Method and apparatus for treating cardiac arrhythmia using auxiliary pulse

• US 5,978,705 A
• Filed: 03/13/1998
• Issued: 11/02/1999
• Est. Priority Date: 03/14/1997
• Status: Expired due to Term

• Current Assignee: UAB Research Foundation (University of Alabama System)
• Original Assignee: UAB Research Foundation (University of Alabama System)
• Inventors: KenKnight, Bruce H., Hahn, Stephen J., Ideker, Raymond E., Booker, Robert S. III
• Primary Examiner(s): Kamm, William E.
• Assistant Examiner(s): Layno, Carl H.
• Application Number:
  US09/039,143
• Time in Patent Office: 599 Days
• Field of Search: 607/5, 607/122
• US Class Current: 607/5
• CPC Class Codes: A61N 1/3918 characterised by shock pathway, e.g. by electrode configuration
• CPC Class Codes: A61N 1/3937 Monitoring output parameters
• CPC Class Codes: A61N 1/3943 for threshold determination

Abstract

An implantable system for the defibrillation or cardioversion of the heart of a patient in need of such treatment comprises a plurality of primary electrodes, a power supply, and a control circuit. Preferably, at least one auxiliary electrode is also included. The plurality of primary electrodes are configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of the heart, the current pathway defining a weak field area in a second portion of the heart. The at least one auxiliary electrode is configured for delivering an auxiliary pulse to the a portion of the heart where the primary shock field intensity is at or near a minimum. The control circuit is operatively associated with the primary electrodes, the auxiliary electrode, and the power supply, with the control circuit configured for delivering a cardioversion sequence comprising an auxiliary pulse sufficient to induce a cessation of propagation in the weak field area through the auxiliary electrode, followed by a defibrillation pulse through the primary electrodes delivered during the cessation of propagation in the weak field area.

Claims

1. An implantable system for the defibrillation or cardioversion of the heart of a patient in need of such treatment, said system comprising:

a primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart;

at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area;

a power supply; and

a control circuit operatively associated with said primary electrodes, said auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising an auxiliary pulse sufficient to induce a cessation of propagation in said weak field area through said auxiliary electrode, followed by a defibrillation pulse through said primary electrodes delivered during said cessation of propagation in said weak field area;

wherein said control circuit is configured to deliver a biphasic auxiliary pulse and a biphasic defibrillation pulse, with the first phase of said defibrillation pulse in opposite polarity to said auxiliary pulse.

2. A system according to claim 1, wherein said control circuit is configured so that a trailing edge voltage of said auxiliary pulse is equal to a leading edge voltage of said defibrillation pulse.

3. A system according to claim 1, wherein said control circuit is configured to deliver a monophasic auxiliary pulse of from 0.5 to 10 milliseconds in duration.

4. A system according to claim 1, wherein said control circuit is configured to deliver said defibrillation pulse within 20 milliseconds after said auxiliary pulse.

5. A system according to claim 1, wherein said at least one auxiliary electrode is configured for positioning through the coronary sinus and in either the apical third of the posterior cardiac vein or the apical half of the great cardiac vein.

6. A system according to claim 1, wherein each of said at least one auxiliary electrode is carried by a transvenous lead.

7. A system according to claim 1, wherein said power supply includes a capacitor.

8. A system according to claim 1, wherein said power supply includes a single capacitor, and wherein said control circuit is configured so that both said auxiliary pulse and said defibrillation pulse are generated by the discharge of said single capacitor.

9. A system according to claim 1, wherein said power supply includes a first and second capacitor, and wherein said control circuit is configured so that said auxiliary pulse is generated by the discharge of said first capacitor and said defibrillation pulse is generated by the discharge of said second capacitor.

10. A system according to claim 1, wherein said power supply includes a first and second capacitor, and wherein said control circuit is configured so that said auxiliary pulse is generated by the discharge of said first and second capacitors, and said defibrillation pulse is generated by the discharge of said first and second capacitors.

