Method and apparatus for providing limited back-flow in a blood pump during a non-pumping state

• US 20030144574A1
• Filed: 12/19/2002
• Published: 07/31/2003
• Est. Priority Date: 12/19/2001
• Status: Abandoned Application

• Current Assignee: University Of Pittsburgh (University of Pittsburgh of The Commonwealth System of Higher Education), Vascor, Inc.
• Original Assignee: Vascor, Inc.
• Inventors: Paden, Brad, Capone, Christopher D., Holmes, John A., Sofranko, Richard A., Moore, Daniel R., Prem, Edward K., Wu, Zhongjun, Antaki, James, Heilman, Marlin S., Parisi, Carl M., Kolenik, Steve A., Burgreen, Greg, Borzelleca, David
• Application Number:
  US10/325,275
• Publication Number:
  US 20030144574A1
• Time in Patent Office: Days
• US Class Current: 600/16
• CPC Class Codes: A61M 2205/0266 Shape memory materials
• CPC Class Codes: A61M 2206/16 Rotating swirling helical flow, e.g. by tangential inflows
• CPC Class Codes: A61M 39/24 Check- or non-return valves
• CPC Class Codes: A61M 60/148 in line with a blood vessel using resection or like techniques, e.g. permanent endovascular heart assist devices
• CPC Class Codes: A61M 60/178 drawing blood from a ventricle and returning the blood to the arterial system via a cannula external to the ventricle, e.g. left or right ventricular assist devices
• CPC Class Codes: A61M 60/237 the blood flow through the rotating member having mainly axial components, e.g. axial flow pumps
• CPC Class Codes: A61M 60/422 the force acting on the blood contacting member being electromagnetic, e.g. using canned motor pumps
• CPC Class Codes: A61M 60/812 Vanes or blades, e.g. static flow guides
• CPC Class Codes: A61M 60/814 Volutes
• CPC Class Codes: A61M 60/822 specially adapted for being actively controlled
• CPC Class Codes: A61M 60/833 Occluders for preventing backflow
• CPC Class Codes: A61M 60/892 Active valves, i.e. actuated by an external force
• CPC Class Codes: A61M 60/894 Passive valves, i.e. valves actuated by the blood
• CPC Class Codes: A61M 60/896 having flexible or resilient parts, e.g. flap valves
• CPC Class Codes: F04D 15/0022 throttling valves or valves varying the pump inlet opening or the outlet opening
• CPC Class Codes: F16K 1/22 with axis of rotation crossing the valve member, e.g. butterfly valves
• CPC Class Codes: F16K 15/03 with a hinged closure member or with a pivoted closure member
• CPC Class Codes: F16K 15/035 with a plurality of valve members
• CPC Class Codes: F16K 15/144 the closure elements being fixed along all or a part of their periphery
• CPC Class Codes: F16K 15/16 with tongue-shaped laminae
• CPC Class Codes: F16K 15/18 : with actuating mechanism; Combined check valves and actuated valves
• CPC Class Codes: F16K 15/1825 : for check valves with flexible valve members
• CPC Class Codes: F16K 7/10 : with inflatable member

Abstract

A method and apparatus as described herein for substantially, but not entirely, blocking back-flow through a blood pump when the blood pump is not pumping blood wherein the method and apparatus can operate passively or actively if the blood pump stops pumping in order to provide a limited back-flow through the blood pump to prevent clot formation.

Claims

1. A blood pump comprising an inlet, an outlet, a rotor cooperating with a stator for pumping blood through at least one blood flow path from said inlet to said outlet, said rotor movable axially with respect to said stator between a pumping position and a non-pumping position, a portion of said rotor configured to substantially but not entirely restrict a reverse flow of blood from said outlet to said inlet when said rotor is moved to said non-pumping position such that a limited reverse blood flow is permitted.

