Unitary subcutaneous only implantable cardioverter-defibrillator and optional pacer

Claims

What is claimed is:

1. A unitary subcutaneous implantable cardioverter-defibrillator comprising: a long thin housing with first and second ends that is curved in a shape of a patient's rib wherein the housing contains a source of electrical energy, a capacitor, and operational circuitry that senses the presence of potentially fatal heart rhythms; cardioversion/defibrillation electrodes located at the ends of the housing; means for delivering electrical cardioversion-defibrillation energy when the operational circuitry senses a potentially fatal heart rhythm; and the absence of a transvenous, intracardiac, or epicardial, electrode.

2. The unitary subcutaneous implantable cardioverter-defibrillator of claim 1 wherein the electrical cardioversion-defibrillating energy is equal to or greater than 800 Volts.

3. The unitary subcutaneous implantable cardioverter-defibrillator of claim 2 wherein the electrical cardioversion-defibrillating energy ranges from about 800 volts to about 2000 volts.

4. The unitary subcutaneous implantable cardioverter-defibrillator of claim 1 wherein the electrical cardioversion-defibrillating energy ranges from about 40 Joules to about 150 Joules.

5. The unitary subcutaneous implantable cardioverter-defibrillator of claim 1 further comprising at least two sensing electrodes located on the housing.

6. The unitary subcutaneous implantable cardioverter-defibrillator of claim 5 wherein the sensing electrodes are spaced apart by about 1 to about 10 cm.

7. The unitary subcutaneous implantable cardioverter-defibrillator of claim 6 wherein the first and second sensing electrodes are spaced apart by about 4 cm.

8. The unitary subcutaneous implantable cardioverter-defibrillator of claim 1 wherein the operational circuitry can also sense the presence of bradycardia rhythm.

9. The unitary subcutaneous implantable cardioverter-defibrillator of claim 8 further comprising means for delivering cardiac pacing energy when the operational circuitry senses a bradycardia rhythm.

10. The unitary subcutaneous implantable cardioverter-defibrillator of claim 1 wherein the operational circuitry is programmable.

11. The unitary subcutaneous implantable cardioverter-defibrillator of claim 1 wherein the operational circuitry can detect tachycardia.

12. The unitary subcutaneous implantable cardioverter-defibrillator of claim 11 further comprising means for delivering antitachycardia pacing when the operational circuitry senses a tachycardia rhythm.

13. The unitary subcutaneous implantable cardioverter-defibrillator of claim 11 wherein the ventricular tachycardia detected is greater than 240 beats per minute.

14. The unitary subcutaneous implantable cardioverter-defibrillator of claim 1 wherein the operational circuitry can detect atrial tachycardia and atrial fibrillation.

15. The unitary subcutaneous implantable cardioverter-defibrillator of claim 14 wherein the operational circuitry can deliver defibrillation energy to treat the detected atrial fibrillation.

16. The unitary subcutaneous implantable cardioverter-defibrillator of claim 1 wherein the operational circuitry can induce ventricular tachycardia or ventricular fibrillation.

17. The unitary subcutaneous implantable cardioverter-defibrillator of claim 16 wherein the ventricular tachycardia or ventricular fibrillation is induced by shocks on the T wave.

18. The unitary subcutaneous implantable cardioverter-defibrillator of claim 16 wherein the ventricular tachycardia or ventricular fibrillation is induced by low direct current voltage applied during the entire cardiac cycle.

19. The unitary subcutaneous implantable cardioverter-defibrillator of claim 1 wherein the electrical cardioversion-defibrillating energy is delivered in a biphasic wave form.

20. The unitary subcutaneous implantable cardioverter-defibrillator of claim 1 wherein the capacitance is about 50 to about 200 micro farads.

21. The unitary subcutaneous implantable cardioverter-defibrillator of claim 1 wherein the housing is malleable.

22. The unitary subcutaneous implantable cardioverter-defibrillator of claim 1 wherein the housing is provided with at least one sensing electrode.

