Method for improving cardiac function following delivery of a defibrillation shock

• US 6,556,865 B2
• Filed: 01/29/2001
• Issued: 04/29/2003
• Est. Priority Date: 01/29/2001
• Status: Expired due to Term

• Current Assignee: UAB Research Foundation (University of Alabama System)
• Original Assignee: UAB Research Foundation (University of Alabama System)
• Inventors: Walcott, Gregory P., Ideker, Raymond E., Chapman, Fred William
• Primary Examiner(s): Getzow, Scott M.
• Application Number:
  US09/772,225
• Publication Number:
  US 20020133205A1
• Time in Patent Office: 820 Days
• Field of Search: 607/4-8, 607/14
• US Class Current: 607/6
• CPC Class Codes: A61N 1/3962 in combination with another heart therapy
• CPC Class Codes: A61N 1/39622 Pacing therapy

Abstract

A method of reducing the likelihood of pulseless electrical activity (PEA) after defibrillation in a subject comprises administering to a subject afflicted with fibrillation a first treatment waveform, the first treatment waveform insufficient to defibrillate the heart; and then administering to the subject a second treatment waveform that defibrillates the heart and restores organized electrical activity in the heart. The first treatment waveform reduces the likelihood of onset of PEA following the second treatment waveform, as compared to that likelihood which would be present in the absence of the first treatment waveform.

Claims

1. A method of reducing the likelihood of onset of pulseless electrical activity after defibrillation in a subject afflicted with a fibrillating heart, said method comprising the steps of:

administering to a subject afflicted with fibrillation a first treatment waveform, said first treatment waveform insufficient to defibrillate said heart and insufficient to reduce the defibrillation threshold of said subject; and

then

administering to said subject a second treatment waveform that defibrillates said heart and restores organized electrical activity in said heart;

with said first treatment waveform reducing the likelihood of onset of pulseless electrical activity following said second treatment waveform as compared to that likelihood which would be present in the absence of said first treatment waveform.

2. A method according to claim 1, wherein said fibrillation is ventricular fibrillation.

3. A method according to claim 1, wherein said first treatment waveform comprises a single electrical pulse.

4. A method according to claim 1, wherein said first treatment waveform comprises a series of electrical pulses.

5. A method according to claim 1, wherein said second treatment waveform comprises a single electrical pulse.

6. A method according to claim 1, wherein said second treatment waveform comprises a series of electrical pulses.

7. A method according to claim 1, wherein said first treatment waveform is administered by external electrodes and has an energy of from about 1 to 400 Joules.

8. A method according to claim 1, wherein said first treatment waveform is administered by internal electrodes and has an energy of from about 0.1 to 50 Joules.

9. A method according to claim 1, wherein said first treatment waveform and said second treatment waveform are sequential.

10. A method according to claim 1, wherein said second treatment waveform immediately follows said first treatment waveform.

11. A method according to claim 1, wherein said second treatment waveform follows said first treatment waveform by from 1 millisecond to 10 seconds.

12. A method according to claim 1, wherein said first treatment waveform and said second treatment waveform are at least partially interleaved.

13. A method according to claim 1, wherein said first treatment waveform is delivered through the same set of electrodes as said second treatment waveform.

14. A method according to claim 1, wherein said first treatment waveform is delivered through a different set of electrodes as said second treatment waveform.

15. A method according to claim 1, wherein said first treatment waveform is delivered by at least one cutaneous electrode.

16. A method according to claim 1, wherein said first treatment waveform is delivered by at least one subcutaneous electrode.

17. A method according to claim 1, wherein said first treatment waveform is delivered by at least one epicardial electrode.

18. A method according to claim 1, wherein said first treatment waveform is delivered by at least one transveneous electrode.

19. A method according to claim 1, wherein said first treatment waveform is delivered by at least one transveneous coronary sinus electrode positioned in the coronary sinus or a cardiac vein.

