Intravascular blood pump

Abstract

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

Description

Technical Field

[0001] The present invention relates to an intravascular blood pump, in particular a percutaneously insertable blood pump for supporting blood circulation in humans or also animals. For example, the blood pump can be designed to be percutaneously inserted into a patient's femoral artery and guided through the patient's vascular system, for example to support or replace the pumping action of the heart. Background Art

[0002] 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 housed and driven by an external motor via a long, flexible drive shaft, the present invention is also applicable to other types of intravascular blood pumps.

[0003] The above-mentioned inflatable type of blood pump is known, for example, from US 2013 / 0303969 A1, which discloses a catheter pump assembly. An inflatable shell is located at the distal end of the catheter. The inflatable shell surrounds an inflatable rotor driven by a flexible drive shaft, which extends through the first lumen of the catheter. For example, the distal portion of the catheter pump assembly can be placed inside the heart through a percutaneous approach using the Seldinger technique. The drive shaft contains 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 arranged at the end of the catheter and the proximal end of the rotor. In this article, "proximal" and "distal" refer to what is seen relative to the doctor. Therefore, when placing a catheter, the proximal end means something that is relatively close to the doctor, and the distal end means something that is relatively far away from the doctor.

[0004] During use of an intravascular blood pump, the rotor and the drive shaft are required to rotate at significant speeds. Therefore, it is desirable to provide a bearing that rotatably supports the drive shaft with low friction while maintaining high durability. Summary of the invention

[0005] According to a first aspect of the present invention, an intravascular blood pump comprises a catheter and a housing, a rotor being contained in the housing, and the housing being attached to the distal end of the catheter. In addition, 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 at the proximal end of the rotor. The proximal bearing comprises a bearing sleeve and an outer bearing ring, wherein the bearing sleeve comprises a proximal portion located at the proximal end of the outer bearing ring, and the proximal portion of the bearing sleeve forms an axial bearing with the proximal surface of the outer bearing ring. The bearing sleeve also comprises a distal portion extending distally from the proximal portion of the sleeve into the outer bearing ring, wherein the distal portion of the bearing sleeve forms a radial bearing with the outer bearing ring. The design of the described proximal bearing can advantageously achieve low friction and high durability, particularly when providing a cleaning fluid to flow through a gap defined by a radial bearing.

[0006] Preferably, the bearing sleeve is fixedly connected to the flexible drive shaft. The bearing sleeve may be crimped, welded, fused, glued or shrunk to the flexible drive shaft. Gluing the bearing sleeve may advantageously avoid any deformation or warping of the bearing sleeve.

[0007] The proximal bearing is preferably located in the distal end region of the catheter and / or in the proximal end region of the housing. Alternatively, the proximal bearing, preferably an axial proximal bearing, can be located at any position in the catheter, and there can even be a plurality of proximal bearings, the term "proximal" here meaning that the bearing is located at any position proximal to the rotor. Preferably, the outer bearing ring is fixedly connected in the distal end region of the catheter or in 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 certain 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.

[0008] Preferably, the limiting member is located within the conduit and / or housing at the proximal end of the bearing sleeve. It may be fixedly mounted within the proximal end of the housing or within the distal end of the conduit. The limiting member acts as a stop to limit the axial movement of the bearing sleeve relative to the outer bearing ring. The limiting member may advantageously prevent the bearing sleeve from sliding out of the outer bearing ring. In some embodiments, the limiting member forms 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 to allow the passage of cleaning fluid.

[0009] 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.

[0010] Preferably, the radial bearing gap 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 gap is about 3.5 µm wide. A cleaning fluid can be pushed through the radial bearing gap of the proximal bearing. If the radial bearing gap is configured in this way, the cleaning fluid can flow at a reproducible rate at a suitable cleaning fluid pressure.

[0011] Preferably, the flexible drive shaft is at least partially filled with a sealant. Preferably, the sealant completely permeates 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. Examples of sealants for the purposes of the present invention are adhesives, polymers and / or thermoplastics.

[0012] Preferably, the bearing sleeve and / or the outer bearing ring comprises 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 may include a coating. Preferably, the bearing sleeve and / or the outer bearing ring has a hard coating, such as a DLC coating. Advantageously, a bearing sleeve or an outer bearing ring designed in this way allows the proximal bearing to be lightweight and durable.

[0013] Preferably, the proximal end region of the housing and / or the distal end region of the catheter comprises one or more radial through holes. The radial through holes may increase elasticity to allow the proximal bearing to be press-fitted into the housing and / or the catheter. The through holes further allow for the introduction of glue and position monitoring when the proximal bearing is inserted. It is noteworthy 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 fill the gap completely. The diameter of the radial through holes may be between 0.5 mm and 1 mm. An elongated hole elongated in the circumferential direction is advantageous for filling the notch of the bearing, in which case the aforementioned diameter refers to the smaller diameter of the elongated hole.

[0014] Preferably, the flexible drive shaft comprises a reinforcing element extending longitudinally within the central tubular cavity of the drive shaft, preferably a coaxial hard reinforcing rod. More specifically, in some embodiments, the drive shaft is reinforced by the reinforcing element 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, for example made of spring steel, wire or carbon wire. In one embodiment, the wire is made of 1.4310 stainless steel.

[0015] The bearing sleeve may comprise a portion extending distally from the outer bearing ring, and the rotor may be mounted on said portion extending distally from the outer bearing ring. Such a design may allow a particularly stable construction of the rotor. In particular, the bearing sleeve may extend along a major part of the axial length of the rotor, more preferably to the distal end of the rotor.

[0016] The rotor is preferably located 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 prevents the rotor from becoming stuck in the proximal bearing.

[0017] Preferably, the rotor is additionally supported in a distal bearing.

[0018] The flexible shaft preferably extends through the entire catheter. The drive shaft is preferably hollow. The flexible drive shaft is preferably composed of or includes a flexible cable, which is preferably formed by fiber layers of different orientations. In particular, the flexible drive shaft is most preferably composed of a plurality of coaxial windings, preferably with different winding directions, particularly preferably with alternating winding directions, extending spirally 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 0.4mm and 2mm, more preferably between 0.6mm and 1.2mm, and particularly preferably between 0.8mm and 1.0mm. The proximal end of the flexible drive shaft is preferably attached to an external electric motor. The flexible drive shaft is used to transfer torque from the electric motor to a rotor at the distal end of the drive shaft. In some cases, the flexible drive shaft may include a hard rigid shaft at its distal end, and the rotor is attached to the rigid shaft inside the housing to provide stability for the rotor.