11. A system according to claim 1, wherein said control circuit is configured so that said auxiliary pulse is not more than 50% of the peak current and not more than 30% of the delivered energy of said defibrillation pulse.

12. An implantable system for the defibrillation of the ventricles of the heart of a patient in need of such treatment, said system comprising:

a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart;

at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area, with said at least one auxiliary electrode configured for positioning through the coronary sinus and in a vein on the surface of the left ventricle of said heart;

a power supply; and

a control circuit operatively associated with said primary electrodes, said at least one auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising a biphasic auxiliary pulse through said auxiliary electrode, followed by a biphasic defibrillation pulse through said primary electrodes, with said defibrillation pulse delivered within 20 milliseconds after said auxiliary pulse, and with the first phase of said defibrillation pulse in opposite polarity to said auxiliary pulse.

13. A system according to claim 12, wherein said control circuit is configured so that a trailing edge voltage of said auxiliary pulse is equal to a leading edge voltage of said defibrillation pulse.

14. A system according to claim 12, comprising:

a first primary electrode configured for positioning in the superior vena cava or innominate vein; and

a second primary electrode configured for positioning in the right ventricle.

15. A system according to claim 14, wherein said first and second primary electrodes are carried by a common transvenous lead.

16. A system according to claim 12, comprising:

a first primary electrode configured for positioning in the superior vena cava or innominate vein;

a second primary electrode configured for positioning in the right ventricle; and

a second auxiliary electrode positioned near the right ventricular conus;

with said control circuit configured for delivering said monophasic auxiliary pulse through said first and second auxiliary electrodes.

17. A system according to claim 16, with said second auxiliary electrode configured for positioning in the anterior portion of the right atrial appendage or in the right ventricular outflow track.

18. A system according to claim 16, wherein said second auxiliary electrode is carried by a transvenous lead, and wherein said second auxiliary electrode is positioned on the distal end of said transvenous lead.

19. A system according to claim 16, wherein said first and second primary electrodes are carried by a common transvenous lead.

20. A system according to claim 12, wherein said power supply includes a single capacitor, and wherein said control circuit is configured so that both said auxiliary pulse and said defibrillation pulse are generated by the discharge of said single capacitor.

21. A system according to claim 12, wherein said power supply includes a first and second capacitor, and wherein said control circuit is configured so that said auxiliary pulse is generated by the discharge of said first capacitor and said defibrillation pulse is generated by the discharge of said second capacitor.

22. A system according to claim 12, wherein said power supply includes a first and second capacitor, and wherein said control circuit is configured so that said auxiliary pulse is generated by the discharge of said first and second capacitors, and said defibrillation pulse is generated by the discharge of said first and second capacitors.

23. An implantable system for the defibrillation or cardioversion of the heart of a patient in need of such treatment, said system comprising:

a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart;

at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area;

a power supply; and

a control circuit operatively associated with said primary electrodes, said auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising a defibrillation pulse through said primary electrodes, followed by an auxiliary pulse sufficient to induce a cessation of propagation in said weak field area through said auxiliary electrode;

wherein said control circuit is configured to deliver a biphasic auxiliary pulse and a biphasic defrillation pulse; and

wherein said control circuit is configured so that a leading edge voltage of said auxiliary pulse is equal to a trailing edge voltage of said defibrillation pulse.

24. A system according to claim 23, wherein said control circuit is configured to deliver a monophasic auxiliary pulse of from 0.5 to 10 milliseconds in duration.

25. A system according to claim 23, wherein said control circuit is configured to deliver said defibrillation pulse within 20 milliseconds after said auxiliary pulse.

26. A system according to claim 23, wherein said at least one auxiliary electrode is configured for positioning through the coronary sinus and in a vein on the surface of the left ventricle of said heart.

27. A system according to claim 23, wherein said at least one auxiliary electrode is configured for positioning through the coronary sinus and in either the apical third of the posterior cardiac vein or the apical half of the great cardiac vein.

