Intravascular blood pump

Abstract

An intravascular blood pump (1) comprises a catheter (5), a rotor (10), a housing (11) housing the rotor (10), and a drive shaft (12) extending through the catheter (5) and rotatably supported in a proximal bearing (13) located at a proximal end of the rotor (10). The proximal bearing (13) comprises a bearing sleeve (13) and an outer bearing ring (32). The bearing sleeve (30) includes a proximal end portion at a proximal end of the outer bearing ring (32), the proximal end portion of the bearing sleeve (30) forming an axial bearing with a proximal end surface of the outer bearing ring (32). The bearing sleeve (30) further includes a distal end portion extending distally from the proximal end portion (30a) of the bearing sleeve (30) into the outer bearing ring (32), wherein the distal end portion of the bearing sleeve (30) forms a radial bearing with the outer bearing ring (32).

Description

[0001] Divisional application

[0002] This application is a divisional application of the patent application with the application number 2021800119451, the international filing date of January 28, 2021, the date of entry into the Chinese national phase of July 29, 2022, and the invention title of "Intravascular Blood Pump". Technical Field

[0003] The present invention relates to an intravascular blood pump, in particular a percutaneously insertable blood pump for supporting the blood circulation of a human or also an animal. For example, the blood pump can be designed to be percutaneously inserted into the femoral artery of a patient and guided through the patient's vascular system to, for example, support or replace the pumping action of the heart. Background Art

[0004] Although the present invention will be described in the context of an intravascular blood pump having an expandable housing in which an expandable rotor is accommodated and driven by an extracorporeal motor via a long and flexible drive shaft, the present invention can also be applied to other types of intravascular blood pumps.

[0005] The above-mentioned expandable type of blood pump is known, for example, from US2013 / 0303969A1 which discloses a catheter pump assembly. The expandable housing is located at the distal end of the catheter. The expandable housing surrounds an expandable rotor driven by a flexible drive shaft that extends through a first lumen of the catheter. For example, the distal portion of the catheter pump assembly can be placed inside the heart through a percutaneous access using the Seldinger technique. The drive shaft includes a central lumen that allows a guide wire and its guide to pass through the drive shaft to achieve precise positioning of the catheter pump assembly inside the heart. The rotor is rotatably supported in a proximal bearing disposed at the catheter end and the proximal end of the rotor. Here, "proximal" and "distal" refer to what is seen by the doctor. Thus, when placing the catheter, the proximal represents something relatively close to the doctor, while the distal represents something relatively far from the doctor.

[0006] During the use of an intravascular blood pump, the rotor and the drive shaft need to rotate at a significant speed. Therefore, there is a need to provide a bearing that rotatably supports the drive shaft with low friction while maintaining high durability. Summary of the Invention

[0007] According to a first aspect of the present invention, an intravascular blood pump includes a catheter and a housing. A rotor is received within the housing, and the housing is attached to the distal end portion of the catheter. Further, in the intravascular blood pump disclosed herein, a flexible drive shaft extends through the catheter. The flexible drive shaft is connected to the rotor and is rotatably supported in a proximal bearing located proximal to the rotor. The proximal bearing includes a bearing sleeve and an outer bearing ring, wherein the bearing sleeve includes a proximal portion located proximal to the outer bearing ring, and this proximal portion of the bearing sleeve forms an axial bearing with the proximal surface of the outer bearing ring. The bearing sleeve further includes a distal portion extending distally from the proximal portion of the sleeve into the outer bearing ring, and this distal portion of the bearing sleeve forms a radial bearing with the outer bearing ring. The described design of the proximal bearing can advantageously achieve low friction and high durability, especially when a cleaning fluid is provided to flow through the gap defined by the radial bearing.

[0008] Preferably, the bearing sleeve is fixedly connected to the flexible drive shaft. The bearing sleeve can be crimped, welded, fused, glued, or shrunk onto the flexible drive shaft. Gluing the bearing sleeve can advantageously avoid any deformation or warping of the bearing sleeve.

[0009] The proximal bearing is preferably located within the distal end region of the catheter and / or within the proximal end region of the housing. Alternatively, the proximal bearing, preferably the axial proximal bearing, can be located at any position within the catheter, and there can even be multiple proximal bearings. The term "proximal" here refers to any position of the bearing proximal to the rotor. Preferably, the outer bearing ring is fixedly connected within the distal end region of the catheter or within the proximal end region of the housing. The outer bearing ring can be press-fitted and / or glued into the catheter and / or the housing. In some embodiments, the outer bearing ring can be assembled to both the housing and the catheter, thereby connecting the housing to the catheter. The proximal bearing located at the distal end of the catheter or the proximal end of the housing can provide particularly stable support for the drive shaft and the rotor.

[0010] Preferably, a limiting member is located proximal to the bearing sleeve within the catheter and / or the housing. It can be fixedly mounted within the proximal end of the housing or within the distal end of the catheter. The limiting member serves as a stopper to limit the axial movement of the bearing sleeve relative to the outer bearing ring. The limiting member can advantageously prevent the bearing sleeve from slipping out of the outer bearing ring. In some embodiments, the limiting member forms a part of the proximal bearing. Preferably, the inner diameter of the limiting member is slightly larger than the diameter of the flexible drive cable to avoid frictional contact therewith and allow the cleaning fluid to pass through.

[0011] The inner diameter of the bearing ring is preferably between 0.6 mm and 2.2 mm, more preferably between 0.9 mm and 1.3 mm. The axial length of the bearing ring preferably corresponds to between one and two times the inner diameter of the bearing ring, more preferably between 1.2 and 1.6 times the inner diameter of the bearing ring. In a particularly preferred embodiment, the inner diameter is 1.1 mm and the axial length is 1.6 mm.

[0012] Preferably, the radial bearing clearance between the outer bearing ring and the bearing sleeve is between 1 μm and 10 μm, more preferably between 2 μm and 8 μm wide. Most preferably, the radial bearing clearance is approximately 3.5 μm wide. The cleaning fluid can be pushed through the radial bearing clearance of the proximal bearing. If the radial bearing clearance is constructed in this way, the cleaning fluid can flow at a reproducible speed under a suitable cleaning fluid pressure.

[0013] Preferably, the flexible drive shaft is at least partially filled with a sealant. Preferably, the sealant completely penetrates the flexible drive shaft and forms a watertight drive shaft at at least one location. In this case, the sealant is a substance that can penetrate the layers as a fluid and then harden sufficiently to prevent the penetration of the cleaning fluid. For the purposes of the present invention, examples of sealants are adhesives, polymers, and / or thermoplastics.

[0014] Preferably, the bearing sleeve and / or the outer bearing ring comprise one or more ceramics and / or metals. The metal is preferably MP35, 35NLT, nitinol, or stainless steel. If made of metal, the bearing sleeve and / or the outer bearing can comprise a coating. Preferably, the bearing sleeve and / or the outer bearing ring have a hard coating, such as a DLC coating. Advantageously, the bearing sleeve or the outer bearing ring designed in this way allows the proximal bearing to be lightweight and durable.

[0015] Preferably, the proximal end region of the housing and / or the distal end region of the conduit comprise one or more radial through-holes. The radial through-holes can increase the elasticity to allow press-fitting the proximal bearing into the housing and / or the conduit. The through-holes further allow the introduction of glue and position monitoring when inserting the proximal bearing. It is noted that the glue is used to seal the gap between the bearing and the housing to avoid leakage of the cleaning fluid, i.e., care should be taken to completely fill the gap. The diameter of the radial through-holes can be between 0.5 mm and 1 mm. Elongated holes elongated in the circumferential direction are advantageous for filling the notches of the bearing, in which case the aforementioned diameter refers to the smaller diameter of the elongated holes.

[0016] Preferably, the flexible drive shaft comprises a reinforcing element longitudinally extending in the central lumen of the drive shaft, preferably a coaxial rigid reinforcing rod. More specifically, in some embodiments, the drive shaft is reinforced at its distal end region. This is particularly advantageous when the drive shaft extends into the rotor and, in some embodiments, extends to the distal end of the rotor. Thus, the reinforcing element can extend from the proximal end region of the proximal bearing to the distal end of the drive shaft. The reinforcing element is preferably a metal rod, such as made of spring steel, wire, or carbon fiber. In one embodiment, the wire is made of 1.4310 stainless steel.

[0017] The bearing sleeve may include a portion extending distally from the outer bearing ring, and the rotor may be mounted on the portion extending distally from the outer bearing ring. Such a design may allow for a particularly stable configuration of the rotor. In particular, the bearing sleeve may extend along a major portion of the axial length of the rotor, more preferably extending to the distal end of the rotor.

