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 flexible drive shaft (12) extending through the catheter (5) and connected to the rotor. The drive shaft (12) comprises at least one outer layer (28) and at least one inner layer (29). The drive shaft (12) is rotatably supported in a proximal bearing (13) located at the proximal end of the rotor (10). An outer layer (28) of the drive shaft (12) is absent or thinned at a position where the drive shaft (12) is supported in the proximal bearing (13).

Description

[0001] Divisional application

[0002] This application is a divisional application of the patent application with the international application date of January 28, 2021, application number 202180011952.1, the date of entry into the Chinese national phase on July 29, 2022, and the invention name being "Intravascular Blood Pump". Technical Field

[0003] The present invention relates to an intravascular blood pump, in particular a percutaneously insertable blood pump for supporting blood circulation in humans or 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

[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 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.

[0005] The above-mentioned expandable type of blood pump is known, for example, from US2013 / 0303969A1, which discloses a catheter pump assembly. An expandable shell is located at the distal end of the catheter. The expandable shell surrounds an expandable 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 via a percutaneous approach using the Seldinger technique. The drive shaft contains a central lumen that allows a guidewire 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 document, "proximal" and "distal" refer to what is seen by the doctor. Therefore, when the catheter is placed, the proximal end refers to something that is relatively close to the doctor, while the distal end refers to something that is relatively far away from the doctor.

[0006] During insertion of an intravascular blood pump, it is advantageous for the catheter to be as small as possible, as this allows for better maneuverability of the intravascular blood pump through the patient's vasculature.Therefore, there is a need to reduce the outer diameter size of the catheter of an intravascular blood pump. Summary of the Invention

[0007] According to a first aspect of the present invention, an intravascular blood pump comprises a catheter and a housing, a rotor being housed in the housing, and the housing being attached to the distal end of the catheter. Furthermore, in the intravascular blood pump disclosed herein, a flexible drive shaft extends through the catheter and is connected to the rotor, the drive shaft comprising at least one outer layer and at least one inner layer. The drive shaft is rotatably supported in a proximal bearing located proximal to the rotor. 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 anywhere in the catheter, and there can even be multiple proximal bearings, the term "proximal" here meaning that the bearing is located anywhere proximal to the rotor. At least one outer layer of the drive shaft is absent or thinned at the location where the drive shaft is supported in the proximal bearing.

[0008] Preferably, the axial length of the location where at least one outer layer is absent or thinned is 1 to 15 times, preferably 2 to 5 times, the diameter of the drive shaft in the thinned portion, for example, between 2 mm and 5 mm. At least one outer layer and at least one inner layer are made of a flexible material, preferably metal. In some embodiments, at least one of the inner layers can be a wire or cable.

[0009] The drive shaft preferably extends through the entire catheter. The drive shaft is preferably hollow. The drive shaft is preferably composed of or includes a flexible cable, which is preferably formed by fiber layers of different orientations. In particular, the 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 drive shaft may include two coaxial windings with opposite winding directions, and the outer diameter of the drive shaft may be between 0.4 mm and 2 mm, preferably between 0.6 mm and 1.2 mm, particularly preferably between 0.8 mm and 1.0 mm. The proximal end of the drive shaft is preferably attached to an extracorporeal electric motor. The 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 drive shaft may include a hard rigid shaft at its distal end, to which the rotor is attached inside the housing to provide stability for the rotor.

[0010] In some embodiments, at least one of the outer layer and / or 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 be braided, for example similar to the outer sheath of a kernmantle rope. The windings of a 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 spiral hands, for example alternating hands 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.

[0011] Preferably, the drive shaft is at least partially filled with a sealant that penetrates into at least one inner layer. More preferably, the sealant penetrates into all layers, i.e. at least one outer layer and at least one inner layer. In this case, the sealant is a substance that can penetrate into the layers as a fluid and then harden sufficiently to prevent the cleaning fluid from penetrating through the corresponding 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 drive shaft, can be partially or completely filled with sealant. Examples of sealants for the purposes of the present invention are adhesives, polymers and / or thermoplastics.

[0012] For example, the proximal bearing is configured to be cleaned with a cleaning fluid. The cleaning fluid reduces friction and removes frictional heat from the proximal bearing. It also prevents blood from entering through the bearing gap. If the cleaning fluid could flow through the drive shaft in addition to the bearing gap during its passage through the proximal bearing, it would be difficult to establish a defined cleaning fluid flow. Therefore, if the drive shaft is filled with a sealant, this can prevent the cleaning fluid from flowing through the drive shaft and promote the formation of a defined cleaning fluid flow through the proximal bearing.

