Magnetically suspended fluid pump and control system

• US 5,928,131 A
• Filed: 11/26/1997
• Issued: 07/27/1999
• Est. Priority Date: 11/26/1997
• Status: Expired due to Fees

• Current Assignee: Vascor, Inc.
• Original Assignee: Vascor, Inc.
• Inventors: Prem, Edward K.
• Primary Examiner(s): Kamm, William E.
• Assistant Examiner(s): SCHAETZLE, KENNEDY
• Application Number:
  US08/978,670
• Time in Patent Office: 608 Days
• Field of Search: 600/16-18, 623/3, 417/352-354, 310/46, 310/178, 310/90.5
• US Class Current: 600/16
• 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 60/196 replacing the entire heart, e.g. total artificial hearts [TAH]
• CPC Class Codes: A61M 60/232 Centrifugal 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 60/515 Regulation using real-time patient data
• CPC Class Codes: A61M 60/538 Regulation using real-time blood pump operational parameter data, e.g. motor current
• 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 60/824 Hydrodynamic or fluid film bearings
• 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: F04D 13/0646 the hollow pump or motor shaft being the conduit for the working fluid
• CPC Class Codes: F04D 29/048 magnetic; electromagnetic
• CPC Class Codes: F16C 2316/18 Pumps for pumping blood
• CPC Class Codes: F16C 2360/44 Centrifugal pumps
• CPC Class Codes: F16C 32/0444 Details of devices to control the actuation of the electromagnets
• CPC Class Codes: F16C 32/047 Details of housings; Mounting of active magnetic bearings

Abstract

A blood pump for assisting a heart is provided having a stator and a rotor. The rotor is magnetically radially supported creating a suspension gap between the stator and the rotor. The rotor can be supported axially by a Lorentz force bearing and can be magnetically rotated. The stator can have a single or double volute pump chamber and the rotor can have an impeller portion for pumping blood. The rotor can have a center bore as a primary blood flowpath. The suspension gap can be a secondary blood flowpath. The blood pump can also have an axial position controller and a flow rate controller. The axial position controller can cause the axial bearing to adjust the position of the rotor. The flow rate controller can have a member for measuring a dimension of a heart ventricle to control the flow rate to avoid overly distending or contracting the ventricle. A method of operating the flow rate controller to create a pulsatile flow rate is also provided. Additionally, the blood pump can be part of a cardiac assist and arrhythmia control system. Moreover, a method of operating the flow rate controller can be provided which reduces the amount of energy needed to treat fibrillation. The method can include operating the flow rate controller to reduce a radial dimension of the ventricle prior to delivering defibrillation energy such that the ventricle contains less blood which absorbs less energy so that a larger fraction of the energy is delivered to the heart.

Claims

1. A blood pump apparatus implantable in a patient comprising:

a. a hollow stator member having an interior wall portion and a stator pump portion;

b. a rotor member having an outer wall portion and a rotor pump portion and said rotor member disposed in said hollow stator member for rotation therein;

c. a magnetic suspension having a stator magnet portion carried by said stator member and a rotor magnet portion carried by said rotor member, said stator member and rotor magnet portions cooperating to magnetically support said rotor member radially in said hollow stator member such that an annular magnetic suspension gap is created between said interior wall portion and said outer wall portion;

d. a magnetic drive having a stator motor portion carried by said stator member and a rotor motor portion carried by said rotor member, said stator motor portion and said rotor motor portion cooperating to magnetically rotate said rotor member relative to said stator member to pump blood through said stator and rotor pump portions; and

e. a Lorentz-force axial bearing having a stator axial bearing portion carried by said stator member and a rotor axial bearing portion carried by said rotor member, said stator axial bearing portion and said rotor axial bearing portion cooperating to magnetically support said rotor member axially in said stator member.

2. The blood pump of claim 1 further comprising an axial position controller to control said Lorentz force axial bearing to maintain said rotor member at a defined setpoint relative to said stator member.

