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EP-4159268-B1 - BLOOD PUMP

EP4159268B1EP 4159268 B1EP4159268 B1EP 4159268B1EP-4159268-B1

Inventors

  • Grauwinkel, Marius
  • KERKHOFFS, WOLFGANG

Dates

Publication Date
20260506
Application Date
20200313

Claims (13)

  1. An intravascular blood pump (1) for percutaneous insertion into a patient's blood vessel, comprising: a pump casing (2) having a blood flow inlet (21) and a blood flow outlet (22), an impeller (3) arranged in said pump casing (2) so as to be rotatable about an axis of rotation (10), the impeller (3) having blades (31) sized and shaped for conveying blood from the blood flow inlet (21) to the blood flow outlet (22), a drive unit (4) for rotating the impeller (3), the drive unit (4) comprising a plurality of posts (40) arranged about the axis of rotation (10), wherein each of the posts (40) has a longitudinal axis (LA) and an impeller-side end (420) pointing towards the impeller (3), and a coil winding (44) disposed around each of the posts (40) and having an impeller-side end (424) pointing towards the impeller (3), the coil windings (44) being controllable so as to create a rotating magnetic field, wherein the impeller (3) comprises a magnetic structure (32) arranged to interact with the rotating magnetic field so as to cause rotation of the impeller (3), a spacer (7) configured to keep constant a distance between at least two of the posts (40), wherein the spacer (7) has a shape of a disk with openings (71) for receiving said at least two of the posts (40), characterised in that the spacer (7) is arranged at the impeller-side ends (420) of the at least two of the posts (40).
  2. Intravascular blood pump (1) according to claim 1, wherein the impeller-side end (420) of the at least one of the posts (40) is flat and oriented perpendicular to the axis of rotation (10).
  3. Intravascular blood pump (1) according to claim 1 or 2, wherein at least one of the posts (40) does not extend with its impeller-side end (420) radially over the impeller-side end (424) of the coil winding (44) disposed around the at least one of the posts (40), wherein the term radially relates to a direction traverse to the longitudinal axis (LA) of the at least one of the posts (40).
  4. Intravascular blood pump (1) according to any one of claims 1 to 3, wherein the term radially relates to a direction perpendicular to the longitudinal axis (LA) of the at least one of the posts (40).
  5. Intravascular blood pump (1) according to claim 4, wherein said openings (71) each have a shape corresponding to a cross-section (84) of a respective one of said at least two of the posts (40).
  6. Intravascular blood pump (1) according to any one of claims 1 to 5, wherein the spacer (7) has a thickness of between 0.05 and 0.3 mm, preferably between 0.066 and 0.2 mm, and more preferably approximately or exactly 0.1 mm.
  7. Intravascular blood pump (1) according to any one of claims 1 to 6, wherein the spacer (7) is made of a non-ferromagnetic material.
  8. Intravascular blood pump (1) according to claim 7, wherein the spacer (7) is made of titanium.
  9. Intravascular blood pump (1) according to any one of claims 1 to 8, wherein the coil winding (44) extends with its impeller-side end up to the spacer (7).
  10. Intravascular blood pump (1) according to any one of claims 1 to 9, wherein the at least one of the posts comprises or consists of a discontinuous soft magnetic material which is discontinuous regarding electric conductivity in a cross-section transverse to a longitudinal axis (LA) of the respective post (40).
  11. Intravascular blood pump (1) according to any one of claims 1 to 10, wherein a back plate (50) which magnetically connects ends of the posts (40) opposite to the impeller-side ends (420) comprises a soft magnetic material which is discontinuous regarding electric conductivity in a cross-section parallel to the axis of rotation (10).
  12. Intravascular blood pump (1) according to any one of claims 1 to 11, wherein the at least one of the posts (40) has a triangular cross-section transverse to the longitudinal axis (LA) of the respective post (40).
  13. Intravascular blood pump (1) according to claim 12, wherein a side of the at least one post (40) having the triangular cross section faces away from the axis of rotation (10) and bends around the axis of rotation (10).