[0013] Preferably, at a position where at least one outer layer of the drive shaft is absent or thinned, the bearing sleeve surrounds at least one inner layer or the at least one thinned outer layer, and the bearing sleeve forms the inner surface of the proximal bearing. The bearing sleeve may be a hollow cylinder surrounding at least one inner layer or the at least one thinned outer layer. If the drive shaft inside the bearing sleeve is filled with a sealant, it is possible to advantageously prevent the cleaning fluid from flowing through the bearing sleeve. However, in some cases, it may be difficult to completely fill the sealant in a drive shaft with multiple layers. This may result in residual cleaning fluid flowing through the drive shaft. In some embodiments, there is only one inner layer, and this inner layer and at least one outer layer are composed of wound filaments. At the same time, at least one outer layer may be completely removed at the position of the sleeve. In a design with more than two outer layers, one outer layer or multiple outer layers may be removed so that only at least one inner layer remains. In this case, filling the interior of the bearing sleeve with the sealant with at least one inner layer may be particularly effective in blocking the flow through the drive shaft. This is because the sealant does not have to penetrate into the space between the layers to completely seal the interior of the bearing sleeve. The bearing sleeve can advantageously provide a smooth inner bearing surface in the proximal bearing.

[0014] 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 the at least one thinned outer layer. The outer diameter of the bearing sleeve is approximately equal to the outer diameter of at least one outer layer of the drive shaft, and preferably may be slightly larger than at least one outer layer of the drive shaft to facilitate equipment assembly. In this way, the inner radial bearing surface of the proximal bearing corresponds to the outer diameter of the drive shaft, and preferably may be slightly larger than at least one outer layer of the drive shaft to facilitate equipment assembly.

[0015] At least one inner layer may be axially disconnected within the bearing sleeve. If at least one inner layer is axially disconnected inside 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 disconnection, before the next successive portion of at least one outer layer can be installed on at least one inner layer, at least one inner layer must be fed through the bearing sleeve. This is particularly advantageous in embodiments where at least one inner layer extends distally beyond the proximal bearing.

[0016] In some embodiments, the internal space of the bearing sleeve is hydraulically separated, that is, 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. Then the two ends of at least one axially disconnected inner layer can be respectively inserted into the corresponding one of the blind holes. The wall between the holes prevents any cleaning fluid from flowing through the bearing sleeve, so that at least one axially disconnected inner layer does not need to be sealed, but only attached to the bearing sleeve.

[0017] Preferably, the bearing sleeve is fixedly attached to the at least one inner layer or the at least one thinned outer layer of the drive shaft. The at least one bearing sleeve can be crimped, welded, fused, glued, or shrink-fitted to the at least one inner layer or the at least one thinned outer layer. Gluing the bearing sleeve advantageously prevents any deformation or warping of the bearing sleeve.

[0018] The proximal bearing preferably comprises a bearing sleeve and an outer bearing ring, wherein the bearing sleeve is rotatably supported in the outer bearing ring. Thus, the bearing sleeve and the outer bearing ring form a radial bearing.

[0019] 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 approximately 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 an appropriate cleaning fluid pressure.

[0020] Preferably, the bearing sleeve and / or outer bearing ring comprise one or more ceramics and / or metals. The metal is preferably MP35, 35NLT, Nitinol, or stainless steel. In the case of metal, the bearing sleeve and / or outer bearing may include a coating, preferably a hard coating, such as a DLC coating. Advantageously, designing the bearing sleeve and / or outer bearing ring in this manner allows the proximal bearing to be lightweight and durable.

[0021] In a preferred embodiment, one or more protective rings may be provided that extend over at least one outer layer of the drive shaft and corresponding portions of the bearing sleeve. This effectively reduces the risk of drive shaft fracture due to stiffness changes at the transition between at least one inner layer of the drive shaft, which has a smaller diameter, and at least one outer layer of the drive shaft, which has a larger diameter. Preferably, a distal protective ring is provided to extend over the distal portions of the drive shaft and the bearing sleeve, and a proximal protective ring is provided to extend over the proximal portions of the drive shaft and the bearing sleeve. Alternatively, the bearing sleeve and one protective ring may form a single, integral component.

[0022] The proximal bearing, comprising a bearing sleeve and a protective ring, can preferably be assembled as follows. The at least one inner layer and the at least one outer layer of the drive shaft can be mechanically separated from each other, or they can be assembled during production so that the at least one inner layer protrudes from the at least one outer layer. After mechanically separating the at least one outer layer from the at least one inner layer, the at least one outer layer is pulled out of the at least one inner layer while being slightly rotated. A first protective ring is placed over the at least one outer layer of the drive shaft, with the longer portion of the first protective ring mechanically or otherwise secured to the at least one outer layer of the drive shaft. The shorter portion of the first protective ring overlaps the at least one inner layer of the drive shaft. A low-viscosity adhesive is then introduced into the overlapped area and used to glue the bearing sleeve to the at least one inner layer of the drive shaft. The bearing sleeve is positioned so that it protrudes into and overlaps the first protective ring. After the adhesive cures, the combination of the drive shaft, first protective ring, and bearing sleeve can be tested for liquid impermeability. The outer bearing ring is then positioned over the bearing sleeve. The at least one previously removed outer layer is pushed onto the at least one inner layer until it contacts the bearing sleeve and glued into place. A second protective ring is then placed on top of the at least one previously removed outer layer, overlapping the bearing sleeve. The second protective ring is positioned so that a predetermined axial play is established between the outer bearing ring and the bearing sleeve. The overlap of the bearing sleeve and the protective ring may result in radial stabilization of the bearing sleeve and may prevent abrupt changes in stiffness at the ends of the bearing sleeve. The second protective ring is then mechanically or otherwise secured to the drive shaft. Securing the protective ring to the at least one outer layer further prevents the at least one outer layer from loosening. The protective ring preferably has an inner diameter that is at least as wide as the outer diameter of the bearing sleeve. The protective ring preferably surrounds the end of the at least one outer layer adjacent to the bearing sleeve.

