Artificial hearts with permanent magnet bearings

• US 5,507,629 A
• Filed: 06/17/1994
• Issued: 04/16/1996
• Est. Priority Date: 06/17/1994
• Status: Expired due to Term

• Current Assignee: M.D. Robert Jarvik
• Original Assignee: M.D. Robert Jarvik
• Inventors: Jarvik, Robert
• Primary Examiner(s): FREAY, CHARLES GRANT
• Application Number:
  US08/261,858
• Time in Patent Office: 669 Days
• Field of Search: 417/356, 417/365, 417/423.3, 417/423.12, 415/900, 623/3, 310/90.5, 384/907.1
• US Class Current: 417/423.3
• 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 60/17 inside a ventricle, e.g. intraventricular balloon pumps
• 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 60/419 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 60/804 Impellers
• CPC Class Codes: A61M 60/82 Magnetic bearings
• CPC Class Codes: A61M 60/825 Contact bearings, e.g. ball-and-cup or pivot bearings
• CPC Class Codes: A61M 60/863 Apex rings
• CPC Class Codes: A61M 60/88 Percutaneous cables
• CPC Class Codes: F16C 2316/18 Pumps for pumping blood
• CPC Class Codes: F16C 39/063 Permanent magnets
• CPC Class Codes: Y10S 415/90 Rotary blood pump

Abstract

Highly-miniaturized rotary artificial hearts small enough to be implanted within the natural heart are provided. The entire radial load of a high-speed pump rotor and most of the axial load is carried by a radially stable arrangement of high-energy-product permanent magnets. The rotor is fully suspended and rotated magnetically, with the exception of a single thrust-bearing contact point which utilizes ultra-hard, wear-resistant material, preferentially diamond, located at the axis of rotation in a high-flow region of the pump. No sensors or electromagnets are required for the bearings. One preferred embodiment utilizes dual mirror-image axial or mixed flow impellers mounted on a single axis so as to pump from a central inflow port out both ends of the device. This achieves thrust balancing, reduces pump speed by approximately half for a given flow and pressure, and is well-accommodated anatomically with double outflow grafts, one anastomosed directly to the aorta within the heart, and the second connected via the apex to the descending thoracic aorta.

Claims

1. A rotary pump comprising;

a. housing means adapted to contain a rotor therewithin,

b. pump impeller means carried by a rotor,

c. permanent magnet radial bearing means including stationary permanent magnets supported in said housing and rotating permanent magnets mounted to said rotor configured to support the entire radial load of said rotor during usual operation,

d. mechanical thrust bearing means including a wear-resistant bearing member affixed to said rotor at one end of the axis of rotation of the rotor and a stationary wear resistant mechanical bearing member affixed to said housing in direct proximity thereto so as to carry the thrust load on the rotor while maintaining the rotor in such a position that the stationary and rotating permanent magnets of the radial bearing means are in stable functional alignment and,

e. power means to impart rotational force to said rotor and thereby actuate said pump.

2. The rotary pump of claim 1 adapted to pump blood in which the contact surface area of said mechanical thrust bearing is minimized and said housing and rotor are configured to wash the mechanical thrust bearing with a stream of blood of high enough velocity to prevent thrombus accumulation severe enough to impair the function of the pump.

3. The rotary pump of claim 1 in which magnetic means are provided to bias said rotor axially such that the rotating and stationary surfaces of said thrust bearing are retained in contact with one another.

4. The rotary pump of claim 1 in which two mechanical thrust bearings are provided, one at each end of the axis of rotation of the rotor, and the rotor is thereby axially confined.

5. The rotary pump of claim 1 adapted to pump blood, in which two mechanical thrust bearings are provided, one at each end of the axis of rotation of the rotor, the rotor is thereby axially confined, and said rotor and housing are configured to wash both mechanical thrust bearings with a stream of blood of high enough velocity to prevent thrombus accumulation severe enough to impair the function of the pump.

6. The rotary pump of claim 1 in which mechanical radial position limiting means are provided, said means comprising mechanical radial bearing means having so large a gap between rotating and stationary components thereof that radial displacement of the rotor must exceed the radial displacement under usual magnetically supported radial load conditions before mechanical contact of the limiting means can occur.

7. A dual outlet rotary blood pump comprising;

a. a housing having a central inlet through which blood enters and two outlets through which blood is ejected,

b. a rotor disposed for rotation within said housing upon which two pump impellers are mounted,

c. bearing means supporting said rotor for rotation within said housing,

d. said impellers configured such that rotation of the rotor in one direction pumps blood from the central opening to both outlets,

e. power means to impart rotational force to said rotor and thereby actuate said pump, and,

f. connector means to surgically affix said blood pump to the vascular system so as to provide relatively low pressure blood to the central inlet and to connect each outlet to blood vessels at arterial pressure such that the thrust load on each impeller acts to counterbalance the thrust load on the other impeller.

8. A bearing and rotor system adapted to carry and drive the impeller of a rotary pump comprising;

a. a stationary frame having permanent magnets affixed thereto,

b. a rotor having permanent magnets mounted thereupon in a configuration that provides radial magnetic bearing support forces in combination with the magnetic fields produced by said permanent magnets mounted on said stationary frame,

c. thrust bearing means mounted on the stationary frame and on each end of the rotor configured to confine the rotor axially in a position where it is radially supported by said magnetic radial bearing forces, and is free to rotate about its axis,

in which mechanical radial position limiting means are provided, said means comprising mechanical radial bearing means having so large a gap between rotating and stationary components thereof that radial displacement of the rotor must exceed the radial displacement under usual magnetically supported radial load conditions before mechanical contact of the limiting means can occur.

9. A rotary blood pump comprising;

a. a blood pumping rotor contained in a pump housing,

b. permanent magnetic bearing means adapted to support the radial load of the rotor without any electromagnetic radial bearing components,

c. mechanical or a combination of mechanical and permanent magnet axial thrust bearing means adapted to function without any electromagnetic thrust bearing components,

d. power means to rotate the rotor and thereby pump the blood.

10. The blood pump of claim 9 in which the rotor includes a hydrodynamic impeller.

11. The rotary blood pump of claim 9 in which the power means includes an electric motor and some of the blood pumped passes through a channel within said electric motor.