1A and 1B, the outer diameter of the driven magnet 116 may be approximately the same as the outer diameter of the combination of the driven magnet 116 and magnet bearing 126 except where the magnet bearing 126 is secured to the driven magnet 116. For example, in such an embodiment, the driven magnet 116 may include a reduced diameter portion, such as a distal shoulder 110, to accommodate the magnet bearing 126. The distal shoulder 110 may facilitate securing the bearing assembly 124 such that the bearing assembly 124 provides improved radial restraint relative to the impeller assembly 106.

[0044] The exemplary circulatory assist device 100 shown in Figures 1A-1D is not intended to suggest any limitations as to the scope of use or functionality of the embodiments of the present disclosure. Nor should the exemplary circulatory assist device 100 be interpreted as having any dependencies or requirements relating to any single component or combination of components shown herein. In addition, the various components shown in Figures 1A-1D may be combined in embodiments with various of the other components shown therein (and / or components not shown), all of which are contemplated to be within the scope of the present disclosure.

[0045] Figure 2A shows a side cross-sectional view of an exemplary percutaneous mechanical circulatory assist device 200 (also referred to interchangeably herein as a "blood pump") in accordance with an embodiment of the subject matter disclosed herein, and Figure 2B shows a perspective view of blood pump 200 shown in Figure 2A in accordance with an embodiment of the subject matter disclosed herein. According to an embodiment, blood pump 200 and / or any number of various components thereof may be the same as or similar to corresponding components of circulatory assist device 100 shown in Figures 1A and 1B.

[0046] As shown in FIG. 2A, the blood pump 200 includes a magnetic drive housing 204 including a magnetic field source 201 configured to generate a varying magnetic field to drive rotation of the impeller 216 to provide blood flow through the blood pump 200. In the embodiment shown in FIG. 2A, the magnetic field source 201 includes a permanent drive magnet 220 that rotates on a motor 202 and is configured to cause rotation of a permanent driven magnet 218 coupled to the impeller 216 to provide blood flow through the blood pump 200. As shown, the driven magnet 218 includes a proximal side 222 and a distal side 224. In an alternative embodiment, as described above but not shown here, the magnetic field source 201 can include a series of electromagnetic coils or a stator and a motor to generate a magnetic field to cause rotation of a permanent driven magnet coupled to the impeller to provide blood flow through the blood pump.

[0047] A controller (not shown) is operably coupled to motor 202 and configured to regulate motor 202. The controller may be disposed within magnetic drive housing 204 in embodiments, or may be disposed outside magnetic drive housing 204 (e.g., in a catheter handle, a separate housing, etc.) in other embodiments. In embodiments, the controller may include multiple components, one or more of which may be disposed within magnetic drive housing 204. According to embodiments, the controller coupled to motor 202 may be similar to the controller coupled to motor 102 described in FIG. 1A.

[0048] As shown in FIG. 2A , the impeller assembly 206 is disposed within an impeller assembly housing 208, which includes an inlet opening (not shown) defined therein and a number of outlet openings 212. A longitudinal axis 242 extends through the impeller assembly 206. According to an embodiment, the magnetic drive housing 204 and the impeller assembly housing 208 may be integral with one another. In other embodiments, the magnetic drive housing 204 and the impeller assembly housing 208 may be separate components configured to be removably or permanently coupled together. The impeller assembly 206 includes an impeller 216 and a driven magnet 218 coupled to the impeller 216. The driven magnet 218 and the impeller 216 may be coupled in a number of ways, including the use of adhesives, mechanical coupling, or an interference fit. The driven magnet 218 may be any type of magnetic rotor capable of being driven by the drive magnet 220. When a magnetic field is applied to the driven magnet 218 by the drive magnet 220, the driven magnet 218 rotates, causing the impeller 216 to rotate. The rotation of the impeller 216 induces blood flow through the blood pump 200.

[0049] 2B shows a perspective view of the blood pump 200 shown in FIG. 2A, in accordance with an embodiment of the subject matter disclosed herein. As shown, an impeller assembly 206, including an impeller 216, is disposed within an impeller assembly housing 208, which includes an inlet opening 210 and several outlet openings 212.

[0050] 2A , the driven magnet 218 and impeller 216 may be coupled via a drive shaft 214 that is coupled to the impeller 216 and configured to rotate with the impeller 216. The driven magnet 218 may be coupled to the drive shaft 214 and impeller 216 in a variety of ways, including the use of adhesives, mechanical bonding, or an interference fit. The drive shaft 214 may be at least partially disposed within the impeller 216. The drive shaft 214 may also be at least partially surrounded by the driven magnet 218. The drive shaft 214 may be made from any number of different rigid materials, such as, for example, steel, titanium alloy, cobalt chrome alloy, nitinol, high strength ceramic, and / or the like.