[0023] In some embodiments, a proximal protection ring, overlapping the bearing sleeve, can be positioned axially between the outer bearing ring and the restraining member. The restraining member acts as a limiter to restrict axial movement of the drive shaft relative to the outer bearing ring. In one embodiment, a rotor or rotor shaft mounted distally to the outer bearing ring can form the distal protection ring. In this case, the restraining member advantageously prevents the rotor or rotor shaft from contacting the outer bearing ring.

[0024] As described above, the proximal bearing is preferably located in the distal end region of the catheter and / or the proximal end region of the housing. The outer bearing ring is preferably fixed to the proximal end portion of the catheter and / or the housing. If the proximal bearing is cleaned, the cleaning fluid can exit the catheter through the bearing clearance of the proximal bearing. The inner diameter of the outer bearing ring of the proximal bearing is preferably between 0.6 mm and 2.2 mm, more preferably between 0.9 mm and 1.3 mm. The bearing clearance of the proximal bearing is preferably between 1 μm and 10 μm, more preferably between 2 μm and 8 μm.

[0025] Preferably, the protective ring is fixedly connected to the drive shaft.Preferably, the protective ring is crimped, welded, melted, glued or shrunk onto the at least one outer layer and / or the bearing sleeve.

[0026] Preferably, the protective ring comprises one or more ceramics and / or metals, in particular MP35, 35NLT, Nitinol or stainless steel. In the case of metal, the protective ring may be hard-coated, for example DLC-coated.

[0027] Preferably, at least the proximal protective ring provides an axial bearing surface in the proximal bearing. The surface of the proximal protective ring facing the outer bearing ring preferably forms an axial bearing with the opposing surface of the outer bearing ring. The distal and proximal protective rings preferably form stop elements for the outer bearing ring to prevent it from slipping off the bearing sleeve.

[0028] 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 the outer and / or inner windings thereof. The first adhesive can be a sealant. The first adhesive preferably has a particularly low viscosity to be able to completely penetrate the outer and / or inner windings. 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. The second adhesive is preferably used to connect the sleeve and / or at least one protective ring to the 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.

[0029] According to a particularly preferred embodiment, the bearing sleeve extends into the rotor. Typically, the bearing sleeve is harder 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.

[0030] 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 about 3.5 μm wide.

[0031] The intravascular blood pump may further include a distal bearing for rotatably supporting the distal end of the rotor. The distal bearing is located within or at the distal end of the rotor. Preferably, the distal bearing includes a static support member that protrudes into or abuts 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.

[0032] In another embodiment, the drive shaft is not supported in a distal bearing. Instead, the rotor can be 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 the static support member extending into or against the rotor. In this way, tendon structures are less likely to become stuck on 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 lifespan.

[0033] Preferably, the bearing sleeve includes a proximal portion located proximally of the outer bearing ring and forming an axial bearing with the proximal surface of the outer bearing ring. The bearing sleeve preferably includes 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 described proximal bearing design advantageously achieves low friction and high durability, particularly when a cleaning fluid is provided to flow through the radial bearing.

[0034] This particular design of bearing sleeve is particularly useful for proximal bearings that are positioned next to the rotor rather than deep within the conduit. In this case, the outer bearing ring is located, and in particular, fixedly connected, within the distal end region of the conduit or within the proximal end region of the housing. The outer bearing ring can be press-fitted and / or glued into the conduit and / or housing. In some embodiments, the outer bearing ring can be assembled to both the housing and the conduit, thereby connecting the housing to the conduit. The proximal bearing located at the distal end of the conduit or the proximal end of the housing provides a particularly stable support for the drive shaft and rotor.

[0035] The above-mentioned limiting member can be located at the proximal end of the bearing sleeve inside the conduit and / or housing to prevent the bearing sleeve from sliding out of the outer bearing ring. Preferably, the inner diameter of the limiting member is slightly larger than the diameter of the flexible drive cable to avoid friction contact with it and allow the cleaning fluid to pass through.

[0036] 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 can increase the elasticity to allow the proximal bearing to be press-fitted into the housing and / or the catheter. The through holes further allow the introduction of glue and position monitoring when inserting the proximal bearing. It is worth noting that the glue is used to seal the gap between the bearing and the housing to avoid leakage of the cleaning fluid, that is, care should be taken to completely fill the gap. The diameter of the radial through hole can be between 0.5 mm and 1 mm. Elongated holes extending 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 hole.