[0018] The rotor is preferably at a distance between 0.001 mm and 8 mm from the distal surface of the outer bearing ring. A minimum distance between the rotor and the proximal bearing is desirable as this may prevent the rotor from jamming in the proximal bearing.

[0019] Preferably, the rotor is additionally supported in the distal bearing.

[0020] The flexible drive shaft preferably extends through the entire catheter. The drive shaft is preferably hollow. The flexible drive shaft preferably consists of or includes a flexible cable, which is preferably formed by fiber layers of different orientations. In particular, the flexible drive shaft most preferably consists of a plurality of coaxial windings, preferably having different winding directions, particularly preferably having alternating winding directions, spirally extending around a lumen extending axially along the drive shaft. For example, the flexible drive shaft may include two coaxial windings with opposite winding directions. The outer diameter of the drive shaft may preferably be between 0.4 mm and 2 mm, more preferably between 0.6 mm and 1.2 mm, particularly preferably between 0.8 mm and 1.0 mm. The proximal end of the flexible drive shaft is preferably attached to an extracorporeal electric motor. The flexible drive shaft is used to transfer torque from the electric motor to the rotor at the distal end of the drive shaft. In some cases, the flexible drive shaft may include a rigid shaft at its distal end, to which the rotor is attached inside the housing in order to provide stability for the rotor.

[0021] In one embodiment, the flexible drive shaft includes at least one outer layer and at least one inner layer. At least one outer layer of the flexible drive shaft is preferably absent or thinned at the portion where the flexible drive shaft is supported in the proximal bearing. Thus, the drive shaft has a portion with a reduced diameter, and at least the distal portion of the bearing sleeve that forms a radial bearing together with the outer bearing ring is disposed in this portion. Preferably, the axial length of the portion where at least one outer layer is absent or thinned is between 1 and 15 times the diameter of the drive shaft in this portion, preferably between 2 and 5 times, for example between 2 mm and 5 mm.

[0022] At least one outer layer and at least one inner layer are preferably made of metal. More preferably, all layers may be made of metal. In some embodiments, at least one inner layer and / or at least one outer layer may be a wire or cable. The outer layer and / or the inner layer may be made of a hollow metal tube.

[0023] In some embodiments, at least one of the at least one outer layer and / or at least one of the at least one inner layer comprises or consists of filaments wound into one or more windings. Each filament may comprise one or more strands, for example it may be twisted. Instead of winding the filaments in a layer, the filaments may preferably be braided, for example similar to the outer sheath of a kernmantle rope. The windings of at least one inner layer or at least one outer layer may form a helix. Alternatively, some or all of the layers may consist of two or more helices, which are preferably axially displaced, similar to a multi-start thread. Different layers may have different helix handings, for example, an alternating hand from one layer to the next adjacent layer. The filaments may consist of metal or may comprise metal and other additional materials, such as a surface coating.

[0024] Preferably, the flexible drive shaft is at least partially filled with a sealant that penetrates into at least one inner layer. If the layer comprises pores or is made of filaments, the sealant may penetrate across the layers. In some cases, these layers, particularly one or more filaments of the flexible drive shaft, may be partially or fully filled with the sealant.

[0025] For example, the proximal bearing and / or the distal bearing are configured to be cleaned with a cleaning fluid. The cleaning fluid may reduce friction and carry away frictional heat from the proximal bearing. Also, it may prevent blood from entering through the bearing clearance. If the cleaning fluid can flow through the flexible drive shaft in addition to the bearing clearance during its passage through the proximal bearing, it is difficult to generate a defined cleaning fluid flow. Therefore, if the flexible drive shaft is filled with a sealant, the cleaning fluid can be prevented from flowing through the drive shaft, and a defined cleaning fluid flow through the proximal bearing can be promoted.

[0026] If the flexible drive shaft is filled with a sealant inside the bearing sleeve, it can advantageously prevent the cleaning fluid from flowing through the bearing sleeve. However, in some cases, it may be difficult to completely fill a flexible drive shaft with multiple layers with sealant. This may result in residual cleaning fluid flowing through the flexible drive shaft. In some embodiments, there is only one inner layer, and this inner layer as well as at least one outer layer consist of wound filaments. At the same time, at least one outer layer may be completely removed at the position of the sleeve.

[0027] Further in an alternative, in a design with more than two outer layers, one or more outer layers may be removed so that only at least one inner layer remains. In this case, filling at least one inner layer inside the bearing sleeve with a sealant may be particularly effective in preventing flow through the flexible drive shaft. This is because the sealant does not have to penetrate into the space between the layers to completely seal the inside of the bearing sleeve.

[0028] In another embodiment, the inner diameter of the bearing sleeve is approximately equal to the outer diameter of at least one inner layer of the drive shaft or the outer diameter of at least one outer layer that is thinned. Preferably, the bearing sleeve is fixedly connected to at least one inner layer of the flexible drive shaft or at least one outer layer that is thinned. The outer diameter of the distal portion of the bearing sleeve is approximately equal to the outer diameter of at least one outer layer. Thus, the inner radial bearing surface of the proximal bearing corresponds to the outer diameter of the drive shaft and preferably can be slightly larger than at least one outer layer of the drive shaft to facilitate device assembly.

[0029] At least one inner layer may be axially discontinuous within the bearing sleeve. If at least one inner layer is axially discontinuous within the bearing sleeve, it may be particularly easy to fix the bearing sleeve on top of at least one inner layer. In the case of an inner layer without axial discontinuity, at least one inner layer must be fed through the bearing sleeve before the next successive portion of at least one outer layer can be set onto at least one inner layer. This is particularly advantageous in embodiments where at least one inner layer extends distally beyond the proximal bearing.

[0030] In some embodiments, the internal space of the bearing sleeve is hydraulically separated, i.e., liquid cannot flow internally from one side of the bearing sleeve to the other. In some embodiments, the bearing sleeve may not be a cylinder with a through-hole, but a cylinder with a wall separating two blind holes. Then the two ends of at least one axially discontinuous inner layer can be respectively inserted into a corresponding one of the blind holes. The wall between the holes prevents any cleaning fluid from flowing through the bearing sleeve, such that at least one axially discontinuous inner layer does not need to be sealed but only attached to the bearing sleeve.

[0031] In a preferred embodiment, only the distal portion of the bearing sleeve is mounted on the diameter-reduced portion of the drive shaft, while the proximal portion has an increased inner diameter and extends proximally over at least one outer layer of the flexible drive shaft. Thus, the risk of drive shaft breakage due to stiffness changes at the transition between different diameters is effectively reduced. A distal protective ring with substantially the same function can be provided at the distal transition between different diameters and can extend over both at least one outer layer of the flexible shaft and the distal extension portion of this part of the bearing sleeve.

[0032] The proximal bearing with a bearing sleeve and a distal protective ring can be preferably assembled as follows. At least one inner layer and at least one outer layer of the drive shaft can be mechanically separated from each other or can be installed during production such that at least one inner layer protrudes from at least one outer layer. After mechanically separating at least one outer layer from the inner layer, at least one outer layer is pulled out of the inner layer while being slightly rotated. On at least one outer layer of the drive shaft, the distal portion of the bearing sleeve is positioned such that the longer portion of the first protective ring is mechanically or otherwise fixed to at least one outer layer of the drive shaft. The shorter portion of the distal portion of the bearing sleeve overlaps with at least one inner layer of the drive shaft. Thereafter, a low-viscosity adhesive is introduced into the overlapping area and used to glue the distal portion of the bearing sleeve to at least one inner layer of the drive shaft. The distal portion of the bearing sleeve is positioned to extend into and overlap with the proximal portion of the bearing sleeve. After the adhesive cures, the combination of the drive shaft and the bearing sleeve can be tested for liquid impermeability. Then the outer bearing ring is positioned on the distal portion of the bearing sleeve. The at least one outer layer that was previously removed is pushed onto at least one inner layer until it contacts the bearing sleeve and is glued in place. Then, the distal protective ring is placed on top of the at least one outer layer that was previously removed to overlap with the distal portion of the bearing sleeve. The distal protective ring is positioned such that a predetermined axial play is set between the outer bearing ring and the bearing sleeve. Then the distal protective ring is mechanically or otherwise fixed to the drive shaft. Fixing the protective ring to at least one outer layer can additionally prevent the loosening of at least one outer layer. Thus, both the distal protective ring and the proximal portion of the bearing sleeve surround the end of at least one outer layer adjacent to the bearing sleeve.