[0051] As shown in FIG. 2A, the impeller assembly 206, including the driven magnet 218, is held within the impeller assembly housing 208 by a bearing assembly 226. According to an embodiment, the bearing assembly 226 can be located near a distal side 224 of the driven magnet 218. According to an embodiment, the bearing assembly 226 can include different types of bearings. The bearing assembly 226 can also include a lubricant, while in other embodiments, the bearing assembly 226 can be lubricant-free. As shown in FIG. 2A, the bearing assembly 226 includes a magnet bearing 228 and a housing bearing 230. The driven magnet 218 can have a reduced diameter portion, such as a distal shoulder 236, to facilitate securing the magnet bearing 228 to the driven magnet 218. As shown, the bearing assembly 226 has a proximal side 232 that contacts a distal face of the distal shoulder 236 of the driven magnet 218. As shown, the housing bearing 230 includes a proximal inner lip 231 that contacts the magnet bearing 228. The proximal inner lip 231 carries thrust loads and prevents the driven magnet 218 from bottoming out against the proximal end 233 of the impeller assembly housing 208.

[0052] 2A, the bearing assembly 226, including the magnet bearing 228 and the housing bearing 230, is located longitudinally near the center of mass of the impeller assembly 206. The bearing assembly 226 is optimized when the magnet bearing 228 and the housing bearing 230 are aligned with the center of mass of the impeller assembly 206. The location of the bearing assembly 226 may be offset from the center of mass of the impeller assembly 206 by approximately 0.050 inches (1.27 mm) based on practical considerations of component assembly, but is optimized when located longitudinally as close as possible to the center of mass of the impeller assembly 206.

[0053] As shown in Figure 2A, cavity 234 is formed by proximal side 232 of bearing assembly 226, impeller assembly housing 208, and driven magnet 218. By increasing the size of driven magnet 218 compared to driven magnet 116 shown in Figure 1A, the size of cavity 234 is reduced compared to cavity 132 shown in Figure 1A. In some embodiments, a liquid may be disposed within cavity 234, as described above. In other embodiments, cavity 234 may remain empty.

[0054] According to one embodiment shown in FIG. 2A, the magnet bearing 228 may be mounted on a housing bearing 230 on the outside of the impeller assembly housing 208 so that the distal faces of the magnet bearing 228 and the housing bearing 230 are flush with one another. The distal side 224 of the driven magnet 218 may then be coupled to the proximal side of the magnet bearing 228. The magnet bearing 228 and the driven magnet 218 may be coupled by press fit, adhesive, mechanical bonding, sintering, welding, or any method known to one of ordinary skill in the art. As shown, the driven magnet 218 may include a proximal shoulder 238 and the drive shaft 214 may include a head 240. The drive shaft 214 may be placed over the proximal inner diameter of the driven magnet 218 until the drive shaft head 240 bottoms out against the proximal shoulder 238 of the driven magnet 218 and coupled in place as described above. The impeller 216 may then be mounted onto the drive shaft 214 and bonded in place by press fitting, adhesives, mechanical bonding, sintering, welding, or any method known to one of ordinary skill in the art. The order of bonding the drive shaft 214 and impeller 216 may be reversed from that described above. In other embodiments, the drive shaft 214 may be removed and the impeller 216 may be bonded in place to the driven magnet 218 by press fitting, adhesives, mechanical bonding, sintering, welding, or any method known to one of ordinary skill in the art. The impeller assembly 206 and bearing assembly 226 may then be mounted into the impeller assembly housing 208 and bonded in place by press fitting, adhesives, mechanical bonding, sintering, welding, or any method known to one of ordinary skill in the art.

[0055] As shown, the outer diameter of the driven magnet 218 may be larger than the inner diameter of the housing bearing 230, except where the magnet bearing 228 is secured to the driven magnet 218. For example, in such an embodiment, the driven magnet 218 may include a reduced diameter portion, such as a distal shoulder 236, to accommodate the magnet bearing 228 and the housing bearing 230, such that the outer diameter of the combination of the driven magnet 218, magnet bearing 228, and housing bearing 230 may be approximately the same as the outer diameter of the remainder of the driven magnet 218. In other words, the outer diameter of the driven magnet 218 may be very close to the inner diameter of the impeller assembly housing 208, except for the distal shoulder 236 of the driven magnet 218. By increasing the size of the distal shoulder 236 and mounting the magnet bearing 228 and housing bearing 230 on the driven magnet 218, a larger driven magnet may be used as compared to the embodiment shown in FIG. 1A. Additionally, the size and / or thickness of the bearing assembly 226 may be adjusted. In some embodiments, the bearing assembly 226 may be thicker to maintain its mechanical integrity and durability.

[0056] The exemplary circulatory assist device 200 shown in Figures 2A-2B is not intended to suggest any limitations as to the scope of use or functionality of the embodiments of the present disclosure. Nor should the exemplary circulatory assist device 200 be interpreted as having any dependencies or requirements relating to any single component or combination of components shown herein. In addition, the various components shown in Figures 2A-2B may be combined in embodiments with various of the other components shown therein (and / or components not shown), all of which are contemplated to be within the scope of the present disclosure.