23. The unitary subcutaneous implantable cardioverter-defibrillator of claim 1 wherein the housing is provided with one or more sensing electrodes, and wherein said cardioverter-defibrillator is further provided with a subcutaneous electrode with one or more sensing electrodes, and means for selecting two sensing electrodes from the sensing electrodes located on the housing and the sensing electrode located on the subcutaneous electrode that provide adequate QRS wave detection.

24. The unitary subcutaneous implantable cardioverter-defibrillator of claim 1 wherein the electrical cardioversion-defibrillating energy is delivered for about 10 to about 20 milliseconds total duration and with the initial positive phase containing approximately 2/3 of the energy delivered.

25. The unitary subcutaneous implantable cardioverter-defibrillator of claim 1 wherein the operational circuitry comprises an impedance detection for measuring the undulations in transthoracic impedance created during respiration.

26. The unitary subcutaneous implantable cardioverter-defibrillator of claim 25 wherein the operational circuitry can also measure the cardiac output using transthoracic impedance.

27. The unitary subcutaneous implantable cardioverter-defibrillator of claim 1 wherein the housing ranges in length from about 15 to about 20 cm.

28. The unitary subcutaneous implantable cardioverter-defibrillator of claim 27 wherein the unitary subcutaneous implantable cardioverter-defibrillator is provided in different incremental sizes.

29. The unitary subcutaneous implantable cardioverter-defibrillator of claim 1 further comprising a plug-in core member inside the housing of the unitary subcutaneous implantable cardioverter-defibrillator wherein the plug-in core member contains the source of electrical energy, the capacitor, and the operational circuitry.

30. The unitary subcutaneous implantable cardioverter-defibrillator of claim 29 wherein the housing ranges in length from about 15 to about 20 cm.

31. The unitary subcutaneous implantable cardioverter-defibrillator of claim 29 wherein the unitary subcutaneous implantable cardioverter-defibrillator is provided in different incremental sizes.

32. A method of implanting a unitary implantable subcutaneous cardioverter-defibrillator in a patient comprising the steps of; making only one skin incision in the thoracic region of the patient; inserting a curved introducer through the skin incision to make a subcutaneous path in the thoracic region such that the path terminates subcutaneously at an end location that if a straight line were drawn from the skin incision to the end location, the line would intersect the heart of the patient; implanting a unitary subcutaneous cardioverter-defibrillator that has a long thin housing that is curved in a shape of a patient's rib; and closing the skin incision.

33. The method of implanting a subcutaneous cardioverter-defibrillator of claim 32 further comprising the step of injecting a local anesthetic through the curved introducer.

34. The method of implanting a subcutaneous cardioverter-defibrillator of claim 32 wherein the skin incision is located in the left anterior axillary line approximately at the level of the patient's cardiac apex.

35. A unitary cardioverter-defibrillator for subcutaneous implantation, comprising: a canister comprising a biocompatible housing enclosing and containing cardioversion-defibrillation circuitry, said housing having a downward taper continuously formed along at least one exterior periphery of the biocompatible housing; and a pair of electrodes formed on opposite ends of the biocompatible housing and electrically interfaced to the cardioversion-defibrillation circuitry to deliver an electrical therapy to the heart of a patient.

36. A unitary cardioverter-defibrillator according to claim 35, further comprising: at least one sensing electrode formed on, and electrically insulated from, the biocompatible housing and electrically interfaced to the cardioversion-defibrillation circuitry.

37. A unitary cardioverter-defibrillator according to claim 35, further comprising: at least one electrically insulated surface defined on an outer surface of the biocompatible housing and juxtaposed to the pair of electrodes.

38. A unitary cardioverter-defibrillator according to claim 37, further comprising: at least one sensing electrode formed on the at least one electrically insulated surface and electrically interfaced to the cardioversion-defibrillation circuitry.

39. A unitary cardioverter-defibrillator according to claim 37, further comprising: an insulated margin around at least one of the pair of electrodes along the at least one electrically insulated surface and defining a concentrated electrically conductive surface.