[0033] Thus, the proximal portion of the bearing sleeve is axially placed between the outer bearing ring and the limiting member. As described above, the limiting member serves as a limiter that restricts the axial movement of the drive shaft relative to the outer bearing ring. In one embodiment, a rotor or a rotor shaft mounted at the distal end of the outer bearing ring can form the protective ring, in which case the limiting member advantageously prevents the rotor or the rotor shaft from contacting the outer bearing ring.

[0034] Preferably, the proximal portion of the protective ring and / or the bearing sleeve is fixedly connected to the flexible drive shaft. Preferably, the protective ring is crimped, welded, fused, glued or shrunk onto at least one outer layer and / or the bearing sleeve.

[0035] Preferably, the protective ring comprises one or more ceramics and / or metals, particularly MP35, 35NLT, nitinol or stainless steel. In the case of a metal, the protective ring can be hard-coated, for example DLC-coated.

[0036] The surface of the proximal portion of the bearing sleeve facing the bearing ring preferably forms an axial bearing with the opposing surface of the bearing ring. The distal protective ring preferably forms a stop element for the bearing ring to prevent the bearing ring from slipping off the bearing sleeve.

[0037] Preferably, two different adhesives are used on the drive shaft. The first adhesive is preferably used to penetrate at least one outer layer and / or at least one inner layer, in particular its outer and / or inner winding portions. The first adhesive can be a sealant. The first adhesive preferably has a particularly low viscosity in order to be able to fully penetrate the outer and / or inner winding portions. Before hardening, the first adhesive preferably has a viscosity in the range of 80 cPs to 200 cPs. A suitable adhesive is a two-component epoxy resin. A different second adhesive is preferably used to connect the sleeve and / or the distal protective ring to the flexible drive shaft. Preferably, the first adhesive has a lower viscosity than the second adhesive. The second adhesive preferably has a medium or pasty viscosity. A suitable adhesive is a two-component epoxy resin.

[0038] According to a particularly preferred embodiment, the bearing sleeve extends into the rotor. Generally, the bearing sleeve is harder than the drive shaft, such that the rotor can have a more rigid support compared to other embodiments where the rotor is mounted on the distal end of the drive shaft.

[0039] Preferably, the radial bearing clearance between the outer bearing ring and the bearing sleeve is between 1 μm and 10 μm, more preferably between 2 μm and 8 μm wide, and preferably approximately 3.5 mm wide.

[0040] The intravascular blood pump may further include a distal bearing for rotatably supporting the distal end of the rotor. The distal bearing is located inside or at the distal end of the rotor. Preferably, the distal bearing includes a static support member that protrudes into or abuts against the distal end of the rotor. Alternatively, the distal end of the drive shaft or the bearing sleeve can be supported by the distal bearing.

[0041] In another embodiment, the drive shaft is not supported in the distal bearing. Alternatively, the rotor is preferably mounted respectively on the very end of the drive shaft or on the distal extension of the proximal bearing sleeve, such that the distal end of the rotor is supported by a static support member that extends into or abuts against the rotor. In this way, tendinous structures are less likely to be caught by the rotating components, especially if no rotating structure extends beyond the leading edge of the rotating blade. This can result in a safer intravascular blood pump with a longer lifespan.

[0042] The intravascular blood pump is preferably designed as an expandable blood pump with a housing having an expandable portion. In some embodiments, the housing comprises or consists of a shape memory material, particularly nitinol. The diameter of the intravascular blood pump that can be inserted percutaneously is typically limited by the inner diameter of the smallest blood vessel through which it is to pass. The intravascular blood pump can be moved through the blood vessel with the housing in a contracted state. Upon reaching the heart or a larger blood vessel, the housing of the intravascular blood pump can expand. This allows a larger blood pump to be inserted percutaneously into the heart compared to other possible means. Using such a larger blood pump, a greater blood flow can be generated.

[0043] When the blood pump is designed as an expandable pump, a sleeve is preferably provided around the portion of the drive shaft near the rotor, and the housing and the rotor are configured to be at least partially transferred into the sleeve. During this transfer, the expandable portion of the housing and the rotor are compressed from an expanded state to a compressed state at least in a radial direction transverse to the longitudinal extension. Preferably, a part of the rotor, such as the rotor blades, or the entire rotor, is also expandable to allow a larger rotor to be inserted into the heart, which can increase the flow rate.

[0044] In some embodiments, the static support member of the distal bearing projects against the distal end of the rotor. Compared with embodiments where the static support member projects into the rotor, a particularly flexible pump portion of the intravascular blood pump can be formed. The high flexibility of the pumping device is particularly advantageous during the insertion and removal of the intravascular blood pump. If the static support member does not project into the rotor but is only placed against the distal end of the rotor, the static support member may intentionally move away from the rotor when the pump portion is bent during the manipulation of the pumping device through the blood vessel. When the pump portion reaches its final destination inside the heart, it can straighten, and the static support member can return to its position where it projects against the distal end of the rotor.

[0045] Preferably, the static support member is attached to the distal end of the housing, wherein the expansion of the housing can provide an axial force to the distal end of the rotor through the static support member. Preferably, this force is equal to or less than 1.8 N. When the static support member projects against the distal end of the rotor, it can limit the further expansion of the housing.

[0046] When the housing is compressed, the static support member preferably moves away from the distal end of the rotor. In this state, as the relative radial movement between the static support member and the rotor becomes possible, the pump portion becomes more flexible. This can be advantageous during the insertion or removal of the intravascular blood pump.

[0047] In some embodiments, the intravascular blood pump includes a nose portion located at the distal end of the rotor. When the housing is in its expanded state, the nose portion protrudes into a static support member, which preferably has a correspondingly formed recess. The purpose of the nose portion is to center the rotation of the rotor and bring the rotor and the static support member into the correct relative position after the housing expands. The nose portion preferably protrudes between 0.1 mm and 2 mm from the peripheral surface of the rotor, more preferably between 0.2 mm and 1 mm, and most preferably between 0.3 mm and 0.5 mm. The depth of the recess in the static support member corresponds to the nose portion and is preferably between 0.1 mm and 2 mm, more preferably between 0.2 mm and 1 mm, and most preferably between 0.3 mm and 0.5 mm.

[0048] In some embodiments where the static support member protrudes into the rotor, the rotor includes an axial stop for the static support member, such as a recess having a bottom or step portion at its distal end. The bottom or step portion defines an axial stop for the proximal end of the static support member in the distal end of the rotor. This is particularly advantageous in the case of an expandable blood pump. In its expanded state, the proximal end of the static support member that axially protrudes into the rotor can contact the axial stop, thereby preventing further expansion of the housing and thus limiting the width of the radial clearance between the outer edge of the rotor blade and the inner surface of the expandable housing. Optionally, in the expanded state of the expandable blood pump, a gap can be formed between the proximal end of the static support member and the axial stop, which is preferably between 0.01 mm and 1 mm wide in the axial direction, more preferably between 0.01 mm and 0.1 mm, and most preferably between 0.01 mm and 0.05 mm.

[0049] The length of the recess at the distal end of the rotor measured in the axial direction can be, for example, between 0.5 mm and 8 mm, preferably between 1 mm and 5 mm, and particularly preferably between 1.5 mm and 2.5 mm. When the housing is moved into the cannula, the housing is preferably axially stretched by 0.5 mm to 2.5 mm, more preferably 1 mm to 2 mm, and most preferably approximately 1.7 mm.

[0050] Inside the distal end portion of the drive shaft, i.e., inside the rotor shaft, the intravascular blood pump may include an optional fluid line arranged to direct a cleaning fluid through the rotor to the distal bearing. In some embodiments, the rotor includes a hollow portion that is part of the fluid line, wherein the intravascular blood pump is arranged to direct the cleaning fluid through the hollow portion of the rotor to the distal bearing. The cleaning fluid may be delivered to the fluid line through a catheter. The cleaning fluid may enter the catheter and / or the drive shaft within the housing of the motor. The cleaning fluid may flow within the catheter adjacent to the drive shaft. In the case where the drive shaft is hollow, the cleaning fluid may flow partially, mostly, or entirely through the drive shaft lumen. From the distal end portion of the catheter to the rotor, the cleaning fluid may flow through the drive shaft. At least in the space between the distal end portion of the catheter and the proximal end portion of the rotor, the drive shaft may include a lid to prevent leakage of the cleaning fluid from the space.

[0051] Alternatively, the cleaning fluid may not be directed through the main lumen of the catheter containing the drive shaft, but rather through one or more separate secondary lumens.