[0037] Preferably, the flexible drive shaft includes a reinforcing element longitudinally extending within the central lumen of the drive shaft, preferably a coaxial rigid 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, such as made of spring steel, wire or carbon fiber. In one embodiment, the wire is made of 1.4310 stainless steel.

[0038] The bearing sleeve includes a portion extending distally from the outer bearing ring, and the rotor can be mounted on the portion extending distally from the outer bearing ring. This design can allow for a particularly stable construction of the rotor. In particular, the bearing sleeve can extend along a major part of the axial length of the rotor, more preferably extending to the distal end of the rotor.

[0039] The rotor is preferably at a distance between 0.001 mm and 8 mm from the distal surface of the outer bearing ring. The minimum distance between the rotor and the proximal bearing is desired as this can prevent the rotor from getting stuck in the proximal bearing.

[0040] The intravascular blood pump is preferably designed as an inflatable blood pump having a housing with an inflatable portion. In some embodiments, the housing comprises or consists of a shape memory material, particularly nitinol. The diameter of a percutaneously insertable blood pump is typically limited by the inner diameter of the smallest blood vessel to be traversed. 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 be inflated. This allows for the percutaneous insertion of a larger blood pump into the heart compared to possible other means. Using such a larger blood pump, a higher blood flow rate may be achieved.

[0041] When the blood pump is designed as an inflatable 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 inflatable portion of the housing and the rotor are compressed from an inflated state to a compressed state at least in a radial direction transverse to the longitudinal extension. Preferably, a part of the rotor, such as rotor blades, or the entire rotor, is also inflatable to allow for the insertion of a larger rotor into the heart, which can increase the flow rate.

[0042] In some embodiments, the static support member of the distal bearing protrudes to abut 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 placed only 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 maneuvering of the pumping device through a blood vessel. When the pump portion reaches its final destination inside the heart, it can be straightened, and the static support member can be restored to its position in which it protrudes to abut the distal end of the rotor.

[0043] Preferably, a static support member is attached to the distal end of the housing, wherein expansion of the housing can 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 can 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 includes 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 into the correct relative position after expansion of the housing. The nose preferably protrudes from the surrounding surface of the rotor by 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. The depth of the recess in the static support member corresponds to that of 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 includes an axial stop for the static support member, such as a recess having a bottom or step at its distal end. The bottom or step defines an axial stop for the proximal end of the static support member within the distal end of the rotor. This is particularly advantageous in the context of expandable blood pumps. In its expanded state, the proximal end of the static support member, which protrudes axially into the rotor, can contact the axial stop, thereby preventing further expansion of the housing and thereby limiting the width of the radial gap between the outer edges 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 can form a gap, 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 wide.

[0047] 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, 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 direct 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 direct a cleaning fluid through the hollow portion of the rotor to the distal bearing. The cleaning fluid can be delivered to the fluid line via a catheter. The cleaning fluid can enter the catheter and / or the drive shaft within the motor housing. The cleaning fluid can 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 completely through the drive shaft lumen. The cleaning fluid can flow through the drive shaft from the distal end of the catheter to the rotor. The drive shaft can include a cover in at least the space between the distal end of the catheter and the proximal end of the rotor to prevent the cleaning fluid from leaking out of the space.

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

[0050] In the distal end region of the catheter, the cleaning fluid is preferably transferred into 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, the 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 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 can allow for higher rotational speeds, lower power consumption, and a longer blood pump lifespan. 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.

[0052] In an alternative embodiment, the proximal and / or distal bearings are not cleaned. Thus, 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 such that the cleaning fluid can flow out between the static support member and the distal end of the rotor, where the static support member projects 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 may be arranged such that any cleaning fluid passing through the hollow drive shaft or the rotor shaft flows out through the distal bearing entirely or at least in part. 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 projecting 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.

[0054] 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.

[0055] The static support member preferably includes a pin that extends from a distal end to a proximal end and projects 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.

[0056] 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.

[0057] Preferably, the inner diameter of the distal end of the rotor where the static support member, particularly the pin, axially projects into 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.

[0058] In some embodiments, the pin is particularly long and projects into the rotor and extends proximally through the entire rotor. Preferably, the pin exits the rotor at the proximal end and continues inside the drive shaft, for example, terminating within the proximal bearing. In this case, the end of the pin can be arranged inside the portion of the drive shaft that is within the proximal bearing. By using such a long pin that extends through the entire length of the rotor and into the proximal bearing, a particularly rigid and low-vibration pump can be formed. Alternatively, the pin can further extend 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 a drive shaft that is hollow only along a portion of its length.

[0059] Preferably, the material of the pin 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 pin can include a coating, such as a hard coating, such as a diamond-like carbon (DLC) coating.