2. A blood pump comprising an inlet, an outlet, a rotor cooperating with a stator for pumping blood through at least one blood flow path from said inlet to said outlet, and a backflow check valve substantially but not entirely restricting a reverse flow of blood from said outlet to said inlet such that a limited reverse flow is permitted responsive to a predetermined reduction in rotation speed of said rotor.

3. The blood pump of claim 2 wherein said back flow check valve member further comprises a balloon member centrally positioned in said at least one blood flow path, said balloon member having a fixed end attached to said stator, said balloon member inflatable to substantially but not entirely block said at least one flow path to permit said limited reverse flow and contractible to present a minimal impedance to forward blood flow.

4. The blood pump of claim 3 further comprising said fixed end of said balloon member attached to said stator near said outlet.

5. The blood pump of claim 3 further comprising said fixed end of said balloon member attached to at least one cross member and said at least one cross member attached to said stator near said inlet.

6. The blood pump of claim 5 further comprising said at least one cross member having a wide dimension and a thin dimension and said at least one cross member positioned generally parallel to and at least partially across said at least one blood flow path such that said thin dimension presents minimal impedance to blood flow.

7. The blood pump of claim 3 further comprising:

a. said balloon member having an elliptical shape with a long axis generally coaxial with an axis of rotation of said rotor; and

b. said balloon member having plurality of curved lobe portions, said plurality of curved lobe portions defining a maximum diameter at a midpoint of said balloon member, said maximum diameter substantially but not entirely equal to a diameter of said blood flow path.

8. The blood pump of claim 7 further comprising a support frame disposed within said balloon member, said support frame having at least one lobe support member which supports at least one of said plurality of curved lobe portions of said balloon member, said support frame having at least one passageway therethrough, one end of said at least one passageway connectable to a source of pressure and another end of said passageway communicating within said balloon member to at least one of inflate and deflate said balloon member.

9. The blood pump of claim 2 wherein said back flow check valve member further comprises a disk member centrally positioned in said at least one blood flow path, said disk member pivotable to a first position wherein a face of said disk member substantially but not entirely blocks said at least one blood flow path to permit said limited reverse flow between an outer periphery of said disk and a bore of said stator which defines said at least one blood flow path, and said disk member pivotable to a second position wherein a thickness of said disk member is substantially aimed along said at least one blood flow path so as to present minimal obstruction of forward blood flow.

10. The blood pump of claim 9 further comprising a strut having a first end pivotably connected to said disk member and a second end connected to said stator near said outlet.

11. The blood pump of claim 10 further comprising at least one cross member, said second end of said strut attached to said at least one cross member, and said at least one cross member attached to said stator near said inlet.

12. The blood pump of claim 11 further comprising said at least one cross member having a wide dimension and a thin dimension and said at least one cross member positioned generally parallel to and at least partially across said at least one blood flow path such that said thin dimension presents minimal impedance to blood flow.

13. The blood pump of claim 12 further comprising said at least one cross member positioned at an angle to said at least one blood flow path such that characteristics of blood flow across said at least one cross member are affected.

14. The blood pump of claim 9 further comprising said outer periphery of said disk member configured to enhance said limited reverse blood flow when said disk member is in said first position.

15. The blood pump of claim 9 further comprising a hole thru said face of said disk member.

16. The blood pump of claim 9 further comprising said disk member biased in said first position and said disk member moving to said second position when sufficient forward flow is present to pivot said disk to said second position.

17. The blood pump of claim 2 wherein said back flow check valve member further comprises a flapper valve centrally positioned in said at least one blood flow path, said flapper valve having a plurality of leaflets movable between a first position wherein faces of said plurality of leaflets substantially but not entirely block said at least one blood flow path to permit said limited reverse flow between an outer periphery formed by said plurality of leaflets and a bore in said stator which defines said at least one blood flow path, and a second position wherein a thickness of each of said plurality of leaflets is substantially aimed along said at least one blood flow path so as to present a minimum obstruction to forward blood flow.

18. The blood pump of claim 17 further comprising at least one cross member and said plurality of leaflets supported by said at least one cross member.