[0052] In the distal end region of the catheter, the cleaning fluid is preferably transferred into the fluid line inside the rotor shaft. In some cases, the rotor shaft or the rotor hub may have a central lumen to accommodate the fluid line. In particular, in the case of a hollow drive shaft, the drive shaft may extend into the rotor to form both the rotor shaft and the fluid line, or the hollow drive shaft may be extended by a hollow tube to form both the rotor shaft and the fluid line. Alternatively, the distal extension portion of the bearing sleeve of the proximal bearing may form the hollow drive shaft. The hollow drive shaft may be permeable to the cleaning fluid at some locations.

[0053] In the cleaned proximal and / or distal bearings, blood is less likely to enter the bearing clearance. Thus, blood clots are prevented. Additionally, compared to alternative bearings in the prior art, the cleaned bearings may have less friction. In particular, the cleaning fluid lubricates the bearings and can carry away frictional heat from the bearings. This may allow for higher rotational speeds, lower power consumption, and longer blood pump life. The cleaning fluid may be any biocompatible fluid suitable for cleaning the bearings. Examples of suitable medical fluids include saline solutions, glucose solutions, and / or water, each of which may or may not contain heparin.

[0054] In an alternative embodiment, the proximal and / or distal bearings are not cleaned. Thus, there is no delivery of the cleaning fluid to the proximal and / or distal bearings, and the intravascular blood pump may not include a fluid line.

[0055] The distal bearing is preferably arranged such that cleaning fluid can flow out between the static support member and the distal end of the rotor, with the static support member protruding into or against the rotor. Preferably, the distal bearing is arranged such that the cleaning fluid flows from the distal end of the fluid line to the distal bearing. In particular, the intravascular blood pump can be arranged such that any cleaning fluid passing through the hollow drive shaft or rotor shaft exits entirely or at least in part through the distal bearing. By applying a suitable pressure, the cleaning fluid can be driven through the bearing clearance of the distal bearing, which in some embodiments is the clearance defined by the static support member and the adjacent part of the rotor. Preferably, the pressure of the cleaning fluid is in the range of 300 mmHg (0.4 bar) to 1500 mmHg (2 bar), more preferably in the range of 600 mmHg (0.8 bar) to 1100 mmHg (about 1.5 bar). If the distal bearing is cleaned and the rotor includes a nose protruding into the static support member, the nose may include at least one opening to allow the cleaning fluid to enter the bearing clearance between the nose and the static support member.

[0056] In some embodiments, the distal end of the static support member is mounted at the distal end of the housing. The distal end of the housing can provide stable support for the static support member that supports the distal end of the rotor.

[0057] The static support member preferably includes a pin that extends from the distal end to the proximal end and protrudes against or preferably into the distal end of the rotor. Thus, the pin can be arranged to form the distal bearing of the rotor. In embodiments where the distal bearing is cleaned, the pin is preferably arranged such that the cleaning fluid can flow out between the pin and the rotor mounted on the pin.

[0058] Preferably, the pin has a circular cross-section. However, in the distal portion of the pin that is outside the rotor, other cross-sections are also possible. For example, the pin can have an oval cross-section. In some embodiments, the pin can be hollow. Alternatively, the pin can be made of solid material. Preferably, the pin tapers towards its proximal end. The pin can be elastically bendable, preferably such that the rotor remains concentric with the housing during bending of the pump head.

[0059] Preferably, the inner diameter at which the distal end of the rotor is axially protruded into the static support member, particularly the pin, is between 0.3 mm and 1.5 mm, more preferably between 0.5 mm and 1.2 mm, and most preferably between 0.7 mm and 0.9 mm wide. Preferably, the radial bearing clearance between the outer side of the pin and the opposing bearing surface is between 1 μm and 10 μm, more preferably between 2 μm and 8 μm wide.

[0060] In some embodiments, the pins are particularly long and protrude into the rotor and extend proximally through the entire rotor. Preferably, the pins exit the rotor at the proximal end and continue inside the drive shaft, for example, terminating within the proximal bearing. In this case, the end of the pin can be disposed inside the portion of the drive shaft located within the proximal bearing. By using such long pins that extend through the entire length of the rotor and into the proximal bearing, a particularly rigid and low-vibration pump can be formed. Alternatively, the pins can further extend to a point proximal to the proximal end of the proximal bearing. The pins extending through the rotor can be cleaned or uncleaned and can be used in combination with a hollow drive shaft or a drive shaft that is hollow only along a portion of its length.

[0061] Preferably, the material of the pins includes at least one of the following materials: a biocompatible material, particularly MP35N, 35NLT, nitinol, stainless steel (particularly medical-grade stainless steel), and one or more of ceramics. The surface of the pins can include a coating, such as a hard coating, such as a diamond-like carbon (DLC) coating.

[0062] Preferably, during the operating state of the intravascular blood pump, the length of the pins protruding into the distal end of the rotor is between 0.5 mm and 8 mm, preferably between 1 mm and 5 mm, and particularly preferably between 1.5 mm and 2.5 mm. The longer the internal length, the harder the rotor support, and thus, the better the controllability of the width of the gap between the outer edge of the rotor blade and the inner surface of the housing. The blades must not touch the inner surface of the housing, and the gap should be large enough to prevent blood damage. The harder-supported rotor can also operate with lower offset and less vibration, thereby improving blood compatibility.

[0063] When the housing and the rotor are in a compressed state, the pins can have a length sufficient to remain within the distal end of the rotor. The length of the pins remaining within the distal end of the rotor when the housing and the rotor are in a compressed state is preferably greater than 1.5 mm, more preferably greater than 1.7 mm, and most preferably greater than 2 mm. When the housing and the rotor are compressed before deploying the blood pump, the housing extends in the longitudinal direction, and the static support members extending into the distal end of the housing, particularly the pins, may completely move out of the rotor. Then, when the housing expands again, the pins may not move back into the rotor, and the pump may not operate properly. Therefore, if the selected pins have a sufficient length such that the pins remain inside the rotor even in the compressed state of the housing, such problems can be avoided.

[0064] In embodiments having pins, the distal bearing surface is the surface of the pins and the distal outer bearing surface, which can be provided by the rotor itself or by the sleeve of the distal bearing in the hub of the rotor. In some cases, the distal outer bearing surface can be provided by the above-mentioned strengthening elements.

[0065] The sleeve of the distal bearing may have an inner diameter preferably in the range of 0.3 mm to 1.5 mm, more preferably in the range of 0.5 mm to 1.2 mm, and most preferably in the range of 0.7 mm to 0.9 mm.

[0066] In some embodiments, the intravascular blood pump includes a flexible atraumatic tip to avoid damage to the patient's tissue. The atraumatic tip may be made of a flexible medical-grade polymer such as or polyurethane. Preferably, the flexible atraumatic tip is designed to be pigtail or J-shaped.

[0067] According to a second aspect of the present invention, the above intravascular blood pump is used inside a patient, i.e., it is inserted and operated inside the patient to support blood flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Hereinafter, the present invention will be explained by way of example with reference to the drawings. The drawings are not drawn to scale. In the drawings, the same or corresponding components shown in the respective figures are denoted by the same numerals.

[0069] For clarity, not every component will be labeled in each figure. In the figures:

[0070] Figure 1 A schematic view of an intravascular blood pump located in the left ventricle of the heart is shown;

[0071] Figure 2 A schematic view of the intravascular blood pump is shown;

[0072] Figure 3A and Figure 3B A schematic view of the intravascular blood pump in the expanded state and the compressed state is shown;

[0073] Figure 4A 、 Figure 4B and Figure 4C A schematic view of an intravascular blood pump according to a first embodiment having a static support member extending into the distal end of the rotor is shown;

[0074] Figure 5 A schematic view of an intravascular blood pump according to a second embodiment having a static support member extending into the distal end of the rotor is shown;

[0075] Figures 6A to 6D A schematic view of an intravascular blood pump according to a third embodiment having a rotor with a nose at its distal end is shown;

[0076] Figure 7 A schematic view of an intravascular blood pump having a proximal bearing and a distal bearing is shown;

[0077] Figure 8A andFigure 8B A schematic diagram showing the path of the cleaning fluid in an intravascular blood pump;

[0078] Figure 9A Showing a drive shaft including an outer layer and an inner layer;

[0079] Figure 9B Showing a drive shaft having a bearing sleeve, an outer bearing ring, and a protective ring;

[0080] Figure 10A Showing a hydraulically separated bearing sleeve;

[0081] Figure 10B Showing a bearing having a limiting member;

[0082] Figure 11A and Figure 11B Showing a bearing having a limiting member and a rotor;

[0083] Figure 12A and Figure 12B Showing two different embodiments of a proximal bearing having an outer bearing ring and a specially formed bearing sleeve;

[0084] Figures 13A to 13D Showing a hydrodynamic axial bearing. Detailed Description

[0085] Figure 1 Showing the use of the intravascular blood pump 1, which, in this particular example, is used to support the left ventricle 2 of the human heart. The intravascular blood pump 1 includes a catheter 5 and a pumping device, which includes a pump portion 4 mounted in the distal end region of the catheter 5. The intravascular blood pump 1 can be placed inside the heart using a percutaneous, transluminal technique. For example, the intravascular blood pump 1 can be introduced through the femoral artery. However, alternative vascular accesses are also possible, such as access through the subclavian artery. After passing through the femoral artery, the catheter 5 can be pushed into the aorta such that the pump portion 4 reaches the heart through the aortic valve. Figure 1 The positioning of the pump portion 4 is only an example, and different placements are possible, such as positioning the pump portion 4 in the right ventricle of the heart.

