INTRAVASALE BLUTPUMPE

Description

[0001] The invention relates to an intravascular blood pump for supporting blood circulation in the human or, where appropriate, animal body. It is inserted percutaneously, for example, into the femoral artery, and guided through the body's vascular system, for example, to support or replace the pumping action of the heart. The invention also relates to a system comprising such an intravascular blood pump. Furthermore, a method for supporting blood circulation using such an intravascular blood pump is disclosed.

[0002] The demands placed on such blood pumps in terms of service life and small size are constantly increasing. The smallest pumps of this type have an outer diameter of approximately 4 mm. Further reduction of the outer diameter is limited, among other things, by the mechanical components used in the pump, which are not available in arbitrarily small sizes. Furthermore, the mechanical components are subjected to enormous stress. Due to their small size and the considerable volume flows to be pumped in the human bloodstream, these pumps operate at high speeds of several tens of thousands of revolutions per minute. While these types of blood pumps were originally intended only for short-term cardiac support, they are increasingly being used for long-term therapy lasting several days or even weeks.

[0003] EP 0 961 621 B1 discloses an intravascular blood pump comprising a drive part, a catheter connected to the proximal end of the drive part, through which lines for supplying power to the drive part run, and a pump part attached to the distal end of the drive part. The drive part comprises a motor housing with an electric motor arranged therein, wherein the motor shaft of the electric motor projects distally from the drive part and into the pump part. The pump part, in turn, comprises a tubular pump housing in which an impeller rotates, which is seated on the end of the motor shaft projecting from the motor housing. The motor shaft is mounted in the motor housing in exactly two bearings, which are spaced as far apart as possible from one another to ensure runout-free, centrically precise guidance of the impeller in the pump housing.While a radial ball bearing is used for the bearing at the proximal end of the motor housing, the impeller-side bearing is also designed as a shaft seal to prevent blood from entering the motor housing. In practice, blood entry into the motor housing is further counteracted by flowing a rinsing fluid through the motor housing and the impeller-side bearing, which serves as a shaft seal. This occurs at a rinsing fluid pressure that exceeds the prevailing blood pressure.

[0004] The intravascular blood pump normally pumps blood from distal to proximal through the pump housing and past the motor housing. Reverse pumping is also possible. In both cases, the impeller generates axial forces during blood pumping, which are transferred via the motor shaft to the bearings and absorbed by the radial ball bearing.

[0005] US 2010 / 0174131 A1 discloses a corresponding pump with axial and radial plain bearings.

[0006] Based on this prior art, the object of the present invention is to propose measures to further reduce the size of such intravascular blood pumps and increase their service life.

[0007] This object is achieved by an intravascular blood pump having the features of claim 1. Advantageous further developments and refinements of the invention are specified in dependent claims.

[0008] The blood pump according to the invention, in which the motor shaft is mounted in the motor housing in exactly two bearings that are maximally spaced from each other, namely at the proximal end and at the distal end of the motor housing, is also characterized by the fact that it is axially mounted in the motor housing by means of an axial bearing, wherein the axial bearing is an axial plain bearing or a combined radial-axial plain bearing. The axial forces of the motor shaft therefore do not need to be absorbed by a radial ball bearing arranged at the proximal end of the motor housing. The radial ball bearing can therefore be made correspondingly smaller and is replaced according to the invention by another compact radial bearing, namely a radial plain bearing. This, in turn, makes it possible to develop blood pumps with a reduced outer diameter.

[0009] Accordingly, according to the invention, the radial bearings for the motor shaft at the proximal end and / or at the distal end of the motor housing are each designed as plain bearings. Since these radial bearings essentially serve only to precisely guide the shaft centrically and therefore only have to absorb small radial forces, they can be designed as simple plain bearings. A radial plain bearing requires significantly less space in the radial direction than a rolling element bearing with its inner and outer rings. This, in turn, has a positive effect on the possibilities for manufacturing blood pumps with a small outer diameter.