40. A unitary cardioverter-defibrillator according to claim 37, wherein the at least one electrically insulated surface is constructed from at least one of a silicon, polyurethane, ceramic, titanium-ceramic bonded, Parylene-coated, and other biocompatible material.

41. A unitary cardioverter-defibrillator according to claim 35, further comprising: monitoring circuitry integral to the cardioversion-defibrillation circuitry and deriving physiological measures relating to at least one of QRS signal morphology, QRS signal frequency content, QRS R-R interval stability data, and QRS amplitude characteristics.

42. A unitary cardioverter-defibrillator according to claim 35, further comprising: a pulse generator integral to the cardioversion-defibrillation circuitry and producing an anti-arrhythmia waveform for anti-arrhythmia therapy via the pair of electrodes responsive to the cardioversion-defibrillation circuitry.

43. A unitary cardioverter-defibrillator according to claim 42, further comprising: the pulse generator generating the anti-arrhythmia waveform as a biphasic waveform with characteristics comprising at least one of a capacitance between approximately 50 .mu.F and 200 mF, voltage between approximately 800 V and 2000 V, energy between 40 J and 150 J, and a duration between approximately 5 msec to 25 msec.

44. A unitary cardioverter-defibrillator according to claim 43, further comprising: the cardioversion-defibrillation circuitry initiating the anti-arrhythmia therapy upon a cardiac ventricular rate of around 240 bpm sustained over an at least 4 second interval.

45. A unitary cardioverter-defibrillator according to claim 43, further comprising: the cardioversion-defibrillation circuitry confirming the anti-arrhythmia therapy upon a cardiac ventricular rate of around 240 bpm sustained over an approximately 1 second interval.

46. A unitary cardioverter-defibrillator according to claim 43, further comprising: the cardioversion-defibrillation circuitry terminating the anti-arrhythmia therapy upon a cardiac ventricular rate of around 240 bpm sustained over an at least 4 second interval.

47. A unitary cardioverter-defibrillator according to claim 43, further comprising: power supply components integral to the cardioversion-defibrillation circuitry, consisting essentially of four or more batteries and four or more capacitors and providing power sufficient to generate the anti-arrhythmia waveform.

48. A unitary cardioverter-defibrillator according to claim 35, further comprising: pacing circuitry operatively conjunctive to the cardioversion-defibrillation circuitry which generates at least one of an anti-bradycardia and an anti-tachycardia pacing waveform via the pair of electrodes responsive to the cardioversion-defibrillation circuitry.

49. A unitary cardioverter-defibrillator according to claim 35, further comprising: induction circuitry integral to the cardioversion-defibrillation circuitry which generates low amplitude voltage on a T-wave of an ECG via the pair of electrodes responsive to the cardioversion-defibrillation circuitry.

50. A unitary cardioverter-defibrillator according to claim 35, further comprising: a pair of semi-converging tapers continuously formed about opposite sides of the downward taper.

51. A unitary cardioverter-defibrillator according to claim 50, further comprising: at least one surface of the biocompatible housing formed in at least one of a curved and non-linear surface.

52. A unitary cardioverter-defibrillator according to claim 51, further comprising: the at least one surface formed as a radian bend curving continuously approximately axial to the biocompatible housing.

53. A unitary cardioverter-defibrillator according to claim 35, further comprising: at least one of a fractalized and a wrinkled surface formed on the outer surface of the biocompatible housing.

54. A unitary cardioverter-defibrillator according to claim 35, wherein the biocompatible housing is constructed from at least one of a titanium alloy and another biocompatible material, such other material being malleable.

55. A unitary cardioverter-defibrillator according to claim 35, further comprising: monitoring circuitry integral to the cardioversion-defibrillation circuitry and obtaining physiological measures via the pair of electrodes.

56. A unitary cardioverter-defibrillator according to claim 35, further comprising: each of the pair of electrodes formed non-circumferentially on the biocompatible housing and with an overall electrically active component of less than approximately 10 cm.sup.2.

57. A unitary cardioverter-defibrillator according to claim 35, further comprising: each of the pair of electrodes interfacing with high voltage and low impedance circuitry.