20. A system for the defibrillation of the heart of a patient in need of such treatment, which system provides reduced likelihood of onset of pulseless electrical activity after defibrillation in a subject afflicted with a fibrillating heart, said system comprising:

a power supply; and

a controller operatively associated with said power supply, said controller configured for delivering a defibrillation sequence comprising a first treatment waveform, said first treatment waveform insufficient to defibrillate said heart and insufficient to reduce the defibrillation threshold of said subject; and

then a second treatment waveform that defibrillates said heart and restores organized electrical activity in said heart;

with said first treatment waveform reducing the likelihood of onset of pulseless electrical activity following said second treatment waveform as compared to that likelihood which would be present in the absence of said first treatment waveform.

21. A system according to claim 20, wherein said fibrillation is ventricular fibrillation.

22. A system method according to claim 20, wherein said first treatment waveform comprises a single electrical pulse.

23. A system according to claim 20, wherein said first treatment waveform comprises a series of electrical pulses.

24. A system according to claim 20, wherein said second treatment waveform comprises a single electrical pulse.

25. A system according to claim 20, wherein said second treatment waveform comprises a series of electrical pulses.

26. A system according to claim 20, further comprising:

a plurality of external electrodes operatively associated with said controller,

and wherein said first treatment waveform is administered by external electrodes and has an energy of from about 1 to 400 Joules.

27. A system according to claim 20, further comprising:

a plurality of internal electrodes operatively associated with said controller;

and wherein said first treatment waveform is administered by internal electrodes and has an energy of from about 0.1 to 50 Joules.

28. A system according to claim 20, wherein said controller is configured so that said first treatment waveform and said second treatment waveform are sequential.

29. A system according to claim 20, wherein said controller is configured so that said second treatment waveform immediately follows said first treatment waveform.

30. A system according to claim 20, wherein said controller is configured so that said second treatment waveform follows said first treatment waveform by from 1 millisecond to 10 seconds.

31. A system according to claim 20, wherein said controller is configured so that said first treatment waveform and said second treatment waveform are at least partially interleaved.

32. A system according to claim 20, wherein said controller is configured so that said first treatment waveform is delivered through the same set of electrodes as said second treatment waveform.

33. A system according to claim 20, wherein said controller is configured so that said first treatment waveform is delivered through a different set of electrodes as said second treatment waveform.

34. A system according to claim 20, further comprising at least one cutaneous electrode operatively associated with said controller, and wherein said controller is configured so that said first treatment waveform is delivered by said at least one cutaneous electrode.

35. A system according to claim 20, further comprising at least one subcutaneous electrode operatively associated with said controller, and wherein said first treatment waveform is delivered by said at least one subcutaneous electrode.

36. A system according to claim 20, further comprising at least one epicardial electrode operatively associated with said controller, and wherein said first treatment waveform is delivered by at least one epicardial electrode.

37. A system according to claim 20, further comprising at least one transveneous electrode operatively associated with said controller, and wherein said first treatment waveform is delivered by said at least one transveneous electrode.

38. A system according to claim 20, further comprising at least one transveneous coronary sinus electrode operatively associated with said controller, and wherein said first treatment waveform is delivered by said at least one transveneous coronary sinus electrode.

39. A method for the external defibrillation of the heart of a patient afflicted with ventricular fibrillation, comprising the steps of:

externally administering to said patient a first treatment waveform, said first treatment waveform insufficient to defibrillate said heart and insufficient to reduce the defibrillation threshold of said subject; and

then

externally administering to said subject a second treatment waveform that defibrillates said heart and restores organized electrical activity in said heart.

40. A method according to claim 39, wherein:

said first treatment waveform is administered for a time of 0.05 to 10 seconds; and

said second treatment waveform is administered within 5 seconds of said first treatment waveform.

41. A method according to claim 39, further comprising the step of:

generating a warning signal during said first treatment waveform.

42. A method according to claim 41, wherein said warning signal comprises an auditory, visual, or tactile signal.

43. A method according to claim 41, wherein said step of externally administering to said patient a first treatment waveform is preceded by the step of:

determining the presence or absence of a likelihood of pulseless electrical activity following defibrillation, and wherein;

said step of administering said first treatment waveform is carried out if a likelihood of pulseless electrical activity following defibrillation is determined, and said step of administering said first treatment waveform is eliminated if a likelihood of pulseless electrical activity following defibrillation is not determined.