[0010] At the same time, this measure extends the service life of the blood pump because the radial bearing is relieved of load due to the reduced axial forces, which a radial bearing is not primarily designed to absorb anyway, so that it is subject to less wear.

[0011] Alternatively, the invention can be integrated into existing sizes to increase service life and reduce complexity.

[0012] In particular, according to the invention, the radial plain bearing located at the proximal end of the motor housing is made of ceramic, with the ceramic bearing directly abutting the circumferential surface of the motor shaft, which in turn is made of shatter-resistant ceramic. The radial bearing located at the distal end of the motor housing can also be constructed in a similar manner. The ceramic surface of the ceramic bearing and the opposite ceramic surface of the motor shaft form a contact surface.

[0013] The axial forces acting on the motor shaft are opposite to the direction of flow. If the blood pump is designed to pump alternately in the proximal and distal directions, the axial forces acting on the motor shaft are in the distal direction in one case and in the proximal direction in the other. Accordingly, in such a blood pump, two axial plain bearings or axial-radial plain bearings must be provided in the motor housing for the axial support of the motor shaft. The axial plain bearing can be simply formed by a disk arranged on the motor shaft, which is supported against a circumferential shoulder of the motor housing. In the case of an axial-radial plain bearing, the disk has a convex or concave, particularly spherical, bearing surface. The term "axial plain bearing" is used synonymously for both variants: axial plain bearing and radial-axial plain bearing.

[0014] The motor housing itself is filled with a suitable fluid that forms a lubricating film in the bearing gap of the axial plain bearing. Alternatively, flushing fluid supplied through a flushing fluid supply line, which flows through the radial bearing located at the distal end of the motor housing, can also flow through the bearing gap of the axial plain bearing and thus be used to form the lubricating film in the bearing gap. To ensure that the flushing fluid reaches the distal radial bearing at a pressure that exceeds the applicable blood pressure, a channel can be provided in at least one of the surfaces forming the bearing gap of the axial plain bearing. This channel penetrates the bearing gap from radially outside to radially inside, so that the flushing fluid can flow through this channel to the distal radial bearing. This channel does not necessarily have to be located in a bearing gap surface, but can also be implemented as a separate channel or as a bore.However, providing the channel in one of the bearing gap surfaces has the advantage that the lubricating film in the bearing gap heats up less, because part of the lubricating film is constantly replaced by incoming flushing fluid. The channel is preferably located in the stationary bearing gap surface to minimize radial flow.

[0015] The axial plain bearing is preferably designed as a hydrodynamic plain bearing. In contrast to a simple plain bearing, in a hydrodynamic plain bearing a pressure is built up in the lubricating film by the pumping action of the two surfaces moving relative to each other. For this purpose, according to a preferred variant, the bearing gap can be designed as a converging gap in some areas in the circumferential direction of the axial plain bearing. In this case, the moving surface is preferably flat, i.e. the opposite stationary surface of the bearing gap has ramps that converge towards the moving surface in the direction of rotation of the moving surface. This creates a wedge in the bearing gap into which the lubricating fluid is transported, building up pressure that causes the moving surface to move away from the static surface. In this state, sliding friction on a fluid film prevails, which is virtually wear-free.Since the blood pump normally pumps continuously at high speed, the blood pump is particularly wear-resistant and therefore suitable for long-term use.

[0016] In the simplest embodiment, the moving disc can be designed as a swash plate and simply form the convergent gap or wedge through its inclined position.

[0017] Instead of a bearing gap with converging surface zones, one of the surfaces forming the bearing gap can have one or more spirally arranged grooves. In this case, the relative movement of the two surfaces pumps the lubricating fluid along the grooves to the bearing center, building up pressure there, which in turn causes the two surfaces to move away from each other. In the spiral groove bearing variant, it is preferable to provide the spirally arranged grooves in the moving surface, as this allows for more effective delivery of the lubricating fluid into the grooves.

