Step-down skeletal muscle energy conversion system

• US 5,984,857 A
• Filed: 08/29/1994
• Issued: 11/16/1999
• Est. Priority Date: 09/30/1991
• Status: Expired due to Term

• Current Assignee: Thoratec LLC
• Original Assignee: Thoratec Laboratories Corp. (Thoratec LLC)
• Inventors: Litwak, Philip, Rueff, John Robert, Harvey, Robert Joseph, Farrar, David John, Buck, Keith Evan
• Primary Examiner(s): Lacyk, John P.
• Application Number:
  US08/297,151
• Time in Patent Office: 1,905 Days
• Field of Search: 600/16-18, 623/3, 623/14
• US Class Current: 600/16
• CPC Class Codes: A61M 60/139 inside the aorta, e.g. intra-aortic balloon pumps
• 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 60/183 drawing blood from both ventricles, e.g. bi-ventricular assist devices [BiVAD]
• 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 60/274 the inlet and outlet being the same, e.g. para-aortic counter-pulsation blood pumps
• CPC Class Codes: A61M 60/295 Balloon pumps for circulatory assistance
• CPC Class Codes: A61M 60/405 the force acting on the blood contacting member being hydraulic or pneumatic
• CPC Class Codes: A61M 60/427 the force acting on the blood contacting member being hydraulic or pneumatic
• CPC Class Codes: A61M 60/495 Electromagnetic force
• CPC Class Codes: A61M 60/882 Devices powered by the patient, e.g. skeletal muscle powered devices

Abstract

This invention provides a simple skeletal muscle linear pull energy convertor which can harness the maximal amount of muscle power for a wide variety of implantable medical devices, including the full range of circulatory support devices. The muscle powered system provides completely implantable circulatory support as an alternative to cardiac transplantation, with a quality of life relatively free from external batteries, transcutaneous energy transmission and other electromechanical hardware.

Claims

1. An apparatus for use in a skeletal muscle energy conversion system, said apparatus comprising:

stimulator means for effecting the linear contraction of a skeletal muscle to thereby produce a force;

hydraulic conversion means adapted to connect the muscle for converting the linear contractile energy produced by the muscle into high pressure hydraulic energy;

step-down actuator means coupled to said conversion means for converting high pressure hydraulic energy into low pressure hydraulic energy generally corresponding to that of physiological pressure; and

an implantable medical device operated by low pressure hydraulic energy received from said actuator means.

2. The apparatus of claim 1 further comprising muscle attachment means adapted to connect the muscle to be stimulated to said conversion means.

3. The apparatus of claim 1 wherein said hydraulic conversion means is disposed external of the thoracic cavity and is coupled by a small hydraulic transmission line to said actuator means positioned directly inside of the thoracic cavity in close proximity to the heart.

4. The apparatus of claim 1 wherein said hydraulic conversion means comprises a small diameter, low volume converter piston, a converter piston shaft adapted to connect said piston to the muscle, a converter cylinder in which said converter piston is slidably disposed, and an output high pressure hydraulic transmission line.

5. The apparatus of claim 4 wherein said conversion means further comprises convertor piston seals for sealing said convertor piston within said convertor cylinder and convertor shaft seals for sealing said convertor piston shaft and said convertor piston.

6. The apparatus of claim 5 wherein at least one of said convertor piston seals and said convertor shaft seals is a rolling diaphragm.

7. The apparatus of claim 5 wherein at least one of said convertor piston seals and said convertor shaft seals is a bellows.

8. The apparatus of claim 4 wherein said convertor piston is non-circular.

9. The apparatus of claim 4 wherein said convertor cylinder is curved.

10. The apparatus of claim 4 wherein said actuator means comprises:

a first small diameter, low volume actuator piston;

a second larger volume actuator piston; and

a mechanical transmission line therebetween;

wherein said first actuator piston receives a small volume of high pressure hydraulic fluid through said output high pressure hydraulic transmission line of said hydraulic conversion means and converts the hydraulic energy therein to mechanical energy, which is then transmitted to said second actuator piston through said mechanical transmission line such that said second actuator piston displaces a larger volume of low pressure hydraulic fluid utilized as low pressure hydraulic energy in the operation of said implantable medical device.

11. The apparatus of claim 10 wherein the peak high pressure in the high pressure hydraulic fluid is between about 80 and 200 psi and the low pressure hydraulic fluid is maintained at a pressure up to approximately 4 psi.

12. The apparatus of claim 11 wherein when said implantable medical device provides right ventricular circulatory support, the peak pressure in the low pressure hydraulic fluid is approximately between 0.5 and 1.0 psi.

13. The apparatus of claim 11 wherein when said implantable medical device provides left ventricular support, the peak pressure in the low pressure hydraulic fluid is approximately between 2.0 and 4.0 psi.