[0057] Previous magnetically driven blood pumps have been known to incorporate at least two bearing assemblies, one located near the proximal end of the impeller assembly and another located near the distal end of the impeller assembly to restrict the longitudinal and radial motion of the impeller assembly. Such designs, with bearings attached to the longitudinal ends of the impeller, are based on having bearings incorporating features that impart a force perpendicular to the longitudinal axis to prevent the impeller from moving in either direction longitudinally. To restrict radial motion, arc or journal bearing-like features are incorporated into the distal and proximal bearings. Such designs typically achieve rotational restriction of the impeller through a total of four to six blood contacting components. In such designs, the bearing assemblies near the proximal end of the impeller assembly may be located between the magnetic field source and the driven magnet.

[0058] One advantage of locating the bearing assemblies 124, 226 longitudinally near the center of mass of the impeller assembly 106, 206 as shown in the embodiment of Figures 1A-2B is that bearings are not necessarily required between the driven magnets 116, 218 and the magnetic field source 101, 201. As a result, the driven magnets 116, 218 and the magnetic field source 101, 201 can be located closer to each other than in designs in which the bearing assemblies are located at the proximal end of the impeller assembly. For example, in the embodiment shown in Figures 1A-2B, the distance between the driving magnets 118, 220 and the magnetic field source 101, 201 can be as little as 0.012 inches (0.305 mm), and preferably less than 0.030 inches (0.762 mm). By decreasing the distance between the driven magnets 118, 220 and the magnetic field source 101, 201, less magnetic flux is lost to space and magnetic torque transfer is increased. Improved capture of magnetic flux from the magnetic field source 101, 201 by reducing the spatial distance from the magnetic field source 101, 201 to the driven magnet 116, 218 allows for increased torque for higher flow designs, use of more corrosion resistant magnets, and smaller form factors. Reducing the distance between the driven magnet 116, 218 and the magnetic field source 101, 201 can increase the magnetic torque transmitted to the driven magnet 116, 218 by more than 100%. Reducing the spacing between the magnetic field source and the driven magnet also allows for the use of non-mechanically contacting magnetic fields to regulate longitudinal forces, impeller rotation, and stability. Additionally, such a configuration can improve magnet durability. Also, reducing the distance between the magnetic field source 101, 201 and the driven magnet 116, 218 may allow for the use of a mechanical enclosure on the driven magnet 116, 218, or the use of a more corrosion resistant magnet material such as samarium cobalt, or the use of a more durable magnet with lower magnetic strength, as shown below in connection with Figures 3A-3B. Such a configuration may also provide an opportunity to improve the power efficiency of a battery powered blood pump.

[0059] Additionally, reducing the distance between the magnetic field source 101, 201 and the driven magnet 116, 218 may allow for the use of smaller driving magnets, improved efficiency from the electromagnetic coils, and / or smaller driven magnets to generate the same blood flow rate as designs incorporating larger driving and driven magnets separated by a greater distance. The flow rate of a blood pump depends on, among other factors, the torque transmission, overall pump design including impeller size, operating speed, and the design of the impeller and flow lumen which determine the flow profile. For a given pump design and target flow rate, there is an amount of torque required to drive the impeller assembly. The magnetic coupling must be able to transmit this amount of torque. The amount of torque that can be transmitted is a function of magnet size and spacing. In general, greater torque can be transmitted by larger magnets and / or magnets spaced closer together. In some embodiments, the size of the driving magnet and / or driven magnet may be adjusted to match the torque requirements of the desired flow rate from the blood pump. Other considerations may affect magnet size, including blood pump form factor, magnet material, and the contribution of the magnet(s) to hemolysis. Reducing the size of the driven magnet may also reduce the amount of hemolysis caused by use of the blood pump, for example, by allowing a greater amount of space between the impeller assembly housing and the driven magnet, thus reducing the shear stress acting on the blood in areas such as cavities 132, 234.

[0060] Another advantage of the embodiment shown in FIGS. 1A-2B is that the impeller assembly 106, 206 may be constrained both longitudinally and radially with only one bearing assembly. As mentioned above, previous blood pumps are known to incorporate at least two bearing assemblies, often with one bearing assembly located near the proximal end of the impeller assembly and another bearing assembly located near the distal end of the impeller assembly to constrain the longitudinal and radial motion of the impeller assembly. In contrast, by requiring only one bearing assembly, the embodiments disclosed herein reduce the number of blood contacting bearing assemblies, preferably reducing the number of bearings to two. Reducing the number of surfaces exposed to blood reduces the risk of hemolysis and thrombosis caused by blood interacting with the bearing surfaces. Such a configuration also simplifies the assembly of the blood pump and can also reduce the stiffness length of the blood pump, which can improve the delivery of percutaneous based devices. The simplification of the number of components interacting in a tightly constrained manner is also beneficial to the manufacturability of the blood pump and its components.