19. The blood pump of claim 17 wherein said plurality of leaflets is four leaflets and further comprising a pair of cross members and a pair of said four leaflets supported by each of said pair of cross members.

20. The blood pump of claim 18 further comprising said at least one cross member attached to said stator near said inlet.

21. The blood pump of claim 18 further comprising a strut having a first end attached to said at least one cross member and a second end attached to said stator near said outlet.

22. The blood pump of claim 21 further comprising at least one additional cross member, said second end of said strut attached to said at least one additional cross member, and said at least one additional cross member attached to said stator near said inlet.

23. The blood pump of claim 18 further comprising said at least one cross member having a wide dimension and a thin dimension and said at least one cross member positioned generally parallel to and at least partially across said at least one blood flow path such that said thin dimension presents minimal impedance to blood flow.

24. The blood pump of claim 23 further comprising said at least one cross member positioned at an angle to said at least one blood flow path such that characteristics of blood flow across said at least one cross member are affected.

25. The blood pump of claim 18 further comprising a generally cylindrical support member attached to at least one of said at least one cross member and at least one of said plurality of leaflets, and said generally cylindrical support member having a diameter substantially but not entirely equal to a diameter of said blood flow path such that said limited reverse blood flow occurs around an outer periphery of said generally cylindrical support member.

26. The blood pump of claim 17 further comprising said outer periphery formed by said plurality of leaflets configured to one of increase and decrease said limited reverse blood flow when said disk member is in said first position.

27. The blood pump of claim 17 wherein said plurality of leaflets are comprised of a flexible material such that movement between said first and second positions is accomplished via bending of said flexible material.

28. The blood pump of claim 27 wherein said flexible material comprises a material which contracts and expands responsive to electrical stimulation.

29. The blood pump of claim 28 wherein said material further comprises Nitinol.

30. The blood pump of claim 2 wherein said back flow check valve member further comprises a substantially planar spiral valve centrally positioned in said at least one blood flow path, said spiral valve being a continuous flexible member having one fixed end and one free end extending from said fixed end in a spiral manner in a common plane with said fixed end, said continuous flexible member movable between a first position wherein said free end is generally planar with said fixed end, and a second position wherein said free end is translated in a direction generally normal to said common plane such that a generally conical shape is formed, said spiral valve substantially but not entirely blocking said at least one flow path in said first position to permit said limited reverse flow, and said spiral valve presenting a minimum impedance to forward blood flow in said second position.

31. The blood pump of claim 30 further comprising at least one cross member and said free end attached to said at least one cross member.

32. The blood pump of claim 31 further comprising said at least one cross member attached to said stator near said inlet.

33. The blood pump of claim 32 further comprising said at least one cross member having a wide dimension and a thin dimension and said at least one cross member positioned generally parallel to and at least partially across said at least one blood flow path such that said thin dimension presents minimal impedance to blood flow.

34. The blood pump of claim 33 further comprising said at least one cross member positioned at an angle to said at least one blood flow path such that characteristics of blood flow across said at least one cross member are affected.

35. The blood pump of claim 31 further comprising a strut having one end attached to said at least one cross member and a second end attached to said stator near said outlet.

36. The blood pump of claim 35 further comprising at least one additional cross member, said second end of said strut attached to said at least one additional cross member, and said at least one additional cross member attached to said stator near said inlet.

37. The blood pump of claim 30 further comprising no gap between adjacent edges of said continuous flexible member.

38. The blood pump of claim 30 further comprising a gap between adjacent edges of said continuous flexible member such that some reverse blood flow is permitted through said spiral valve via said gap when said free end is at said first position.

39. The blood pump of claim 30 further comprising said continuous flexible member having a thickness which varies along a length thereof from said fixed end to said free end.

40. The blood pump of claim 30 further comprising said continuous flexible member having a width which varies along a length thereof from said fixed end to said free end.

41. The blood pump of claim 30 further comprising at least one hole in said continuous flexing member.

42. The blood pump of claim 41 further comprising said at least one hole located at said free end of said continuous flexing member near a center of said spiral valve member.