[0060] Preferably, during the operation 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, 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 blade must not touch the inner surface of the housing, and the gap should be large enough to prevent blood damage. A harder supported rotor can also operate with lower offset and less vibration, thus improving blood compatibility.

[0061] When the housing and the rotor are in a compressed state, the pin can have a length sufficient to remain within the distal end of the rotor. The length of the pin 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 member, particularly the pin, extending into the distal end of the housing may completely move out of the rotor. Then, when the housing expands again, the pin may not move back into the rotor, and the pump may not operate properly. Therefore, if the selected pin has a sufficient length such that the pin remains inside the rotor even in the compressed state of the housing, this problem can be avoided.

[0062] In embodiments with pins, the distal bearing surface is the surface of the pin and the distal outer bearing surface, which can 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 can be provided by the above-mentioned strengthening element.

[0063] The sleeve of the distal bearing can 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 or polyurethane. Preferably, the flexible atraumatic tip is designed to be pigtail or J-shaped.

[0065] According to a second aspect of the present invention, the above-mentioned intravascular blood pump is used in a patient's body, that is, it is inserted and operated in the patient's body to support blood flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] 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.

[0067] For clarity, not every component is labeled in every figure. In the figures:

[0068] Figure 1 A schematic diagram of an intravascular blood pump located within the left ventricle of the heart is shown;

[0069] Figure 2 A schematic diagram of an intravascular blood pump is shown;

[0070] Figure 3A and Figure 3B A schematic diagram showing an intravascular blood pump in an expanded state and a compressed state;

[0071] 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 the rotor according to a first embodiment;

[0072] 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;

[0073] Figures 6A to 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;

[0074] Figure 7 A schematic diagram of an intravascular blood pump having a proximal bearing and a distal bearing is shown;

[0075] Figure 8A and Figure 8B A schematic diagram showing the path of a cleaning fluid in an intravascular blood pump;

[0076] Figure 9A A drive shaft comprising an outer layer and an inner layer is shown;

[0077] Figure 9B A drive shaft with a bearing sleeve, an outer bearing ring and a protective ring is shown;

[0078] Figure 10A The hydraulically separated bearing sleeve is shown;

[0079] Figure 10B A bearing with a restraining member is shown;

[0080] Figure 11A and Figure 11B A bearing with a restraining member and a rotor is shown;

[0081] Figure 12A and Figure 12BTwo different embodiments of a proximal bearing with an outer bearing ring and a specially formed bearing sleeve are shown;

[0082] Figures 13A to 13D A hydrodynamic axial bearing is shown. DETAILED DESCRIPTION

[0083] 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.

[0084] 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 houses a drive shaft 12 driven by an electric motor 8, which is preferably located outside the patient's body. The drive shaft 12 drives the rotor contained within the pump portion 4. At its distal end, the pump portion 4 has a flexible, atraumatic tip 9 in the form of a pigtail or J-shape, which facilitates the placement of the blood pump 1 within a blood vessel by assisting in its navigation within the patient's vascular system. In addition, the softness of the flexible, atraumatic tip 9 allows the pump portion 4 to atraumatically support itself against the wall of the left ventricle 2.

[0085] Figure 2The intravascular blood pump 1 is shown in greater detail. A rotor 10 is located within a housing 11. In this embodiment, both the rotor 10 and the housing 11 are compressible. In this state, the intravascular blood pump 1 is delivered through the patient's vascular system with both the rotor 10 and the housing 11 in their compressed states. Once the pump portion 4 is in its target position, the housing 11 and rotor 10 are expanded. A 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. The drive shaft 12, with the rotor 10 disposed at its distal end, can be seen protruding from the distal end of the catheter 5. As the rotor 10 within the housing 11 rotates via the drive shaft 12, blood is drawn into the blood inlet 6 at the distal end of the housing 11 and, through the housing 11, into the downstream conduit 20, which is attached to the housing 11 and extends proximally. The blood is then discharged from the downstream conduit 20 into the aorta through a blood outlet 7 disposed more proximally therein, which includes multiple outlet openings. 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. Downstream conduit 20 generally expands primarily due to the active blood flow generated by rotor 10 during rotation. By placing blood inlet 6 within left ventricle 2 and blood outlet 7 within the aorta, intravascular blood pump 1 can support the patient's systemic blood circulation. If the intravascular blood pump 1 is configured and positioned differently, it can be used to support the patient's pulmonary blood circulation, for example.

[0086] 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, as will be combined with Figure 4A 、 Figure 4C and Figure 5 As 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 (approximately 1.5 bar).

[0087] 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 shown).

[0088] Figure 3A and Figure 3B respectively show the pump section 4, its rotor 10, and the housing 11 in the expanded state and the compressed state. The cannula 16 is disposed at the distal end of the conduit 5. Initially, before the intravascular blood pump 1 is deployed, the pump section 4 is disposed inside the cannula 16 in its compressed state. The cannula 16 can be the cannula 16 belonging to the conduit 5 or a peel-away sheath for assisting in inserting the conduit 5 into the patient's body. When the doctor determines that the conduit 5 is properly 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 and / or due to its superelastic 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.