[0019] In one embodiment, the flexible drive shaft comprises at least one outer layer and at least one inner layer. The at least one outer layer of the flexible drive shaft is preferably absent or thinned at the portion of the flexible drive shaft supported in the proximal bearing. Thus, the drive shaft has a portion of reduced diameter, and at least the distal portion of the bearing sleeve that forms a radial bearing together with the outer bearing ring is arranged in this portion. Preferably, the axial length of the portion where the at least one outer layer is absent or thinned is between 1 and 15 times, preferably between 2 and 5 times, the diameter of the drive shaft in this portion, for example between 2 mm and 5 mm.

[0020] At least one outer layer and at least one inner layer are preferably made of metal. More preferably, all layers can be made of metal. In some embodiments, at least one inner layer and / or at least one outer layer can be a wire or cable. The outer layer and / or the inner layer can be made of a hollow metal tube.

[0021] 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 a wire wound into one or more windings. Each wire may comprise one or more strands, which may be twisted, for example. Instead of winding the wires in layers, the wires may preferably be braided, for example similar to the outer rope sheath of a kernmantle rope. The windings of at least one inner layer or at least one outer layer may form a spiral. Alternatively, some or all layers may consist of two or more spirals, which are preferably axially displaced, similar to a multi-start thread. Different layers may have different spirals, for example, alternating from one layer to the next adjacent layer. The wires may consist of metal, or may comprise metal and other additional materials, such as a surface coating.

[0022] Preferably, the flexible drive shaft is at least partially filled with a sealant that penetrates into at least one inner layer. If the layers include holes or are made of wires, the sealant may penetrate across the layers. In some cases, the layers, in particular one or more wires of the flexible drive shaft, may be partially or completely filled with a sealant.

[0023] For example, the proximal bearing and / or the distal bearing are configured to be cleaned with a cleaning fluid. The cleaning fluid can reduce friction and carry away friction heat from the proximal bearing. Likewise, it can also prevent blood from entering through the bearing gap. If the cleaning fluid can flow through the flexible drive shaft in addition to the bearing gap on its way 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.

[0024] If the flexible drive shaft is filled with sealant inside the bearing sleeve, it can be advantageously prevented that the cleaning fluid flows through the bearing sleeve. However, in some cases, it may be difficult to completely fill the flexible drive shaft with multiple layers with sealant. This may cause residual cleaning fluid to flow through the flexible drive shaft. In some embodiments, there is only one inner layer, and the inner layer and at least one outer layer are composed of winding wires. At the same time, at least one outer layer can be completely removed at the location of the sleeve.

[0025] In a further alternative, in designs having 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 of the interior of the bearing sleeve with a sealant may be particularly effective in blocking flow through the flexible drive shaft. This is because the sealant does not have to penetrate into the spaces between the layers to completely seal the interior of the bearing sleeve.

[0026] 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 thinned outer layer. Preferably, the bearing sleeve is fixedly connected to at least one inner layer or at least one thinned outer layer of the flexible drive shaft. The outer diameter of the distal portion of the bearing sleeve is approximately equal to the outer diameter of the at least one outer layer. In this way, the inner radial bearing surface of the proximal bearing corresponds to the outer diameter of the drive shaft and may preferably be slightly larger than at least one outer layer of the drive shaft to facilitate assembly of the device.

[0027] The at least one inner layer may be axially interrupted within the bearing sleeve. If the at least one inner layer is axially interrupted inside the bearing sleeve, it may be particularly easy to fix the bearing sleeve on top of the at least one inner layer. Without an axially interrupted inner layer, the at least one inner layer would have to be fed through the bearing sleeve before the next continuation of the at least one outer layer could be arranged on the at least one inner layer. This is particularly advantageous in embodiments in which the at least one inner layer extends distally beyond the proximal bearing.

[0028] In some embodiments, the interior space of the bearing sleeve is hydraulically separated, i.e., liquid cannot flow from one side of the bearing sleeve to the other side inside. 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. The two ends of the at least one inner layer that is axially disconnected can then be inserted into a corresponding one of the blind holes. The wall between the holes prevents any cleaning fluid from flowing through the bearing sleeve, so that the at least one inner layer that is axially disconnected does not need to be sealed, but is only attached to the bearing sleeve.

[0029] In a preferred embodiment, only the distal portion of the bearing sleeve is mounted on the reduced diameter drive shaft portion, while the proximal portion has an increased inner diameter and extends proximally on at least one outer layer of the flexible drive shaft. Thereby, the risk of the drive shaft breaking due to the change in stiffness at the transition between different diameters is effectively reduced. A distal protection ring having substantially the same function may be provided at the distal transition between different diameters and may extend both on at least one outer layer of the flexible shaft and on the distal extension of that portion of the bearing sleeve.

[0030] The proximal bearing with a bearing sleeve and a distal protective ring can preferably be 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 so 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 slightly turning. On at least one outer layer of the drive shaft, the distal portion of the bearing sleeve is positioned so 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 so that it extends into the proximal portion of the bearing sleeve and overlaps with the proximal portion of the bearing sleeve. After the adhesive is cured, the combination of the drive shaft and the bearing sleeve can be tested for liquid impermeability. The outer bearing ring is then positioned on the distal portion of the bearing sleeve. The at least one outer layer previously removed is pushed onto the at least one inner layer until it contacts the bearing sleeve and is glued in place. A distal protection ring is then placed on top of the at least one outer layer previously removed so as to overlap the distal portion of the bearing sleeve. The distal protection ring is positioned so that a predetermined axial play is set between the outer bearing ring and the bearing sleeve. The distal protection ring is then mechanically or otherwise fixed to the drive shaft. Fixing the protection ring to the at least one outer layer can additionally prevent loosening of the at least one outer layer. Thus, both the distal protection ring and the proximal portion of the bearing sleeve surround the end of the at least one outer layer adjacent to the bearing sleeve.

[0031] 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 acts as a limiting member to limit the axial movement of the drive shaft relative to the outer bearing ring. In one embodiment, the rotor or rotor shaft mounted at the distal end of the outer bearing ring may form a protective ring, in which case the limiting member advantageously prevents the rotor or rotor shaft from contacting the outer bearing ring.

[0032] Preferably, the proximal end 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 the at least one outer layer and / or the bearing sleeve.

[0033] Preferably, the protection ring comprises one or more ceramics and / or metals, in particular MP35, 35NLT, Nitinol or stainless steel. In the case of metal, the protection ring may be hard-coated, for example DLC-coated.

