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EP-4279119-B1 - BLOOD PUMP

EP4279119B1EP 4279119 B1EP4279119 B1EP 4279119B1EP-4279119-B1

Inventors

  • ABOULHOSN, WALID
  • SIESS, THORSTEN

Dates

Publication Date
20260506
Application Date
20150318

Claims (14)

  1. A blood pump (1), comprising: - a pump casing (2) having a blood flow inlet (5) and a blood flow outlet (6) connected by a passage (7), - an impeller (3) arranged in said pump casing (2) so as to be rotatable about an axis of rotation (9), the impeller (3) being provided with blades (4) sized and shaped for conveying blood along the passage (7) from the blood flow inlet (5) to the blood flow outlet (6), the impeller (3) being rotatably supported in the pump casing (2) by a first bearing (10) at a first axial end of the impeller (3) and a second bearing (20) axially spaced apart from the first bearing (10), wherein the first bearing (10) comprises a projection (11) extending along the axis of rotation (9) and connected to one of the impeller (3) and the pump casing (2) and a cavity (13) in the other one of the impeller (3) and the pump casing (2), the projection (11) comprising an enlarged portion (12) that engages the cavity (13) such that the first bearing (10) and the second bearing (20) are arranged to bear axial forces in the same axial direction, characterized in that a wall of the cavity (13) comprises at least two sections (17) separated by a gap (18), the gap (18) being in fluid connection with the passage (7) and allowing blood to enter the cavity (13).
  2. The blood pump of claim 1, wherein the enlarged portion (12) is enclosed in the cavity (13).
  3. The blood pump of claim 1 or 2, wherein the cavity (13) corresponds in size and shape to the enlarged portion (12).
  4. The blood pump of any one of claims 1 to 3, wherein the enlarged portion (12) is at least partially spherical in shape.
  5. The blood pump of any one of claims 1 to 4, wherein the enlarged portion (12) is snap fitted into the cavity (13).
  6. The blood pump of any one of claims 1 to 5, wherein the second bearing (20) is a contact-type bearing comprising a bearing surface (23) of the impeller (3) facing a bearing surface (22) of the pump casing (2).
  7. The blood pump of any one of claims 1 to 6, wherein the second bearing (20) is a pivot bearing.
  8. The blood pump of any one of claims 1 to 7, further comprising a shaft (14) extending along and rotatable about the axis of rotation (9) and having the impeller (3) mounted thereon, the shaft (14) having a first end portion (19) forming part of the first bearing (10) and a second end portion (24) forming part of the second bearing (20).
  9. The blood pump of claim 8, wherein the first end portion (19) of the shaft (14) comprises the enlarged portion (12).
  10. The blood pump of claim 9, wherein the shaft (14) has an outer diameter that is substantially equal to an outer diameter of the enlarged portion (12), wherein the projection (11) forms a neck arranged between the enlarged portion (12) and a remainder of the shaft (14).
  11. The blood pump of any one of claims 8 to 10, wherein the second end portion (24) of the shaft (14) comprises a bearing surface (23) of the second bearing (20), said bearing surface (23) being concave.
  12. The blood pump of any one of claims 1 to 11, wherein the enlarged portion (12) comprises at least one magnet (40) and the pump casing (2) comprises at least one magnet (41) that are arranged such that a repelling magnetic force between said magnets (40, 41) pointing in an axial direction away from the second bearing (20) is caused.
  13. The blood pump of any one of claims 1 to 12, wherein at least one of the bearing surfaces of at least one of the first and second bearings (10, 20) is supported by at least one spring, wherein the at least one spring is arranged to bear axial forces in an axial direction from the second bearing towards the first bearing.
  14. The blood pump of any one of claims 1 to 13, wherein the blood pump (1) is an axial blood pump, a centrifugal blood pump or a mixed-type blood pump.

Description

BACKGROUND This invention relates to blood pumps to be implanted in a patient for supporting the patient's heart. In particular, the blood pump may be used as a "bridge to recovery" device, whereby the blood pump temporarily supports the patient's heart until it has sufficiently recovered. 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. Blood pumps may be inserted into a patient's vessel such as the aorta by means of a catheter, or may be placed in the thoracic cavity. 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 is rotatably supported within the pump casing, with the impeller being provided with blades for conveying blood. The impeller is supported within the pump casing by means of at least one bearing, which may be of different types depending on the intended use of the blood pump, for instance whether the blood pump is intended only for short term use (some hours or some days) or long term use (weeks or years). A variety of bearings are known, such as contact-type bearings and non-contact bearings. In non-contact bearings the bearing surfaces do not contact each other, e.g. in magnetic bearings, in which the bearing surface "levitate" due to repelling magnetic forces. Generally, contact-type bearings may include all types of bearings, in which the bearing surfaces may contact at least partially during operation of the pump at any time (i.e. always or intermittently), e.g. in slide bearings, pivot bearings, hydrodynamic bearings, hydrostatic bearings, ball bearings etc. or any combination thereof. In particular, contact-type bearings may be "blood immersed bearings", where the bearing surfaces have blood contact. Contact-type bearings, such as pivot bearings, may heat up during use and are subject to mechanical wear. Mechanical wear may be increased by a magnetic coupling between the electric motor of the pump and the impeller for driving the impeller. When the contact-type bearing and the magnetic coupling are disposed at the same axial end of the impeller, mechanical wear of the bearing may increase because the magnetic coupling attracts the impeller, thereby increasing the contact pressure on the bearing surfaces. This may lead to a high load (e.g. 10 Newton) on a small bearing surface (e.g. in a pivot bearing in catheter pump e.g. in the range of 1 mm in diameter). WO 03/075981 A1 discloses a blood pump wherein hydrodynamic axial forces are born by the axial bearings. SUMMARY OF THE INVENTION It is a primary object of the present invention to provide a blood pump having an impeller that is supported in a pump casing by means of a bearing, wherein mechanical wear of the bearing can be reduced. In particular, it is another object of the present invention to relieve a bearing in a blood pump from excessive loading. The primary object is achieved according to the present invention by a blood pump with the features of independent claim 1. Preferred embodiments and further developments of the invention are specified in the claims dependent thereon. Like known blood pumps, the blood pump according to the invention comprises a pump casing having a blood flow inlet and a blood flow outlet connected by a passage. An impeller or rotor is arranged in said pump casing so as to be rotatable about an axis of rotation, which may be the longitudinal axis of the impeller, with the impeller being provided with blades sized and shaped for conveying blood along the passage from the blood flow inlet to the blood flow outlet. The impeller is rotatably supported in the pump casing by a first bearing at a first axial end of the impeller and a second bearing axially spaced apart from the first bearing. According to the invention, the first bearing comprises a projection extending along the axis of rotation and connected to one of the impeller and the pump casing and a cavity in the other one of the impeller and the pump casing. The term "cavity" may comprise any kind of cavity, hollow space, recess, opening, or bore. The projection comprises an enlarged portion that engages the cavity such that the first and second bearings are arranged to bear axial forces in the same axial direction. For instance, the enlarged portion may be supported by or enclosed in the cavity. In other words, the first bearing relieves the second bearing by carrying at least part of the axial force that acts on the bearing surfaces of the second bearing. Since both bearings support the impeller in the same "bearing direction", the load on each of the bearings can be reduced. They "share" the load. This is achieved by providing simple mechanical means in the form of a projection with an enlarged portion and a corresponding cavity such t