58. A unitary cardioverter-defibrillator according to claim 57, further comprising: a plurality of sensing electrodes formed on the biocompatible housing, each sensing electrode interfacing with low voltage and high impedance circuitry.

59. A unitary cardioverter-defibrillator according to claim 58, further comprising: each such sensing electrode formed on opposite ends of the biocompatible housing.

60. A unitary cardioverter-defibrillator according to claim 58, further comprising: each such sensing electrode formed between the pair of electrodes.

61. A unitary cardioverter-defibrillator according to claim 58, further comprising: at least one such sensing electrode formed non-circumferentially on the biocompatible housing.

62. A unitary cardioverter-defibrillator for subcutaneous implantation, comprising: a canister comprising a biocompatible housing enclosing and containing cardioversion-defibrillation circuitry; and a pair of electrodes formed on opposite ends of the biocompatible housing and electrically interfaced to the cardioversion-defibrillation circuitry to deliver an electrical therapy to the heart of a patient; wherein said canister has two ends, one end being a thicker end within which the cardioversion-defibrillation circuitry is contained.

63. A unitary cardioverter-defibrillator according to claim 62, further comprising: a core operational member containing the cardioversion-defibrillation circuitry separate from the biocompatible housing; and a hollow recess formed within the biocompatible housing operationally disposed to receive the core operational member.

64. A unitary cardioverter-defibrillator according to claim 63, further comprising: a plurality of connectors matchingly formed on a proximal end of the core operational member and on the distal end of the hollow recess, each connector interfacing the cardioversion-defibrillation circuitry to the pair of electrodes.

65. A unitary cardioverter-defibrillator according to claim 63, further comprising: an endcap with ribbed fittings formed along a proximal end of the core operational member and hermetically fitting within the hollow recess.

66. A unitary cardioverter-defibrillator for subcutaneous implantation, comprising: a canister comprising a biocompatible housing enclosing and containing cardioversion-defibrillation circuitry; and a pair of electrodes formed on opposite ends of the biocompatible housing and electrically interfaced to the cardioversion-defibrillation circuitry to deliver an electrical therapy to the heart of a patient; wherein the biocompatible housing has one of several incremental sizes.

67. A unitary cardioverter-defibrillator for subcutaneous implantation, comprising: a canister comprising a biocompatible housing enclosing and containing cardioversion-defibrillation circuitry; and a pair of electrodes formed on opposite ends of the biocompatible housing and electrically interfaced to the cardioversion-defibrillation circuitry to deliver an electrical therapy to the heart of a patient; wherein the biocompatible housing is shaped conformal to the rib cage.

68. A unitary cardioverter-defibrillator for subcutaneous implantation, comprising: a canister comprising a biocompatible housing enclosing and containing cardioversion-defibrillation circuitry; and a pair of electrodes formed on opposite ends of the biocompatible housing and electrically interfaced to the cardioversion-defibrillation circuitry to deliver an electrical therapy to the heart of a patient; wherein the biocompatible housing is further formed conformal to at least one of the fourth, fifth and sixth anterior rib spaces of a patient.

69. A unitary subcutaneous cardioverter-defibrillator with electrically active canister for minimally invasive implantation, comprising: a subcutaneously implantable canister comprising a sterilizable biocompatible housing enclosing and containing cardioversion-defibrillation circuitry interfaceable through the biocompatible housing, the biocompatible housing formed into a partially curved surface along a longitudinal axis, with a downward taper continuously formed along an exterior periphery of the biocompatible housing, and a pair of semi-converging tapers continuously formed about opposite sides of the downward taper; and a pair of electrodes formed on opposite and facing ends of the biocompatible housing and electrically interfaced via one or more internal conductors to the cardioversion-defibrillation circuitry to deliver an electrical therapy to the heart of a patient therebetween.

70. A unitary subcutaneous cardioverter-defibrillator according to claim 69, further comprising: the pair of electrodes further interfacing with sensing circuitry and providing a sensing function to the cardioversion-defibrillation circuitry.