44. A method according to claim 41, further comprising the step of generating a warning signal prior to said first treatment waveform.

45. A method according to claim 41, further comprising the step of generating a warning signal during said second treatment waveform.

46. A method according to claim 39, wherein said first treatment waveform has an energy of from about 1 to 400 Joules.

47. A method according to claim 39, wherein said second treatment waveform has an energy of from about 100 to 400 Joules.

48. A method according to claim 39, wherein said first treatment waveform and said second treatment waveform are sequential.

49. A method according to claim 41, wherein said second treatment waveform immediately follows said first treatment waveform.

50. A method according to claim 41, wherein said first treatment waveform and said second treatment waveform are at least partially interleaved.

51. An external defibrillation system for the external defibrillation of the heart of a patient afflicted with ventricular fibrillation, comprising:

a power supply; and

a controller operatively associated with said power supply, said controller configured for delivering a defibrillation sequence comprising a first treatment waveform, said first treatment waveform insufficient to defibrillate said heart and insufficient to reduce the defibrillation threshold of said subject; and

then a second treatment waveform that defibrillates said heart and restores organized electrical activity in said heart.

52. A system according to claim 51, said controller configured so that

said first treatment waveform is administered for a time of 0.05 to 10 seconds; and

said second treatment waveform is administered within 5 seconds of said first treatment waveform.

53. A system according to claim 51, further comprising a warning signal generator operatively associated with said controller, and with said controller configured to generate a warning signal during said first treatment waveform.

54. A system according to claim 53, wherein said warning signal generator is an auditory, visual, or tactile signal generator.

55. A system according to claim 53, further comprising

means for determining the likelihood of pulseless electrical activity following defibrillation configured so that said step of administering said first treatment waveform is carried out if a likelihood of pulseless electrical activity following defibrillation is determined, and said step of administering said first treatment waveform is eliminated if a likelihood of pulseless electrical activity following defibrillation is not determined.

56. A system according to claim 53, wherein said controller is configured to generate a warning signal prior to said first treatment waveform.

57. A system according to claim 53, wherein said controller is configured to generate a warning signal during said second treatment waveform.

58. A system according to claim 51, wherein said controller is configured so that said first treatment waveform has an energy of from about 1 to 400 Joules.

59. A system according to claim 51, wherein said controller is configured so that said second treatment waveform has an energy of from about 100 to 400 Joules.

60. A system according to claim 51, wherein said controller is configured so that said first treatment waveform and said second treatment waveform are sequential.

61. A system according to claim 51, wherein said controller is configured so that said second treatment waveform immediately follows said first treatment waveform.

62. A system according to claim 51, wherein said controller is configured so that said first treatment waveform and said second treatment waveform are at least partially interleaved.

63. A method of reducing the likelihood of onset of pulseless electrical activity after defibrillation with an implantable defibrillator in a subject afflicted with a fibrillating heart, said method comprising the steps of:

administering to a subject afflicted with fibrillation a first treatment waveform, said first treatment waveform insufficient to defibrillate said heart and insufficient to reduce the defibrillation threshold of said subject; and

then

administering to said subject a second treatment waveform that defibrillates said heart and restores organized electrical activity in said heart;

with said first treatment waveform reducing the likelihood of onset of pulseless electrical activity following said second treatment waveform as compared to that likelihood which would be present in the absence of said first treatment waveform.

64. A method according to claim 63, wherein at least one of said first and second treatment waveforms is delivered by an electrode positioned in the coronary sinus, in a vein on the surface of the left ventricle, or in a vein at the junction of the right and left ventricles.

65. A method according to claim 63, wherein at least one of said first and second treatment waveforms is delivered by an electrode positioned on an external surface portion of said implantable defibrillator.

66. A method according to claim 63, wherein said first treatment waveform is delivered between at least a first electrode and second electrode;

said first electrode selected from the group consisting of right ventricle, superior vena cava, and right atrium electrodes; and

said second electrode selected from the group consisting of thoracic, superior vena cava, left ventricle, coronary sinus, left ventricle vein electrodes and left and right ventricle junction vein electrodes.