Description

This invention relates to a blood pump, in particular an intravascular blood pump for percutaneous insertion into a patient's blood vessel, to support a blood flow in a patient's blood vessel. The blood pump has an improved drive unit. BACKGROUND OF INVENTION Blood pumps of different types are known, such as axial blood pumps, centrifugal (i.e. radial) blood pumps or mixed-type blood pumps, where the blood flow is caused by both axial and radial forces. Intravascular blood pumps are inserted into a patient's vessel such as the aorta by means of a catheter. A blood pump typically comprises a pump casing having a blood flow inlet and a blood flow outlet connected by a passage. In order to cause a blood flow along the passage from the blood flow inlet to the blood flow outlet, an impeller or rotor is rotatably supported within the pump casing, with the impeller being provided with blades for conveying blood. Blood pumps are typically driven by a drive unit, which can be an electric motor. For instance, US 2011/0238172 A1 discloses extracorporeal blood pumps having an impeller which may be magnetically coupled to an electric motor. The impeller comprises magnets which are disposed adjacent to magnets in the electric motor. Due to attracting forces between the magnets in the impeller and in the motor, rotation of the motor is transmitted to the impeller. In order to reduce the number of rotating parts, it is also known from US 2011/0238172 A1 to utilize a rotating magnetic field, with the drive unit having a plurality of static posts arranged about the axis of rotation, and each post carrying a wire coil winding and acting as a magnetic core. A control unit sequentially supplies a voltage to the coil windings to create the rotating magnetic field. In order to provide a sufficiently strong magnetic coupling, the magnetic forces have to be high enough, which can be achieved by a sufficiently high current supplied to the drive unit or by providing large magnets, which, however, leads to a large overall diameter of the blood pump. EP 3222301 B1 discloses a blood pump, in particular an intravascular blood pump, having a magnetic coupling between the drive unit and the impeller, wherein the blood pump has a compact design, and in particular a high ratio of pumping power to size of the pump, resulting in sufficiently small outer dimensions to allow the blood pump to be inserted transvascularly, transvenously, transarterially or transvalvularly or being even smaller for reasons of handling and convenience. More specifically, the blood pump in EP 3222301 B1 comprises a pump casing with a blood flow inlet and a blood flow outlet, an impeller and a drive unit for rotating the impeller. By rotation of the impeller about an axis of rotation and inside of the pump casing, blood can be conveyed from the blood flow inlet to the blood flow outlet by blades of the impeller. The drive unit comprises a plurality of preferably six posts and a back plate connecting rear ends of the posts to act as a yoke. The posts are arranged in a circle around the axis of rotation, as seen in a plane which is perpendicular to the axis of rotation, wherein each of the posts has a longitudinal axis, which is preferably parallel to said axis of rotation. The posts each have a shaft and an inclined head portion at the impeller-side end of the shaft opposite the rear end, the head portion extending radially over the shaft so as to form a shoulder which can act as an axial stop for a coil winding disposed around each of the posts. In order to generate a rotating magnetic field for driving the impeller, the coil windings can be controlled in a coherent manner. The impeller comprises a magnetic structure in the form of a magnet which is arranged to interact with the rotating magnetic field such that the impeller follows its rotation. Further prior art can be found in: EP 3 456 367 A1, WO 2014/035354 A1. A disadvantage of the state of the art is that the head portions extending radially over the shafts have a small distance to each other. The result is that there is a considerable parasitic magnetic flux between the head portions which is lost for the generation of torque. It is an objective of the invention to improve the drive unit in this regard. SUMMARY OF THE INVENTION The invention is defined in the appended claims. The blood pump of the present invention corresponds to the afore-mentioned blood pump. Accordingly, it may be an axial blood pump or a diagonal blood pump, which pumps partly axially and partly radially, (the diameter of pure centrifugal blood pumps is usually too large for intravascular applications). However, according to one aspect of the invention, at least one of the posts - preferably each post - does not extend with its impeller-side end radially over the impeller-side end of the respective coil winding, wherein the term "radially" relates to a direction traverse, preferably perpendicular, to the longitudinal axis of the respective