[0034] The surface of the proximal portion of the bearing sleeve facing the bearing ring preferably forms an axial bearing with an opposing surface of the bearing ring.The distal protection ring preferably forms a stop element for the bearing ring to prevent the bearing ring from sliding off the bearing sleeve.

[0035] 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. The first adhesive can be a sealant. The first adhesive preferably has a particularly low viscosity so as to be able to fully penetrate the outer and / or inner winding. Before hardening, the first adhesive preferably has a viscosity in the range of 80cPs to 200cPs. A suitable adhesive is a two-component epoxy resin. A different second adhesive is preferably used to connect the sleeve and / or the distal protection 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.

[0036] According to a particularly preferred embodiment, the bearing sleeve extends into the rotor. Typically, the bearing sleeve is stiffer than the drive shaft, so that the rotor can have a more rigid support than other embodiments in which the rotor is mounted on the distal end of the drive shaft.

[0037] Preferably, the radial bearing gap 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, preferably approximately 3.5 mm wide.

[0038] 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 the distal end of the rotor or protrudes to abut against the distal end of the rotor. Alternatively, the distal end of the drive shaft or the bearing sleeve may be supported by the distal bearing.

[0039] In another embodiment, the drive shaft is not supported in a distal bearing. Instead, the rotor is preferably mounted on the very end of the drive shaft or on a distal extension of the proximal bearing sleeve, respectively, so that it is the distal end of the rotor that is supported by a static support member extending into the rotor or extending against the rotor. In this way, tendinous structures are less likely to be caught by rotating components, especially if no rotating structure extends beyond the leading edge of the rotating blades. This can result in a safer intravascular blood pump with a longer life.

[0040] The intravascular blood pump is preferably designed as an expandable blood pump having a housing having an expandable portion. In some embodiments, the housing comprises or consists of a shape memory material, in particular nitinol. The diameter of a percutaneously insertable blood pump is typically limited by the inner diameter of the smallest blood vessel to be passed through. 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 percutaneously inserted into the heart than would otherwise be possible. Using such a larger blood pump, a greater blood flow may be generated.

[0041] When the blood pump is designed as an expandable pump, a sleeve is preferably arranged around the portion of the drive shaft located 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 portion of the rotor, such as a rotor blade, or the entire rotor, is also expandable to allow a larger rotor to be inserted into the heart, which can increase the flow rate.

[0042] In some embodiments, the static support member of the distal bearing protrudes to abut against the distal end of the rotor. Compared to embodiments in which the static support member protrudes 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 insertion and removal of the intravascular blood pump. If the static support member does not protrude into the rotor, but is only placed against the distal end of the rotor, the static support member may be intentionally moved 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 be restored to its position in which it protrudes to abut against the distal end of the rotor.

[0043] Preferably, the static support member is attached to the distal end of the housing, wherein expansion of the housing may provide an axial force to the distal end of the rotor through the static support member. Preferably, the force is equal to or less than 1.8 N. When the static support member protrudes against the distal end of the rotor, it may limit further expansion of the housing.

[0044] When the housing is compressed, the static support member preferably moves away from the distal end of the rotor. In this state, the pump portion becomes more flexible as relative radial movement of the static support member and the rotor becomes possible. This may be advantageous during insertion or removal of the intravascular blood pump.

[0045] In certain embodiments, the intravascular blood pump comprises a nose at the distal end of the rotor. When the housing is in its expanded state, the nose protrudes into the static support member, which preferably has a correspondingly formed recess. The purpose of the nose is to center the rotation of the rotor and to bring the rotor and the static support member to the correct relative position after expansion of the housing. The nose preferably protrudes 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 from the surrounding surface of the rotor. The depth of the recess in the static support member corresponds to the nose 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.

[0046] In some embodiments in which the static support member protrudes into the rotor, the rotor comprises an axial stop for the static support member, such as a recess with a bottom or a step at its distal end. The bottom or the step 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 protruding axially into the rotor may contact the axial stop, thereby preventing further expansion of the housing and thus limiting the radial gap width between the outer edge of the rotor blades and the inner surface of the expandable housing. Optionally, in the expanded state of the expandable blood pump, the proximal end of the static support member and the axial stop may form a gap, the gap preferably being between 0.01 mm and 1 mm, more preferably between 0.01 mm and 0.1 mm, and most preferably between 0.01 mm and 0.05 mm wide in the axial direction.

[0047] The length of the recess at the distal end of the rotor measured in the axial direction may be, for example, between 0.5 mm and 8 mm, preferably between 1 mm and 5 mm, particularly preferably between 1.5 mm and 2.5 mm. When the housing is moved into the sleeve, the housing is preferably stretched axially by 0.5 mm to 2.5 mm, more preferably by 1 mm to 2 mm, most preferably by about 1.7 mm.

[0048] Inside the distal end of the drive shaft, i.e., inside the rotor shaft, the intravascular blood pump may include an optional fluid line arranged to guide a cleaning fluid through the rotor to the distal bearing. In some embodiments, the rotor includes a hollow portion as part of the fluid line, wherein the intravascular blood pump is arranged to guide a 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 in the housing of the motor. The cleaning fluid may flow in the catheter adjacent to the drive shaft. In the case where the drive shaft is hollow, the cleaning fluid may flow partially, mostly or completely through the drive shaft lumen. From the distal end of the catheter to the rotor, the cleaning fluid may flow through the drive shaft. At least in the space between the distal end of the catheter and the proximal end of the rotor, the drive shaft may include a cover to prevent the cleaning fluid from leaking from the space.

[0049] Alternatively, the cleaning fluid may not be directed through a primary lumen of a catheter containing the drive shaft, but rather through one or more separate secondary lumens.

[0050] At the distal end region of the catheter, the cleaning fluid is preferably transferred to a 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, a distal extension 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.

[0051] In the cleaned proximal and / or distal bearings, blood is less likely to enter the bearing gap. Thus, blood clots are prevented. In addition, the cleaned bearings may have less friction than alternative bearings in the prior art. In particular, the cleaning fluid lubricates the bearings and can carry away frictional heat from the bearings. This can allow higher rotational speeds, lower power consumption, and longer blood pump life. The cleaning fluid can be any biocompatible fluid suitable for cleaning bearings. Examples of suitable medical fluids include saline solutions, glucose solutions, and / or water, each of which may or may not contain heparin.