[0089] 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 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 pulls the housing 11 back into the cannula 16, which causes the housing 11 to compress radially and extend longitudinally, so that the distal end of the housing 11 together with the static support member 18 and its pin 19 move 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.

[0090] In the prior art distal bearing 14, the drive shaft 12 sometimes extends distally into the rotor 10 and into the distal bearing 14. However, this may 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 the static support member 18, which 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.

[0091] Figure 4A and Figure 4B shows in more detail the pump section 4 according to the first embodiment, which includes 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 portion of the housing) at the distal end of the conduit 5 proximal to the rotor 10 and in a distal bearing 14 located at the distal end of the rotor 10. In 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 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 reinforced, for example by injection molding a 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 reinforced 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 slipped over the thinned end and extended distally to form the rotor shaft and the bearing portion. Cleaning fluid can be delivered to the distal bearing 14 through 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 extended distally to form the rotor shaft and the bearing portion. Cleaning fluid can be delivered to the distal bearing 14 through the fluid line 15 in the rotor shaft. Figure 4A In the illustrated embodiment, a cleaning fluid can 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.

[0092] 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 wall of the heart, 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 the damage to the 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 the diameter of the rotor 10 to be larger, which allows a higher flow rate of the intravascular blood pump 1 without the housing 11 touching the rotor 10.

[0093] 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 with its pin 19 into the recess 17 . Figure 4AThe bottom 19 of the recess 17 therein 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 Figure 4A therein, the fluid line 15 penetrates the bottom of the recess 17 to allow the cleaning fluid to exit the distal bearing 14 between the pin 19 and the recess 17.

[0094] Figure 4B The embodiment of the intravascular blood pump 1 therein is similar to Figure 4A the embodiment in Figure 4B However, importantly, Figure 4B the distal bearing in

[0095] 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 cleaning fluid at all. Figure 4C In the embodiment of

[0096] the pin 19 is particularly long and extends proximally through the rotor shaft and into the drive shaft 12. In Figure 4C the embodiment of

[0097] Figure 4C the proximal bearing 13 in Figure 4A and Figure 4B is located inside the housing 11, distal to the position of the proximal bearing 13 in

[0098] Figure 4C The pin 19 in Figure 4CThe long pin 19 may be combined with a drive shaft that is only partially hollow along its length.

[0099] Figure 5 A pump portion 4 according to a second embodiment is shown, also having a compressible housing 11 and a rotor 10 driven by a hollow drive shaft 12. The hollow drive shaft 12 is rotatably supported in a proximal bearing 13 disposed 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 pin 19 are such that the pin 19 exits 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 re-expands. Preferably, the pin 19 is long enough to remain within the rotor 10 when the housing 11 is compressed. This avoids situations where the pin 19 cannot re-enter the rotor 10 when the housing 11 expands. In some cases, the required bearing clearance is not necessary along the entire length of the pin 19 for proper function. On the contrary, it is sufficient that the bearing gap between the outer side of the pin 19 and its opposing bearing surface is between 1 μm and 10 μm, more preferably between 2 μm and 8 μm wide at at least one location.

[0100] 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.

[0101] Likewise, cleaning fluid can be supplied through fluid line 15 of drive shaft 12 toward distal bearing 14, passing through pin 19 forming a distal radial bearing for rotor 10, and exiting at the distal end of rotor 10. This prevents blood from entering rotor 10, reduces friction, and cools distal bearing 14. Alternatively, distal bearing 14 may not be cleaned. Thus, fluid line 15 may be omitted.

[0102] In addition, Figure 5 In the embodiment shown, when the housing 11 is expanded, the pin 19 is received within the central tube 15 of the rotor 10. 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, so as to form a stop for the pin 19.

[0103] Figure 6A 、 Figure 6B 、 Figure 6C andFigure 6D Shows 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 , a fluid line 15 inside the distal end of the drive shaft 12 leads to an opening in the nose portion 21 through which cleaning fluid can enter the bearing clearance of the distal bearing 14 between the nose portion 21 and a corresponding recess 22 at the proximal end of the static support member 18. However, in Figure 6D , the distal bearing 14 is not cleaned. Therefore, Figure 6D the embodiment in does not have a fluid line 15 and an opening in the nose portion 21. The non-cleaned distal bearing 14 can reduce the amount of cleaning fluid required to operate the intravascular blood pump 1. In combination with the non-cleaned proximal bearing 13, the intravascular blood pump 1 may not require cleaning fluid at all.

[0104] When the housing 11 is compressed, the nose portion 21 moves out of the recess 22, so that 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 center the rotor 10 relative to the static support member 18. Figure 6B Shows an enlarged cross-section of 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 through which the fluid line 15 enters the distal bearing clearance.