67. A method according to claim 63, wherein said second treatment waveform is delivered between at least a first electrode and second electrode;

said first electrode selected from the group consisting of right ventricle, superior vena cava, and right atrium electrodes; and

said second electrode selected from the group consisting of thoracic, superior vena cava, left ventricle, coronary sinus, left ventricle vein electrodes, and left and right ventricle junction electrodes.

68. A method according to claim 63, wherein said first treatment waveform has an energy of from about 0.1 to 50 Joules.

69. A method according to claim 63, wherein said second treatment waveform has an energy of from about 1 to 50 Joules.

70. A method according to claim 63, wherein said first treatment waveform and said second treatment waveform are sequential.

71. A method according to claim 63, wherein said second treatment waveform immediately follows said first treatment waveform.

72. A method according to claim 63, wherein said first treatment waveform and said second treatment waveform are at least partially interleaved.

73. An implantable defibrillator for defibrillating the heart of a subject in need thereof, comprising:

a power supply; and

a controller operatively associated with said power supply, said controller configured for delivering a defibrillation sequence comprising a first treatment waveform, said first treatment waveform insufficient to defibrillate said heart and insufficient to reduce the defibrillation threshold of said subject; and

then a second treatment waveform that defibrillates said heart and restores organized electrical activity in said heart;

with said first treatment waveform reducing the likelihood of onset of pulseless electrical activity following said second treatment waveform as compared to that likelihood which would be present in the absence of said first treatment waveform.

74. A system according to claim 73, further comprising an electrode configured for positioning in the coronary sinus or in a vein on the surface of the left ventricle of said heart, wherein at least one of said first and second treatment waveforms is delivered by said electrode.

75. A system according to claim 73, further comprising an electrode positioned on an external surface portion of said implantable defibrillator, wherein at least one of said first and second treatment waveforms is delivered by said electrode.

76. A system according to claim 73, further comprising at least a first electrode and a second electrode, and wherein said controller is configured so that said first treatment waveform is delivered between said first electrode and second electrode;

said first electrode selected from the group consisting of right ventricle, superior vena cava, and right atrium electrodes; and

said second electrode selected from the group consisting of thoracic, superior vena cava, left ventricle, coronary sinus, left ventricle vein electrodes, and left and right ventricle junction vein electrodes.

77. A system according to claim 73, further comprising at least a first electrode and a second electrode, and wherein said controller is configured so that said second treatment waveform is delivered between said first electrode and second electrode;

said first electrode selected from the group consisting of right ventricle, superior vena cava, and right atrium electrodes; and

said second electrode selected from the group consisting of thoracic, superior vena cava, left ventricle, coronary sinus, left ventricle vein electrodes, and left and right ventricle junction vein electrodes.

78. A system according to claim 73, said controller configured so that said first treatment waveform has an energy of from about 0.1 to 50 Joules.

79. A system according to claim 73, said controller configured so that said second treatment waveform has an energy of from about 1 to 50 Joules.

80. A system according to claim 73, said controller configured so that said first treatment waveform and said second treatment waveform are sequential.

81. A system according to claim 73, said controller configured so that said second treatment waveform immediately follows said first treatment waveform.

82. A system according to claim 73, said controller configured so that said first treatment waveform and said second treatment waveform are at least partially interleaved.

84. A system according to claim 81, said controller configured so that

said first treatment waveform is administered for a time of 0.05 to 10 seconds;

and

said second treatment waveform is administered within 5 seconds of said first treatment waveform.

83. A defibrillation system for the defibrillation of the heart of a patient afflicted with ventricular fibrillation, comprising:

a detector for detecting electrical activity from the heart of said patient during ventricular fibrillation;

a power supply;

a signal analyzer for determining the likelihood of pulseless electrical activity in said patient after delivery of a defibrillation treatment waveform to said patient; and

a controller operatively associated with said detector, said power supply and said signal analyzer, said controller configured for delivering a defibrillation sequence, said defibrillation sequence optionally comprising a first treatment waveform, said first treatment waveform insufficient to defibrillate said heart, and then delivering a second treatment waveform that defibrillates said heart and restores organized electrical activity in said heart;

and wherein said first treatment waveform is delivered when a high likelihood of pulseless electrical activity after defibrillation is determined, and said first treatment waveform is not delivered when a low likelihood of pulseless electrical activity after defibrillation is determined.