[0018] If, due to the design, the axial thrust (F ax rotor) of the pumping device is greater than the load-bearing capacity of the axial plain bearing, the axial thrust of the pumping device can be partially compensated by a suitable axial arrangement of the rotating magnet in the motor. According to the invention, the rotating magnet behaves like a submersible magnet that magnetically wants to remain in the center of the static motor part. If this is now pulled out of this rest position, a magnetic force is generated in the opposite direction (F ax magnet). This force can be used in the direction of the axial thrust (F ax rotor) for further axial stabilization or in the opposite direction and relieve the axial plain bearing. Furthermore, the resulting force on the axial bearing can be adjusted by varying the pressure of the flushing fluid (cf. Fig. 2 ).

[0019] It is further preferred if the surfaces forming the bearing gap of the axial plain bearing are made of ceramic, preferably zirconium oxide. High-strength, low-wear surfaces can be produced from ceramic. In particular, the entire distal end of the motor housing, including the surface for the axial plain bearing, can be easily manufactured from a single-piece ceramic part, thus keeping the overall manufacturing costs of the blood pump low.

[0020] The connecting wires of the electric motor housed in the motor housing are normally routed around the proximal radial bearing and electrically connected, in particular soldered, to the power supply lines running inside the catheter. According to a preferred embodiment of the invention, the connecting wires of the electric motor are now routed through the outer ring of the radial bearing or, advantageously, in one or more radially outer grooves of the outer ring. This saves installation space in the radial direction, which in turn is beneficial for the development of blood pumps with a small outer diameter. For example, this allows for space for pressure measurement and its implementation at the proximal end of the motor.

[0021] The connecting wires can advantageously be soldered to the power supply lines on a surface of the motor housing proximal to the proximal radial bearing. This is advantageous because the direct electrical connection of the electric motor's connecting wires to the power supply lines can be difficult due to the thinness of the connecting wires and the comparatively thickness of the power supply lines. If the relevant surface of the electric motor is made of a plastic or ceramic, as explained below, the soldering area can be coated with a conductive material, for example, with copper, before soldering, and the connecting wires and the power supply lines are each soldered separately in this area.

[0022] Preferably, the relevant part of the motor housing is then embedded in plastic, with the soldering points and preferably also the motor windings being embedded, so that the soldering points are electrically insulated on the one hand and mechanically protected on the other.

[0023] During operation, the blood pump is connected to a rinsing fluid source and fluid is fed through the rinsing fluid line into the motor housing. The rinsing fluid then flows through the axial plain bearing and further through the distal radial bearing. In the axial plain bearing, it forms the lubricating film in the bearing gap. However, the pressure with which the rinsing fluid flows through the motor housing has a negative effect on the width of the bearing gap. The higher the rinsing fluid pressure, the smaller the bearing gap width and the thinner the lubricating film between the sliding surfaces. The thinner the lubricating film, the greater the motor current required to overcome the frictional forces and drive the electric motor. This is disadvantageous for the control of the blood pump because the current flow rate is normally determined using stored characteristic curves based solely on the motor current and the speed (both known variables).If the irrigation fluid pressure also affects the motor current, another factor would need to be considered. Given that the same blood pump type can be operated for a wide variety of applications with different irrigation fluid pressures between 300 and 1400 mmHg, it is important to avoid a dependence of the motor current on the irrigation fluid pressure.

[0024] This can actually be achieved if the rinsing fluid chosen is one with a viscosity that is significantly higher than the viscosity of water (η = 0.75 mPa • s at 37°C). This is because with a highly viscous rinsing fluid, the fluid film is maintained even at high pressures and the friction of the axial plain bearing is therefore independent of the rinsing fluid pressure. It has been found that with a rinsing fluid whose viscosity at 37°C is approximately 1.2 mPa • s or even higher, the axial plain bearing can be designed as a simple plain bearing and does not need to be designed as a hydrodynamic plain bearing. Good results have been achieved, for example, with a ≥ 20% glucose solution between ceramic surfaces made of zirconium oxide.