71. A unitary subcutaneous cardioverter-defibrillator according to claim 69, further comprising: at least one of the pair of electrodes formed as a concentrated electrically conductive surface defined about a surface of the biocompatible housing and facing the heart when implanted.

72. A unitary subcutaneous cardioverter-defibrillator according to claim 69, further comprising at least one electrically insulated surface defined about a surface of the biocompatible housing facing away from the heart and juxtaposed to the pair of electrodes.

73. A unitary subcutaneous cardioverter-defibrillator according to claim 72, further comprising: an insulating area substantially interposed between the pair of electrodes and the at least one electrically insulated surface.

74. A unitary subcutaneous cardioverter-defibrillator according to claim 69, further comprising: at least one sensing electrode formed on, and electrically insulated from, the pair of electrodes and electrically interfaced to the cardioversion-defibrillation circuitry, each sensing electrode interfacing with sensing circuitry and providing a sensing function to the cardioversion-defibrillation circuitry.

75. A unitary subcutaneous cardioverter-defibrillator according to claim 74, further comprising: an electrically insulated surface about each at least one sensing electrode abutting the biocompatible housing and marginal to the pair of electrodes.

76. A unitary subcutaneous cardioverter-defibrillator according to claim 74, further comprising: each of the sensing electrodes formed in locations comprising at least one of a location between the pair of electrodes and outside the pair of electrodes.

77. A unitary subcutaneous cardioverter-defibrillator according to claim 74, further comprising: at least one such sensing electrode formed non-circumferentially along an interior surface of the biocompatible housing.

78. A unitary subcutaneous cardioverter-defibrillator according to claim 69, wherein at least one surface of the biocompatible housing forms a continuous radian curve.

79. A unitary subcutaneous cardioverter-defibrillator according to claim 69, further comprising: a pulse generator integral to the cardioversion-defibrillation circuitry and generating an anti-arrhythmia biphasic waveform with characteristics comprising at least one of a capacitance between approximately 50 .mu.F and 200 .mu.F, voltage between approximately 800 V and 2000 V, energy between 40 J and 150 J, and a duration between approximately 5 msec to 25 msec.

80. A unitary subcutaneous cardioverter-defibrillator according to claim 69, further comprising: the cardioversion-defibrillation circuitry comprising at least one of: monitoring circuitry deriving physiological measures relating to at least one of QRS signal morphology, QRS signal frequency content, QRS R-R interval stability data, and QRS amplitude characteristics; a pulse generator producing an anti-arrhythmia waveform for anti-arrhythmia therapy via the pair of electrodes responsive to the cardioversion-defibrillation circuitry; pacing circuitry operatively conjunctive to the cardioversion-defibrillation circuitry which generates at least one of an anti-bradycardia and an anti-tachycardia pacing waveform via the pair of electrodes responsive to the cardioversion-defibrillation circuitry; and induction circuitry generating low amplitude voltage on a T-wave of an ECG via the pair of electrodes responsive to the cardioversion-defibrillation circuitry.

81. A unitary subcutaneous cardioverter-defibrillator according to claim 69, wherein the biocompatible housing is constructed from at least one of a titanium alloy and another biocompatible material, such another material being malleable.

82. A unitary subcutaneous cardioverter-defibrillator with electrically active canister for minimally invasive implantation, comprising: a subcutaneously implantable canister comprising a sterilizable biocompatible housing enclosing and containing cardioversion-defibrillation circuitry interfaceable through the biocompatible housing, the biocompatible housing formed into a partially curved surface along a longitudinal axis; and a pair of electrodes formed on opposite and facing ends of the biocompatible housing and electrically interfaced via one or more internal conductors to the cardioversion-defibrillation circuitry to deliver an electrical therapy to the heart of a patient therebetween; wherein a thicker end is defined on one end of the canister, said thicker end being sized to contain the cardioversion-defibrillation circuitry exclusive of the remainder of the canister.

83. A unitary subcutaneous cardioverter-defibrillator according to claim 82 further comprising: self-contained power supply components contained within the biocompatible housing and integral to the cardioversion-defibrillation circuitry, consisting essentially of four or more batteries and four or more capacitors and providing power sufficient to generate the anti-arrhythmia biphasic waveform.