3. The blood pump of claim 2 further comprising an axial position sensor having a stator sensor portion carried by said stator member and a rotor sensor portion carried by said rotor member, said stator sensor portion and said rotor sensor portion cooperating to detect an axial position of said rotor member relative to said stator member.

4. The blood pump of claim 3 wherein said Lorentz force axial bearing further comprises displacement means for axially displacing said rotor member relative to said stator member.

5. The apparatus of claim 4 wherein said displacement means is a bi-directional displacement means.

6. The blood pump of claim 1 wherein said magnetic rotation drive comprises a slotless, brushless DC motor having a coreless armature.

7. A blood pump apparatus implantable in a patient comprising:

a. a hollow stator member having an interior wall portion and a stator pump portion;

b. a rotor member having an outer wall portion and a rotor pump portion and said rotor member disposed in said hollow stator member for rotation therein;

c. a magnetic suspension having a stator magnet portion carried by said stator member and a rotor magnet portion carried by said rotor member, said stator member and rotor magnet portions cooperating to magnetically support said rotor member radially in said rotor chamber such that an annular magnetic suspension gap is created between said interior wall portion and said outer wall portion;

d. a magnetic drive having a stator motor portion carried by said stator member and a rotor motor portion carried by said rotor member, said stator motor portion and said rotor motor portion cooperating to magnetically rotate said rotor member relative to said stator member to pump blood through said stator and rotor pump portions;

e. a Lorentz-force axial bearing having a stator axial bearing portion carried by said stator member and a rotor axial bearing portion carried by said rotor member, said stator axial bearing portion and said rotor axial bearing portion cooperating to magnetically support said rotor member axially in said stator member;

f. an axial position controller to control said Lorentz force axial bearing to maintain said rotor member at a defined setpoint relative to said stator member;

g. an axial position sensor having a stator sensor portion carried by said stator member and a rotor sensor portion carried by said rotor member said stator sensor portion and said rotor sensor portion cooperating to detect an axial position of said rotor member relative to said stator member;

h. wherein said Lorentz force axial bearing further comprises displacement means for axially displacing said rotor member relative to said stator member;

i. wherein said displacement means is a bi-directional displacement means; and

j. wherein said axial position controller varies said setpoint and controls said displacement means to axially displace said rotor member to correspond to said setpoint.

8. The blood pump of claim 7 wherein said setpoint corresponds to a point where a steady state axial load applied to said rotor member is at least partially offset by an inherent axial force produced by said magnetic radial suspension such that power dissipation in said Lorentz force axial bearing is reduced.

9. The blood pump of claim 8 wherein said axial position controller detects net positive current flow in said Lorentz force axial bearing and varies said setpoint responsive to said net positive current flow towards a setpoint where current flow in said Lorentz force axial bearing is generally minimal and controls said displacement means to axially displace said rotor member to said setpoint.

10. A blood pump apparatus implantable in a patient comprising:

a. a hollow stator member having an interior wall portion and a stator pump portion;

b. a rotor member having an outer wall portion and a rotor pump portion and said rotor member disposed in said hollow stator member for rotation therein;

c. a magnetic suspension having a stator magnet portion carried by said stator member and a rotor magnet portion carried by said rotor member, said stator member and rotor magnet portions cooperating to magnetically support said rotor member radially in said rotor chamber such that an annular magnetic suspension gap is created between said interior wall portion and said outer wall portion;

d. a magnetic drive having a stator motor portion carried by said stator member and a rotor motor portion carried by said rotor member, said stator motor portion and said rotor motor portion cooperating to magnetically rotate said rotor member relative to said stator member to pump blood through said stator and rotor pump portions;

e. a Lorentz-force axial bearing having a stator axial bearing portion carried by said stator member and a rotor axial bearing portion carried by said rotor member, said stator axial bearing portion and said rotor axial bearing portion cooperating to magnetically support said rotor member axially in said stator member; and

f. an artificial heart valve assembly for preventing retrograde blood flow and said valve assembly is operatively connected between said stator pump portion and a circulatory system.