[0086] The pump section 4 includes a rotor 10 to cause blood to flow from a blood flow inlet 6 at the distal end of the pump section 4 towards a blood flow outlet 7 proximal to the blood flow inlet 6. The catheter 5 houses a drive shaft 12 driven by an electric motor 8, which is preferably placed outside the patient's body. The drive shaft 12 drives the rotor contained within the pump section 4. At its distal end, the pump section 4 has a flexible atraumatic tip 9, which has a pigtail or J-shaped form, which facilitates the placement of the intravascular blood pump 1 by assisting in the guidance within the patient's vascular system. In addition, the softness of the flexible atraumatic tip 9 allows the pump section 4 to support itself against the wall of the left ventricle 2 without trauma.

[0087] Figure 2 The intravascular blood pump 1 is shown in more detail. The rotor 10 is located inside a housing 11. In this embodiment, both the rotor 10 and the housing 11 are compressible. In this case, the intravascular blood pump 1 is delivered through the patient's vascular system when both the rotor 10 and the housing 11 are in their compressed state. Once the pump section 4 is in its target position, the housing 11 and the rotor 10 expand. The flexible atraumatic tip 9 is located at the distal end of the housing 11. The drive shaft 12 is implemented as a drive shaft cable. It can be seen that the drive shaft 12 with the rotor 10 arranged at its distal end protrudes from the distal end of the catheter 5. When the rotor 10 inside the housing 11 rotates by means of the drive shaft 12, blood is sucked into the blood flow inlet 6 at the distal end of the housing 11 and enters the downstream conduit 20 through the housing 11, which is attached to the housing 11 and extends proximally. Then, the blood is discharged from the downstream conduit 20 through a more proximal blood flow outlet 7 provided in the downstream conduit 20 into the aorta, and the blood flow outlet includes a plurality of outlet openings. The downstream conduit 20 is made of a flexible material such that it can be compressed by the aortic valve when the patient's heart beats. The downstream conduit 20 generally expands mainly due to the active blood flow generated by the rotor 10 during rotation. By placing the blood flow inlet 6 inside the left ventricle 2 and the blood flow outlet 7 inside the aorta, the intravascular blood pump 1 can support the patient's systemic blood circulation. If the construction and placement position of the intravascular blood pump 1 are different, it can be used, for example, alternatively to support the patient's pulmonary blood circulation.

[0088] In this example, a liquid, in particular a cleaning fluid, is supplied from outside the patient through the catheter 5 to the pump section 4. Inside the pump section 4, the liquid can be used to clean one or more bearings to reduce friction and cool the pump section 4, as will be described in connection with Figure 4A 、 Figure 4C and Figure 5This will be further explained. Preferably, the liquid is used to at least clean the distal bearing. In this case, the pressure of the cleaning fluid is selected to be higher than the patient's blood pressure to prevent blood from entering the bearing. Preferably, the pressure of the cleaning fluid is in the range of 300 mmHg (0.4 bar) to 1500 mmHg (2 bar), more preferably in the range of 600 mmHg (0.8 bar) to 1100 mmHg (about 1.5 bar).

[0089] The housing 11 is preferably made of a shape memory material such as Nitinol and provides a cage around the rotor 10. As Figure 5 shown, the central portion of the housing 11 carries a sleeve that defines a passage through which blood is pumped by means of the rotor 10. At the proximal and distal ends of the passage, the housing 11 allows blood to be drawn into the housing 11 and pushed out of the housing 11 into the downstream conduit 20 (as Figure 2 shown).

[0090] Figure 3A and Figure 3B show the pump section 4, its rotor 10, and the housing 11 in the expanded state and the compressed state, respectively. The cannula 16 is arranged at the distal end of the catheter 5. Initially, before the intravascular blood pump 1 is deployed, the pump section 4 is arranged inside the cannula 16 in its compressed state. The cannula 16 can be the cannula 16 belonging to the catheter 5 or a peel-away sheath for assisting in inserting the catheter 5 into the patient's body. When the doctor determines that the catheter 5 is correctly placed inside the patient's vascular system, he or she will push the housing 11 out of the cannula 16. In the case where the cannula 16 is removed, the housing 11 will expand due to its shape memory properties. At the same time, the rotor 10 expands due to its elasticity. As the housing 11 expands radially away from the drive shaft 12, it contracts in the longitudinal direction.

[0091] The rotor 10 is supported in the distal portion of the rotor 10 by a distal bearing 14 that includes a static support member 18 having a pin 19. The static support member 18 is attached to the housing 11 at one end and extends with its pin 19 into the distal end of the rotor 10 at the other end such that the pin 19 can move axially inside the distal end of the rotor 10 when the housing 11 expands. Preferably, the pin 19 is long enough to remain inside the rotor 10 when the housing 11 is in its compressed state. When the intravascular blood pump 1 is in its expanded state and needs to be removed from the heart, the doctor will pull the housing 11 back into the cannula 16, which will cause the housing 11 to be radially compressed and longitudinally extended, so that the distal end of the housing 11 together with the static support member 18 and its pin 19 moves away from the rotor 10, and the pin 19 extends into the distal end of the rotor 10. The resulting smaller diameter of the housing 11 facilitates the removal of the intravascular blood pump 1 from the patient.

[0092] In the prior art distal bearing 14, the drive shaft 12 sometimes extends distally into the distal bearing 14 at the distal end of the rotor 10. However, this can cause the tendinous chords of the heart to become entangled with the drive shaft 12, potentially leading to blood clotting and device failure. Therefore, it is advantageous to use a static support member 18 that does not involve rotating components at the distal end of the rotor 10 and at the distal end of the rotor blades as part of the distal bearing 14.

[0093] Figure 4A and Figure 4B More particularly, the pump section 4 according to the first embodiment is shown, which includes a housing 11 and a rotor 10 driven by a drive shaft 12. The drive shaft 12 is rotatably supported at the distal end of a catheter 5 at the proximal end of the rotor 10 (or in the proximal portion of the housing) in a proximal bearing 13 and in a distal bearing 14 located at the distal end of the rotor 10. In Figure 4A the drive shaft 12 is hollow at its distal end, or more specifically, the rotor shaft is hollow to form a fluid line 15 through which a cleaning fluid can be pumped to the distal bearing 14. In the case where the drive shaft is hollow and extends to the distal end of the rotor 10, the rotor 10 can be formed directly on the distal end of the drive shaft 12 such that the rotor shaft is formed by the drive shaft, where in the regions of the proximal and distal bearings, the drive shaft 12 can be strengthened, for example, by injection molding of a plastic material, and suitable external and internal bearing surface treatments can be provided respectively. Alternatively, the entire end region of the bearing portion including the drive shaft 12 can be strengthened in order to obtain a more rigid structure of the pump section. For example, the drive shaft 12 tapers at its distal end, and a rigid hollow tube slides over the tapered end and extends distally to form the rotor shaft and the bearing portion. The cleaning fluid can be delivered to the distal bearing 14 through the fluid line 15 in the rotor shaft. In Figure 4A the embodiment shown, the cleaning fluid can be pushed through the central fluid line 15 to exit the drive shaft 12 at its distal end and further enter the blood flow through the bearing clearance of the distal bearing 14. Cleaning of the distal bearing 14 by the cleaning fluid results in reduced friction and thus reduced wear on the distal bearing 14, and in addition, prevents blood from entering and blocking the bearing clearance.