85. A system according to claim 83, further comprising a user interface operatively associated with said controller, and with said controller configured to generate a warning signal during said first treatment waveform.

86. A system according to claim 85, wherein said warning signal is an auditory, visual, or tactile signal.

87. A system according to claim 85, wherein said defibrillator is an external defibrillator.

88. A system according to claim 85, wherein said controller is configured to generate a warning signal prior to said first treatment waveform.

89. A system according to claim 85, wherein said controller is configured to generate a warning signal during said second treatment waveform.

90. A system according to claim 83, wherein said controller is configured so that said first treatment waveform has an energy of from about 1 to 400 Joules.

91. A system according to claim 83, wherein said controller is configured so that said second treatment waveform has an energy of from about 100 to 400 Joules.

92. A system according to claim 83, wherein said controller is configured so that said first treatment waveform and said second treatment waveform are sequential.

93. A system according to claim 83, wherein said controller is configured so that said second treatment waveform immediately follows said first treatment waveform.

94. A system according to claim 83, wherein said controller is configured so that said first treatment waveform and said second treatment waveform are at least partially interleaved.

95. A system according to claim 83, wherein said signal analyzer determines the likelihood of pulseless electrical activity by determining a viability index associated with the viability of the heart.

96. A system according to claim 95, wherein said first treatment waveform is delivered when the viability index indicates a high likelihood of pulseless electrical activity.

97. A system according to claim 96, wherein the viability index is determined based on the duration for which the patient is in ventricular fibrillation.

98. A system according to claim 96, wherein the viability index is determined based on an analysis of the patient waveform during ventricular fibrillation.

99. A system according to claim 98, wherein the analysis of the patient waveform produces a power spectrum of the patient waveform.

100. A system according to claim 98, wherein the analysis of the patient waveform produces a scaling structure of the patient waveform.

101. A system according to claim 98, wherein the analysis of the patient waveform produces an amplitude and frequency of the patient waveform.

102. A system according to claim 98, wherein the analysis of the patient waveform produces a median frequency of the patient waveform.

103. A system according to claim 98, wherein the analysis of the patient waveform produces a centroid frequency of the patient waveform.

104. A system according to claim 98, wherein the analysis of the patient waveform produces a combination of at least two of a power spectrum, a scaling structure, an amplitude and frequency, a median frequency and a centroid frequency of the patient waveform.

105. A system according to claim 96 wherein the viability index is determined based on cardiac motion of the patient'"'"'s heart.

106. A system according to claim 96, wherein the viability index is determined based on user input.

107. A system according to claim 96, wherein the viability index is determined based on physiological measurements indicative of blood flow.

108. A system according to claim 107, wherein the physiological measurements are electrical measurements.

109. A system according to claim 107, wherein the physiological measurements are physical measurements.

110. A system according to claim 107, wherein the physiological measurements are chemical measurements.

111. A system according to claim 107, wherein the physiological measurements are a combination of at least two of electrical measurements, physical measurements and chemical measurements.

112. A system for defibrillation of the heart of a patient afflicted with ventricular fibrillation, comprising:

a detector for detecting electrical activity from the heart of said patient during ventricular fibrillation;

a power supply;

a controller operatively associated with said detector and said power supply, said controller configured for delivering a defibrillation sequence, said defibrillation sequence optionally comprising a first treatment waveform, said first treatment waveform insufficient to defibrillate said heart, and then delivering a second treatment waveform that defibrillates said heart and restores organized electrical activity in said heart;

and wherein said first treatment waveform is delivered when a high likelihood of pulseless electrical activity after defibrillation is determined, and said first treatment waveform is not delivered when a low likelihood of pulseless electrical activity after defibrillation is determined.

113. A system according to claim 112, wherein the likelihood of pulseless electrical activity is determined manually after delivery of a defibrillation treatment waveform to said patient.

114. A system according to claim 112, wherein the likelihood of pulseless electrical activity is determined automatically after delivery of a defibrillation treatment waveform to said patient by a signal analyzer operatively associated with said controller.

