Subcutaneous cardiac stimulator device and method generating uniform electric field through the heart

• US 20030045904A1
• Filed: 04/17/2002
• Published: 03/06/2003
• Est. Priority Date: 09/18/2000
• Status: Active Grant

• Current Assignee: Cameron Health Inc (Boston Scientific Corporation)
• Original Assignee: Alan H. Ostroff, Gary H. Sanders, Gust H. Bardy, Riccardo Cappato, William J.B. Rissmann
• Inventors: Rissmann, William J.B., Ostroff, Alan H., Bardy, Gust H., Sanders, Gary H., Cappato, Riccardo
• Granted Patent: US 7,194,302 B2
• Time in Patent Office: Days
• US Class Current: 607/4
• CPC Class Codes: A61N 1/0504 Subcutaneous electrodes
• CPC Class Codes: A61N 1/3756 Casings with electrodes thereon, e.g. leadless stimulators
• CPC Class Codes: A61N 1/3912 Output circuitry therefor, e.g. switches
• CPC Class Codes: A61N 1/3931 Protecting, e.g. back-up systems
• CPC Class Codes: A61N 1/3968 Constructional arrangements, e.g. casings A61N1/375 takes precedence

Abstract

A subcutaneous cardiac device includes two electrodes and a stimulator that generates a pulse to the electrodes. The electrodes are implanted between the skin and the rib cage of the patient and are adapted to generate an electric field corresponding to the pulse, the electric field having a substantially uniform voltage gradient as it passes through the heart. The shapes, sizes, positions and structures of the electrodes are selected to optimize the voltage gradient of the electric field, and to minimize the energy dissipated by the electric field outside the heart. More specifically, the electrodes have contact surfaces that contact the patient tissues, said contact surfaces having a total contact area of less than 100 cm². In one embodiment, one or both electrodes are physically separated from the stimulator. In another embodiment a unitary housing holds the both electrodes and the stimulator. Sensor circuitry may also includes in the stimulator for detecting intrinsic cardiac activity through the same electrodes.

Claims

1. A cardiac device comprising:

a first and a second subcutaneous electrode; and

a cardiac stimulator electrically connected to said first and second electrodes and adapted to apply electrical pulses between said first and second electrodes, said first and second electrodes cooperating with said cardiac stimulator to generate an electric field across a substantial portion of the heart of a patient when said first and second electrodes are implanted at respective first and second positions within the patient, and wherein said first and second electrodes have respective contact surfaces that, in implantation, are in electrical contact with tissues, said contact surfaces having a surface area of less than 100 cm².

2. The device of claim 1 wherein said first electrode has a surface area of less than 20 cm².

3. The device of claim 2 wherein said first electrode has a surface area of about 5-15 cm².

4. The device of claim 1 wherein said second electrode has a surface area of less than 50 cm².

5. The device of claim 4 wherein said second electrode has a surface area of about 15-40 cm².

6. The device of claim 1 wherein said electric field is characterized by a voltage gradient in the range of about 3-8 V/cm across the heart.

7. The device of claim 1 wherein said cardiac stimulator is disposed in an implantable housing.

8. The device of claim 7 further comprising leads connecting said housing to said electrodes.

9. The device of claim 8 wherein said housing has an external surface and at least one of said electrodes is formed on said external surface.

11. The device of claim 9 wherein both said electrodes are formed on said external surface.

12. A cardiac device comprising:

a first electrode having a first electrode center and a second electrode having a second electrode center; and

a cardiac stimulator electrically connected to said first and second electrodes and adapted to selectively apply electrical pulses between said first and second electrodes;

said first electrode being adapted to be implanted subcutaneously in the vicinity of the sternum with said first electrode center being disposed on a first line perpendicular to the central axis through the patient and said second electrode being adapted to be implanted subcutaneously on the left side of the patient with said second electrode center being disposed on a second line perpendicular to said central axis; and

wherein said first and second lines define a predetermined angle therebetween.

13. The device of claim 12 wherein said first line defines an angle of 5 to 30 degrees with a third line extending perpendicularly from the central axis and extending from said central axis to the sternum.

14. The device of claim 12 wherein said second line defines an angle of 60-120 degrees with a third line perpendicular to the central axis and extending from the central axis to the sternum.

15. The device of claim 12 wherein said first and second lines define an angle less than 90 degrees.

16. The device of claim 12 wherein first and second electrodes are in fixed positions with respect to each other.

17. The device of claim 12 wherein the centers said first and second electrodes are separated from each other by about chord length of 10-25 cm.

18. The device of claim 12 wherein said cardiac stimulator is disposed in an implantable housing.

19. The device of claim 18 further comprising leads connecting said housing to said electrodes.

20. The device of claim 18 wherein said housing has an external surface and at least one of said electrodes is formed on said external surface.