[0061] Another related advantage of the embodiments disclosed herein is that the bearing assemblies 124, 226 are longitudinally positioned or aligned near the center of mass of the impeller assembly 106, 206, which improves the overall radial stability of the impeller assembly 106, 206 by constraining motion of the impeller assembly 106, 206 near the center of gravity of the impeller assembly 106, 206. Such positioning of the bearing assemblies 124, 226 may also protect against component imbalances that cause eccentric impeller motion that may result in increased shear rates on blood flowing through the blood pump 100, 200.

[0062] Figure 3A shows a perspective view of an embodiment of a bearing assembly 300 in accordance with an embodiment of the subject matter disclosed herein, and Figure 3B shows a cross-sectional side view of the bearing assembly 300 shown in Figure 3A in accordance with an embodiment of the subject matter disclosed herein. According to an embodiment, the bearing assembly 300 and / or any number of various components thereof may be the same as or similar to corresponding components of the circulatory assist device 100 shown in Figures 1A-1D and / or corresponding components of the circulatory assist device 200 shown in Figures 2A-2B.

[0063] As shown in FIGS. 3A and 3B, the bearing assembly 300 includes a magnet bearing 302 and a housing bearing 304. The magnet bearing 302 can completely encapsulate the driven magnet 306 and act as a hermetic seal for the driven magnet 306. The housing bearing 304 is disposed near the impeller 308 and is attached to an impeller assembly housing (not shown). The driven magnet 306 can be made of a material that is susceptible to corrosion in contact with blood, such as Ne-Fe-B (neodymium). The bearing assembly 300, including the magnet bearing 302 and the housing bearing 304, can be made of a corrosion-resistant material, such as silicone nitride, sapphire, Vespel, torlon, PTFE, or any other material known by one of ordinary skill in the art that is corrosion-resistant. Thus, in some embodiments, the completely encapsulated driven magnet 306 is less susceptible to corrosion and has improved durability. In other embodiments, the driven magnet 306 itself can be made of samarium cobalt to improve corrosion resistance and durability.

[0064] As shown in FIG. 3B, the magnet bearing 302 may mate with the housing bearing 304 via a wedge shape 310. In some embodiments, the shape may be a "U" or a "V." In other embodiments, the fit may be of an alternative design that combines longitudinal and radial restraints via alternative angled contact designs. In yet other embodiments, the magnet bearing 302 and the housing bearing 304 may be designed to prevent the buildup of heat, friction, or other issues that are detrimental to the operation or structural integrity of the bearing assembly 300.

[0065] The exemplary bearing assembly 300 shown in Figures 3A and 3B is not intended to suggest any limitations as to the scope of use or functionality of the embodiments of the present disclosure. Nor should the exemplary bearing assembly 300 be construed as having any dependencies or requirements relating to any single component or combination of components shown herein. In addition, the various components shown in Figures 3A and 3B may be combined in embodiments with various of the other components shown therein (and / or components not shown), all of which are considered to be within the scope of the present disclosure.

[0066] 4 illustrates a side cross-sectional view of an exemplary percutaneous mechanical circulatory assist device 400 (also referred to interchangeably herein as a "blood pump") in accordance with an embodiment of the subject matter disclosed herein. According to an embodiment, blood pump 400 and / or any number of its various components may be the same as or similar to corresponding components of circulatory assist device 100 shown in FIGS. 1A and 1B, or may be the same as or similar to corresponding components of circulatory assist device 200 shown in FIGS. 2A and 2B.

[0067] As shown in FIG. 4, the blood pump 400 includes a magnetic drive housing 402 including a magnetic field source 404 configured to generate a varying magnetic field to drive rotation of an impeller 406 to provide blood flow through the blood pump 400. In the embodiment shown in FIG. 4, the magnetic field source 404 includes a permanent drive magnet 408 that is rotated by a motor 410 and configured to cause rotation of a permanent driven magnet 412 coupled to the impeller 406 to provide blood flow through the blood pump 400. As shown, the driven magnet 412 includes a proximal side 414 and a distal side 416. In an alternative embodiment, as described above but not shown here, the magnetic field source 404 can include a series of electromagnetic coils or a stator and a motor to generate a magnetic field to cause rotation of a permanent driven magnet coupled to the impeller to provide blood flow through the blood pump.

[0068] A controller (not shown) is operably coupled to motor 410 and configured to regulate motor 410. The controller may be located within motor 410 in embodiments, or may be located outside motor 410 (e.g., in a catheter handle, a separate housing, etc.) in other embodiments. In some embodiments, the controller may include multiple components, one or more of which may be located within motor 410. According to some embodiments, the controller coupled to motor 410 may be similar to the controller coupled to motor 102 described in connection with FIG. 1A.

