Centrifugal blood pump

• US 5,863,179 A
• Filed: 11/03/1997
• Issued: 01/26/1999
• Est. Priority Date: 06/25/1993
• Status: Expired due to Fees

• Current Assignee: ARG Medical Solutions LLC
• Original Assignee: Baxter International Inc.
• Inventors: Westphal, Dieter, Reul, Helmut, Rau, Guenter
• Primary Examiner(s): KWON, JOHN
• Application Number:
  US08/963,591
• Time in Patent Office: 449 Days
• Field of Search: 415/206, 415/900, 417/423.12, 417/424.1
• US Class Current: 415/206
• 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 60/232 Centrifugal pumps
• CPC Class Codes: A61M 60/419 the force acting on the blood contacting member being permanent magnetic, e.g. from a rotating magnetic coupling between driving and driven magnets
• CPC Class Codes: A61M 60/806 Vanes or blades
• CPC Class Codes: A61M 60/812 Vanes or blades, e.g. static flow guides
• CPC Class Codes: A61M 60/825 Contact bearings, e.g. ball-and-cup or pivot bearings
• CPC Class Codes: F04D 13/027 Details of the magnetic circuit
• CPC Class Codes: F04D 29/0465 Ceramic bearing designs
• CPC Class Codes: F04D 29/0467 Spherical bearings
• CPC Class Codes: F04D 29/242 Geometry, shape
• CPC Class Codes: Y10S 415/90 Rotary blood pump

Abstract

A magnetically-driven centrifugal blood pump includes a housing and an impeller mounted for rotation within. The impeller includes a generally disk-shaped base plate and a plurality of curvilinear vanes extending axially upward therefrom. The vanes project radially outward from the base plate approximately one-third of their curvilinear length. The housing includes a rear wall spaced from the impeller base plate across a constant gap, with a sloped transition wall surrounding the rear wall and joining it to a peripheral wall. A tangential outlet is provided in the peripheral wall. A front wall extends inward from the peripheral wall with a slight conicity to an axial inlet. The vanes each have a front edge which slopes away from the front wall in the radially outward direction to provide a widening gap therebetween. The vanes have inner ends which together define a vane-free inner region below and slightly larger than the inlet. The curvature of each vane changes along its length, and a tangent angle progresses from the inner end to the outer end according to a preferred formula. Desirably, the impeller includes a pair of low magnetic retentivity plates, such as steel, which are driven by an external drive which sets up a rotating magnetic field.

Claims

1. A centrifugal blood pump, comprising:

a rigid housing having an axial inlet opening to a wider pumping chamber formed generally symmetrically about an axis, and a tangential outlet from the pumping chamber;

the pumping chamber including a generally radially disposed front wall adjacent and surrounding the inlet, a peripheral wall connected to the front wall defining the outer boundary of the pumping chamber, the tangential outlet opening from the peripheral wall, a transition wall connected to the peripheral wall and sloped therefrom radially inward and away from the front wall, and a radially disposed rear wall connected to the transition wall; and

an impeller mounted for axial rotation within the pumping chamber, the impeller having a circular base plate parallel to and axially spaced from the rear wall, the base plate having a diameter approximately equal to the diameter of the rear wall, the impeller further including a plurality of curvilinear vanes projecting axially upward from the base plate, each of the vanes having a radially inner end spaced from the axis of the pumping chamber to define collectively therebetween a void, each of the vanes having a rear edge connected to the base plate and continuing radially outwardly therefrom toward the peripheral wall to terminating in outer ends, each vane further including a front edge sloping away from the front wall from the inner end to the outer end.

2. The pump of claim 1, wherein the vanes are curved and have a length, the vanes extending outward from the plate approximately one-third of their length.

3. The pump of claim 1, wherein the axial height of each vane decreases by approximately half from the inner end to the outer end.

4. The pump of claim 3, wherein the front wall has a slight conicity of between about 3°

to 10°

.

5. The pump of claim 1, wherein the outer ends of the vanes define a circle with a first diameter, and at least some of the inner ends are equidistantly spaced from the axis so that a circular vane-free region is formed therewithin having a second diameter, the ratio of the second diameter to the first diameter being between about 0.25 to 0.5.

6. The pump of claim 5, wherein the ratio is about 0.375.

7. The pump of claim 5, wherein the inlet is formed centrally in the front wall and opens to the pumping chamber with a third diameter, and wherein the second diameter is greater than the third diameter.

8. The pump of claim 1, wherein an angle of contact of each vane is defined by an included angle between radial vectors through the inner and outer ends, and the angle of contact is between about 90°

to 120°

.

9. The pump of claim 8, wherein the angle of contact is about 100°

.

10. The pump of claim 1, wherein the inner end of each vane forms a leading angle with respect to a tangent to a circular vane-free region defined by the inner ends of at least some of the vanes, and the outer end of each vane forms a trailing angle with respect to a tangent to the circle defined by the vane outer ends, the trailing angle being greater than the leading angle.