115. A system according to claim 114, wherein the signal analyzer determines the likelihood of pulseless electrical activity by determining a viability index associated with the viability of the heart.

116. A system according to claim 115, wherein said first treatment waveform is delivered if the viability index indicates that the viability of the heart is insufficient.

117. A system according to claim 116, wherein the viability index is determined based on the duration for which the patient is in ventricular fibrillation.

118. A system according to claim 117, wherein the physiological measurement is an electrical measurement.

119. A system according to claim 117, wherein the physiological measurement is a physical measurement.

120. A system according to claim 117, wherein the physiological measurement is a chemical measurement.

121. A system according to claim 117, wherein the physiological measurement is a combination of at least two of an electrical measurement, physical measurement and chemical measurement.

122. A system according to claim 116, wherein the viability index is determined based on an analysis of the patient waveform during ventricular fibrillation.

123. A system according to claim 122, wherein the analysis of the patient waveform produces a power spectrum of the patient waveform.

124. A system according to claim 122, wherein the analysis of the patient waveform produces a scaling structure of the patient waveform.

125. A system according to claim 122, wherein the analysis of the patient waveform produces an amplitude and frequency of the patient waveform.

126. A system according to claim 122, wherein the analysis of the patient waveform produces a median frequency of the patient waveform.

127. A system according to claim 122, wherein the analysis of the patient waveform produces a centroid frequency of the patient waveform.

128. A system according to claim 122, wherein the analysis of the patient waveform produces a combination of at least two of a power spectrum, a scaling structure, an amplitude and frequency, a median frequency and a centroid frequency of the patient waveform.

129. A system according to claim 116 wherein the viability index is determined based on cardiac motion of the patient'"'"'s heart.

130. A system according to claim 116, wherein the viability index is determined based on user input.

131. A system according to claim 116, wherein the viability index is determined based on a physiological measurement indicative of blood flow.

132. A system according to claim 116, further comprising a user interface operatively associated with said controller, said user interface configured for reporting an indicia of the viability index to an operator so that the operator may optionally determine based on the viability index whether the first treatment waveform is to be delivered to the patient.

133. A system according to claim 116, wherein said first treatment waveform delivered to the patient is adjusted based on the viability index.

134. A method for the external defibrillation of the heart of a patient afflicted with ventricular fibrillation, comprising the steps of:

externally administering to said patient a first treatment waveform, said first treatment waveform insufficient to defibrillate said heart; and

externally administering to said subject a second treatment waveform that defibrillates said heart and restores organized electrical activity to said heart;

wherein said first treatment waveform is administered when a high likelihood of pulseless electrical activity after defibrillation is determined, and said first treatment waveform is not administered when a low likelihood of pulseless electrical activity after defibrillation is determined.

135. A method according to claim 134, wherein the likelihood of pulseless electrical activity is determined manually after delivery of a defibrillation treatment waveform to said patient.

136. A method according to claim 134, wherein the likelihood of pulseless electrical activity is determined automatically after delivery of a defibrillation treatment waveform to said patient.

137. A method according to claim 136, wherein the likelihood of pulseless electrical activity is represented as a viability index associated with the viability of the heart, and wherein said first treatment waveform is delivered if the viability index indicates a high likelihood of pulseless electrical activity.

138. A method according to claim 137, wherein the viability index is determined based on the duration for which the patient is in ventricular fibrillation.

139. A method according to claim 137, wherein the viability index is determined based on an analysis of the patient waveform during ventricular fibrillation.

140. A method according to claim 139, wherein the analysis of the patient waveform produces a power spectrum of the patient waveform.

141. A method according to claim 139, wherein the analysis of the patient waveform produces a scaling structure of the patient waveform.

142. A method according to claim 139, wherein the analysis of the patient waveform produces an amplitude and frequency of the patient waveform.

143. A method according to claim 139, wherein the analysis of the patient waveform produces a median frequency of the patient waveform.

144. A method according to claim 139, wherein the analysis of the patient waveform produces a centroid frequency of the patient waveform.

