Centrifugal blood pump for cardiac assist

• US 4,135,253 A
• Filed: 11/30/1976
• Issued: 01/23/1979
• Est. Priority Date: 11/30/1976
• Status: Expired due to Term

• Current Assignee: Hemadyne Corporation
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Gates, William H., Reich, Sanford
• Primary Examiner(s): Frinks, Ronald L.
• Application Number:
  US05/746,008
• Time in Patent Office: 784 Days
• Field of Search: 3/1.7, 3/1, 128/1 D, 128/DIG. 3, 417/420, 415/DIG. 4, 415/112, 415/212 R, 415/215, 415/206
• US Class Current: 623/3.13
• 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 60/422 the force acting on the blood contacting member being electromagnetic, e.g. using canned motor pumps
• CPC Class Codes: A61M 60/806 Vanes or blades
• CPC Class Codes: A61M 60/827 Sealings between moving parts
• CPC Class Codes: A61M 60/829 having a purge fluid supply
• CPC Class Codes: F04D 13/024 a magnetic coupling
• CPC Class Codes: F04D 29/108 the sealing fluid being other than the working liquid or being the working liquid treated
• CPC Class Codes: Y10S 415/90 Rotary blood pump

Abstract

A centrifugal blood pump and method of pumping blood is disclosed to provide assistance for a dysfunctional heart. The pump is provided with a magnetic drive system which permits a synchronous magnetic coupling with a separate power unit disposed immediately adjacent the pump housing. The pump has a single moving part which includes the combination of an impeller connected to a magnetic drive rotor. The impeller is of improved blade and hub design to automatically move blood, and minimize formation of blood clots and fibrous amalgamation in the region of blood flow. Further, the impeller blades are configured to extend almost completely across the bottom surface of the impeller hub to enhance efficiency and clot-free operation. The magnetic drive system floats on a fluid surface of saline solution, which hydrodynamically supports and lubricates the magnetic drive rotor contained in a compartment separate from the impeller and facilitates a prolonged period of service-free operation.

Claims

1. A centrifugal blood pump comprising:

(a) pump housing means having a first chamber, a second chamber and baffle means disposed therebetween and having an aperture communicating between said first and second chamber including an inlet and an outlet for receiving and dispensing blood into and from said first chamber respectively;

(b) rotor means rotatively mounted within said second chamber and adapted to be rotated by drive means coupled thereto;

(c) an impeller rotatively disposed within said first chamber and connected by coupling means to said rotor means through said aperture of said baffle plate to be rotated thereby, said impeller including a plurality of blades extending from an axis thereof, whereby blood is pumpled from said inlet to said outlet;

(d) seal means disposed between said coupling means and said aperture for isolating a lubricating solution disposed within said second chamber from the blood pumped through the first chamber; and

(e) said impeller includes a hub having a shank end connected via a shank to said impeller, and a conical end, said plurality of blades extending from said hub, each of said plurality of blades having an edge extending from a point disposed relatively close to said baffle plate and adjacent to said shank along a countour corresponding to that of said baffle plate, said shank end of said hub configured to extend from said adjacent points and increasingly away from said baffle plate to thereby define a portion of each of said plurality of blades disposed between said shank end of said hub and said baffle plate for rapidly moving the blood in the vicinity of said shank.

2. A centrifugal blood pump as claimed in claim 1, wherein said hub includes an outer circumference and each of said plurality of blades extends from said hub along a line disposed generally tangential with said outer circumference.

3. A centrifugal blood pump comprising:

a) a cylindrical pump housing having a scroll pump chamber within said housing, a rotor housing connected to said pump housing having a rotor chamber and a baffle plate separating said pump housing from said rotor housing, an axially disposed aperture in said baffle plate, an impeller having a first shank and disposed in said pump housing;

b) a rotor having a second shank and disposed in said rotor housing, said impeller being connected to said rotor by passing said first shank through said axially disposed aperture in said baffle plate and connected to said second shank;

c) a seal surrounding said first shank and affixed in said axially disposed aperture of said baffle plate to prevent blood in said pump chamber from seeping into said rotor chamber;

d) an axially disposed first inlet in said pump housing for bringing blood into said pump chamber;

e) a transverse first outlet in said pump housing for removing blood from said pump chamber;

f) a second inlet in said rotor chamber for bringing a saline solution lubricant into said rotor chamber; and

g) a second outlet in said rotor chamber for removing the saline solution lubricant from said rotor chamber.