[0025] The invention is explained below by way of example with reference to the accompanying drawings, in which: Figure 1a schematic representation of the introduction of a blood pump in front of the left ventricle, with positioning of its suction cannula in the left ventricle, Figure 2a schematic longitudinal section of an embodiment of the blood pump, Figure 3an enlarged representation of detail III from Figure 2 , Figure 4 a variant of detail III from Figure 3 , Figure 5 an enlarged view of detail IV from Figure 2 , Figures 6A and 6B show an axial plain bearing surface in plan view and as a developed view according to a first embodiment, Figure 7 shows an axial plain bearing surface in cross section according to a second embodiment, and Figure 8 shows an axial plain bearing surface in plan view according to a third embodiment.

[0026] In Figure 1The use of a blood pump 10 to support the left ventricle is shown. The blood pump has a motor part 11 and a pump part 12, which are arranged coaxially one behind the other and result in a rod-shaped design. The pump part is extended by a flexible suction tube 13, which has openings at its end and / or in its side wall for blood access to the pump. The end of the blood pump 10 facing away from the suction tube 13 is connected to a catheter 14, which has been inserted through the aortic arch 15a and the aorta 16. The blood pump 10 is positioned so that it lies primarily in the ascending aorta 15b, but the pump part 12 with the suction tube 13 lies essentially in the left ventricle 17. The aortic valve 18 rests against the outside of the pump housing or the suction tube 13 when closed.The blood pump 10 with the upstream suction tube 13 is advanced into the position shown by advancing the catheter 14, optionally using a guidewire. The suction tube 13 passes the aortic valve 18 retrogradely, so that blood is sucked through the suction tube 13 and pumped into the aorta 16. In this respect, the blood pump corresponds to the blood pump known from EP 0 961 621 B1.

[0027] The use of the blood pump is not limited to the Figure 1 The application shown is limited to this, which is merely a typical example. The pump can also be inserted through other peripheral vessels, such as the subclavian artery, or placed in the right heart.

[0028] Figure 2shows a preferred embodiment of the blood pump with the motor part 11 and the pump part 12 firmly connected thereto. The motor part 11 has an elongated housing 20 in which the electric motor 21 is housed. The stator 24 of the electric motor 21 has, in the usual way, numerous windings distributed around the circumference as well as a magnetic return path 28 in the longitudinal direction. It is firmly connected to the motor housing. The stator 24 surrounds the rotor 26, which is connected to the motor shaft 25 and consists of permanent magnets magnetized in the effective direction. The motor shaft 25 extends over the entire length of the motor housing 20 and projects distally therefrom. There, it carries an impeller 34 with projecting vanes 36 or pump blades that rotate in a tubular pump housing 32, which in turn is firmly connected to the motor housing 20.

[0029] The flexible catheter 14 is sealingly connected to the proximal end of the motor housing 20. Electrical cables 23 for powering and controlling the electric motor 21 run through the catheter 14. Furthermore, a flushing fluid line 29 runs through the catheter 14 and penetrates the proximal end wall 22 of the motor housing 20. Flushing fluid is fed into the interior of the motor housing 20 through the flushing fluid line 29 and exits through the end wall 30 at the distal end of the motor housing. The flushing pressure is selected to be higher than the prevailing blood pressure to prevent blood from entering the motor housing and is between 300 and 1400 mmHg, depending on the application.

[0030] When the impeller 34 rotates, blood is sucked in through the front intake opening 37 of the pump housing 32 and conveyed axially backward within the pump housing 32. The blood flows out of the pump section 12 through outlet openings 38 in the pump housing 32 and continues along the motor housing 20. This ensures the dissipation of the heat generated in the drive. It is also possible to operate the pump section in the opposite direction, with blood being sucked in along the motor housing 20 and exiting through the opening 37.