11. The blood pump of claim 10 wherein said artificial heart valve is a solenoid actuated valve.

12. A blood pump apparatus implantable in a patient comprising:

a. a hollow stator member having an interior wall portion and a stator pump portion;

b. a rotor member having an outer wall portion and a rotor pump portion and said rotor member disposed in said hollow stator member for rotation therein;

c. a magnetic suspension having a stator magnet portion carried by said stator member and a rotor magnet portion carried by said rotor member, said stator member and rotor magnet portions cooperating to magnetically support said rotor member radially in said rotor chamber such that an annular magnetic suspension gap is created between said interior wall portion and said outer wall portion;

d. a magnetic drive having a stator motor portion carried by said stator member and a rotor motor portion carried by said rotor member, said stator motor portion and said rotor motor portion cooperating to magnetically rotate said rotor member relative to said stator member to pump blood through said stator and rotor pump portions;

e. a Lorentz-force axial bearing having a stator axial bearing portion carried by said stator member and a rotor axial bearing portion carried by said rotor member, said stator axial bearing portion and said rotor axial bearing portion cooperating to magnetically support said rotor member axially in said stator member; and

f. said rotor member having a center bore forming a blood flow path in fluid communication with said stator pump portion.

13. The blood pump of claim 12 wherein said stator pump portion comprises an annular volute pump chamber and said annular volute pump chamber having an outlet passage.

14. The blood pump of claim 13 further comprising a septum formed in said annular volute pump chamber and said septum dividing said annular volute pump chamber into an annular double volute pump chamber such that each annular volute of said annular double volute pump chamber is radially opposed to offset radially forces inherent in each annular volute.

15. The blood pump of claim 14 wherein said rotor pump portion comprises an impeller and said impeller is disposed in said annular volute pump chamber for rotation therein by said magnetic drive to pump blood through said outlet passage.

16. The blood pump of claim 15 wherein said center bore is provided through said impeller and said impeller having a plurality of raised vanes thereon and said plurality of raised vanes in fluid communication with said center bore for drawing blood therethrough.

17. The blood pump of claim 16 wherein said raised vanes are curved opposite a direction of rotation of said impeller.

18. The blood pump of claim 12 wherein said magnetic suspension gap is in fluid communication with said pump chamber forming a blood flow path.

19. The blood pump of claim 18 wherein said center bore is a primary blood flow path and said magnetic suspension is a secondary blood flow path.

20. The blood pump of claim 19 wherein said stator pump portion comprises an annular volute pump chamber and said annular volute pump chamber having an outlet passage.

21. The blood pump of claim 20 further comprising a septum formed in said annular volute pump chamber and said septum dividing said annular volute pump chamber into an annular double volute pump chamber such that each annular volute of said annular double volute pump chamber is radially opposed to offset radially forces inherent in each annular volute.

22. The blood pump of claim 21 wherein said rotor pump portion comprises an impeller and said impeller is disposed in said annular volute pump chamber for rotation therein by said magnetic drive to pump blood through said outlet passage.

23. The blood pump of claim 22 wherein said center bore is provided through said impeller and said impeller having a plurality of raised vanes thereon and said plurality of raised vanes in fluid communication with said center bore for drawing blood therethrough.

24. The blood pump of claim 23 wherein said plurality of raised vanes have end portions in fluid communication with said annular magnetic suspension gap for drawing blood therethrough.