28. A system according to claim 23, wherein each of said plurality of primary electrodes is carried by a transvenous lead.

29. A system according to claim 23, wherein each of said at least one auxiliary electrode is carried by a transvenous lead.

30. A system according to claim 23, wherein said power supply includes a capacitor.

31. A system according to claim 23, wherein said power supply includes a single capacitor, and wherein said control circuit is configured so that both said auxiliary pulse and said defibrillation pulse are generated by the discharge of said single capacitor.

32. A system according to claim 23, wherein said power supply includes a first and second capacitor, and wherein said control circuit is configured so that said auxiliary pulse is generated by the discharge of said first capacitor and said defibrillation pulse is generated by the discharge of said second capacitor.

33. A system according to claim 23, wherein said power supply includes a first and second capacitor, and wherein said control circuit is configured so that said auxiliary pulse is generated by the discharge of said first and second capacitors, and said defibrillation pulse is generated by the discharge of said first and second capacitors.

34. An implantable system for the defibrillation of the ventricles of the heart of a patient in need of such treatment, said system comprising:

a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart;

at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area, with said at least one auxiliary electrode configured for positioning through the coronary sinus and in a vein on the surface of the left ventricle of said heart;

a power supply; and

a control circuit operatively associated with said primary electrodes, said at least one auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising a biphasic defibrillation pulse through said primary electrodes followed by a biphasic auxiliary pulse through said auxiliary electrode, with said auxiliary pulse delivered within 20 milliseconds after said auxiliary pulse, and with the first phase of said defibrillation pulse in opposite polarity to said auxiliary pulse;

wherein said system further comprises

a first primary electrode configured for positioning in the superior vena cava or innominate vein;

a second primary electrode configured for positioning in the right ventricle; and

a second auxiliary electroden positioning near the right ventricular conus;

with said control circuit configured for delivering said monophasic auxiliary pulse through said first and second auxiliary electrode.

35. A system according to claim 34, wherein said control circuit is configured so that a leading edge voltage of said auxiliary pulse is equal to a trailing edge voltage of said defibrillation pulse.

36. A system according to claim 34, with said second auxiliary electrode configured for positioning in the anterior portion of the right atrial appendage or in the right ventricular outflow track.

37. A system according to claim 34, wherein said second auxiliary electrode is carried by a transvenous lead, and wherein said second auxiliary electrode is positioned on the distal end of said transvenous lead.

38. A system according to claim 34, wherein said first and second primary electrodes are carried by a common transvenous lead.

39. A system according to claim 34, wherein said power supply includes a single capacitor, and wherein said control circuit is configured so that both said auxiliary pulse and said defibrillation pulse are generated by the discharge of said single capacitor.

40. A system according to claim 34, wherein said power supply includes a first and second capacitor, and wherein said control circuit is configured so that said auxiliary pulse is generated by the discharge of said first capacitor and said defibrillation pulse is generated by the discharge of said second capacitor.

41. A system according to claim 34, wherein said power supply includes a first and second capacitor, and wherein said control circuit is configured so that said auxiliary pulse is generated by the discharge of said first and second capacitors, and said defibrillation pulse is generated by the discharge of said first and second capacitors.

42. An electrode lead useful for the cardioversion or defibrillation of a patient'"'"'s heart, comprising:

an elongate transvencous electrode lead having a distal end portion, with said lead configured for positioning said distal end portion within the right atrial appendage; and

a primary electrode connected to said electrode lead and positioned on said distal end portion;

further comprising a secondary pace/sense electrode connected to said electrode lead at said distal end portion;

wherein said secondary pace/sense electrode is connected to said electrode lead in a position proximal to said electrode.

43. An electrode lead according to claim 42, wherein said secondary pace/sense electrode comprises a pair of ring electrodes.