[0069] As shown in FIG. 4 , the impeller assembly 418 is disposed within an impeller assembly housing 420 that includes an inlet opening 422 and a number of outlet openings 424 defined therein. A longitudinal axis 426 extends through the impeller assembly 418. According to some embodiments, as shown, the magnetic drive housing 402 and the impeller assembly housing 420 may be integral with one another. In other embodiments, the magnetic drive housing 402 and the impeller assembly housing 420 may be separate components configured to be removably or permanently coupled together. The impeller assembly 418 includes an impeller 406 and a driven magnet 412. The driven magnet 412 and the impeller 406 may be coupled in a variety of ways, including the use of adhesives, mechanical coupling, or an interference fit. The driven magnet 412 may be any type of magnetic rotor capable of being driven by the magnetic field source 404. When a magnetic field is applied to the driven magnet 412 by the magnetic field source 404, the driven magnet 412 rotates, causing the impeller 406 to rotate. The rotation of the impeller 406 induces blood flow through the blood pump 400.

[0070] 4, the driven magnet 412 and impeller 406 may be coupled via a drive shaft 428 that is coupled to the impeller 406 and configured to rotate with the impeller 406. The driven magnet 412 may be coupled to the drive shaft 428 and impeller 406 in a variety of ways, including the use of adhesives, mechanical bonding, or an interference fit. The drive shaft 428 may be at least partially disposed within the impeller 406. The drive shaft 428 may also be at least partially surrounded by the driven magnet 412. The drive shaft 428 may be made from any number of different rigid materials, such as, for example, steel, titanium alloy, cobalt chrome alloy, nitinol, high strength ceramic, and / or the like.

[0071] As shown in FIG. 4, the impeller assembly 418 is coupled to and retained within the impeller assembly housing 420 by a bearing assembly 430. According to some embodiments, the bearing assembly 430 may be located near the distal side 416 of the driven magnet 412. According to some embodiments, the bearing assembly 430 may include different types of bearings. The bearing assembly 430 may also include a lubricant, while in other embodiments, the bearing assembly 430 may not include a lubricant. As shown in FIG. 4, the bearing assembly 430 includes a first bearing 432, which may also be referred to as a housing bearing, and a second bearing 434, which may also be referred to as a thrust bearing. The thrust bearing 434 rotates with the shaft 428 and other components of the impeller assembly 418. The thrust bearing 434 contacts a proximal side 436 of the impeller 406 and a distal side 438 of the housing bearing 432. Bearing assembly 430, including first bearing 432 and second bearing 434, may be made of one or more corrosion-resistant materials, such as silicon nitride, ceramic, sapphire, Vespel, Torlon, PTFE, or any other corrosion-resistant material known to one of ordinary skill in the art.

[0072] Continuing with reference to FIG. 4, the housing bearing 432 contacts the impeller assembly housing 420. More specifically, the impeller assembly housing 420 includes a recess or pocket 440 that receives the housing bearing 432. The housing bearing 432 rotatably supports the shaft 428, and the housing bearing 432 includes rounded exterior corners 442 that reduce or minimize hemolysis of blood flowing through the device 400. In some embodiments, by having the driven magnet 412 behind the housing bearing 432, the housing bearing 432 can reduce or minimize the amount of blood that contacts the driven magnet 412, facilitating the reduction of hemolysis. In some embodiments, the housing bearing 432 can be longitudinally positioned near the center of mass of the impeller assembly 418. The device 400 can be optimized when the housing bearing 432 is aligned with the center of mass of the impeller assembly 418. The location of the housing bearing 432 may be offset from the center of mass of the impeller assembly 418 by approximately 0.050 inches (1.27 mm) based on practical considerations of component assembly, but is optimized when located longitudinally as close as possible to the center of mass of the impeller assembly 418. In other embodiments, the housing bearing 432 may not be aligned with the center of mass of the impeller assembly 418, or the location of the housing bearing 432 may be offset a greater distance from the center of mass of the impeller assembly 418, depending on the size and configuration of the housing bearing 432.

[0073] The bearing assembly 430 is used to regulate the forces associated with the impeller assembly 418. In part, the bearing assembly 430 utilizes the magnetic force of the driven magnet 412 to regulate the axial load of the impeller assembly 418. Specifically, the axial attractive force between the magnetic field source 404 and the driven magnet 412 is greater than the thrust force from the impeller assembly 418 which pushes the impeller assembly 418 in a distal direction, thus preventing axial movement of the impeller assembly 418 in a distal direction. The thrust bearing 434 provides axial restraint by opposing the axial magnetic attractive force from the magnetic field source 404 and the driven magnet 412. The housing bearing 432 provides radial restraint for the impeller assembly 418.

[0074] Continuing with reference to FIG. 4, the impeller assembly housing 420 includes a channel 444 disposed on a proximal side of at least one of the plurality of outlet openings 424. The channel 444 is configured to receive a guidewire (not shown) passing from within the impeller housing 420 to the outside of the impeller housing 420 through one of the plurality of outlet openings 424. In some embodiments, the channel 444 may extend the entire length of the housing bearing 432. The channel 444 provides a surface for the guidewire to gradually transition from within the impeller housing 420 to the outside of the impeller housing 420, reducing the possibility of damage to the guidewire due to contact with the impeller housing 420 and reducing the angle of the guidewire during the transition from within the impeller housing 420 to the outside of the impeller housing 420. The resting surface of the housing bearing 432 may allow for configurations such as adhesive fillets or soft polymer components to prevent the proximal end of the outlet opening 424 from having a metal edge that may damage the guidewire.