[0031] The motor shaft 25 is mounted on the one hand at the proximal end of the motor housing and on the other hand at the distal end of the motor housing in radial bearings 27 and 31. In this embodiment, the radial bearings are each designed as simple plain bearings. In addition, the motor shaft 25 is also axially mounted in the motor housing 20. The axial bearing 40 is also designed as a plain bearing. The axial plain bearing 40 is described below with reference to Figure 3 explained in more detail. It serves to absorb axial forces of the motor shaft 25, which act in the distal direction when the impeller 34 conveys blood from distal to proximal. If the blood pump is used to convey blood also or only in the opposite direction, a corresponding axial plain bearing 40 must be provided (also / or) in a corresponding manner at the proximal end of the motor housing 20.

[0032] The blood pump according to Fig. 2Alternatively, it can be used without irrigation fluid for short-term use of a few hours. In this case, the sliding bearings are lubricated once, and the distal sliding bearing 31 is also provided with a radial lip seal to prevent blood from entering. An irrigation fluid line can then be advantageously dispensed with altogether.

[0033] Figure 3 shows section III from Figure 2 in greater detail. The radial plain bearing 31 and the axial plain bearing 40 are particularly visible. The bearing gap of the radial plain bearing 31 is formed, on the one hand, by the circumferential surface of the motor shaft 25, which is not DLC-coated according to the invention here, and, on the other hand, by the surface of the through-bore in the distal end wall 30 of the motor housing 20, which is made as a ceramic part, for example, from zirconium oxide.

[0034] The bearing gap of the axial plain bearing 40 is formed, on the one hand, by the axially inner surface 41 of the end wall 30 and a surface 42 opposite it. This opposite surface 42 is part of a ceramic disk 44, which sits on the motor shaft 25 distally from the rotor 26 and rotates with the rotor 26. A channel 43 in the bearing gap surface 41 of the end wall 30 ensures that flushing fluid can flow between the bearing gap surfaces 41 and 42 of the axial plain bearing 40 to the radial plain bearing 31 and exit distally from the motor housing 20. The flushing fluid is selected with a viscosity of at least 1.2 mPa • s at 37°C. 20% glucose solution, for example, has proven suitable. Figure 3 The axial plain bearing 40 shown is a normal plain bearing. Hydrostatic plain bearing variants are described below with regard to the Figures 6A / B, 7 and 8. Contrary to what is shown, the axial gap of the axial plain bearing 40 is very small, at just a few µm.

[0035] Instead of the axial plain bearing 40 and radial plain bearing 31, a combined radial-axial plain bearing 46 with a concave bearing shell in which a convex bearing surface runs can also be realized. Such a variant is shown in Figure 4illustrated using a spherical plain bearing 46. The bearing gap surface 41 is spherically concave, and the opposite bearing gap surface 42 is correspondingly spherically convex. The channel 43 is again located in the stationary bearing gap surface 41 of the end wall 30. Alternatively, the stationary bearing gap surface 41 of the end wall 30 can be convex and the opposite bearing gap surface 42 can be concave. The surfaces 42, 43 can also be conical instead of spherical. Preferably, a corresponding radial-axial plain bearing is provided on both sides of the motor housing 20 in order to prevent radial offset upon axial migration of the shaft 25. The advantage of a combined axial-radial plain bearing is its higher load-bearing capacity. The disadvantage, however, is the larger friction diameter.

[0036] Figure 5shows the radial bearing 27 at the proximal end of the motor housing 20. Here, too, the motor shaft 25 is not provided with a DLC coating according to the invention and runs in a bearing bush that forms an integral part of the proximal end wall 22 of the motor housing 20, which is also made of ceramic. In this respect, the radial plain bearing 27 corresponds to the radial plain bearing 31.