[0052] In an alternative embodiment, the proximal and / or distal bearings are not cleaned. Therefore, there is no delivery of cleaning fluid to the proximal and / or distal bearings, and the intravascular blood pump may not include a fluid line.

[0053] The distal bearing is preferably arranged so that a cleaning fluid can flow out between the static support member and the distal end of the rotor, the static support member protruding into the rotor or protruding against the rotor. Preferably, the distal bearing is arranged so 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 so that any cleaning fluid passing through the hollow drive shaft or the rotor shaft flows out entirely or at least partially through the distal bearing. By applying a suitable pressure, the cleaning fluid can be driven through the bearing gap of the distal bearing, which in some embodiments is the gap defined by the adjacent parts of the static support member and 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 gap between the nose and the static support member.

[0054] In some embodiments, the distal end of the static support member is mounted on the distal end of the housing. The distal end of the housing can provide stable support for the static support member supporting the distal end of the rotor.

[0055] The static support member preferably comprises a pin extending from the distal end to the proximal end and protruding to abut against or preferably into the distal end of the rotor. The pin can thus be arranged to form a distal bearing for the rotor. In embodiments where the distal bearing is cleaned, the pin is preferably arranged so that cleaning fluid can flow between the pin and the rotor mounted on the pin.

[0056] Preferably, the pin has a circular cross section. However, in the distal portion of the pin located outside the rotor, other cross sections are equally possible. For example, the pin may have an elliptical cross section. In some embodiments, the pin may be hollow. Alternatively, the pin may be made of solid material. Preferably, the pin tapers towards its proximal end. The pin may be resiliently bendable, preferably so that during bending of the head of the pump, the rotor remains concentric with the housing.

[0057] Preferably, the inner diameter of the distal end of the rotor, where the static support member, in particular the pin, protrudes axially therein, 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 bearing surface opposite thereto is between 1 µm and 10 µm, more preferably between 2 µm and 8 µm wide.

[0058] In some embodiments, the pin is particularly long and protrudes into the rotor and extends proximally through the entire rotor. Preferably, the pin leaves the rotor proximally and continues inside the drive shaft, for example, terminating in the proximal bearing. In this case, the end of the pin can be arranged inside the portion of the drive shaft located in the proximal bearing. By using such a long pin extending through the entire length of the rotor and entering the proximal bearing, a particularly stiff and low-vibration pump can be formed. Alternatively, the pin can extend further to a point proximal to the proximal bearing. The pin extending through the rotor can be cleaned or uncleaned and can be used in combination with a hollow drive shaft or with a drive shaft that is hollow only along a portion of its length.

[0059] Preferably, the material of the pin comprises at least one of the following materials: a biocompatible material, in particular one or more of MP35N, 35NLT, Nitinol, stainless steel (in particular medical grade stainless steel) and ceramic. The surface of the pin may comprise a coating, such as a hard coating, such as a diamond-like carbon (DLC) coating.

[0060] Preferably, during the operating state of the intravascular blood pump, the length of the pin protruding into the distal end of the rotor is between 0.5 mm and 8 mm, preferably between 1 mm and 5 mm, particularly preferably between 1.5 mm and 2.5 mm. The longer the inner length, the stiffer the rotor support and, therefore, the better the controllability of the width of the gap between the outer edge of the rotor blades 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 damage to the blood. A stiffer supported rotor can also run with lower deflections and less vibrations, thereby improving blood compatibility.

[0061] The pin may have a length sufficient to remain within the distal end of the rotor when the housing and the rotor are in a compressed state. The length of the pin that remains 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 the blood pump is deployed, the housing extends in the longitudinal direction, and the static support members extending into the distal end of the housing, in particular the pin, may move completely out of the rotor. Then, when the housing expands again, the pin may not move back into the rotor, and the pump may not function properly. Therefore, if the selected pin has a sufficient length so that the pin remains inside the rotor even in the compressed state of the housing, this problem can be avoided.

[0062] In embodiments with a pin, the distal bearing surface is the surface of the pin and the distal outer bearing surface, which may be provided by the rotor itself or by a sleeve of the distal bearing in the hub of the rotor. In some cases, the distal outer bearing surface may be provided by a reinforcing element as described above.

[0063] 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.

[0064] In some embodiments, the intravascular blood pump includes a flexible atraumatic tip to avoid damage to the patient's tissue. The atraumatic tip can be made of a flexible medical grade polymer such as Pebax® or polyurethane. Preferably, the flexible atraumatic tip is designed as a pigtail or J-shape.

[0065] According to a second aspect of the invention, the above-described intravascular blood pump is for use in a patient, ie it is inserted and operated in the patient to support blood flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] In the following, the present invention will be explained by way of example with reference to the accompanying drawings. The drawings are not drawn to scale. In the drawings, the same or corresponding parts shown in the various figures are represented by the same numbers. For the sake of clarity, not every component will be labeled in every figure. In the drawings:

[0067] Figure 1 A schematic diagram of an intravascular blood pump located within the left ventricle of the heart is shown;

[0068] Figure 2 A schematic diagram of an intravascular blood pump is shown;

[0069] Figure 3A and Figure 3B A schematic diagram showing an intravascular blood pump in an expanded state and a compressed state;

[0070] Figure 4A , Figure 4B and Figure 4C shows a schematic diagram of an intravascular blood pump having a static support member extending into the distal end of a rotor according to a first embodiment;

[0071] Figure 5 shows a schematic diagram of an intravascular blood pump having a static support member extending into the distal end of the rotor according to a second embodiment;

[0072] FIG. 6A to FIG. 6D shows a schematic diagram of an intravascular blood pump having a rotor with a nose at its distal end according to a third embodiment;

[0073] Figure 7 A schematic diagram of an intravascular blood pump having a proximal bearing and a distal bearing is shown;

[0074] Fig. 8A and Figure 8B A schematic diagram showing the path of a cleaning fluid in an intravascular blood pump;

[0075] Fig. 9A A drive shaft including an outer layer and an inner layer is shown;

[0076] Fig. 9B A drive shaft with a bearing sleeve, an outer bearing ring and a protective ring is shown;

[0077] Fig. 10A A hydraulically separated bearing sleeve is shown;

[0078] Fig. 10B A bearing having a limiting member is shown;

[0079] Fig.11A and Fig. 11B A bearing with a restraining member and a rotor is shown;

[0080] Fig. 12A and Fig. 12B Two different embodiments of a proximal bearing with an outer bearing ring and a specially formed bearing sleeve are shown;

[0081] FIG. 13A to FIG. 13D A hydrodynamic axial bearing is shown. DETAILED DESCRIPTION

[0082] Figure 1 The use of an intravascular blood pump 1 is shown, in this particular example, for supporting the left ventricle 2 of a human heart. The intravascular blood pump 1 comprises a catheter 5 and a pumping device comprising 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 via the femoral artery. However, alternative vascular access is also possible, such as access via the subclavian artery. After passing through the femoral artery, the catheter 5 can be pushed into the aorta so that the pump portion 4 reaches the heart through the aortic valve. Figure 1 The positioning of the pump portion 4 is by way of example only, and different placements are possible, such as positioning the pump portion 4 within the right ventricle of the heart.