43. The blood pump of claim 30 wherein said free end of said continuous flexing member extends outward from said fixed end in a spiral manner into a different plane from said common plane such that in said first position said spiral valve has a generally conical shape, and in said second position said free end is translated further away from said fixed end such that said spiral valve has an extended conical shape when said free end is at said second position.

44. The blood pump of claim 2 wherein said back flow check valve member further comprises a pair of flexible valve members centrally positioned in said at least one blood flow path, said pair of flexible valve members having fixed ends and free ends, said fixed ends held in generally parallel spaced relationship to each others said free ends movable between a first position and a second position, said free ends biased away from each other in said first position and sized to at least substantially block said at least one blood flow path in said first position such that spacing between said fixed ends primarily defines said limited reverse blood flow, said free ends generally parallel to each other and generally aligned with said at least one blood flow path in said second position such that there is minimal impedance to forward blood flow.

45. The blood pump of claim 44 further comprising said fixed end of at least one of said pair of flexible valve members having at least one hole therethrough to enhance said limited reverse blood flow between said non flexing portions.

46. The blood pump of claim 44 further comprising at least one cross member, said pair of flexible valve members attached to said at least one cross member, and said cross member attached to said stator.

47. The blood pump of claim 46 further comprising said at least one cross member having a wide dimension and a thin dimension and said at least one cross member positioned generally parallel to and at least partially across said at least one blood flow path such that said thin dimension presents minimal impedance to blood flow.

48. The blood pump of claim 47 further comprising said at least one cross member positioned at an angle to said at least one blood flow path such that characteristics of blood flow across said at least one cross member are affected.

49. The blood pump of claim 44 further comprising said free ends having an arcuate shape, in said first position a periphery of said arcuate shape at least partially contacting an inner surface of a bore in said stator which defines said at least one blood flow path, and said periphery having features which enable at least a portion of said limited reverse flow of blood to occur between said periphery of said free ends and said bore in said rotor.

50. The blood pump of claim 49 further comprising said periphery configured to one of increase and decrease said limited reverse blood flow when said free ends are in said first position.

51. The blood pump of claim 50 wherein said features further comprise at least one of grooves, notches, and channels.

52. The blood pump of claim 44 further comprising said pair of flexible valve members having a thickness which varies along a length thereof.

53. The blood pump of claim 2 wherein said back flow check valve member further comprises:

a. a membrane having a portion thereof adjacent said at least one blood flow path, said portion thereof movable between a first position wherein said portion is biased into said at least one blood flow path such that said membrane substantially but not entirely blocks said at least one blood flow path to provide said limited reverse flow, and a second position wherein said portion is substantially withdrawn from said at least one blood flow path minimize impedance to forward blood flow; and

b. a pusher member movable between a third position wherein said pusher member moves said portion to said first position, and a fourth position wherein said pusher member moves said portion to said second position, said pusher member movable between said third and fourth positions responsive at least to rotation speed of said rotor.

54. The blood pump of claim 53 further comprising said membrane and said pusher member carried by said rotor.

55. The blood pump of claim 54 further comprising said pusher member movable from said third position to said fourth position via centrifugal force created by rotation of said rotor.

56. The blood pump of claim 53 further comprising said membrane and said pusher member carried by said stator.

57. The blood pump of claim 56 further comprising a first control member biasing said pusher member in said third position and a second control member selectively controllable to overcome said first control member to move said pusher member to said fourth position.

58. The blood pump of claim 57 wherein said first control member comprises a resiliently compressible member and said second control member comprises a contractible member which contracts responsive to electrical stimulation to compress said resiliently compressible member and move said pusher member to said fourth position, and said contractible member returning to an un-contracted position responsive to an absence of said electrical stimulation such that said resiliently compressible member returns said pusher member to said third position.

59. The blood pump of claim 57 wherein said second contractible member is made from Nitinol.