[0037] Distributed over the circumference of the end wall 22 are three axially extending grooves 50 at a distance of 120°, of which Figure 2only one is visible. Thin connecting wires 51 lead through these grooves 50 to the windings of the stator 24. The connecting wires 51 are soldered to the proximal side of the end wall 20, with the soldering point 52 first being made conductive with a local copper coating. The end of the power supply line 23 is also soldered to the same soldering point 52. The wires of the stator windings can be connected to the power supply lines using all conventional joining methods (soldering, welding, clamping, laser welding, gap welding, contact bonding, etc.). The end wall 22, including the connecting wires 51 and the soldering points 52, is then coated with a plastic material, whereby the motor windings of the stator are also coated at the same time. This can be done, for example, using vacuum encapsulation.

[0038] The blood pump described above does not use radial ball bearings for the motor shaft 25, which are difficult to install and have a minimum diameter of 3 mm. This makes it possible to manufacture pumps with even smaller outer diameters, for example, as small as 3 mm. Furthermore, the service life of this blood pump is significantly longer than those with radial ball bearings due to reduced wear. Runtimes of more than 30 days can thus be achieved with low wear. This is extremely important, as the bearings and the smooth running of the impeller are crucial for minimizing blood damage.

[0039] Figure 6A shows a top view of the surface 41 of the distal end wall 30 of the motor housing 20 according to an alternative embodiment. Figure 6B shows a development of surface 41 from Figure 6AThe surface 41 itself is stationary. The direction indicated by the arrow indicates the direction in which the opposing surface 42 of the plain bearing 40 moves. This also corresponds to the direction in which the lubricating film moves within the bearing gap relative to the stationary surface 41. Accordingly, the surface 41 has ramps arranged one behind the other, which, together with the opposing moving surface 42, which is flat, form converging gaps. This builds up hydrodynamic pressure in the lubricating film, ensuring that the surfaces forming the bearing gap remain at a distance.

[0040] A design of the rotating surface with the ramp-like structures according to the Figures 6A and 6B is beneficial for the performance of the axial plain bearing, but leads to an increased radial conveying effect in the bearing gap, which opposes the conveying direction of the flushing fluid. Figure 7The simplest form of a ramp-like implementation of the convergent gap is shown in the form of a swash plate. Here, the disc 44 is simply installed at an angle or ground to a minimal angle. The inclination is typically 1 to 5 µm.

[0041] Figure 8 shows another variant for a hydrodynamically acting surface of the axial plain bearing 40. This is a so-called spiral groove bearing, which is preferably formed on the moving surface of the bearing gap, thus accordingly on the surface 42 of the ceramic disc 44. In this case, several grooves 45 are arranged spirally in the surface 42. The grooves 45 are in Figure 8 only schematically indicated. If the ceramic disc 44 is in the position indicated by the arrow in Figure 8indicated direction, the lubricating film is conveyed radially inwards along the grooves 45 and builds up a pressure there, which in turn ensures that the surfaces forming the bearing gap are kept at a distance from one another.

Claims

1. An intravascular blood pump (10), comprising - a drive part (11) which has a motor housing (20) with a proximal end and a distal end and an electric motor (21) arranged in the motor housing, wherein the electric motor has a motor shaft (25) which protrudes with one end from the distal end of the motor housing (20) and is radially mounted (27, 31) in the motor housing both at the proximal end and at the distal end of the motor housing, wherein the radial mounting (27) of the motor shaft (25) at the proximal end of the motor housing (20) and / or the radial mounting (31) of the motor shaft (25) at the distal end of the motor housing (20) is configured as a radial plain bearing and the motor shaft (25) is mounted axially in the motor housing (20) by means of at least one axial plain bearing (40) or radial-axial plain bearing (46), - a catheter (14) which is connected to the proximal end of the motor housing (20) and along which there extend lines (23) for power supply to the electric motor, and - a pump section (12) having a tubular pump housing (32) which is fastened to the distal end of the motor housing (20), and an impeller (34) which sits on the end of the motor shaft (25) protruding out of the distal end of the motor housing (20) and is rotatable in the pump housing (32), characterized in that the motor shaft (25) is made of ceramic and one of the surfaces forming the bearing gap of the radial bearing (27, 31) configured as a radial plain bearing is a ceramic surface, and the correspondingly other one of the surfaces forming the bearing gap is formed by the ceramic shaft, wherein the motor shaft (25) in the motor housing (20) is mounted in exactly two bearings that are spaced apart maximally, namely at the proximal end and at the distal end of the motor housing (25).

