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EP-4241829-B1 - BLOOD PUMP

EP4241829B1EP 4241829 B1EP4241829 B1EP 4241829B1EP-4241829-B1

Inventors

  • SIESS, THORSTEN
  • WANG, JIMPO
  • SPANIER, GERD

Dates

Publication Date
20260506
Application Date
20170321

Claims (15)

  1. A blood pump (1) 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), and - 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) includes a shaft portion (41) and a head portion (42), with the head portion (42) pointing towards the impeller (3), wherein a coil winding (47) is disposed about the shaft portion (41) of each of the posts (40), the coil windings (47) being sequentially controllable so as to create a rotating magnetic field, wherein the impeller (3) comprises at least one magnet (32) arranged to interact with the rotating magnetic field so as to cause rotation of the impeller (3), wherein the drive unit (4) further comprises a back plate (50) which engages ends (44) of the shaft portions (41) of the posts (40) opposite the head portions (42), characterized in that the back plate (50) comprises a plurality of apertures (51) arranged about the axis of rotation (10) and receiving said ends (44) of the shaft portions (41).
  2. The blood pump of claim 1, wherein the head portion (42) of at least one of the posts (40) has a top surface (43) inclined at an angle relative to a plane perpendicular to the axis of rotation (10), wherein preferably a distance between the axis of rotation (10) and a center of said inclined surface (43) in a radial direction is less than or equal to a distance between the axis of rotation (10) and a center of a cross-sectional area of the shaft portion (41) of the respective post (40) in a radial direction.
  3. The blood pump of claim 2, wherein at least one of the head portions (42) is substantially triangular in cross-section along a plane including the axis of rotation (10).
  4. The blood pump of claim 2 or 3, wherein the inclined surfaces (43) of the head portions (42) form a conical surface, wherein preferably the at least one magnet (32) of the impeller (3) defines a conical recess (35) corresponding in size and shape to the conical surface formed by the head portions (42) of the posts (40).
  5. The blood pump of any one of claims 2 to 4, wherein the at least one magnet (32) of the impeller (3) has a surface (33) facing the head portions (42) of the posts (40) and being inclined at an angle (34) corresponding to the angle of the inclined surface (43) of at least one of the head portions (42).
  6. The blood pump of any one of claims 2 to 5, wherein the angle is between about 0° and 90°, preferably between about 30° and 60°, more preferably about 45°, wherein the inclined surfaces (43) preferably face radially outwards.
  7. The blood pump of any one of claims 1 to 6, wherein the impeller (3) comprises at least two of the magnets (32), preferably at least four, more preferably six, still preferably eight, wherein the magnets (32) preferably are separated by radially extending gaps (66).
  8. The blood pump of any one of claims 1 to 7, wherein the drive unit (4) comprises at least two of the posts (40), preferably at least four, more preferably six, still preferably eight.
  9. The blood pump of any one of claims 1 to 8, wherein each of the head portions (42) has a larger cross-sectional dimension than the respective shaft portion (41) in a plane perpendicular to the axis of rotation (10), wherein preferably the respective coil winding (47) does not extend beyond the head portion (42) at least in a radial direction.
  10. The blood pump of any one of claims 1 to 9, wherein the apertures (51) receive reduced-diameter end portions (44) of the shaft portions (41) of the posts (40).
  11. The blood pump of any one of claims 1 to 10, wherein the apertures (51) extend completely through the back plate (50).
  12. The blood pump of any one of claims 1 to 11, further comprising a housing (60) surrounding the drive unit (4).
  13. The blood pump of any one of claims 1 to 12, wherein the drive unit (4) has a central opening (54) extending along the axis of rotation (10), preferably for receiving an elongate pin (15), with an axial end surface of the pin (15) forming a bearing surface for the impeller (3).
  14. The blood pump of any one of claims 1 to 13, wherein the drive unit (4) is disposed inside the pump casing (2).
  15. The blood pump of any one of claims 1 to 14, wherein a magnetically insulating material is disposed between the head portions (42) of adjacent posts (40).

Description

BACKGROUND 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 which allows for reduction of the outer diameter of the blood pump. An example of a prior art device is disclosed in US 2014/030122 A1. Blood pumps of different types are known, such as axial blood pumps, centrifugal 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 1 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. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a blood pump, preferably an intravascular blood pump or transvalvular blood pump, having a magnetic coupling between the drive unit and the impeller, wherein the blood pump has a compact design, in particular a sufficiently small outer diameter to allow the blood pump to be inserted transvascularly, transvenously, transarterially or transvalvularly. This object is achieved according to the present invention by a blood pump having the features of independent claim 1. Preferred embodiments and further developments of the invention are specified in the claims dependent thereon. According to the invention, the blood pump, which preferably is an intravascular blood plump and may be one of an axial blood pump, a centrifugal blood pump and a mixed-type blood pump, comprises a drive unit for rotating the impeller. The drive unit comprises a plurality of posts, such as at least two, at least three, at least four, at least five or preferably six posts, that are arranged about the axis of rotation. Higher numbers of posts, such as eight, ten or twelve, may be possible. The number of posts is preferably even for a balanced control of the impeller, but it may also be odd, such as three or five. Each of the posts includes a shaft portion and a head portion, with the head portion pointing towards the impeller. In order to create a rotating magnetic field, a coil winding is disposed about the shaft portion of each of the posts, with the coil windings being sequentially controllable so as to create the rotating magnetic field. The impeller comprises at least one magnet, which is arranged to magnetically couple the impeller to the drive unit, i.e. to interact with the rotating magnetic field so as to cause rotation of the impeller. A drive unit that creates a rotating electromagnetic field allows for simplification of the mechanics of the blood pump by reducing the number of moving parts compared to a common electric motor. This also reduces wear, because no contact bearing for an electric motor is necessary. The magnetic coupling between the drive unit and the impeller not only causes rotation of the impeller but also permits correct alignment of the impeller. In particular, the magnetic coupling may provide an axial as well as a radial bearing. In order to increase the density of the magnetic coupling between the drive unit and the magnets of the impeller, it may be advantageous to activate several posts simultaneously, where "activate" means to supply electric power to the respective coil winding in order to create a respective pole magnet. For example, more than half of the posts may be activated at the same time, such as four of six posts, depending on the number of posts and number of magnets in the impeller. P