14. The apparatus of claim 13 wherein the peak low pressure hydraulic fluid is between about 2.5 psi and about 2.8 psi.

15. The apparatus of claim 1 wherein said actuator means comprises a first small diameter, low volume actuator piston, shaft and cylinder assembly, a second larger volume actuator piston, shaft and cylinder assembly, and a mechanical transmission line therebetween.

16. The apparatus of claim 15 wherein said actuator means further comprises actuator piston rings and actuator shaft seals.

17. The apparatus of claim 16 wherein at least one of said actuator piston rings and said actuator shaft seals is a rolling diaphragm.

18. The apparatus of claim 17 wherein at least one of said actuator piston rings and said actuator shaft seals is a bellows.

19. The apparatus of claim 15 wherein at least one of said first and second actuator pistons is non-circular.

20. The apparatus of claim 15 wherein at least one of said first and second actuator cylinders is curved.

21. The apparatus of claim 15 wherein said mechanical transmission line is disposed such that said first and second actuator pistons operate at a 90°

angle to one another.

22. The apparatus of claim 15 wherein said mechanical transmission line is disposed such that a stroke of said first actuator piston and a stroke of said second actuator piston are not equidistant.

23. The apparatus of claim 1 wherein said implantable medical device comprises a circulatory support device.

24. The apparatus of claim 1 further comprising a hydraulic access port permitting connection of said hydraulic conversion means to an extracorporeal power source when the linear contractile force of the muscle is not utilized.

25. The apparatus of claim 1 further comprising a hydraulic access port permitting adjustment of the high pressure hydraulic fluid which thereby allows for adjusting the muscle pre-stretch to achieve maximum power.

26. The apparatus of claim 1 wherein said implantable medical device includes a low pressure actuated blood pumping device.

27. The apparatus of claim 1 wherein said implantable medical device includes an intraaortic balloon.

28. The apparatus of claim 1 wherein said implantable medical device includes a counterpulsation device.

29. The apparatus of claim 1 wherein said implantable medical device includes an intraventricular blood displacement pump.

30. The apparatus of claim 1 wherein said implantable medical device includes a ventricular assist device.

31. The apparatus of claim 1 wherein said implantable medical device includes an artificial heart.

32. An apparatus for use in an implantable energy conversion system, said apparatus comprising:

hydraulic conversion means for converting a linear energy input into high pressure hydraulic power;

actuator means coupled to said conversion means for converting high pressure hydraulic power into low pressure hydraulic power generally corresponding to that of cardiovascular pressure; and

an implantable medical device operated by low pressure hydraulic power received from said actuator means.

33. The apparatus of claim 32 wherein said hydraulic conversion means comprises a small diameter, low volume convertor piston, a convertor piston shaft connecting said piston to the input energy source, a convertor cylinder in which said convertor piston is slidably disposed, and an output high pressure hydraulic transmission line.

34. The apparatus of claim 33 wherein said conversion means further comprises convertor piston rings for sealing said convertor piston within said convertor cylinder and convertor shaft seals for connecting said convertor piston shaft and said convertor piston.

35. The apparatus of claim 33 wherein at least one of said convertor piston rings and said convertor shaft seals is a rolling diaphragm.

36. The apparatus of claim 33 wherein said convertor piston is non-circular.

37. The apparatus of claim 33 wherein said convertor cylinder is curved.

38. The apparatus of claim 33 wherein said actuator means comprises:

a first small diameter, low volume actuator piston;

a second larger volume actuator piston; and

a mechanical transmission line therebetween;

wherein said first actuator piston receives a small volume of high pressure hydraulic fluid through said output high pressure hydraulic transmission line of said convertor piston and converts the hydraulic energy therein to mechanical energy, which is then transmitted to said second actuator piston through said mechanical transmission line such that said second actuator piston displaces a larger volume of low pressure hydraulic fluid utilized in the operation of said implantable medical device.

39. The apparatus of claim 38 wherein the peak high pressure hydraulic fluid is about 100 psi and the peak low pressure hydraulic fluid is approximately between 2.5 and 2.8 psi.

40. An apparatus for use in a skeletal muscle energy conversion system, said apparatus comprising:

first and second stimulator means for effecting the linear contraction of right and left similar skeletal muscles, respectively, to thereby produce a contraction force in each muscle;

hydraulic conversion means adapted to connect the muscles for converting the linear contractile force produced by the muscles into high pressure hydraulic power;

step-down actuator means coupled to said conversion means for converting high pressure hydraulic power into low pressure hydraulic power generally corresponding to that of cardiovascular pressure; and

an implantable medical device operated by low pressure hydraulic power received from said actuator means.

41. A skeletal muscle energy conversion system comprising:

stimulator means for effecting the linear contraction of a skeletal muscle to thereby produce a force;

hydraulic conversion means adapted to connect the muscle for converting the linear contractile energy produced by the muscle into high pressure hydraulic energy;

step-down actuator means coupled to said conversion means for converting high pressure hydraulic energy into low pressure hydraulic energy generally corresponding to that of physiological pressure; and

an implantable medical device operated by low pressure hydraulic energy received from said actuator means.