[0083] The pump portion 4 includes a rotor 10 to cause blood to flow from a blood flow inlet 6 at the distal end of the pump portion 4 to a blood flow outlet 7 located proximal to the blood flow inlet 6. The catheter 5 accommodates 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 in the pump portion 4. At its distal end, the pump portion 4 has a flexible atraumatic tip 9, which has the form of a pigtail or J-shape, which facilitates the placement of the intravascular blood pump 1 by helping to guide it within the patient's vascular system. In addition, the softness of the flexible atraumatic tip 9 allows the pump portion 4 to support itself atraumatically against the wall of the left ventricle 2.

[0084] Figure 2 The intravascular blood pump 1 is shown in more detail. The rotor 10 is located inside the 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 part 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 the 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 into the aorta through the blood flow outlet 7 arranged more proximal to the side in the downstream conduit 20, and the blood flow outlet includes a plurality of outlet openings. The downstream conduit 20 is made of a flexible material so that it can be compressed by the aortic valve when the patient's heart beats. The downstream conduit 20 is usually expanded mainly due to the active blood flow generated by the rotor 10 during rotation. By placing the blood flow inlet 6 in the left ventricle 2 and the blood flow outlet 7 in the aorta, the intravascular blood pump 1 can support the patient's systemic blood circulation. If the intravascular blood pump 1 is constructed and placed differently, it can be used to support the patient's pulmonary blood circulation instead, for example.

[0085] In this example, liquid, in particular a cleaning fluid, is supplied from outside the patient's body through the catheter 5 to the pump portion 4. Inside the pump portion 4, the liquid can be used to clean one or more bearings to reduce friction and cool the pump portion 4, such as by combining Figure 4A , Figure 4C and Figure 5 Further explained. Preferably, a liquid is used to clean at least 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).

[0086] The housing 11 is preferably made of a shape memory material such as Nitinol and provides a cage around the rotor 10. Figure 5 As shown, the central portion of the housing 11 carries a sleeve that defines a channel through which blood is pumped by means of the rotor 10. At the proximal and distal ends of the channel, the housing 11 allows blood to be drawn into the housing 11 and pushed out of the housing 11 into the downstream conduit 20 (e.g., Figure 2 as shown).

[0087] Figure 3A and Figure 3B The pump portion 4, its rotor 10 and the housing 11 are shown in an expanded state and a compressed state, respectively. The sleeve 16 is arranged at the distal end of the catheter 5. Initially, before the intravascular blood pump 1 is deployed, the pump portion 4 is arranged inside the sleeve 16 in its compressed state. The sleeve 16 can be a sleeve 16 belonging to the catheter 5 or a peel-off sheath for helping to insert 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 sleeve 16. In the case where the sleeve 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.

[0088] The rotor 10 is supported in the distal portion of the rotor 10 by a distal bearing 14, which includes a static support member 18 with a pin 19, which is attached at one end to the housing 11 and extends at the other end with its pin 19 into the distal end of the rotor 10, so that the pin 19 can move axially inside the distal end of the rotor 10 when the housing 11 is expanded. 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 physician pulls the housing 11 back into the cannula 16, which causes the housing 11 to compress radially and extend longitudinally, thereby moving the distal end of the housing 11 away from the rotor 10 together with the static support member 18 and its pin 19, which extends into the distal end of the rotor 10. The smaller diameter of the housing 11 thus obtained facilitates the removal of the intravascular blood pump 1 from the patient.

[0089] In prior art distal bearings 14, the drive shaft 12 sometimes extends distal to the rotor 10 and into the distal bearing 14. However, this can cause the tendinous chords of the heart to become entangled with the drive shaft 12, possibly leading to clotting and device failure. Therefore, it is advantageous to use a static support member 18 as part of the distal bearing 14 that does not involve rotating components distal to the rotor 10 and distal to the rotor blades.

[0090] Figure 4A and Figure 4B The pump part 4 according to the first embodiment is shown in more detail and comprises a housing 11 and a rotor 10 driven by a drive shaft 12. The drive shaft 12 is rotatably supported in a proximal bearing 13 (or in the proximal part of the housing) at the distal end of the catheter 5 proximal to the rotor 10 and in a distal bearing 14 at the distal end of the rotor 10. Figure 4AIn the embodiment of the present invention, 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, so that the rotor shaft is formed by the drive shaft, wherein in the area of ​​the proximal bearing and the distal bearing, the drive shaft 12 can be strengthened, for example, by injection molding of plastic material and providing suitable external and internal bearing surface treatments, respectively. Alternatively, the entire end area including the bearing portion of the drive shaft 12 can be strengthened in order to obtain a more rigid structure of the pump portion. For example, the drive shaft 12 is thinned at its distal end, and a rigid hollow tube is slid over the thinned end and extends distally to form the rotor shaft and the bearing portion. The cleaning fluid can be delivered to the distal bearing 14 via the fluid line 15 in the rotor shaft. In the embodiment of the present invention, the drive shaft 12 is hollow at its distal end, and a rigid hollow tube is slipped over the thinned end and extends distally to form the rotor shaft and the bearing portion. The cleaning fluid can be delivered to the distal bearing 14 via the fluid line 15 in the rotor shaft. Figure 4A In the illustrated embodiment, a cleaning fluid may be pushed through the central fluid line 15 to exit the drive shaft 12 at its distal end and further into the blood stream through the bearing clearance of the distal bearing 14. Cleaning of the distal bearing 14 by the cleaning fluid results in reduced friction and therefore reduced wear on the distal bearing 14 and, further, prevents blood from entering and clogging the bearing clearance.