[0094] To make the intravascular blood pump 1 efficient, a large rotor diameter is desirable. However, as the gap between the rotor 10 and the housing 11 becomes smaller, the risk of damage to blood cells or the rotor 10 increases. If only the proximal bearing 13 is used, the system may vibrate and the gap between the tips of the blades of the rotor 10 and the inner surface of the housing 11 may change significantly. When the flexible atraumatic tip 9 touches the heart wall, the movement of the heart causes the housing 11 to bend, which may result in the housing 11 touching the rotor 10. Touching between the housing 11 and the rotor 10 during use may greatly increase the damage to blood cells and may also cause particles from the housing 11 and / or the rotor 10 to enter the blood flow and cause wear. By using both the proximal bearing 13 and the distal bearing 14, as Figure 4A and Figure 4B shown, compared to the case of having only one bearing, the position of the rotor 10 is more stable and the change in the size of the gap is smaller. For a given housing 11, this may allow a larger diameter of the rotor 10, which allows a higher flow rate of the intravascular blood pump 1 without the housing 11 touching the rotor 10.

[0095] The rotor 10 includes a recess 17 at its distal end. A static support member 18 fixed relative to the distal end of the housing 11 projects its pin 19 into the recess 17. Figure 4A The bottom 19 of the recess 17 in Figure 4A is formed as a stepped portion and defines a stop within the rotor 10 against which the pin 19 of the static support member 18 can abut. In

[0096] Figure 4B the intravascular blood pump 1 of Figure 4A is similar to the embodiment in Figure 4B However, importantly, Figure 4B the distal bearing in

[0097] Figure 4C is not cleaned but is designed to operate in blood. Therefore, the drive shaft 12 does not need to be hollow. Thus, in Figure 4A and Figure 4B there is no fluid line 15. The bottom of the recess 17 does not contain an opening for the cleaning fluid to flow through the bearing gap between the pin 19 and the recess 17. In such an embodiment, less cleaning fluid may be required. If the proximal bearing 13 is not cleaned, the intravascular blood pump 1 may not require any cleaning fluid at all.

[0097] Figure 4C shows an embodiment similar to Figure 4A and Figure 4B Here, the pin 19 is particularly long and extends proximally through the rotor shaft and into the drive shaft 12. In Figure 4CIn an embodiment, the proximal end portion of the pin 19 is located within a portion of the drive shaft 12 that is inside the proximal bearing 13. In an alternative embodiment, the proximal end portion of the pin 19 may be located, for example, at the proximal end of the proximal bearing 13 or between the rotor 10 and the proximal bearing 13.

[0098] By extending the pin 19 into the proximal bearing 13, a greater stiffness of the intravascular blood pump 1 can be achieved. In addition, Figure 4C the pin 19 shown in can help reduce the vibration of the intravascular blood pump 1 during its operation and can reduce unwanted bending.

[0099] Figure 4C The proximal bearing 13 in is located inside the housing 11, at the distal end of the position of the proximal bearing 13 in Figure 4A and Figure 4B In the illustrated embodiment, the distance between the proximal bearing 13 and the rotor 10 is particularly small, for example, less than the outer diameter of the proximal bearing 13. The short distance can further increase the stiffness of the intravascular blood pump 1.

[0100] Figure 4C The pin 19 in is combined with the hollow drive shaft 12 such that in some embodiments, the cleaning fluid can flow through the drive shaft 12 and through the pin 19 to discharge at the distal end portion of the rotor 10. Alternatively, the cleaning fluid may not be used in some embodiments. In this case, Figure 4C the long pin 19 of can be combined with a drive shaft that is only partially hollow along its length.

[0101] Figure 5 The pump section 4 according to the second embodiment is shown, which also has a compressible housing 11 and a rotor 10 driven by a hollow drive shaft 12 that is rotatably supported in a proximal bearing 13 proximal to the rotor 10 disposed at the distal end portion of the catheter 5. In this embodiment, the pin 19 of the static support member 18 forming a part of the distal bearing 14 has a pointed end. If the dimensions of the housing 11 and the pin 19 are such that the pin 19 moves away from the rotor 10 when the housing 11 is compressed, the tip of the pin 19 facilitates reintroducing the pin 19 into the opening at the distal end portion of the rotor 10 when the housing 11 expands again. Preferably, the pin 19 is long enough such that the pin 19 remains inside the rotor 10 when the housing 11 is in a compressed state. This can avoid the situation where the pin 19 cannot re-enter the rotor 10 when the housing 11 expands. In some cases, it is not necessary to have the required bearing clearance over the entire length of the pin 19 for proper function. Instead, a bearing clearance between the outer side of the pin 19 and its opposing bearing surface that is between 1 μm and 10 μm, more preferably between 2 μm and 8 μm wide at at least one location, is sufficient.

[0102] In this embodiment, instead of providing a bottom or step in the opening at the distal end of the rotor 10, the static support member 18 can be provided with a shoulder against which the rotor 10 abuts in the expanded state of the housing 11, thereby restricting further expansion of the housing 11, if desired. In some embodiments, the distal bearing 14 can be a radial bearing only.

[0103] Similarly, the flushing fluid can be supplied through the fluid line 15 of the drive shaft 12 towards the distal bearing 14, passing through the pin 19 forming the distal radial bearing for the rotor 10 and discharging at the distal end of the rotor 10. This prevents blood from entering the rotor 10, reduces friction and cools the distal bearing 14. Alternatively, the distal bearing 14 can be not flushed. Thus, there can be no fluid line 15.

[0104] In addition, in Figure 5 the embodiment shown, when the housing 11 expands, the pin 19 is received within the central tube 15 of the rotor 10. In this case, for example, the drive shaft 12 can terminate at the distal end surface of the rotor 10. Alternatively, the distal end of the drive shaft 12 can be located inside the rotor 10, for example, at the level of the bottom of the recess 17 as seen in the embodiment of Figure 4A to form a stop for the pin 19.

[0105] Figure 6A , Figure 6B , Figure 6C and Figure 6D show a third embodiment of the pump section 4, which has a compressible housing 11 and a static support member 18 attached to the housing 11. The rotor 10 includes a nose portion 21 at its distal end. In Figure 6A , Figure 6B and Figure 6C , the fluid line 15 inside the distal end of the drive shaft 12 leads to an opening in the nose portion 21 through which the flushing fluid can enter the bearing clearance of the distal bearing 14 between the nose portion 21 and the corresponding recess 22 at the proximal end of the static support member 18. However, in Figure 6D , the distal bearing 14 is not flushed. Thus, Figure 6D the embodiment in

[0106] When the housing 11 is compressed, the nose portion 21 moves out of the recess 22, and thus the intravascular blood pump 1 becomes more flexible. When the housing 11 expands at the target site, the nose portion 21 automatically moves into the recess 22, where the conical or spherical or other converging shape of the nose portion 21 helps to guide the nose portion 21 into the recess 22 and to center the rotor 10 relative to the static support member 18. Figure 6B An enlarged cross-section showing the distal bearing 14, where the nose portion 21 is located at the rotor 10 and the corresponding recess 22. Figure 6B The vertical dotted line in shows Figure 6C the cross-sectional plane of. Figure 6C The cross-section shown shows the distal bearing 14 in concentric circles. From the periphery to the center, the concentric circles show the recess 22, the distal bearing clearance between the recess 22 and the nose portion 21, the nose portion 21, and the opening of the fluid line 15 into the distal bearing clearance.

[0107] Figure 7 Schematically shows the intravascular blood pump 1 and its catheter 5 and its pump portion 4. In this embodiment, the intravascular blood pump 1 includes a proximal bearing 13 inside the distal end of the catheter 5. Inside the proximal bearing 13, the inner bearing sleeve 24 is glued to the drive shaft 12 to provide a smooth bearing surface. To fit the bearing sleeve 24, some of the outer winding portions of the drive shaft 12 are removed to reduce its diameter. The cleaning fluid can now flow through the catheter 5 and leave the proximal bearing 13 through its bearing clearance. Some of the cleaning fluid also flows through the drive shaft 12 into the rotor 10.

[0108] The sleeve 24 of the proximal bearing 13 may have an inner diameter preferably in the range of 0.3 mm to 1.5 mm, more preferably in the range of 0.5 mm to 1.2 mm, and most preferably in the range of 0.7 mm to 0.9 mm.

[0109] The outer diameter of the bearing sleeve 24 of the proximal bearing is preferably between 0.5 mm and 2 mm, more preferably between 0.8 mm and 1.8 mm, and most preferably between 0.9 mm and 1.2 mm. The bearing clearance of the proximal bearing 13 is preferably between 1 μm and 10 μm, more preferably between 2 μm and 8 μm.

[0110] The cleaning fluid flows from the drive shaft 12 inside the rotor through the fluid line 15 and into the recess 17 of the rotor 10. Inside the recess 17, the sleeve of the distal bearing 25 of the rotor 10 is arranged. The inner surface of the sleeve of the distal bearing 25 and the outer surface of the pin 19 form the bearing surface of the distal bearing 14. The cleaning fluid leaves the rotor 10 through the bearing clearance between the sleeve of the distal bearing 25 and the pin 19.