42. An apparatus for use in an implanted skeletal muscle energy conversion system, said apparatus comprising:

stimulator means for effecting the linear contraction of a muscle bundle to thereby produce a force;

conversion means adapted to connect the muscle bundle for converting the linear contractile energy produced by the muscle into useable energy;

muscle attachment means adapted to attach the muscle to said conversion means; and

a circulatory support device coupled to said conversion means and operated by the energy produced therein;

wherein said muscle attachment means comprises a fan-shaped non-biodegradable felt containing plurality of projecting hooks applied to each face of the muscle, and a plurality of sutures through the felt and muscle tissue which in combination ensure proper positioning and contact with the muscle while fibrous tissue forms between said felt and the muscle.

43. The apparatus of claim 42 wherein an outer layer of smooth polyurethane coating is applied to the side of said felt opposite to the side in contact with the muscle, thereby preventing adhesions from limiting movement of the muscle.

44. An apparatus for use in an implanted skeletal muscle energy conversion system, said apparatus comprising:

stimulator means for effecting the linear contraction of a muscle bundle to thereby produce a force;

conversion means adapted to connect the muscle bundle for converting the linear contractile energy produced by the muscle into useable energy;

muscle attachment means adapted to attach the muscle to said conversion means; and

a circulatory support device coupled to said conversion means and operated by the energy produced therein;

wherein said muscle attachment means comprises an attachment strip having a plurality of gripping hooks.

45. The apparatus of claim 44 wherein two attachment strips having a plurality of gripping hooks are applied to opposite surfaces of the muscle and then joined together at one end thereof for connection to said conversion means.

46. The apparatus of claim 44 wherein said strip is backed by a smooth layer of polyurethane to prevent adhesions and allow for sliding motion of the muscle during the contraction thereof.

47. An apparatus for use in an implanted skeletal muscle energy conversion system, said apparatus comprising:

stimulator means for effecting the linear contraction of a muscle bundle to thereby produce a force;

conversion means adapted to connect the muscle bundle for converting the linear contractile energy produced by the muscle into usable energy; and

a circulatory support device coupled to said conversion means and operated by the energy produced therein;

wherein the muscle is wrapped around a bar-like projection of said conversion means and then sewn upon itself, thereby not requiring the attachment means to puncture the muscle.

48. An apparatus for use in an implanted skeletal muscle energy conversion system, said apparatus comprising:

stimulator means for effecting the linear contraction of a muscle bundle to thereby produce a force;

conversion means adapted to connect the muscle bundle for converting the linear contractile energy produced by the muscle into useable energy;

muscle attachment means adapted to attach the muscle to said conversion means; and

a circulatory means adapted to connect the muscle bundle for converting the linear contractile energy produced by the muscle into useable energy;

muscle attachment means for attaching the muscle to said conversion means; and

a circulatory support device coupled to said conversion means and operated by the energy produced therein;

wherein said muscle attachment means comprises a fan-shaped non-biodegradable felt extending into the belly of the muscle so that the tissue of the muscle can grow into the felt.

49. The apparatus of claim 48 wherein an outer layer of smooth polyurethane coating is applied to the backside of said patch thereby preventing adhesions from limiting movement of the muscle.

50. Apparatus for use in an implanted skeletal muscle energy conversion system, said apparatus comprising:

stimulator means for effecting the linear contraction of a skeletal muscle situated in close proximity to the thoracic cavity to thereby produce a force, wherein said skeletal muscle having a first end remaining attached to the skeleton at its normal position and having a majority of the normal blood supply to said skeletal muscle remaining intact;

conversion means adapted to connect to a second end of said skeletal muscle for converting the linear contractile force produced by said skeletal muscle into usable energy;

anchoring means adapted to anchor rigidly said conversion means directly to the skeleton, said usable energy being produced when said force pulls against said rigidly anchored conversion means;

muscle attachment means adapted to attach the muscle to said conversion means; and

an implantable medical device coupled to said conversion means and operated by the useable energy produced therein.

51. Apparatus for use in an implanted skeletal muscle energy conversion system, said apparatus comprising:

stimulator means for effecting the linear contraction of a skeletal muscle to thereby produce a force, wherein said skeletal muscle having a first end remaining attached to the skeleton at its normal position and having a majority of the normal blood supply to a skeletal muscle remaining intact;

hydraulic conversion means adapted to connect to a second end of said skeletal muscle for converting the linear contractile energy input into high pressure hydraulic energy;

actuator means coupled to said conversion means for converting high pressure hydraulic energy into low volume hydraulic energy at about cardiovascular pressure;

muscle attachment means adapted to attach said conversion means to said second end of said skeletal muscle, said attachment means providing a secure junction therebetween;

anchoring means adapted to anchor rigidly said conversion means to the skeleton, said high pressure hydraulic energy being produced when said linear contractile force pulls against said rigidly anchored conversion means; and

an implantable medical device operated by low pressure hydraulic energy received from said actuator means.