[0091] In order for the intravascular blood pump 1 to be efficient, a large rotor diameter is ideal. However, as the gap between the rotor 10 and the housing 11 becomes smaller, the risk of blood cells or the rotor 10 being damaged 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 vary greatly. When the flexible atraumatic tip 9 touches the heart wall, the movement of the heart causes the housing 11 to bend, which may cause the housing 11 to touch the rotor 10. The touching of the housing 11 and the rotor 10 during use may greatly increase damage to blood cells and may also cause particles from the housing 11 and / or the rotor 10 to enter the blood stream causing wear. By using both the proximal bearing 13 and the distal bearing 14, as Figure 4A and Figure 4B As shown, the position of the rotor 10 is more stable and the size of the gap varies less than with only one bearing. For a given housing 11, this can 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.

[0092] The rotor 10 comprises at its distal end a recess 17 . A static support member 18 fixed relative to the distal end of the housing 11 projects into the recess 17 with its pin 19 . Figure 4AThe bottom 19 of the recess 17 in the rotor 10 is formed as a step and defines a stop inside the rotor 10 against which the pin 19 of the static support member 18 can bear. Figure 4A In the embodiment shown in FIG. 1 , the fluid line 15 penetrates the bottom of the recess 17 to allow cleaning fluid to leave the distal bearing 14 between the pin 19 and the recess 17 .

[0093] Figure 4B The embodiment of the intravascular blood pump 1 in Figure 4A However, it is important to Figure 4B The distal bearing in the DRIVE 12 is not cleaned but is designed to run in the blood. Therefore, the drive shaft 12 does not need to be hollow. Figure 4B There is no fluid line 15 in the proximal bearing 13. The bottom of the recess 17 does not contain an opening for 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 cleaning fluid at all.

[0094] Figure 4C Shown with 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. Figure 4C In the embodiment of the present invention, the proximal end of the pin 19 is located in a portion of the drive shaft 12 located inside the proximal bearing 13. In alternative embodiments, the proximal end of the pin 19 may be located at the proximal end of the proximal bearing 13 or between the rotor 10 and the proximal bearing 13, for example.

[0095] By extending the pin 19 into the proximal bearing 13, a greater rigidity of the intravascular blood pump 1 can be achieved. Figure 4C The pins 19 shown in FIG. 1 may help reduce vibrations of the intravascular blood pump 1 during its operation and may reduce undesired bending.

[0096] Figure 4C The proximal bearing 13 is located inside the housing 11. Figure 4A and Figure 4B The proximal bearing 13 is located distally of the rotor 10. In the illustrated embodiment, the distance between the proximal bearing 13 and the rotor 10 is particularly small, for example, smaller than the outer diameter of the proximal bearing 13. The short distance can further increase the stiffness of the intravascular blood pump 1.

[0097] Figure 4C The pin 19 in the rotor 10 is combined with the hollow drive shaft 12 so that in some embodiments, a cleaning fluid can flow through the drive shaft 12 and past the pin 19 to be discharged at the distal end of the rotor 10. Alternatively, in some embodiments, no cleaning fluid may be used. In this case, Figure 4CThe long pin 19 may be combined with a drive shaft that is only partially hollow along its length.

[0098] Figure 5 A pump portion 4 according to a second embodiment is shown, which also has a compressible housing 11 and a rotor 10 driven by a hollow drive shaft 12, which is rotatably supported in a proximal bearing 13 arranged proximal to the rotor 10 at the distal end of the catheter 5. In this embodiment, a pin 19 of a static support member 18 forming 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 leaves the rotor 10 when the housing 11 is compressed, the pointed end of the pin 19 facilitates reintroduction of the pin 19 into the opening at the distal end of the rotor 10 when the housing 11 is expanded again. Preferably, the pin 19 is long enough to allow the pin 19 to remain 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 for the required bearing clearance to exist over the full length of the pin 19 for proper function. On the contrary, it is sufficient that the bearing clearance between the outer side of the pin 19 and its opposing bearing surface is between 1 and 10 μm, more preferably between 2 and 8 μm wide at at least one location.

[0099] In this embodiment, rather than providing a bottom or step in the opening at the distal end of the rotor 10, the static support member 18 may be provided with a shoulder against which the rotor 10 abuts in the expanded state of the housing 11, thereby limiting further expansion of the housing 11, if desired. In some embodiments, the distal bearing 14 may be a radial bearing only.

[0100] Likewise, a cleaning fluid may be supplied through the fluid line 15 of the drive shaft 12 toward the distal bearing 14, passing through the pin 19 forming the distal radial bearing for the rotor 10, and discharged 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 may not be cleaned. Therefore, there may be no fluid line 15.

[0101] In addition, Figure 5 In the illustrated embodiment, the pin 19 is received within the central tube 15 of the rotor 10 when the housing 11 is expanded. In this case, for example, the drive shaft 12 may terminate at the distal end surface of the rotor 10. Alternatively, the distal end of the drive shaft 12 may be located inside the rotor 10, for example, as Figure 4A At the level of the bottom of the recess 17 as seen in the embodiment of FIG. 1 , so as to form a stop for the pin 19 .

[0102] Fig. 6A , Figure 6B , Figure 6C and Fig.6D A third embodiment of a pump portion 4 is shown having a compressible housing 11 and a static support member 18 attached to the housing 11. The rotor 10 comprises a nose 21 at its distal end. Fig. 6A , Figure 6B and Figure 6C In the embodiment, the fluid line 15 inside the distal end of the drive shaft 12 leads to an opening in the nose 21 through which the cleaning fluid can enter the bearing clearance of the distal bearing 14 between the nose 21 and a corresponding recess 22 at the proximal end of the static support member 18. However, in Fig.6D In the embodiment, the distal bearing 14 is not cleaned. Therefore, Fig.6D The embodiment in does not have the fluid line 15 and the opening in the nose 21. The non-cleaning distal bearing 14 can reduce the amount of cleaning fluid required to operate the intravascular blood pump 1. In combination with the non-cleaning proximal bearing 13, the intravascular blood pump 1 may not require cleaning fluid at all.

[0103] When the housing 11 is compressed, the nose 21 moves out of the recess 22, so that the intravascular blood pump 1 becomes more flexible. When the housing 11 is expanded at the target site, the nose 21 automatically moves into the recess 22, wherein the conical or spherical or other gathered shape of the nose 21 helps guide the nose 21 into the recess 22 and center the rotor 10 relative to the static support member 18. Figure 6B An enlarged section of the distal bearing 14 is shown with the nose 21 at the rotor 10 and the corresponding recess 22 . Figure 6B The vertical dot-dash lines in the Figure 6C cross-sectional plane. 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 gap between the recess 22 and the nose 21, the nose 21 and the opening of the fluid line 15 into the distal bearing gap.