[0075] One advantage of locating the bearing assembly 430 as shown in FIG. 4 is that a bearing is not necessarily required between the driven magnet 412 and the magnetic field source 404. As a result, the driven magnet 412 and the magnetic field source 404 can be located closer to each other than in designs where the bearing assembly is located at the proximal end of the impeller assembly. For example, in the illustrated embodiment, the distance between the driven magnet 412 and the magnetic field source 404 can be as small as 0.012 inches (0.305 mm), preferably less than 0.020 inches (0.508 mm), and more preferably less than 0.030 inches (0.762 mm). By reducing the distance between the driven magnet 412 and the magnetic field source 404, the magnetic flux lost to space is reduced, increasing magnetic torque transfer. Improved capture of magnetic flux from the magnetic field source 404 by reducing the spatial distance from the magnetic field source 404 to the driven magnet 412 allows for increased torque for higher flow designs, use of more corrosion resistant magnets, and smaller form factors. A decrease in the distance between the driven magnet 412 and the magnetic field source 404 may increase the magnetic torque transmitted to the driven magnet 412 by 100%.

[0076] Another advantage of the device 400 is that the impeller assembly 418 may be restrained both longitudinally and radially with only one bearing assembly. As discussed above, previous blood pumps have been known to incorporate at least two bearing assemblies, often with one bearing assembly located near the proximal end of the impeller assembly and another bearing assembly located near the distal end of the impeller assembly to restrain the longitudinal and radial motion of the impeller assembly. In contrast, the device 400 lacks a bearing assembly at the distal end 444 of the impeller 406, thereby reducing the number of blood-contacting bearing assemblies, preferably reducing the number of bearings to two. Also, as discussed above, reducing the number of surfaces or structures exposed to blood may reduce the risk of hemolysis and thrombosis and reduce the overall stiffness length of the blood pump.

[0077] In some embodiments, a method of assembling the device 400 may include the following acts: First, the shaft is placed within the impeller 406, and the thrust bearing 434 is placed on the shaft 428 against the proximal side 436 of the impeller 406. The thrust bearing 434 is then secured to the shaft 428 or the impeller 406 (e.g., by adhesive, press fit, mechanical bonding, sintering, welding, or any method known to one of skill in the art). Next, the housing bearing 432 is placed on the shaft 428 proximal to the thrust bearing 434, and the driven magnet 412 is placed on the shaft 428 proximal to the housing bearing 432. Next, the driven magnet 412 is secured to the shaft 428 (e.g., by adhesive, press fit, mechanical bonding, sintering, welding, or any method known to one of skill in the art). Impeller assembly 418 and bearing assembly 430 are then placed into impeller assembly housing 420 and housing bearing 432 is secured to impeller assembly housing 420 (e.g., by adhesive, press fit, mechanical bonding, sintering, welding, or any method known to one of skill in the art).

[0078] The exemplary circulatory assist device 400 shown in Figure 4 is not intended to suggest any limitations as to the scope of use or functionality of the embodiments of the present disclosure. Neither should the exemplary circulatory assist device 400 be interpreted as having any dependencies or requirements relating to any single component or combination of components shown herein. In addition, the various components shown in Figure 4 may be combined in embodiments with various of the other components shown therein (and / or components not shown), all of which are considered to be within the scope of the present disclosure.

[0079] 5 illustrates a side cross-sectional view of an exemplary percutaneous mechanical circulatory assist device 500 (also referred to herein interchangeably as a "blood pump") in accordance with an embodiment of the subject matter disclosed herein. According to an embodiment, blood pump 500, and / or any number of its various components, may be the same as or similar to corresponding components of circulatory assist device 100 shown in FIGS. 1A and 1B, may be the same as or similar to corresponding components of circulatory assist device 200 shown in FIGS. 2A and 2B, or may be the same as or similar to corresponding components of circulatory assist device 400 shown in FIG.

[0080] As shown in FIG. 5, the blood pump 500 includes a magnetic drive housing 502 including a magnetic field source 504 configured to generate a varying magnetic field to drive rotation of an impeller 506 to provide blood flow through the blood pump 500. In the embodiment shown in FIG. 5, the magnetic field source 504 includes a permanent drive magnet 508 that is rotated by a motor 510 and configured to cause rotation of a permanent driven magnet 512 coupled to the impeller 506 to provide blood flow through the blood pump 500. As shown, the driven magnet 512 includes a proximal side 514 and a distal side 516. In an alternative embodiment, as described above but not shown here, the magnetic field source 504 can include a series of electromagnetic coils or a stator and a motor to generate a magnetic field to cause rotation of a permanent driven magnet coupled to the impeller to provide blood flow through the blood pump.