2. The intravascular blood pump according to claim 1, wherein the axial plain bearing (40) or radial-axial plain bearing (46) comprises a disk (44), preferably a ceramic disk, arranged on the motor shaft (25) and supported against a circumferential shoulder of the motor housing (20).

3. The intravascular blood pump according to either of claims 1 and 2, comprising a rinsing-fluid line (29) which is arranged such that fluid fed through the rinsing-fluid line flows through the bearing gap of the axial plain bearing (40) and the radial bearing (31) located at the distal end of the motor housing, or the bearing gap of the radial-axial plain bearing (46).

4. The intravascular blood pump according to any of claims 1 to 3, wherein at least one of the surfaces (41, 42) forming the bearing gap of the axial plain bearing (40) or radial-axial plain bearing (46) has a passage (43) which passes through the bearing gap from radially outside to radially inside.

5. The intravascular blood pump according to any of claims 1 to 4, wherein the bearing gap of the axial plain bearing (40) or radial-axial plain bearing (46) is formed in the circumferential direction as a converging gap in some regions, wherein preferably a moving surface (42) of the surfaces (42, 41) forming the bearing gap of the axial plain bearing (40) or radial-axial plain bearing (46) is flat.

6. The intravascular blood pump according to any of claims 1 to 4, wherein one of the surfaces (41, 42) forming the bearing gap of the axial plain bearing (40) or radial-axial plain bearing (46) has one or more spirally arranged grooves (45), wherein preferably a moving surface (42) of the surfaces (42, 41) forming the bearing gap of the axial plain bearing (40) or radial-axial plain bearing (46) has the spirally arranged groove(s).

7. The intravascular blood pump according to any of claims 1 to 6, wherein the ceramic is zirconium oxide.

8. The intravascular blood pump according to any of claims 1 to 7, wherein the radial bearing (27) located at the proximal end of the motor housing (20) has an outer ring, and lead wires (51) of the electric motor (21) extend through the outer ring or within a radially outer slot (50) of the outer ring.

9. The intravascular blood pump according to claim 8, wherein the lead wires (51) of the electric motor (21) and the lines (23) extending along the catheter (14) are connected electroconductively, in particular soldered, on a surface (52) located proximally of the radial bearing (27) located at the proximal end of the motor housing, wherein preferably the motor housing is at least partially a molded plastic housing, and wherein the solderings (52) are also molded around.

10. A system comprising the intravascular blood pump according to claim 3 and a rinsing-fluid source for supplying the rinsing-fluid line with a fluid whose viscosity at 37°C lies at ≥ 1.2 mPa • s.

11. The intravascular blood pump (10) according to any of claims 1 to 10, wherein the complete distal end of the motor housing (20), including a surface (41) of the axial plain bearing (40) or radial-axial plain bearing (46) is manufactured from a one-piece ceramic.

12. The intravascular blood pump (10) according to any of claims 1 to 11, wherein the axial plain bearing (40) or radial-axial plain bearing (46) is formed by an axially inner surface (41) of an end wall of the motor housing (20) and a surface (42) located opposite thereto, wherein the oppositely located surface (42) forms part of a ceramic disk (44), which sits on the motor shaft (25) distally of a rotor (26) and rotates with the rotor (26).

13. The intravascular blood pump (10) according to claim 12, wherein the bearing gap of the radial plain bearing (31) is formed by the circumferential surface of the motor shaft (25) and a surface of a through bore in a distal end wall (30) of the motor housing (20).

14. The intravascular blood pump (10) according to claim 12, which comprises a bearing bush which forms an integral part of a proximal end wall (22) of the motor housing (20) made of ceramic.