[0104] Figure 7 An intravascular blood pump 1 with its catheter 5 and its pump part 4 is schematically shown. In this embodiment, the intravascular blood pump 1 comprises a proximal bearing 13 inside the distal end of the catheter 5. Inside the proximal bearing 13, an 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 windings 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 cleaning fluid also flows through the drive shaft 12 into the rotor 10.

[0105] 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.

[0106] The outer diameter of the bearing sleeve 24 of the proximal bearing is preferably between 0.5mm and 2mm, more preferably between 0.8mm and 1.8mm, and most preferably between 0.9mm and 1.2mm. The bearing clearance of the proximal bearing 13 is preferably between 1µm and 10µm, more preferably between 2µm and 8µm.

[0107] The cleaning fluid flows from the drive shaft 12 inside the rotor through the fluid line 15 into the recess 17 of the rotor 10. The sleeve of the distal bearing 25 of the rotor 10 is arranged in the recess 17. 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 gap between the sleeve of the distal bearing 25 and the pin 19.

[0108] 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.

[0109] Fig. 8A The cleaning fluid path inside the intravascular blood pump is schematically shown. Inside the housing of the motor 8, the cleaning fluid is supplied into the catheter 5 and into 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 gap to reduce friction and cool the proximal bearing 13. A portion of the cleaning fluid does not leave the catheter 5 through the bearing gap, but flows into the rotor 10 through the drive shaft 12. In some embodiments, the drive shaft 12 may include a cover so 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 pipeline 15 and then enters the recess 17 at the distal end of the rotor 10. In an alternative embodiment, the drive shaft 12 may continue to or enter the recess 17 so that the cleaning fluid flows directly from the drive shaft 12 into the recess 17. From there, the cleaning fluid flows through the bearing clearance of the distal bearing 14 between the pin 19 and the adjacent surface of the rotor 10 .

[0110] Figure 8B Shows something like Fig. 8A Embodiment of a blood pump. Figure 8BThe proximal bearing 13 is Fig. 8A The rotor 10 is closer to the rotor 10 and is separated from the rotor 10 by only a small gap. Through the gap, the cleaning fluid can leave as shown by the arrow.

[0111] Fig. 9A An example of a drive shaft 12 comprising an outer layer 28 and an inner layer 29 is shown. In this embodiment, the outer layer 28 and the inner layer 29 are composed of helically wound wires, wherein the helix of the inner layer 29 is right-handed and the helix of the outer layer 28 is left-handed. Fig. 9A As shown, a piece of outer layer 28 is removed from inner layer 29 and is shown separately. The removal of the piece of outer layer 28 can be performed 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 piece of outer layer 28 and the bearing sleeve 30 can be replaced on the inner layer 29 adjacent.

[0112] Fig. 9B A flexible bearing shaft 12 is shown with an outer layer 28 and an inner layer 29, wherein the outer layer 28 is absent in a central position and the bearing sleeve 30 is located on the inner layer 29 in said central position. Furthermore, on both sides of the bearing sleeve 30 and overlapping it are two protective rings 31, which are slipped over the end of the outer layer 28 facing the bearing sleeve 30. A shorter portion of the protective ring 31 overlaps the bearing sleeve 30, while a larger portion covers 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.

[0113] During assembly, the outer layer 28 can be cut and removed from one end of the drive shaft 12. In this regard, the drive shaft 12 is similar to Fig. 9A . Thereafter, a first protective ring 31 is placed on the end of the remaining outer layer 28. Then, a bearing sleeve 30 is placed on top of the inner layer 29 where the outer layer 28 was removed, overlapping the first protective ring 31. An outer bearing ring 32 is placed on top of the bearing sleeve 30. Then, the previously removed outer layer 28 is mounted again 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.

[0114] The bearing sleeve 30 is rotatably supported in an outer bearing ring 32, which in turn is fixed in a conduit or in the proximal end of a housing in which the rotor is housed. The bearing sleeve 30 and the outer bearing ring 32 form a radial bearing, while the protective ring 31 forms an axial stop and, in some embodiments, also forms an axial bearing with the outer bearing ring 32. The bearing sleeve 30 and the protective ring 31 together can be made of a single piece of material. As described above, the bearing sleeve 30 and the protective ring 31 are fixedly connected to the drive shaft 12, preferably glued. Glue is also used to fill the windings of the inner layer 29 and the outer layer 28 to prevent the cleaning fluid from leaking through the drive shaft 12.

[0115] 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.

[0116] Fig. 10A A hydraulically decoupled bearing sleeve 30 is shown, comprising a wall between two blind holes. The inner layer 29 is disconnected in the axial direction. Each blind hole of the bearing sleeve 30 receives a corresponding axial end of the axially disconnected inner layer 29. The bearing sleeve 30 does not allow any cleaning fluid to pass 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 welding 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.

[0117] Fig. 10B Another embodiment is shown, in which the outer bearing ring 32 forms a radial bearing with the bearing sleeve 30. In addition, the proximal protection ring 31a and the distal protection ring 31b are axially fixed relative to the bearing sleeve 30 in the manner described above. Fig. 10B If the drive shaft 12 moves in the proximal direction, the proximal protection 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 between the proximal surface of the distal protection ring 31b and the distal surface of the outer bearing ring 32 is

[0118] max

[0119] greater than the maximum distance c between the distal end surface of the limiting member 33 and the proximal end surface of the proximal end protection ring 31a

[0120] max

[0121] , then the distal protection 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.

[0122] If the rotor 10 is Fig.11A If the rotor is mounted on the distal protection ring 31b as shown, the distances a, b and c selected according to the above inequalities will prevent the rotor from touching the outer bearing ring 32. Similarly, if Fig. 11B As 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.

[0123] Fig. 12A An intravascular blood pump 1 is shown with a housing 11 and a rotor 10 mounted on a drive shaft 12. The proximal bearing 13 comprises 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 may be hollow to allow a 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 falling 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. Furthermore, 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. The 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 may be distributed circumferentially along the grooves 36 provided in both the limiting member 33 and the outer bearing ring 32. In addition, the radial through holes 34 may 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 the cleaning fluid.

[0124] from Fig. 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.