44. An implantable system for the defibrillation of the ventricles of the heart of a patient in need of such treatment, said system comprising:

a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart, said plurality of primary electrodes including an electrode configured for positioning in the right ventricle;

at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area, with said at least one auxiliary electrode configured for positioning through the coronary sinus and in a vein on the surface of the left ventricle of said heart;

a power supply; and

a control circuit operatively associated with said primary electrodes, said at least one auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising a biphasic defibrillation pulse through said primary electrodes followed by a biphasic auxiliary pulse through said auxiliary electrode, with said auxiliary pulse delivered within 20 milliseconds after said defibrillation pulse,

and with the first phase of said defibrillation pulse in opposite polarity to said auxiliary pulse.

45. A system according to claim 44, further comprising a housing configured for being implanted in the left thoracic region of said patient, said housing containing said power supply and said control circuit, and with said housing having an active external portion serving as a second primary electrode.

46. A system according to claim 45, wherein said auxiliary pulse is delivered between said auxiliary electrode and said second primary electrode.

47. A system according to claim 44, further comprising a second primary electrode configured for positioning in the superior vena cava or innominate vein.

48. A system according to claim 47, wherein said auxiliary pulse is delivered between said auxiliary electrode and said second primary electrode.

49. A system according to claim 44, further comprising:

a housing configured for being implanted in the left thoracic region of said patient, said housing containing said power supply and said control circuit, and with said housing having an active external portion serving as a second primary electrode; and

a third primary electrode configured for positioning in the superior vena cava or innominate vein;

wherein said second and third primary electrodes are electrically common.

50. A system according to claim 49, wherein said auxiliary pulse is delivered between said auxiliary electrode, and said second and third electrically common primary electrodes.

51. A system according to claim 44, wherein said control circuit is configured so that a leading edge voltage of said auxiliary pulse is equal to a trailing edge voltage of said defibrillation pulse.

52. An implantable system for the defibrillation of the ventricles of the heart of a patient in need of such treatment, said system comprising:

a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart, said plurality of primary electrodes including an electrode configured for positioning in the right ventricle;

at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area, with said at least one auxiliary electrode configured for positioning through the coronary sinus and in a vein on the surface of the left ventricle of said heart;

a power supply; and

a control circuit operatively associated with said primary electrodes, said at least one auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising an auxiliary pulse through said auxiliary electrode followed by a biphasic defibrillation pulse through said primary electrodes, with said defibrillation pulse delivered within 20 milliseconds after said auxiliary pulse,

and with the first phase of said defibrillation pulse in opposite polarity to said auxiliary pulse;

further comprising a housing configured for being implanted in the left thoracic region of said patient, said housing containing said power supply and said control circuit and with said housing having an active external portion serving as a second primary electrode.

53. A system according to claim 52, wherein said auxiliary pulse is delivered between said auxiliary electrode and said second primary electrode.

54. A system according to claim 52, wherein said control circuit is configured so that a leading edge voltage of said auxiliary pulse is equal to a trailing edge voltage of said defibrillation pulse.

55. An implantable defibrillator, comprising:

a housing;

a power supply contained within said housing, with said power supply including a storage capacitor; and

a control circuit contained within said housing and operatively associated with said power supply, said control circuit configured for delivering a cardioversion sequence comprising an auxiliary pulse and a defibrillation pulse;

said housing having a volume less than 35 cubic centimeters.

56. An implantable defibrillator according to claim 55, said power supply further comprising a battery.

57. An implantable defibrillator according to claim 55, wherein said control circuit is configured so that said defibrillation pulse follows said auxiliary pulse, and so that a trailing edge voltage of said auxiliary pulse is equal to a leading edge voltage of said defibrillation pulse.

58. An implantable defibrillator according to claim 55, wherein said control circuit is configured so tat said auxiliary pulse follows said defibrillation pulse, and so that a trailing edge voltage of said defibrillation pulse is equal to a leading edge voltage of said auxiliary pulse.