84. A unitary subcutaneous cardioverter-defibrillator with electrically active canister for minimally invasive implantation, comprising: a subcutaneously implantable canister comprising a sterilizable biocompatible housing enclosing and containing cardioversion-defibrillation circuitry interfaceable through the biocompatible housing, the biocompatible housing formed into a partially curved surface along a longitudinal axis; and a pair of electrodes formed on opposite and facing ends of the biocompatible housing and electrically interfaced via one or more internal conductors to the cardioversion-defibrillation circuitry to deliver an electrical therapy to the heart of a patient therebetween; further comprising: a removable core member containing the operational circuitry separate from the biocompatible housing and providing a plurality of electronic connectors; and the biocompatible housing operationally disposed to receive the core operational member via a plurality of matching electronic connectors.

85. A unitary cardioversion-defibrillation device with electrically conductive housing means for subcutaneous implantation, comprising: means for housing and hermetically containing cardioversion-defibrillation circuitry, the housing means defining a curved and substantially electrically insulated outer surface, with a downward taper continuously formed along an exterior periphery of the housing means, and a pair of semi-converging tapers continuously formed about opposite sides of the downward taper; and means for delivering an electrical therapy from opposite and facing ends of the housing means responsive to an autonomously detected arrhythmic condition, the electrical therapy delivering means being electrically connected via one or more internal conductors to the cardioversion-defibrillation circuitry.

86. A unitary cardioversion-defibrillation device according to claim 85, further comprising: means for monitoring and deriving physiological measures relating to at least one of QRS signal morphology, QRS signal frequency content, QRS R-R interval stability data, and QRS amplitude characteristics; means for producing an anti-arrhythmia waveform for anti-arrhythmia therapy via the electrical therapy delivering means responsive to the cardioversion-defibrillation circuitry; means for pacing circuitry operatively conjunctive to the cardioversion-defibrillation circuitry which generates at least one of an anti-bradycardia and an anti-tachycardia pacing waveform via the electrical therapy delivering means responsive to the cardioversion-defibrillation circuitry; and means for induction circuitry generating low amplitude voltage on a T-wave of an ECG via the electrical therapy delivering means responsive to the cardioversion-defibrillation circuitry.

87. A unitary cardioversion-defibrillation device according to claim 85, further comprising: sensing means provided via the electrical therapy delivering means, the sensing means being electrically connected via the one or more internal conductors to the cardioversion-defibrillation circuitry to interface with sensing circuitry.

88. A unitary cardioversion-defibrillation device according to claim 85, further comprising: sensing means provided abutting and electrically insulated from the housing means, the sensing means being electrically connected via the one or more internal conductors to the cardioversion-defibrillation circuitry to interface with sensing circuitry.

89. A subcutaneous cardioverter-defibrillator according to claim 88, further comprising: each of the sensing means formed in locations comprising at least one of a location between the electrical therapy delivering means and outside the electrical therapy delivering means.

90. A unitary cardioversion-defibrillation device according to claim 85, further comprising: at least one electrically insulated surface defined about a surface of the housing means facing the heart and juxtaposed to the electrical therapy delivering means.

91. A unitary cardioversion-defibrillation device according to claim 85, further comprising: pulse generating means integral to the cardioversion-defibrillation circuitry and generating an anti-arrhythmia biphasic waveform with characteristics comprising at least one of a capacitance between approximately 50 .mu.F and 200 .mu.F, voltage between approximately 800 V and 2000 V, energy between 40 J and 150 J, and a duration between approximately 5 msec to 25 msec.

92. A unitary cardioversion-defibrillation device according to claim 85, further comprising: a radian bend continuously formed approximately axial to the housing means.

93. A unitary cardioversion-defibrillation device according to claim 85, further comprising: operational means containing the cardioversion-defibrillation circuitry separate from the housing means and providing-means for connecting along a proximal end; and receiving means formed within a distal end of the housing means operationally disposed to receive the operational means via the connecting means.