[0125] The cleaning fluid squeezed through the proximal bearing 13 from the proximal end to the distal end will first pass through the proximal portion 30a of the bearing sleeve 30 along the radial outer surface of the proximal portion 30a of the bearing sleeve 30, then flow radially inward 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 flow further in the distal direction through the bearing gap formed radially between the distal portion 30b of the bearing sleeve 30 and the radial inner surface of the outer bearing ring 32. The bearing gap can be designed to have a very small tolerance so that the cleaning fluid can flow through the bearing gap in a tightly controlled manner by applying appropriate pressure to the cleaning fluid from the proximal end. 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 to the radial bearing gap between the outer bearing ring 32 and the distal portion 30b of the bearing sleeve 30.

[0126] Fig. 12B Shows Fig. 12A Here, the drive shaft 12 has a portion with a reduced diameter, and the distal end portion 30b of the bearing sleeve 30 is arranged at the portion with a reduced diameter. Fig. 12B Specifically shown in FIG. 3 , the outer diameter of the outer bearing ring 32 can be reduced accordingly, so that, 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.

[0127] like Fig. 12B The structure of the bearing sleeve 30 shown is similar to that described above. Fig. 10A and Fig. 10B More specifically, the proximal portion 30a of the bearing sleeve 30 corresponds to the proximal protection ring 31a (see Fig. 10B ). Therefore, in Fig. 12B In the embodiment shown, a distal bearing ring 31b is also provided which overlaps the distal ends of both the drive shaft 12 and the distal portion 30b of the bearing sleeve 30. Fig. 10A and Fig. 10B The axial movement of the drive shaft 12 within the outer bearing ring 32 is limited in the same manner as described.

[0128] Fig.13A A graphical representation of the stationary surface of a hydrodynamic axial bearing is shown. Specifically, Fig.13A The proximal end surface of the outer bearing ring 32 with the drive shaft 12 located centrally is shown. Fig.13A The curved radial lines in the figure represent raised portions of the bearing surface. Fig. 13B is shown in more detail in . Fig.13A and Fig. 13BThe arrows in the figure show the direction of movement of the opposing surfaces. This corresponds to the direction of movement of the lubricating film in the axial bearing gap. The surface has an inclined surface which, together with the flat opposing stationary surface, forms a converging gap. This causes a build-up of hydrodynamic pressure in the lubricating film. As a result, the surfaces forming the axial bearing gap are kept at a certain distance.

[0129] Fig. 13C The bearing sleeve 30 and the outer bearing ring 32 in the housing 11 are shown. The bearing sleeve 30 has a flat distal surface. Here, the opposite proximal surface of the outer bearing ring 32 is inclined to form a narrowing gap. During use, this forms the lubricating film required for the hydrodynamic bearing.

[0130] Fig.13D The spiral groove of the proximal bearing surface of the outer bearing ring 32 in another embodiment is shown. The spiral groove is preferably configured 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 provided in a spiral shape in the distal surface of the proximal portion 30a of the bearing sleeve 30. When the bearing sleeve 30 is moved along Fig.13D When the bearing rotates in the direction indicated by the arrow in the figure, the lubricating film is transported radially inward along the grooves and creates pressure between the bearing surfaces, keeping them separated.

Claims

1. An intravascular blood pump (1), comprising: Catheter (5); a housing (11) in which a rotor (10) is housed, the housing (11) being attached to a distal end of the catheter (5); a flexible drive shaft (12) extending through the catheter (5) and connected to the rotor (10), the drive shaft (12) being rotatably supported in a proximal bearing (13) located at the proximal end of the rotor (10); The proximal bearing (13) comprises a bearing sleeve (30) and an outer bearing ring (32), wherein the bearing sleeve (30) comprises a proximal portion (30a) located proximal to the outer bearing ring (32), the proximal portion (30a) of the bearing sleeve (30) together with the proximal surface of the outer bearing ring (32) forming an axial bearing of the proximal bearing (13), and The bearing sleeve (30) includes a distal portion (30b) extending distally from the proximal portion (30a) of the bearing sleeve (30) into the outer bearing ring (32), wherein the distal portion (30b) of the bearing sleeve (30) together with the outer bearing ring (32) forms a radial bearing of the proximal bearing (13).

2. Intravascular blood pump (1) according to claim 1, wherein the bearing sleeve (30) is fixedly connected to the flexible drive shaft (12).

3. An intravascular blood pump (1) according to claim 1 or 2, wherein the outer bearing ring (32) is located in the distal end region of the catheter (5) or in the proximal end region of the housing (11).

4. An intravascular blood pump (1) according to claim 1 or 2, wherein a limiting member (33) that limits the axial movement of the bearing sleeve (30) relative to the outer bearing ring (32) is located at the proximal end of the bearing sleeve (30) in at least one of the catheter (5) and the housing (11).

5. Intravascular blood pump (1) according to claim 1 or 2, wherein the flexible drive shaft (12) is at least partially filled with a sealant.

6. Intravascular blood pump (1) according to claim 1 or 2, wherein at least one of the bearing sleeve (30) and the outer bearing ring (32) comprises at least one of the following materials: ceramic and metal.

7. Intravascular blood pump (1) according to claim 1 or 2, wherein at least one of the bearing sleeve (30) and the outer bearing ring (32) comprises a coating.

8. An intravascular blood pump (1) according to claim 1 or 2, wherein one or both of the proximal end region of the housing (11) or the distal end region of the catheter (5) comprises one or more radial through holes.

9. An intravascular blood pump (1) according to claim 1 or 2, wherein the flexible drive shaft (12) comprises a reinforcing element (35) which extends longitudinally within a central lumen of the drive shaft (12).

10. The intravascular blood pump (1) according to claim 1 or 2, wherein a radial bearing clearance between the outer bearing ring (32) and the bearing sleeve (30) is between 2 μm and 10 μm.

11. An intravascular blood pump (1) according to claim 1 or 2, wherein the bearing sleeve (30) includes 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).

12. Intravascular blood pump (1) according to claim 1 or 2, wherein the rotor (10) is located at a distance of between 0.001 mm and 8 mm from the outer bearing ring (32).

13. The intravascular blood pump (1) according to claim 1 or 2, comprising a rinsing fluid supply line arranged to supply rinsing fluid such that the rinsing fluid flows through a gap defined by the radial bearing.

14. An intravascular blood pump (1) according to claim 1 or 2, 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 in the portion with a reduced diameter.

15. Intravascular blood pump (1) according to claim 1 or 2, wherein the rotor (10) and the housing (11) are radially expandable.

16. The intravascular blood pump (1) according to claim 10, wherein the radial bearing clearance between the outer bearing ring (32) and the bearing sleeve (30) is between 3 μm and 4 μm.

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