[0111] The sleeve of the distal bearing 25 has an inner diameter preferably between 0.3 mm and 1.5 mm, more preferably between 0.5 mm and 1.2 mm, and most preferably between 0.7 mm and 0.9 mm. The outer diameter of the sleeve of the distal bearing 25 is preferably between 0.5 mm and 1.7 mm, more preferably between 0.7 mm and 1.4 mm, and most preferably between 0.9 mm and 1.1 mm. The bearing clearance between the pin 19 and the sleeve of the distal bearing 25 is preferably between 1 μm and 10 μm, more preferably between 2 μm and 8 μm.

[0112] Figure 8A Schematically shows the cleaning fluid path inside the intravascular blood pump. Inside the housing of the motor 8, the cleaning fluid is supplied into the catheter 5 and the drive shaft 12. Here, the proximal bearing 13 is schematically drawn, and its components, in particular the outer bearing ring 32 and the bearing sleeve 30, are not shown. At the proximal bearing 13, the cleaning fluid leaves the catheter 5 through the bearing clearance to reduce friction and cool the proximal bearing 13. A part of the cleaning fluid does not leave the catheter 5 through the bearing clearance, but flows into the rotor 10 through the drive shaft 12. In some embodiments, the drive shaft 12 may include a lid such that the cleaning fluid can flow from the catheter 5 to the rotor 10 without leaking from the drive shaft 12 between the distal end of the catheter 5 and the proximal end of the rotor 10. Inside the rotor 10, the cleaning fluid continues to flow through the fluid line 15 and then enters the recess 17 at the distal end of the rotor 10. In an alternative embodiment, the drive shaft 12 may extend into or enter the recess 17 such that the cleaning fluid flows directly from the drive shaft 12 into the recess 17. The cleaning fluid then flows through the bearing clearance of the distal bearing 14 located between the pin 19 and the adjacent surface of the rotor 10.

[0113] Figure 8B Shows an embodiment of a blood pump similar to Figure 8A In Figure 8B the proximal bearing 13 is closer to the rotor 10 than in Figure 8A and is separated from the rotor 10 by only a small gap. Through this gap, the cleaning fluid can leave as shown by the arrow.

[0114] Figure 9A Shows an example of the drive shaft 12 including an outer layer 28 and an inner layer 29. In this embodiment, the outer layer 28 and the inner layer 29 are composed of helically wound silk threads, where the helix of the inner layer 29 is right-handed and the helix of the outer layer 28 is left-handed. As Figure 9AAs shown, an outer layer 28 is removed from the inner layer 29 and shown separately. Removing this outer layer 28 can be done by pulling the outer layer 28 while slightly rotating the outer layer 28. The bearing sleeve 30 can be pushed onto the exposed inner layer 29 until it abuts the outer layer 28, and then the outer layer 28 is reinstalled adjacent to the bearing sleeve 30 onto the inner layer 29.

[0115] Figure 9B A flexible bearing shaft 12 with an outer layer 28 and an inner layer 29 is shown, where there is no outer layer 28 at the central position, and the bearing sleeve 30 is located on the inner layer 29 at the central position. Additionally, on both sides of the bearing sleeve 30 and overlapping it are two protective rings 31, which slide over the ends of the outer layer 28 facing the bearing sleeve 30. The shorter parts of the protective rings 31 overlap the bearing sleeve 30, while the larger parts cover the outer layer 28. In this way, the risk of drive shaft breakage due to stiffness changes at the transition between a small shaft diameter and a large shaft diameter is reduced.

[0116] During assembly, the outer layer 28 can be cut and removed from one end of the drive shaft 12. At this point, the drive shaft 12 is similar to Figure 9A the schematic diagram in. Thereafter, a first protective ring 31 is placed on the end of the remaining outer layer 28. Then, at the place where the outer layer 28 was removed, the bearing sleeve 30 is placed on top of the inner layer 29 and overlaps the first protective ring 31. The outer bearing ring 32 is placed on top of the bearing sleeve 30. Then, the previously removed outer layer 28 is reinstalled on top of the inner layer 29, and the second protective ring 31 overlaps the end of the outer layer 28 and the bearing sleeve 30. The bearing sleeve 30 and the second protective ring 31 can be fixed to the drive shaft 12 using a low-viscosity adhesive. After the adhesive has solidified, the sealing of the bearing sleeve 30 can be tested, i.e., it can be tested whether the cleaning fluid can pass through the bearing sleeve 30.

[0117] The bearing sleeve 30 is rotatably supported in the outer bearing ring 32, where the outer bearing ring 32 is in turn fixed in a conduit or in the proximal end of a housing that houses a rotor. The bearing sleeve 30 and the outer bearing ring 32 form a radial bearing, while the protective rings 31 form an axial stop and, in some embodiments, also form an axial bearing with the outer bearing ring 32. The bearing sleeve 30 and the protective rings 31 together can be made of a single piece of material. As described above, the bearing sleeve 30 and the protective rings 31 are fixedly connected to the drive shaft 12, preferably by gluing. Glue is also used to fill the winding between the inner layer 29 and the outer layer 28 to prevent leakage of the cleaning fluid through the drive shaft 12.

[0118] In this example, the inner diameter of the bearing sleeve 30 is approximately the same as the outer diameter of the inner layer 29. The outer diameter of the bearing sleeve 30 is approximately the same as the outer diameter of the outer layer 28.

[0119] Figure 10A A hydraulically separated bearing sleeve 30 is shown, which includes a wall located between two blind holes. The inner layer 29 is axially discontinuous. Each blind hole of the bearing sleeve 30 receives a respective axial end of the axially discontinuous inner layer 29. The bearing sleeve 30 does not allow any cleaning fluid to pass through in the axial direction. Therefore, the inner layer 29 does not need to be filled with glue to prevent the cleaning fluid from flowing through the inner layer 29. Glue can still be used to attach the inner layer 29 to the bearing sleeve 30, but alternative attachment techniques such as welding, crimping, and fusing are also possible. The outer bearing ring 32 is located on the bearing sleeve 30 and is prevented from being pushed out of the bearing sleeve 30 by two protective rings 31. Similarly, the bearing sleeve 30 and one of the protective rings 31 can be made of a single piece of material.

[0120] Figure 10B Another embodiment is shown, in which the outer bearing ring 32 and the bearing sleeve 30 form a radial bearing. In addition, the proximal protective ring 31a and the distal protective ring 31b are axially fixed relative to the bearing sleeve 30 in the manner described above. If the drive shaft 12 moves distally (to the left in Figure 10B ), the proximal protective ring 31a will abut against the proximal surface of the outer bearing ring 32 and prevent further distal movement. If the drive shaft 12 moves in the proximal direction, the proximal protective ring 31a will abut against the distal surface of the limiting member 33, thereby preventing any further movement in the proximal direction. If the maximum distance a max between the proximal surface of the distal protective ring 31b and the distal surface of the outer bearing ring 32 is greater than the maximum distance c max between the distal surface of the limiting member 33 and the proximal surface of the proximal protective ring 31a, then the distal protective ring 31b will never touch the outer bearing ring 32. This condition is equivalent to the inequality a > b + c, where b + c is a constant.

[0121] If the rotor 10 is mounted on the distal protective ring 31b as Figure 11A shown, the distances a, b, and c selected according to the above inequality will prevent the rotor from touching the outer bearing ring 32. Similarly, as Figure 11B shown, if the rotor 10 is mounted on the distal extension of the bearing sleeve 30, the above condition will prevent the rotor 10 on the bearing sleeve 30 from touching the outer bearing ring 32. Otherwise, the contact between the rotor 10 and the outer bearing ring 32 may cause damage to the rotor 10 or the proximal bearing 13.

[0122] Figure 12AAn intravascular blood pump 1 is shown having a housing 11 and a rotor 10 mounted on a drive shaft 12. The proximal bearing 13 includes a bearing sleeve 30 rotatably supported in an outer bearing ring 32. The drive shaft 12 is glued into the bearing sleeve 30. The drive shaft 12 surrounds a reinforcing element 35 implemented as a coaxial rod for stabilizing the distal end of the drive shaft. The rod extends from the proximal end of the proximal bearing 13 to the distal end of the rotor 10. Alternatively, the drive shaft 12 can be hollow to allow cleaning fluid to reach the distal bearing. A limiting member 33 is located at the proximal end of the bearing sleeve 30 and prevents the bearing sleeve 30 from coming off the outer bearing ring 32. Both the limiting member 33 and the outer bearing ring 32 are press-fitted and / or glued into the distal end of the housing 11. In addition, the limiting member 33 is press-fitted and / or glued into the catheter 5. Thus, the limiting member 33 connects the housing 11 and the catheter 5. Radial through-holes 34 in the housing 11 are used to introduce glue to fixedly connect the limiting member 33 and the outer bearing ring 32 to the housing 11. The glue can be circumferentially distributed along grooves 36 provided in both the limiting member 33 and the outer bearing ring 32. In addition, the radial through-holes 34 can be used for position control of the outer bearing ring 32 and the limiting member 33. Both connections are glued to keep the connection tight and prevent leakage of cleaning fluid.