145. A method according to claim 139, wherein the analysis of the patient waveform produces a combination of at least two of a power spectrum, a scaling structure, an amplitude and frequency, a median frequency and a centroid frequency of the patient waveform.

146. A method according to claim 137 wherein the viability index is determined based on cardiac motion of the patient'"'"'s heart.

147. A method according to claim 137, wherein the viability index is determined based on user input.

148. A method according to claim 137 wherein the viability index is determined based on a physiological measurement indicative of blood flow.

149. A method according to claim 148, wherein the physiological measurement is an electrical measurement.

150. A method according to claim 148, wherein the physiological measurement is a physical measurement.

151. A method according to claim 148, wherein the physiological measurement is a chemical measurement.

152. A method according to claim 148, wherein the physiological measurement is a combination of at least two of an electrical measurement, physical measurement and chemical measurement.

153. A method according to claim 137, further comprising reporting an indicia of the viability index to an operator so that the operator may optionally determine based on the viability index whether the first treatment waveform is to be administered to the patient.

154. A method according to claim 137, wherein said first treatment waveform delivered to the patient is adjusted based on the viability index.

155. A method of reducing the likelihood of onset of pulseless electrical activity after defibrillation in a subject afflicted with a fibrillating heart, said method comprising the steps of:

determining a likelihood of pulseless electrical activity following defibrillation of said heart;

if the likelihood of pulseless electrical activity above a predetermined amount, administering to a subject afflicted with fibrillation a first treatment waveform, said first treatment waveform insufficient to defibrillate said heart; and

then

administering to said subject a second treatment waveform that defibrillates said heart and restores organized electrical activity in said heart;

with said first treatment waveform reducing the likelihood of onset of pulseless electrical activity following said second treatment waveform as compared to that likelihood which would be present in the absence of said first treatment waveform.

156. A method according to claim 155, wherein the step of determining a likelihood of pulseless electrical activity further comprises:

assessing the viability of said heart.

157. A method according to claim 156, wherein the step of assessing the viability of said heart further comprises:

analyzing a waveform of said heart during ventricular fibrillation.

158. A method according to claim 156, wherein the step of assessing the viability of said heart further comprises:

analyzing a waveform of said heart during ventricular fibrillation as a function of the duration the patient has been in ventricular fibrillation.

159. A method according to claim 156, wherein the step of assessing the viability of said heart further comprises:

analyzing a waveform of said heart during ventricular fibrillation as a function of physiological measurements indicative of blood flow.

160. A method according to claim 156, wherein the step of assessing the viability of said heart further comprises:

analyzing a waveform of said heart during ventricular fibrillation as a function of cardiac motion.

161. A method according to claim 156, wherein the step of assessing the viability of said heart further comprises:

analyzing a waveform of said heart during ventricular fibrillation as a function of user inputs.

162. A method according to claim 155, wherein said fibrillation is ventricular fibrillation.

163. A method according to claim 155, wherein said first treatment waveform comprises a single electrical pulse.

164. A method according to claim 155, wherein said first treatment waveform comprises a series of electrical pulses.

165. A method according to claim 155, wherein said first treatment waveform is insufficient to reduce the defibrillation threshold of said subject.

166. A method according to claim 155, wherein said second treatment waveform comprises a single electrical pulse.

167. A method according to claim 155, wherein said second treatment waveform comprises a series of electrical pulses.

168. A method according to claim 155, wherein said first treatment waveform is administered by external electrodes and has an energy of from about 1 to 400 Joules.

169. A method according to claim 155, wherein said first treatment waveform is administered by internal electrodes and has an energy of from about 0.1 to 50 Joules.

170. A method according to claim 155, wherein said first treatment waveform and said second treatment waveform are sequential.

171. A method according to claim 155, wherein said second treatment waveform immediately follows said first treatment waveform.

172. A method according to claim 155, wherein said second treatment waveform follows said first treatment waveform by from 1 millisecond to 10 seconds.

173. A method according to claim 155, wherein said first treatment waveform and said second treatment waveform are at least partially interleaved.

174. A method according to claim 155, wherein said first treatment waveform is delivered through the same set of electrodes as said second treatment waveform.