59. An implantable defibrillator according to claim 55, said housing having a volume of at least 5 cubic centimeters.

60. An implantable system for the defibrillation or cardioversion of the heart of a patient in need of such treatment, said system comprising:

a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart;

at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area;

a power supply; and

a control circuit operatively associated with said primary electrodes, said auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising an auxiliary pulse sufficient to induce a cessation of propagation in said weak field area through said auxiliary electrode, followed by a defibrillation pulse through said primary electrodes delivered during said cessation of propagation in said weak field area;

wherein said at least one auxiliary electrode is configured for positioning through the coronary sinus and in a vein on the surface of the left ventricle of said heart.

61. An implantable system for the defibrillation or cardioversion of the heart of a patient in need of such treatment, said system comprising:

a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart;

at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area;

a power supply; and

a control circuit operatively associated with said primary electrodes, said auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising an auxiliary pulse sufficient to induce a cessation of propagation in said weak field area through said auxiliary electrode, followed by a defibrillation pulse through said primary electrodes delivered during said cessation of propagation in said weak field area;

wherein said at least one auxiliary electrode is configured for positioning through the coronary sinus and in a vein on the postero-lateral surface of the left ventricle of said heart.

62. An implantable system for the defibrillation or cardioversion of the heart of a patient in need of such treatment, said system comprising;

a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart;

at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area;

a power supply; and

a control circuit operatively associated with said primary electrodes, said auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising an auxiliary pulse sufficient to induce a cessation of propagation in said weak field area through said auxiliary electrode, followed by a defibrillation pulse through said primary electrodes delivered during said cessation of propagation in said weak field area;

wherein each of said plurality of primary electrodes is carried by a transvenous lead.

63. An implantable system for the defibrillation or cardioversion of the heart of a patient in need of such treatment, said system comprising:

a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart;

at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area;

a power supply; and

a control circuit operatively associated with said primary electrodes, said auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising an auxiliary pulse sufficient to induce a cessation of propagation in said weak field area through said auxiliary electrode, followed by a defibrillation pulse through said primary electrodes delivered during said cessation of propagation in said weak field area;

wherein said power supply includes a 20 to 400 microfarad capacitor.

64. An implantable system for the defibrillation or cardioversion of the heart of a patient in need of such treatment, said system comprising:

a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart;

at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area;

a power supply; and

a control circuit operatively associated with said primary electrodes, said auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising a defibrillation pulse through said primary electrodes, followed by an auxiliary pulse sufficient to induce a cessation of propagation in said weak field area through said auxiliary electrode;

wherein said control circuit is configured to deliver a monophasic auxiliary pulse of from 0.5 to 10 milliseconds in duration.

65. An implantable system for the defibrillation or cardioversion of the heart of a patient in need of such treatment, said system comprising:

a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart;

at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area;

a power supply; and

a control circuit operatively associated with said primary electrodes, said auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising a defibrillation pulse through said primary electrodes, followed by an auxiliary pulse sufficient to induce a cessation of propagation in said weak field area through said auxiliary electrode;

wherein said at least one auxiliary electrode is configured for positioning through the coronary sinus and in a vein on the postero lateral surface of the left ventricle of said heart.

66. An implantable system for the defibrillation or cardioversion of the heart of a patient in need of such treatment, said system comprising:

a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart;

at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area;

a power supply; and

a control circuit operatively associated with said primary electrodes, said auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising a defibrillation pulse through said primary electrodes, followed by an auxiliary pulse sufficient to induce a cessation of propagation in said weak field area through said auxiliary electrode;

wherein said power supply includes a 20 to 400 microfarad capacitor.

67. An implantable system for the defibrillation or cardioversion of the heart of a patient in need of such treatment, said system comprising:

a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart;

at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area;

a power supply; and

a control circuit operatively associated with said primary electrodes, said auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising a defibrillation pulse through said primary electrodes, followed by an auxiliary pulse sufficient to induce a cessation of propagation in said weak field area through said auxiliary electrode;

wherein said control circuit is configured so that said auxiliary pulse is not more than 50% of the peak current and not more than 30% of the delivered energy of said defibrillation pulse.