[0081] A controller (not shown) is operably coupled to the motor 510 and configured to regulate the motor 510. The controller may be located within the motor 510 in some embodiments, or may be located outside the motor 510 (e.g., in a catheter handle, a separate housing, etc.) in other embodiments. In some embodiments, the controller may include multiple components, one or more of which may be located within the motor 510. According to some embodiments, the controller coupled to the motor 510 may be similar to the controller coupled to the motor 102 described in connection with FIG. 1A.

[0082] As shown in FIG. 5 , the impeller assembly 518 is disposed within an impeller assembly housing 520, which includes an inlet opening 522 and a plurality of outlet openings 524 defined therein. A longitudinal axis 526 extends through the impeller assembly 518. According to some embodiments, as shown, the magnetic drive housing 502 and the impeller assembly housing 520 may be integral with one another. In other embodiments, the magnetic drive housing 502 and the impeller assembly housing 520 may be separate components configured to be removably or permanently coupled together. The impeller assembly 518 includes an impeller 506 and a driven magnet 512. The driven magnet 512 and the impeller 506 may be coupled in a variety of ways, including the use of adhesives, mechanical bonding, or an interference fit. The driven magnet 512 may be any type of magnetic rotor capable of being driven by a magnetic field source 504. When a magnetic field is applied to driven magnet 512 by magnetic field source 504, driven magnet 512 rotates, causing impeller 506 to rotate. The rotation of impeller 506 induces blood flow through blood pump 500.

[0083] 5, the driven magnet 512 and impeller 506 may be coupled via a drive shaft 528 that is coupled to the impeller 506 and configured to rotate with the impeller 506. The driven magnet 512 may be coupled to the drive shaft 528 and impeller 506 in a variety of ways, including the use of adhesives, mechanical bonding, or an interference fit. The drive shaft 528 may be at least partially disposed within the impeller 506. The drive shaft 528 may also be at least partially surrounded by the driven magnet 512. The drive shaft 528 may be made from any number of different rigid materials, such as, for example, steel, titanium alloy, cobalt chrome alloy, nitinol, high strength ceramic, and / or the like.

[0084] As shown in FIG. 5, the impeller assembly 518 is coupled to and retained within the impeller assembly housing 520 by a proximal bearing assembly 530. According to some embodiments, the proximal bearing assembly 530 may be located near the distal side 516 of the driven magnet 512. According to some embodiments, the proximal bearing assembly 530 may include different types of bearings. The proximal bearing assembly 530 may also include a lubricant, while in other embodiments, the proximal bearing assembly 530 may not include a lubricant. As shown in FIG. 5, the proximal bearing assembly 530 includes a first bearing 532, which may also be referred to as a housing bearing, and a second bearing 534, which may also be referred to as a thrust bearing. A third bearing 536, which may also be referred to as a distal bearing, is also included in the impeller assembly 520 and is coupled to the impeller assembly 518. The thrust bearing 534 contacts a proximal side 538 of the impeller 506 and a distal side 540 of the housing bearing 532. Distal bearing 536 is disposed distally relative to impeller 506 and contacts distal support 542 which in turn contacts impeller assembly housing 520. Proximal bearing assembly 530 and distal bearing 536 may be made of one or more materials that are corrosion resistant, such as silicone nitride, ceramic, sapphire, Vespel, Torlon, PTFE, or any other material known to one of ordinary skill in the art that is corrosion resistant.

[0085] Continuing with reference to FIG. 5, the housing bearing 532 contacts the impeller assembly housing 520. More specifically, the impeller assembly housing 520 includes a recess or pocket 544 that receives the housing bearing 532. The housing bearing 532 rotatably supports the shaft 528. In some embodiments, the housing bearing 532 may reduce or minimize the amount of blood that contacts the driven magnet 512, facilitating the reduction of hemolysis. In particular, the housing bearing 532 may include rounded exterior corners 546 that reduce or minimize the hemolysis of blood flowing through the device 500. In some embodiments, by having the driven magnet 512 behind the housing bearing 532, the housing bearing 532 may reduce or minimize the amount of blood that contacts the driven magnet 512, facilitating the reduction of hemolysis. In some embodiments, the housing bearing 532 may be longitudinally disposed near the center of mass of the impeller assembly 518, as previously described. The apparatus 500 may be optimized when the housing bearing 532 is aligned with the center of mass of the impeller assembly 518. In other embodiments, the housing bearing 532 may not be aligned with the center of mass of the impeller assembly 518, depending on the size and configuration of the housing bearing 532.

[0086] In some embodiments, as shown, the driven magnet 512 and the magnetic field source 504 are positioned closer together than in designs where the bearing assembly is located at the proximal end of the impeller assembly. For example, in the embodiment shown, the distance between the driven magnet 512 and the magnetic field source 504 can be as small as 0.012 inches (0.305 mm), preferably less than 0.020 inches (0.508 mm), and more preferably less than 0.030 inches (0.762 mm). By decreasing the distance between the driven magnet 512 and the magnetic field source 504, the magnetic flux lost to space is reduced, increasing the magnetic torque transfer. Improved capture of the magnetic flux from the magnetic field source 504 by reducing the spatial distance from the magnetic field source 504 to the driven magnet 512 allows for increased torque for higher flow designs, the use of more corrosion resistant magnets, and smaller form factors. The reduction in the distance between the driven magnet 512 and the magnetic field source 504 can increase the magnetic torque transferred to the driven magnet 512 by 100%.