94. A unitary cardioversion-defibrillation device according to claim 85, wherein the housing means is constructed from at least one of a titanium alloy and another biocompatible material, such another material being malleable.

95. An implantable unitary subcutaneous cardioverter-defibrillator with electrically active canister, comprising: an implantable canister providing a curved housing enclosing and containing cardioversion-defibrillation circuitry; a pair of electrodes formed on opposite and facing ends of the housing and electrically interfaced via one or more conductors to the cardioversion-defibrillation circuitry to deliver an electrical therapy to the heart of a patient responsive to an autonomously detected arrhythmic condition; and a removable core operational member containing the cardioversion-defibrillation circuitry separate and interchangeably from the housing and providing a plurality of connectors, the housing being operationally disposed to receive the core operational member via a plurality of matching connectors.

96. An implantable unitary subcutaneous cardioverter-defibrillator according to claim 95, further comprising: an electrically insulated surface juxtaposed to the pair of electrodes and substantially interposed therefrom by an electrically insulated area.

97. An implantable unitary subcutaneous cardioverter-defibrillator according to claim 95, further comprising: a plurality of sensing electrodes formed on the housing and electrically connected with the one or more conductors to the cardioversion-defibrillation circuitry, each of the sensing electrodes interfacing with sensing circuitry within the cardioversion-defibrillation circuitry and providing a sensing function.

98. An implantable unitary subcutaneous cardioverter-defibrillator according to claim 97, further comprising: each of the sensing electrodes formed on locations along the, housing comprising at least one of a surface of the implantable canister facing the heart and a surface of the implantable canister facing toward the skin.

99. An implantable unitary subcutaneous cardioverter-defibrillator according to claim 95, further comprising: an anti-arrhythmic pulse generator integral to the cardioversion-defibrillation circuitry and generating an anti-arrhythmia biphasic waveform between the pair of electrodes with characteristics comprising at least one of a capacitance between approximately 50 .mu.F and 200 .mu.F, voltage between approximately 800 V and 2000 V, energy between 40 J and 150 J, and a duration between approximately 5 msec to 25 msec.

100. An implantable unitary subcutaneous cardioverter-defibrillator with electrically active canister, comprising: an implantable canister providing a curved housing enclosing and containing cardioversion-defibrillation circuitry; a pair of electrodes formed on opposite and facing ends of the housing and electrically interfaced via one or more conductors to the cardioversion-defibrillator circuitry to deliver an electrical therapy to the heart of a patient responsive to an autonomously detected arrhythmic condition; a removable core operational member containing the cardioversion-defibrillation circuitry separate and interchangeably from the housing and providing a plurality of connectors, the housing operationally disposed to receive the core operational member via a plurality of matching connectors.

101. A method for providing anti-arrhythmia therapy via a unitary subcutaneous cardioverter-defibrillator, comprising: implanting a canister comprising a curved biocompatible housing subcutaneously in a patient in the anterior thorax approximately level with the inframammary crease and extending posteriorly towards the left posterior axillary line, the biocompatible housing enclosing and containing cardioversion-defibrillation circuitry and defining a pair of electrodes on the outer surface of the biocompatible housing that faces the heart and electrically connected to the cardioversion-defibrillation circuitry; and delivering an electrical therapy comprising an anti-arrhythmia waveform to the heart of a patient from the pair of electrodes.

102. A method according to claim 101, the method further comprising: implanting the canister in a region proximate to at least one of the fourth, fifth and sixth anterior rib spaces of a patient.

103. A method according to claim 101, the method further comprising: providing a plurality of sensing electrodes formed on the canister, electrically isolated from the pair of electrodes, each sensing electrode interfacing with sensing circuitry to the cardioversion-defibrillation circuitry; and monitoring and deriving cardiac physiological measures relating to at least one of QRS signal morphology, QRS signal frequency content, QRS R-R interval stability data, and QRS amplitude characteristics via the sensing electrodes.

104. A method according to claim 101, further comprising: generating low amplitude voltage on a T-wave of an ECG via the pair of electrodes responsive to the cardioversion-defibrillation circuitry.