[0105] Figure 7 Schematically shows the intravascular blood pump 1 and its catheter 5 and its pump section 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, 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 winding portions of the drive shaft 12 are removed to reduce its diameter. Cleaning fluid can now flow through the catheter 5 and out of the proximal bearing 13 through its bearing clearance. Some cleaning fluid also flows through the drive shaft 12 into the rotor 10.

[0106] The sleeve 24 of the proximal bearing 13 can 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.

[0107] 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.

[0108] The cleaning fluid flows through 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, a 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.

[0109] The sleeve of the distal bearing 25 has an inner diameter that is 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.

[0110] Figure 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 clearance to reduce friction and cool the proximal bearing 13. A portion of the cleaning fluid does not leave the catheter 5 through the bearing clearance but instead 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 from there through the bearing clearance of the distal bearing 14 located between the pin 19 and the adjacent surface of the rotor 10.

[0111] Figure 8B Shows an embodiment of a blood pump similar to Figure 8A In Figure 8Bin which the proximal bearing 13 is closer to the rotor 10 than Figure 8A in and is separated from the rotor 10 by only a small gap. Through this gap, the cleaning fluid can leave as indicated by the arrow.

[0112] Figure 9A An example of the drive shaft 12 including 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 filaments, where the helix of the inner layer 29 is right-handed and the helix of the outer layer 28 is left-handed. As Figure 9A shown, a piece of the outer layer 28 is removed from the inner layer 29 and shown separately. Removing this piece of the 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 piece of the outer layer 28 is reinstalled adjacent to the bearing sleeve 30 onto the inner layer 29.

[0113] 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. In addition, on both sides of the bearing sleeve 30 and overlapping it are two protective rings 31 that slide over the ends of the outer layer 28 facing the bearing sleeve 30. The shorter part of the protective ring 31 overlaps the bearing sleeve 30, while the larger part covers the outer layer 28. In this way, the risk of drive shaft breakage caused by the change in stiffness at the transition between the small shaft diameter and the large shaft diameter is reduced.

[0114] 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, the 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 tightness 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.

[0115] The bearing sleeve 30 is rotatably supported in the outer bearing ring 32, where the outer bearing ring 32 is in turn fixed in the conduit or in the proximal end of the housing that houses the rotor. 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 by gluing. Glue is also used to fill the winding of the inner layer 29 and the outer layer 28 to prevent the cleaning fluid from leaking through the drive shaft 12.

[0116] 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.

[0117] 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 disconnected. 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 axially. 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 together.

[0118] Figure 10B Another embodiment is shown, where 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 proximally, 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.

[0119] If the rotor 10 is asFigure 11A If installed on the distal protection ring 31b as 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 installed on the distal extension of the bearing sleeve 30, the above conditions 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.

[0120] Figure 12A An 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 slipping 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.

[0121] 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.

[0122] The cleaning fluid that is squeezed through the proximal bearing 13 from proximal to distal will first flow along the outer radial surface of the proximal portion 30a of the bearing sleeve 30 through the proximal portion 30a of the bearing sleeve 30, then flow radially inward through the bearing clearance 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 clearance 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 clearance 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 clearance 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 clearance between the outer bearing ring 32 and the distal portion 30b of the bearing sleeve 30.

[0123] Figure 12B shows Figure 12A an alternative embodiment of the embodiment. Here, the drive shaft 12 has a diameter-reduced portion, and the distal portion 30b of the bearing sleeve 30 is arranged in the diameter-reduced portion. 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 conduit 5 can also be reduced. In this way, a more flexible and better operable conduit can be achieved.

[0124] As Figure 12B shown, the structure of the bearing sleeve 30 is equivalent to the bearing structure 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 ). Therefore, in the embodiment shown in Figure 12B , a distal bearing ring 31b that overlaps both the drive shaft 12 and the distal end of 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 .

[0125] 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 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 within the axial bearing gap. The surfaces have an inclined surface, which, together with the flat, opposing, stationary surface, forms a converging gap. This causes hydrodynamic pressure to accumulate in the lubricating film. As a result, the surfaces forming the axial bearing gap are kept at a certain distance.

[0126] Figure 13C The bearing sleeve 30 and outer bearing ring 32 are shown within the housing 11. The bearing sleeve 30 has a flat distal surface. 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.

[0127] Figure 13D The spiral grooves of the proximal bearing surface of the outer bearing ring 32 in another embodiment are shown. The spiral grooves are 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 Figure 13D When rotating in the direction of the arrow in the figure, the lubricating film is transported radially inward along the grooves and creates pressure between the bearing surfaces, keeping them apart.

Claims

1. An intravascular blood pump (1), comprising: A catheter (5), A housing (11) that houses a rotor (10), the housing (11) being attached to a distal end portion of the catheter (5), wherein the housing has an expandable portion, and A flexible drive shaft (12) that extends through the catheter (5) and is connected to the rotor (10), the drive shaft (12) including at least one outer layer (28) and at least one inner layer (29), Wherein the drive shaft (12) is rotatably supported in a proximal bearing (13) located at the proximal end of the rotor (10), and wherein the at least one outer layer (28) of the drive shaft (12) is absent or thinned at the position where the drive shaft (12) is supported in the proximal bearing (13).