25. The blood pump of claim 24 wherein said raised vanes are curved opposite a direction of rotation of said impeller.

26. The blood pump of claim 12 further comprising:

a. said hollow stator member having an exterior wall portion spaced apart from said interior wall portion defining a first annular chamber therebetween;

b. said rotor member having an inner wall portion spaced apart from said outer wall portion defining a second annular chamber therebetween and said second annular chamber is disposed near an outer periphery of said rotor member;

c. said stator magnet portion and said stator motor portion and said stator sensor portion and said stator axial bearing portion are carried by said hollow stator member in said first annular chamber; and

d. said rotor magnet portion and said rotor motor portion and said rotor sensor portion and said rotor axial bearing portion are carried by said rotor member in said second annular chamber.

27. The blood pump of claim 26 wherein said interior wall portion of said stator member is a cylindrical interior wall portion and said outer wall portion of said rotor member is a cylindrical outer wall portion.

28. A blood pump apparatus implantable in a patient comprising:

a. a hollow stator member having an interior wall portion and a stator pump portion;

b. a rotor member having an outer wall portion and a rotor pump portion and said rotor member disposed in said hollow stator member for rotation therein;

c. a magnetic suspension having a stator magnet portion carried by said stator member and a rotor magnet portion carried by said rotor member, said stator member and rotor magnet portions cooperating to magnetically support said rotor member radially in said rotor chamber such that an annular magnetic suspension gap is created between said interior wall portion and said outer wall portion;

d. a magnetic drive having a stator motor portion carried by said stator member and a rotor motor portion carried by said rotor member, said stator motor portion and said rotor motor portion cooperating to magnetically rotate said rotor member relative to said stator member to pump blood through said stator and rotor pump portions;

e. a Lorentz-force axial bearing having a stator axial bearing portion carried by said stator member and a rotor axial bearing portion carried by said rotor member, said stator axial bearing portion and said rotor axial bearing portion cooperating to magnetically support said rotor member axially in said stator member; and

f. a flow rate controller to control a flow rate of said blood pump.

29. The blood pump of claim 28 wherein said flow rate controller further comprises:

a. a heart measurement member attachable to a heart ventricle which is assisted by said blood pump;

b. said heart measurement member measuring at least one of distention and contraction of said ventricle; and

c. said flow rate controller utilizing said dimensions to control said flow rate of said blood pump.

30. The blood pump of claim 29 wherein said flow rate is a pulsatile flow rate.

31. The blood pump of claim 29 wherein said heart measurement member comprises:

a. a heart caliper having a pair of arms pivotable relative to each other;

b. each of said pair of arms having one end attachable to an outer surface of said ventricle and an opposite end connected at a pivot point; and

c. an angular measurement device measuring changes in angular position between each of said pair of arms.

32. The blood pump of claim 31 wherein said angular measurement device comprises an electronic eddy current position sensor measuring said changes in angular position between said pair of arms.

33. The blood pump of claim 29 wherein said heart measurement member comprises a pair of ultrasonic transducers positioned at generally opposing sides of said ventricle measuring a radial dimension of said ventricle based upon an elapsed time for an ultrasonic pulse to travel between said pair of transducers.

34. An artificial heart apparatus comprising a pair of blood pumps and each of said pair of blood pumps at least one of assisting and replacing a ventricle of a natural heart, each of said pair of blood pumps having,

a. a hollow stator member having an interior wall portion and a stator pump portion,

b. a rotor member having an outer wall portion and a rotor pump portion and said rotor member disposed in said hollow stator member for rotation therein,

c. a magnetic suspension having a stator magnet portion carried by said stator member and a rotor magnet portion carried by said rotor member, said stator member and rotor magnet portions cooperating to magnetically support said rotor member radially in said rotor chamber such that an annular magnetic suspension gap is created between said interior wall portion and said outer wall portion,

d. a magnetic drive having a stator motor portion carried by said stator member and a rotor motor portion carried by said rotor member, said stator motor portion and said rotor motor portion cooperating to magnetically rotate said rotor member relative to said stator member to pump blood through said stator and rotor pump portions, and

e. a Lorentz-force axial bearing having a stator axial bearing portion carried by said stator member and a rotor axial bearing portion carried by said rotor member, said stator axial bearing portion and said rotor axial bearing portion cooperating to magnetically support said rotor member axially in said stator member.