4. A centrfugal blood pump as claimed in claim 3, wherein said impeller includes a hub having a shank end connected to said shank and a conical end, and a plurality of radiating blades extending from said hub, said blades being generated from said shank, said hub being maintained at a position out of contact with said baffle plate, whereby said blades direct rapidly the blood from between said shank end of said hub and baffle plate.

5. A centrifugal blood pump as claimed in claim 4, wherein said impeller blades are positioned on said impeller hub such that said blades are offset of the axial center line of said hub, and said impeller hub includes a radius of curvature in the direction of rotation of said impeller.

6. A centrifugal blood pump as claimed in claim 4, wherein said conical end of said hub is axially disposed of said cylindrical pump housing and in-line with said first inlet to deflect incoming blood to said impeller blades.

7. A centrifugal blood pump as claimed in claim 5, wherein said baffle plate separating said pump chamber from said rotor chamber is fluid sealed to prevent passage of fluids between said pump chamber and said rotor chamber.

9. A centrifugal blood pump as claimed in claim 3, wherein there is included means for directing the saline solution into said rotor chamber through said second inlet and from said rotor chamber through said second outlet so that the pressure of that saline solution as exerted against said seal is greater than the pressure exerted upon said seal by the blood in said pump chamber.

10. A centrifugal blood pump as claimed in claim 4, wherein said rotor in said rotor chamber includes a magnet and is driven by a magnetic coupling by motor means disposed exterior to said pump.

11. A centrifugal blood pump as claimed in claim 10 wherein said rotor is lubricated by a saline solution, whereby said rotor is maintained in a friction reduced relationship to said rotor housing.

12. A centrifugal blood pump as claimed in claim 11 wherein said rotor housing includes a thrust plate between said rotor housing and said rotor and said rotor is spaced from said baffle plate by a spacer element which includes an axially disposed aperture for receiving therethrough said second shank on said rotor.

8. A centrifugal blood pump as claimed in cliam 7, wherein said baffle plate includes a pump chamber surface and a rotor chamber surface, and said seal includes a lip which extends through said baffle plate to said pump chamber surface and is disposed flush with said pump chamber surface.

13. A centrifugal blood pump comprising:

a housing;

a scroll pump chamber within said housing;

an axial inlet to and tangential outlet from said scroll pump chamber;

pump means within said scroll pump chamber for moving blood therethrough comprising an impeller mounted for rotation in said chamber;

magnetic drive means for driving said pumping means;

a rotor chamber within said housing for enclosing said drive means and for receiving a liquid lubricant; and

at least the portion of said housing enclosing said drive means being electrically non-conductive whereby said drive means may be driven by a mechanically unconnected external source of magnetic energy, wherein an improvement comprising;

a baffle plate disposed between said scroll pump chamber and said rotor chamber and including a center aperture, and said impeller having an impeller shank extending through said center aperture in said baffle plate, said magnetic drive means including a rotor and connected to said impeller shank, a seal disposed in said aperture of said baffle plate to surround said impeller shank and having the property of substantially blocking the passage of the lubricant into said scroll pump chamber, said impeller including a hub from which said shank extends and a plurality of radiating blade members, said hub having a conical end and a shank end, said blade members being secured to the shank end of said hub and said conical end of said hub, said blade members extend from said shank of said hub to maintain said hub out of contact with said baffle plate.

14. A centrifugal blood pump as claimed in claim 13 wherein said blade members being secured to said hub shank end approximate to the point where said shank extends transversely from said hub.

15. A centrifugal blood pump as claimed in claim 14, wherein said blade members are secured offset to said hub at an angle to the axial center line of said hub.

16. A centrifugal blood pump as claimed in claim 15, wherein said rotor housing includes an inlet port and an outlet port for introducing lubricating fluids to said rotor.

17. A centrifugal blood pump as claimed in claim 16, wherein said lubricating fluid is a saline solution.