11. The pump of claim 10, wherein the trailing angle is between about 25°

to 40°

.

12. The pump of claim 11, wherein the trailing angle is about 30°

.

13. The pump of claim 1, wherein the thickness of each vane increases from the inner and outer ends towards the middle of the blade.

14. The pump of claim 1, wherein the centrifugal pump is magnetically driven and includes a plurality of planar members of low magnetic retentivity embedded in the base plate adapted to be driven by an external magnetically-coupled drive.

15. A centrifugal blood pump, comprising:

an outer housing defining a pumping chamber within, the pumping chamber being generally symmetric about a central axis, the housing having a front wall, a rear wall axially spaced from the front wall, and a peripheral wall connecting the front and rear walls;

an inlet in the front wall;

an outlet in the peripheral wall;

an impeller mounted for axial rotation in the pumping chamber and comprising a planar plate axially spaced from a central portion of the rear wall across a rear gap of substantially constant dimension, the impeller further including a plurality of vanes axially projecting from the plate toward the front wall, the vanes extending radially outward from the plate toward the peripheral wall, wherein the rear wall further includes an annular portion surrounding the central portion and sloped toward the front wall from the central portion to the peripheral wall.

16. The pump of claim 15, wherein the vanes are curved and have a length, the vanes extending outward from the plate approximately one-third of their length.

17. The pump of claim 15, wherein the centrifugal pump is magnetically driven and includes a plurality of planar members of low magnetic retentivity embedded in the base plate adapted to be driven by an external magnetically-coupled drive.

18. A centrifugal blood pump, comprising:

an outer housing defining a pumping chamber within, the pumping chamber being generally symmetric about a central axis, the housing having a front wall, a rear wall axially spaced from the front wall, and a peripheral wall connecting the front and rear walls;

an inlet in the front wall;

an outlet in the peripheral wall;

an impeller mounted for axial rotation in the pumping chamber and comprising a planar plate axially spaced from a central portion of the rear wall across a rear gap of substantially constant dimension, the impeller further including a plurality of vanes axially projecting from the plate toward the front wall, the vanes extending radially outward from the plate toward the peripheral wall, wherein the vanes each include an inner end and an outer end, and a front edge which forms a front gap with the front wall, the front gap diverging from the inner end to the outer end to reduce the difference in sheer stresses imposed on the blood at the inner and outer ends, respectively.

19. The pump of claim 18, wherein each vane has an axial height which decreases from the inner end to the outer end.

20. The pump of claim 19, wherein the axial height of each vane decreases by approximately half from the inner end to the outer end.

21. The pump of claim 19, wherein the front wall has a slight conicity of between about 3°

to 10°

.

22. The pump of claim 18, wherein the centrifugal pump is magnetically driven and includes a plurality of planar members of low magnetic retentivity embedded in the base plate adapted to be driven by an external magnetically-coupled drive.

23. A centrifugal blood pump, comprising:

an outer housing defining a pumping chamber within, the pumping chamber being generally symmetric about a central axis, the housing having a front wall, a rear wall axially spaced from the front wall, and a peripheral wall connecting the front and rear walls;

an inlet in the front wall;

an outlet in the peripheral wall;

an impeller mounted for axial rotation in the pumping chamber and comprising a planar plate axially spaced from a central portion of the rear wall across a rear gap of substantially constant dimension, the impeller further including a plurality of vanes axially projecting from the plate toward the front wall, the vanes extending radially outward from the plate toward the peripheral wall, wherein the vanes each include an inner end and an outer end, the outer ends of the vanes defining a circle with a first diameter, and at least some of the inner ends are equidistantly spaced from the axis to define a circular vane-free region therewithin having a second diameter, the ratio of the second diameter to the first diameter being between about 0.25 to 0.5.

24. The pump of claim 23, wherein the ratio is about 0.375.

25. The pump of claim 23, wherein the inlet is formed centrally in the front wall and opens to the pumping chamber with a third diameter, and wherein the second diameter is greater than the third diameter.

26. The pump of claim 23, wherein the vanes are curved.

27. The pump of claim 23, wherein the centrifugal pump is magnetically driven and includes a plurality of planar members of low magnetic retentivity embedded in the base plate adapted to be driven by an external magnetically-coupled drive.

28. A centrifugal blood pump, comprising:

an outer housing defining a pumping chamber within, the pumping chamber being generally symmetric about a central axis, the housing having a front wall, a rear wall axially spaced from the front wall, and a peripheral wall connecting the front and rear walls;

an inlet in the front wall;

an outlet in the peripheral wall;

an impeller mounted for axial rotation in the pumping chamber and comprising a planar plate axially spaced from a central portion of the rear wall across a rear gap of substantially constant dimension, the impeller further including a plurality of vanes axially projecting from the plate toward the front wall, the vanes extending radially outward from the plate toward the peripheral wall, wherein the vanes are curved and each includes an inner end and an outer end, and wherein an angle of contact of each vane is defined by an included angle between radial vectors through the inner and outer ends, and the angle of contact is between about 90°

to 120°

.