21. The device of claim 18 wherein both said electrodes are formed on said external surface.

22. A cardiac device comprising:

a first electrode and a second electrode; and

a cardiac stimulator electrically connected to said first and second electrodes and adapted to selectively apply electrical pulses between said first and second electrodes;

said first electrode being adapted to be implanted subcutaneously adjacent to the sternum and the second electrode being adapted to be implanted subcutaneously at a distance of 15-35 cm from said first electrode, said distance being measured along an imaginary line extending circumferentially around the patient from said sternum at a distance of about 0-3 cm from the ribs.

23. The device of claim 22 wherein said first and second electrodes are adapted to be implanted in the same plane perpendicular to the patient'"'"'s central axis.

24. The device of claim 23 wherein said first and second electrodes are adapted to be implanted to generate an electric field in a plane, said plane passing through the center of the heart.

25. A cardiac device comprising:

an anterior electrode and a posterior electrode, each electrode having an inner surface; and

a cardiac stimulator electrically connected to said first and second electrodes and adapted to selectively apply electrical pulses between said first and second electrodes;

said anterior and posterior electrodes being adapted to be implanted subcutaneously with said inner surfaces pointing inwardly toward the heart, said anterior electrode being further adapted to be implanted near the sternum of the patient;

wherein said inner surfaces are metallic surfaces that present a low tissue/electrode interface when implanted.

26. The device of claim 25 wherein said inner surfaces have respective inner surface areas, wherein said inner surface area of said anterior electrode is not greater than said inner surface area of said posterior electrode.

27. The device of claim 26 wherein said inner surface area of said anterior electrode is smaller than that of said posterior electrode.

28. The device of claim 26 wherein said inner surface area of said anterior electrode is in the range of 5-15 cm².

29. The device of claim 26 wherein said inner surface area of said posterior electrode is in the range of 15-40 cm.

30. The device of claim 25 wherein said electrodes have rounded edges with no sharp corners.

31. The device if claim 25 wherein at least one of said electrodes has an outer surface coated with an insulated material.

32. The device of claim 25 wherein at least one of said electrodes has an outer conductive surface, said one electrode being adapted to be implanted with said outer conductive surface with said outer conductive surface contacting the patient'"'"'s tissues.

36. The device of claim 25 wherein said electrodes are made from a material selected from the group consisting of stainless steel, titanium, titanium iridium, titanium oxides, platinum, and alloys thereof.

37. The device of claim 35 wherein said anterior electrode is adapted to be placed between the spine and the left anterior axillary line.

39. A cardiac device comprising:

first and second subcutaneous electrodes both mounted on a rigid housing; and

a cardiac stimulator within said housing electrically connected to said first and second electrodes and adapted to apply electrical pulses between said first and second electrodes, said first and second electrodes cooperating with said cardiac stimulator to generate an electric field characterized by substantially parallel field lines across a substantial portion of the heart of a patient when said housing is implanted in a plane that is perpendicular to the patient'"'"'s central axis and passes through the patient'"'"'s sternum.

39-1. The device of claim 38 wherein the housing has non-planar surfaces and said first and second electrodes are contained in planes at an angle with respect to each other.

40. The device of claim 38 wherein said rigid device is adapted to be disposed adjacent to the sternum.

50. The method of claim 40 further comprising making a single incision and implanting said first and second electrodes through said single incision.

41. A method of providing cardiac therapy comprising:

implanting a first and a second subcutaneous electrode at respective first and second positions between the skin and the rib cage of a patient, said first and second subcutaneous electrodes having contact surfaces contacting patient tissues on implantation, said contact surfaces having a total surface area of less than 100 cm²; and

providing a cardiac stimulator connected to said first and second subcutaneous electrodes and adapted to generate selectively an electrical pulse;

said electrodes receiving said pulse and being positioned and arranged to generate a corresponding electric field through the heart.

42. The method of claim 41 further comprising selecting said first position and second position in a horizontal plane passing through the center of gravity of the heart.

43. The method of claim 42 further comprising selecting said positions to define with the center of gravity of the heart a plane disposed at a predetermined angle with respect to a horizontal plane.

44. The method of claim 42 further comprising selecting said positions to define said plane at an angle substantially equal to the angle of the ribs with respect to the sternum.

45. The method of claim 41 further comprising selecting said first position along a first line and selecting said second position along a second line, said first and second lines being perpendicular and passing through the center axis of the patient.

46. The method of claim 41 further comprising selecting said first and second lines to define a predetermined angle therebetween.

47. The method of claim 46 further comprising selecting said first and second lines to define an angle of less than 90 degrees.

48. The method of claim 45 further comprising selecting said first line to define an angle of 5 to 30 degrees with a third line, said third line being perpendicular to the center axis and extending between said center axis and the sternum.

49. The method of claim 45 further comprising selecting said second line to define an angle of 60 to 120 degrees with a third line, said third line being perpendicular to the center axis and extending between said center axis and the sternum.