[0123] From Figure 12A It can be seen that the bearing sleeve 30 includes a proximal portion 30a located at the proximal end of the outer bearing ring 32 and a distal portion 30b extending distally from the proximal portion 30a into the outer bearing ring 32. The proximal portion 30a forms an axial bearing with the proximal surface of the outer bearing ring 32, while the distal portion 30b forms a radial bearing with the outer bearing ring 32. The axial bearing and the radial bearing together constitute the proximal bearing 13.

[0124] The cleaning fluid extruded from the proximal to the distal through the proximal bearing 13 will first pass through the proximal portion 30a of the bearing sleeve 30 along the radially outer surface of the proximal portion 30a of the bearing sleeve 30, then flow radially inwards through the bearing gap between the distal surface of the proximal portion 30a and the proximal surface of the outer bearing ring 32, and finally further flow in the distal direction through the bearing gap radially formed between the distal portion 30b of the bearing sleeve 30 and the radially inner surface of the outer bearing ring 32. The bearing gap can be designed to have a very small tolerance so that by applying an appropriate pressure to the cleaning fluid from the proximal end, the cleaning fluid can flow through the bearing gap in a tightly controllable manner. One or more radial notches (not shown) can be provided in the proximal surface of the static outer bearing ring 32 to ensure that during operation, when the rotor 10 pulls the bearing sleeve 30 in the distal direction, the cleaning fluid can flow into the radial bearing gap between the outer bearing ring 32 and the distal portion 30b of the bearing sleeve 30.

[0125] Figure 12B Is shown Figure 12AAlternative embodiments of the embodiments herein. Here, the drive shaft 12 has a portion with a reduced diameter, and the distal portion 30b of the bearing sleeve 30 is disposed in the portion with the reduced diameter. Thus, although not specifically shown in Figure 12B , the outer diameter of the outer bearing ring 32 can be correspondingly reduced, and in turn, the outer diameter of the catheter 5 can also be reduced. In this way, a more flexible and better operable catheter can be achieved.

[0126] As Figure 12B shown, the structure of the bearing sleeve 30 is equivalent to the bearing structures described above with respect to Figure 10A and Figure 10B . More specifically, the proximal portion 30a of the bearing sleeve 30 corresponds to the proximal protective ring 31a (see Figure 10B ). Thus, in the embodiment shown in Figure 12B , a distal bearing ring 31b that overlaps both the distal end of the drive shaft 12 and the distal portion 30b of the bearing sleeve 30 is also provided. It restricts the axial movement of the drive shaft 12 within the outer bearing ring 32 in the same manner as described with respect to Figure 10A and Figure 10B .

[0127] Figure 13A shows a graphical representation of the stationary surface of a hydrodynamic axial bearing. Specifically, Figure 13A shows the proximal surface of the outer bearing ring 32 with the drive shaft 12 located at the center. Figure 13A The curved radial lines in Figure 13B represent the raised portions of the bearing surface, which are shown in more detail in Figure 13A and Figure 13B . The arrows in

[0128] Figure 13C show the direction of movement of the opposing surfaces. This corresponds to the direction of movement of the lubricating film within the axial bearing clearance. This surface has an inclined surface that forms a converging clearance together with the flat opposing stationary surface. This results in the accumulation of hydrodynamic pressure in the lubricating film. Thus, the surfaces forming the axial bearing clearance are maintained at a certain distance.

[0128] Figure 13C shows the bearing sleeve 30 and the outer bearing ring 32 within the housing 11. The bearing sleeve 30 has a flat distal surface. Here, the opposing proximal surface of the outer bearing ring 32 is inclined to form a converging clearance. During use, this forms the lubricating film required for a hydrodynamic bearing.

[0129] Figure 13D shows a helical groove in the proximal bearing surface of the outer bearing ring 32 in another embodiment. The helical groove is preferably formed in the moving surface of the proximal bearing 13, that is, in the proximal portion 30a of the bearing sleeve 30. In this case, a plurality of grooves are arranged in a spiral on the distal surface of the proximal portion 30a of the bearing sleeve 30. When the bearing sleeve 30 moves alongFigure 13D When rotating in the direction indicated by the arrow in [reference], the lubricating film is transported radially inward along the groove and forms a pressure between the bearing surfaces to keep them separated.

Claims

1. An intravascular blood pump (1), comprising: A catheter (5); An expandable housing (11) that houses an expandable rotor (10), the housing (11) being attached to the distal end of the catheter (5); and A flexible drive shaft (12) that extends through the catheter (5) and is connected to the rotor (10), the drive shaft (12) being rotatably supported in a proximal bearing (13) located proximal to the rotor (10); Wherein the proximal bearing (13) includes a bearing sleeve (30) and an outer bearing ring (32), Wherein the bearing sleeve (30) includes a proximal portion (30a) located proximal to the outer bearing ring (32), the proximal portion (30a) of the bearing sleeve (30) and the proximal surface of the outer bearing ring (32) together form an axial bearing of the proximal bearing, and Wherein the axial bearing is a hydrodynamic bearing.

2. The intravascular blood pump (1) according to claim 1, wherein the proximal surface of the outer bearing ring (32) has an inclined surface, and the inclined surface and the flat distal surface of the proximal portion (30a) of the bearing sleeve (30) together form a converging gap.

3. The intravascular blood pump (1) according to claim 1, wherein the proximal surface of the outer bearing ring (32) is inclined to form a converging gap with the flat distal surface of the proximal portion (30a) of the bearing sleeve (30).

4. The intravascular blood pump (1) according to any one of claims 1 to 3, wherein the proximal surface of the outer bearing ring (32) is stationary.

5. The intravascular blood pump (1) according to claim 1, wherein the bearing surface of the proximal bearing (13) has spiral grooves.

6. The intravascular blood pump (1) according to claim 5, wherein the spiral grooves are arranged spirally in the distal surface of the proximal portion (30a) of the bearing sleeve (30).

7. The intravascular blood pump (1) according to any one of claims 1 to 3, wherein the bearing sleeve (30) is fixedly connected to the flexible drive shaft (12).

8. The intravascular blood pump (1) according to any one of claims 1 to 3, wherein the outer bearing ring (32) is located within the distal end region of the catheter (5) or within the proximal end region of the housing (11).

9. The intravascular blood pump (1) according to any one of claims 1 to 3, wherein a limiting member (33) that restricts the axial movement of the bearing sleeve (30) relative to the outer bearing ring (32) is located proximal to the bearing sleeve (30) within at least one of the catheter (5) and the housing (11).

10. The intravascular blood pump (1) according to any one of claims 1 to 3, wherein the flexible drive shaft (12) is at least partially filled with a sealant.

11. The intravascular blood pump (1) according to any one of claims 1 to 3, wherein at least one of the bearing sleeve (30) and the outer bearing ring (32) comprises at least one of the following materials: ceramics and metals.

12. The intravascular blood pump (1) according to any one of claims 1 to 3, wherein at least one of the bearing sleeve (30) and the outer bearing ring (32) comprises a coating.

13. The intravascular blood pump (1) according to any one of claims 1 to 3, wherein one or both of the proximal end region of the housing (11) and the distal end region of the catheter (5) comprise one or more radial through-holes.

14. The intravascular blood pump (1) according to any one of claims 1 to 3, wherein the flexible drive shaft (12) comprises a reinforcing element (35) that extends longitudinally within the central lumen of the drive shaft (12).

15. The intravascular blood pump (1) according to any one of claims 1 to 3, wherein the bearing sleeve (30) comprises a portion extending distally from the outer bearing ring (32), and wherein the rotor (10) is mounted on the portion extending distally from the bearing sleeve (30).

16. The intravascular blood pump (1) according to any one of claims 1 to 3, wherein the rotor (10) is located at a distance between 0.001 mm and 8 mm from the outer bearing ring (32).

17. The intravascular blood pump (1) according to any one of claims 1 to 3, wherein the drive shaft (12) has a portion with a reduced diameter, and at least the distal portion (30b) of the bearing sleeve (30) is arranged at the portion with the reduced diameter.

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