2. A method of manufacturing an intravascular blood pump (1), the intravascular blood pump (1) comprising: A catheter (5), A housing (11) that houses a rotor (10), the housing (11) being attached to a distal end portion 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) including at least one outer layer (28) and at least one inner layer (29), wherein the drive shaft (12) is rotatably supported in a proximal bearing (13) located at the proximal end of the rotor (10), Wherein the method includes the step of thinning or completely removing the at least one outer layer (28) of the drive shaft (12) at the position where the drive shaft (12) is supported in the proximal bearing (13).

3. The method according to claim 2, including the step of at least partially filling the drive shaft (12) with a sealant such that the sealant penetrates into the at least one inner layer (29).

4. The method according to claim 3, wherein the step of at least partially filling the drive shaft (12) with a sealant is performed such that the sealant penetrates into all layers, i.e., into the at least one inner layer (29) and the at least one outer layer (28).

5. The method according to claim 3 or 4, wherein the sealant is a substance configured to penetrate into the layers (28, 29) as a fluid and then harden to prevent a cleaning fluid from penetrating through the corresponding layers (28, 29).

6. The method according to any one of claims 2 to 5, wherein the method includes the step of providing a bearing sleeve (30) at the position where the at least one outer layer (28) of the drive shaft (12) is removed or thinned such that the bearing sleeve (30) surrounds the at least one inner layer (29) or the thinned at least one outer layer (28) and forms an inner surface of the proximal bearing (13).

7. The method according to claim 6, wherein the at least one inner layer (29) is axially discontinuous within the bearing sleeve (30), and the method includes the step of fixing the bearing sleeve (30) on top of the at least one inner layer (29).

8. The method according to claim 6, wherein the at least one inner layer (29) is not axially discontinuous within the bearing sleeve (30), and the method includes the step of feeding the at least one inner layer (29) through the bearing sleeve before mounting the next successive portion of the at least one outer layer (28) on the at least one inner layer (29).

9. The method according to claim 6, wherein the at least one inner layer (29) is axially discontinuous within the bearing sleeve (30), and the bearing sleeve (30) is a cylinder having a wall separating two blind holes such that the internal space of the bearing sleeve (30) is hydraulically separated so that liquid cannot flow internally from one side of the bearing sleeve (30) to the other side, and the method includes the step of inserting the two ends of the axially discontinuous at least one inner layer (29) into respective ones of the blind holes.

10. The method according to any one of claims 6 to 9, wherein the method includes the step of fixedly connecting the bearing sleeve (30) to the at least one inner layer (29) or the thinned at least one outer layer (28) of the drive shaft (12) by crimping, welding, fusing, gluing or shrinking the bearing sleeve (30) onto the at least one inner layer (29) or the thinned at least one outer layer (28).

11. The method according to any one of claims 6 to 9, wherein the method includes the step of providing one or more protective rings (31) to extend over the at least one outer layer (28) of the drive shaft (12) and the corresponding portion of the bearing sleeve (30).

12. The method according to claim 11, including the step of providing a distal protective ring (31b) to extend over the distal portions of the drive shaft (12) and the bearing sleeve (30), and a proximal protective ring (31a) to extend over the proximal portions of the drive shaft (12) and the bearing sleeve.

13. The method according to claim 12, wherein the method includes the step of axially placing the proximal protective ring (31a) between the outer bearing ring (32) and the limiting member (33) such that the limiting member (33) serves as a stop for limiting the axial movement of the drive shaft (12) relative to the outer bearing ring (32).

14. The method according to claim 13, including the step of mounting the rotor (10) or the shaft of the rotor (10) at the distal end of the outer bearing ring (32) to form the distal protective ring (31b), in which case the limiting member (33) prevents contact between the rotor (10) or the rotor shaft and the outer bearing ring (32).

15. The method according to claim 13 or 14, comprising the step of fixing the outer bearing ring (32) to at least one of the conduit (5) and the proximal portion of the housing (11).

16. An intravascular blood pump (1) comprising: a conduit (5), a housing (11) in which a rotor (10) is received, the housing (11) being attached to the distal end of the conduit (5), a flexible drive shaft (12) extending through the conduit (5) and 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 forming an axial bearing of the proximal bearing, and wherein 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) and the outer bearing ring (32) together form a radial bearing of the proximal bearing.

17. An intravascular blood pump (1) comprising a pumping device and a conduit (5), wherein the pumping device includes: a drive shaft (12); a rotor (10) located at the distal end of the drive shaft (12); a housing (11) in which the rotor (10) is received; and a distal bearing (14) for rotatably supporting the distal end of the rotor (10), wherein the distal bearing (14) includes a static support member (18) projecting into or against the distal end of the rotor (10).

18. A method of using the intravascular blood pump (1) according to claim 1 or claim 16 or claim 17 in a patient such that blood flow in the patient is supported by the intravascular blood pump (1).

Images