35. A blood pump apparatus implantable in a patient comprising:

a. a stator member having a stator pump portion;

b. a rotor member having a rotor pump portion and said rotor member disposed adjacent said stator pump portion for rotation;

c. a magnetic suspension having a stator magnet portion carried by said stator member and a rotor magnet portion carried by said rotor member, said stator member and rotor magnet portions cooperating to magnetically support said rotor member radially such that an annular magnetic suspension gap is created between said rotor member and said stator member;

d. a magnetic drive having a stator motor portion carried by said stator member and a rotor motor portion carried by said rotor member, said stator motor portion and said rotor motor portion cooperating to magnetically rotate said rotor member relative to said stator member to pump blood through said stator and rotor pump portions; and

e. a Lorentz-force axial bearing having a stator axial bearing portion carried by said stator member and a rotor axial bearing portion carried by said rotor member, said stator axial bearing portion and said rotor axial bearing portion cooperating to magnetically support said rotor member axially relative to said stator member.

36. The blood pump of claim 35 further comprising an axial position controller to control said Lorentz force axial bearing to maintain said rotor member at a defined setpoint relative to said stator member.

37. The blood pump of claim 36 further comprising an axial position sensor having a stator sensor portion carried by said stator member and a rotor sensor portion carried by said rotor member, said stator sensor portion and said rotor sensor portion cooperating to detect an axial position of said rotor member relative to said stator member.

38. The blood pump of claim 37 wherein said Lorentz force axial bearing further comprises displacement means for axially displacing said rotor member relative to said stator member.

39. The apparatus of claim 38 wherein said displacement means is a bi-directional displacement means.

40. A blood pump apparatus implantable in a patient comprising:

a. a stator member having a stator pump portion;

b. a rotor member having a rotor pump portion and said rotor member disposed adjacent said hollow stator pump portion for rotation;

c. a magnetic suspension having a stator magnet portion carried by said stator member and a rotor magnet portion carried by said rotor member, said stator member and rotor magnet portions cooperating to magnetically support said rotor member radially such that an annular magnetic suspension gap is created between said rotor member and said stator member;

d. a magnetic drive having a stator motor portion carried by said stator member and a rotor motor portion carried by said rotor member said stator motor portion and said rotor motor portion cooperating to magnetically rotate said rotor member relative to said stator member to pump blood through said stator and rotor pump portions;

e. a Lorentz-force axial bearing having a stator axial bearing portion carried by said stator member and a rotor axial bearing portion carried by said rotor member, said stator axial bearing portion and said rotor axial bearing portion cooperating to magnetically support said rotor member axially relative to said stator member;

f. an axial position controller to control said Lorentz force axial bearing to maintain said rotor member at a defined setpoint relative to said stator member;

g. an axial position sensor having a stator sensor portion carried by said stator member and a rotor sensor portion carried by said rotor member, said stator sensor portion and said rotor sensor portion cooperating to detect an axial position of said rotor member relative to said stator member;

h. wherein said Lorentz force axial bearing further comprises displacement means for axially displacing said rotor member relative to said stator member;

i. wherein said displacement means is a bi-directional displacement means; and

j. wherein said axial position controller varies said setpoint and controls said displacement means to axially displace said rotor member to correspond to said setpoint.

41. The blood pump of claim 40 wherein said setpoint corresponds to a point where a steady state axial load applied to said rotor member is at least partially offset by an inherent axial force produced by said magnetic radial suspension such that power dissipation in said Lorentz force axial bearing is reduced.

42. The blood pump of claim 41 wherein said axial position controller detects net positive current flow in said Lorentz force axial bearing and varies said setpoint responsive to said net positive current flow towards a setpoint where current flow in said Lorentz force axial bearing is generally minimal and controls said displacement means to axially displace said rotor member to said setpoint.