[0087] In some embodiments, the method of assembling device 500 may be similar to the method of assembling device 400 described above. Additionally, distal bearing 536 and distal support 542 may be secured to one another and / or to impeller assembly housing 520 (e.g., by adhesive, press fit, mechanical bonding, sintering, welding, or any method known to one of skill in the art) before or after securing housing bearing 532 and impeller assembly 518 to impeller assembly housing 520.

[0088] The exemplary circulatory assist device 500 shown in Figure 5 is not intended to suggest any limitations as to the scope of use or functionality of the embodiments of the present disclosure. Neither should the exemplary circulatory assist device 500 be interpreted as having any dependencies or requirements relating to any single component or combination of components shown herein. In addition, the various components shown in Figure 5 may be combined in embodiments with various of the other components shown therein (and / or components not shown), all of which are considered to be within the scope of the present disclosure.

[0089] Various modifications and additions may be made to the exemplary embodiments discussed without departing from the scope of the present disclosure. For example, while the above embodiments refer to certain features, the scope of the present disclosure also includes embodiments having different combinations of features and embodiments that do not include all of the described features. Accordingly, the scope of the present disclosure is intended to embrace all such alternatives, modifications, and variations that fall within the scope of the claims, together with all equivalents thereof.

Claims

1. 1. A blood pump comprising: A magnetic field source; an impeller assembly including a longitudinal axis, an impeller, and a driven magnet, the driven magnet being longitudinally offset and distally disposed relative to the magnetic field source, the driven magnet being rotatable and longitudinally constrained by the magnetic field source, the driven magnet having a distal side facing the impeller; a bearing assembly adjacent the distal portion of the driven magnet; Equipped with The impeller assembly has a center of mass, and the bearing assembly is longitudinally aligned with the center of mass of the impeller assembly.

2. 2. The blood pump of claim 1, further comprising an impeller assembly housing, the bearing assembly being in contact with the impeller assembly housing, the impeller assembly housing rotatably supporting the impeller assembly via the bearing assembly.

3. The blood pump of claim 2 , wherein the impeller assembly housing includes a recess that receives the bearing assembly.

4. 4. The blood pump of claim 2 or 3, wherein the distance between the magnetic field source and the driven magnet is less than 0.030 inches (0.762 mm).

5. The blood pump of any one of claims 2 to 4, wherein no part of the bearing assembly is located between the driven magnet and the magnetic field source.

6. The blood pump of any one of claims 2 to 5, wherein the impeller assembly housing does not include a bearing assembly disposed at a distal end of the impeller.

7. 7. The blood pump of claim 1, wherein the impeller assembly is rotatable about the longitudinal axis and the bearing assembly is disposed radially outward relative to the longitudinal axis.

8. The blood pump of any one of claims 2 to 6, wherein the impeller assembly further includes a shaft, and the bearing assembly contacts the shaft and the impeller assembly housing.

9. A blood pump comprising: A magnetic field source; an impeller assembly including a longitudinal axis, an impeller, a shaft, and a driven magnet, the driven magnet being longitudinally offset and distally disposed relative to the magnetic field source, the driven magnet being rotatable and longitudinally constrained by the magnetic field source, the driven magnet having a distal side facing the impeller; a bearing assembly adjacent the distal end of the driven magnet; an impeller assembly housing, the bearing assembly being in contact with the impeller assembly housing and the impeller assembly housing rotatably supporting the impeller assembly via the bearing assembly; The bearing assembly includes: a first bearing in contact with the shaft and the impeller assembly housing; a second bearing in contact with the first bearing and the impeller; and A blood pump comprising:

10. 1. A blood pump comprising: A magnetic field source; an impeller assembly including a longitudinal axis, an impeller, a shaft, and a driven magnet, the driven magnet being longitudinally offset and distally disposed relative to the magnetic field source, the driven magnet being rotatable and longitudinally constrained by the magnetic field source; a bearing assembly coupled to the impeller assembly, no portion of the bearing assembly being disposed between the driven magnet and the magnetic field source; and an impeller assembly housing, the bearing assembly being in contact with the impeller assembly housing and the impeller assembly housing rotatably supporting the impeller assembly via the bearing assembly; The bearing assembly includes: a first bearing in contact with the shaft and the impeller assembly housing; a second bearing in contact with the first bearing and the impeller; and A blood pump comprising:

11. The blood pump of claim 10 , wherein the impeller assembly housing includes a recess that receives the bearing assembly.

12. 12. The blood pump of claim 10 or 11, wherein the bearing assembly comprises a magnetic bearing containing the driven magnet.

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