68. An implantable system for the defibrillation of the ventricles of the heart of a patient in need of such treatment, said system comprising:

a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart;

at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area, with said at least one auxiliary electrode configured for positioning through the coronary sinus and in a vein on the surface of the left ventricle of said heart;

a power supply; and

a control circuit operatively associated with said primary electrodes, said at least one auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising a biphasic defibrillation pulse through said primary electrodes followed by a biphasic auxiliary pulse through said auxiliary electrode, with said auxiliary pulse delivered within 20 milliseconds after said auxiliary pulse, and with the first phase of said defibrillation pulse in opposite polarity to said auxiliary pulse;

said system comprising

a first primary electrode configured for positioning in the superior vena cava or innominate vein; and

a second primary electrode configured for positioning in the right ventricle.

69. An implantable system for the defibrillation of the ventricles of the heart of a patient in need of such treatment, said system comprising:

a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart;

at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area, with said at least one auxiliary electrode configured for positioning through the coronary sinus and in a vein on the surface of the left ventricle of said heart;

a power supply; and

a control circuit operatively associated with said primary electrodes, said at least one auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising a biphasic defibrillation pulse through said primary electrodes followed by a biphasic auxiliary pulse through said auxiliary electrode, with said auxiliary pulse delivered within 20 milliseconds after said auxiliary pulse, and with the first phase of said defibrillation pulse in opposite polarity to said auxiliary pulse.

70. An implantable system according to claim 69, wherein said first and second primary electrodes are carried by a common transvenous lead.

71. An implantable system for the defibrillation of the ventricles of the heart of a patient in need of such treatment, said system comprising:

a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart, said plurality of primary electrodes including an electrode configured for positioning in the right ventricle;

at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area, with said at least one auxiliary electrode configured for positioning through the coronary sinus and in a vein on the surface of the left ventricle of said heart;

a power supply; and

a control circuit operatively associated with said primary electrodes, said at least one auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising an auxiliary pulse through said auxiliary electrode followed by a biphasic defibrillation pulse through said primary electrodes, with said defibrillation pulse delivered within 20 milliseconds after said auxiliary pulse,

and with the first phase of said defibrillation pulse in opposite polarity to said auxiliary pulse;

further comprising a second primary electrode configured for positioning in the superior vena cava or innominate vein.

72. A system according to claim 71, wherein said auxiliary pulse is delivered between said auxiliary electrode and said second primary electrode.

73. An implantable system for the defibrillation of the ventricles of the heart of a patient in need of such treatment, said system comprising:

a plurality of primary electrodes configured for delivering a defibrillation pulse along a predetermined current pathway in a first portion of said heart, said current pathway defining a weak field area in a second portion of said heart, said plurality of primary electrodes including an electrode configured for positioning in the right ventricle;

at least one auxiliary electrode configured for delivering an auxiliary pulse to said weak field area, with said at least one auxiliary electrode configured for positioning through the coronary sinus and in a vein on the surface of the left ventricle of said heart;

a power supply; and

a control circuit operatively associated with said primary electrodes, said at least one auxiliary electrode, and said power supply, said control circuit configured for delivering a cardioversion sequence comprising an auxiliary pulse through said auxiliary electrode followed by a biphasic defibrillation pulse through said primary electrodes, with said defibrillation pulse delivered within 20 milliseconds after said auxiliary pulse,

and with the first phase of said defibrillation pulse in opposite polarity to said auxiliary pulse, said system further comprising;

a housing configured for being implanted in the left thoracic region of said patient, said housing containing said power supply and said control circuit, and with said housing having an active external portion serving as a second primary electrode; and

a third primary electrode configured for positioning in the superior vena cava or innominate vein;

wherein said second and third primary electrodes are electrically common.

74. A system according to claim 73, wherein said auxiliary pulse is delivered between said auxiliary electrode, and said second and third electrically common primary electrodes.