29. The pump of claim 28, wherein the angle of contact is about 100°

.

30. The pump of claim 28, wherein the inner end of each vane forms a leading angle with respect to a tangent to a circular vane-free region defined by the inner ends of at least some of the vanes, and the outer end of each vane forms a trailing angle with respect to a tangent to the circle defined by the vane outer ends, the trailing angle being greater than the leading angle.

31. The pump of claim 30, wherein the trailing angle is between about 25°

to 40°

.

32. The pump of claim 31, wherein the trailing angle is about 30°

.

33. The pump of claim 28, wherein the centrifugal pump is magnetically driven and includes a plurality of planar members of low magnetic retentivity embedded in the base plate adapted to be driven by an external magnetically-coupled drive.

34. A centrifugal blood pump, comprising:

an outer housing defining a pumping chamber within, the pumping chamber being generally symmetric about a central axis, the housing having a front wall, a rear wall axially spaced from the front wall, and a peripheral wall connecting the front and rear walls;

an inlet in the front wall;

an outlet in the peripheral wall;

an impeller mounted for axial rotation in the pumping chamber and comprising a planar plate axially spaced from a central portion of the rear wall across a rear gap of substantially constant dimension, the impeller further including a plurality of vanes axially projecting from the plate toward the front wall, each vane has an inner end and extends radially outward from the plate toward the peripheral wall to terminate in an outer end, wherein the inner end of each vane forms a leading angle with respect to a tangent to a circular vane-free region defined by the inner ends of at least some of the vanes, and the outer end of each vane forms a trailing angle with respect to a tangent to the circle defined by the vane outer ends, the trailing angle being greater than the leading angle.

35. The pump of claim 34, wherein the trailing angle is between about 25°

to 40°

.

36. The pump of claim 35, wherein the trailing angle is about 30°

.

37. The pump of claim 34, wherein a tangent angle of each vane increases from the leading angle to a maximum angle at a point between the inner and outer ends, and decreases from the maximum angle to the trailing angle.

38. The pump of claim 37, wherein the tangent angle β

along each vane is defined by the formula;

space="preserve" listing-type="equation">β

(r)=Ar.sup.2 +Br+C,

where r is the radial distance from the axis, A is negative, B is positive, and C is negative.

39. The pump of claim 34, wherein an angle of contact of each vane is defined by an included angle between radial vectors through the inner and outer ends, and the angle of contact is between about 90°

to 120°

.

40. The pump of claim 34, wherein the thickness of each vane increases from the inner and outer ends towards the middle of the blade.

41. The pump of claim 34, wherein the centrifugal pump is magnetically driven and includes a plurality of planar members of low magnetic retentivity embedded in the base plate adapted to be driven by an external magnetically-coupled drive.

42. A centrifugal blood pump, comprising:

an outer housing defining a pumping chamber within, the pumping chamber being generally symmetric about a central axis, the housing having a front wall, a rear wall axially spaced from the front wall, and a peripheral wall connecting the front and rear walls;

an inlet in the front wall;

an outlet in the peripheral wall;

an impeller mounted for axial rotation in the pumping chamber and comprising a planar plate axially spaced from a central portion of the rear wall across a rear gap of substantially constant dimension, the impeller further including a plurality of vanes axially projecting from the plate toward the front wall, each vane has an inner end and extends radially outward from the plate toward the peripheral wall to terminate in an outer end, wherein the vanes are curved and have a curvilinear length, the vanes extending outward from the plate approximately one-third of their length.

43. The pump of claim 42, wherein the outer ends of the vanes defining a circle with a first diameter, and at least some of the inner ends are equidistantly spaced from the axis so that a circular vane-free region is formed therewithin having a second diameter, the ratio of the second diameter to the first diameter being between about 0.25 to 0.5.

44. The pump of claim 43, wherein the inner end of each vane forms a leading angle with respect to a tangent to a circular vane-free region defined by the inner ends of at least some of the vanes, and the outer end of each vane forms a trailing angle with respect to a tangent to the circle defined by the vane outer ends, the trailing angle being greater than the leading angle.

45. The pump of claim 44, wherein the trailing angle is between about 25°

to 40°

.

46. The pump of claim 42, wherein an angle of contact of each vane is defined by an included angle between radial vectors through the inner and outer ends, and the angle of contact is between about 90°

to 120°

.

47. The pump of claim 42, wherein the vanes each include a front edge which forms a front gap with the front wall, the front gap diverging from the inner end to the outer end to reduce the difference in sheer stresses imposed on the blood at the inner and outer ends, respectively.

48. The pump of claim 47, wherein each vane has an axial height which decreases from the inner end to the outer end.

49. The pump of claim 42, wherein the centrifugal pump is magnetically driven and includes a plurality of planar members of low magnetic retentivity embedded in the base plate adapted to be driven by an external magnetically-coupled drive.