175. A method according to claim 155, wherein said first treatment waveform is delivered through a different set of electrodes as said second treatment waveform.

176. A method according to claim 155, wherein said first treatment waveform is delivered by at least one cutaneous electrode.

177. A method according to claim 155, wherein said first treatment waveform is delivered by at least one subcutaneous electrode.

178. A method according to claim 155, wherein said first treatment waveform is delivered by at least one epicardial electrode.

179. A method according to claim 155, wherein said first treatment waveform is delivered by at least one transveneous electrode.

180. A method according to claim 155, wherein said first treatment waveform is delivered by at least one transveneous coronary sinus electrode positioned in the coronary sinus or a cardiac vein.

181. A system for the defibrillation of the heart of a patient in need of such treatment, which system provides reduced likelihood of onset of pulseless electrical activity after defibrillation in a subject afflicted with a fibrillating heart, said system comprising:

a power supply; and

a controller operatively associated with said power supply, said controller configured for determining a likelihood of pulseless electrical activity following defibrillation of said heart in a subject afflicted with fibrillation, and, if the likelihood of pulseless electrical activity above a predetermined amount, delivering a defibrillation sequence comprising a first treatment waveform, said first treatment waveform insufficient to defibrillate said heart; and

then a second treatment waveform that defibrillates said heart and restores organized electrical activity in said heart;

with said first treatment waveform reducing the likelihood of onset of pulseless electrical activity following said second treatment waveform as compared to that likelihood which would be present in the absence of said first treatment waveform.

182. A system according to claim 181, wherein said controller is configured so that a likelihood of pulseless electrical activity is determined by assessing the viability of said heart.

183. A system according to claim 182, wherein said controller is configured so that a likelihood of pulseless electrical activity is determined by analyzing a waveform of said heart during ventricular fibrillation.

184. A system according to claim 182, wherein said controller is configured so that a likelihood of pulseless electrical activity is determined by analyzing a waveform of said heart during ventricular fibrillation as a function of the duration the patient has been in ventricular fibrillation.

185. A system according to claim 182, wherein said controller is configured so that a likelihood of pulseless electrical activity is determined by analyzing a waveform of said heart during ventricular fibrillation as a function of physiological measurements indicative of blood flow.

186. A system according to claim 182, wherein said controller is configured so that a likelihood of pulseless electrical activity is determined by analyzing a waveform of said heart during ventricular fibrillation as a function of cardiac motion.

187. A system according to claim 182, wherein said controller is configured so that a likelihood of pulseless electrical activity is determined by analyzing a waveform of said heart during ventricular fibrillation as a function of user inputs.

188. A system according to claim 181, wherein said fibrillation is ventricular fibrillation.

189. A system method according to claim 181, wherein said first treatment waveform comprises a single electrical pulse.

190. A system according to claim 181, wherein said first treatment waveform comprises a series of electrical pulses.

191. A system according to claim 181, wherein said first treatment waveform is insufficient to reduce the defibrillation threshold of said subject.

192. A system according to claim 181, wherein said second treatment waveform comprises a single electrical pulse.

193. A system according to claim 181, wherein said second treatment waveform comprises a series of electrical pulses.

194. A system according to claim 181, further comprising:

a plurality of external electrodes operatively associated with said controller,

and wherein said first treatment waveform is administered by external electrodes and has an energy of from about 1 to 400 Joules.

195. A system according to claim 181, further comprising:

a plurality of internal electrodes operatively associated with said controller;

and wherein said first treatment waveform is administered by internal electrodes and has an energy of from about 0.1 to 50 Joules.

196. A system according to claim 181, wherein said controller is configured so that said first treatment waveform and said second treatment waveform are sequential.

197. A system according to claim 181, wherein said controller is configured so that said second treatment waveform immediately follows said first treatment waveform.

198. A system according to claim 181, wherein said controller is configured so that said second treatment waveform follows said first treatment waveform by from 1 millisecond to 10 seconds.

199. A system according to claim 181, wherein said controller is configured so that said first treatment waveform and said second treatment waveform are at least partially interleaved.

200. A system according to claim 181, wherein said controller is configured so that said first treatment waveform is delivered through the same set of electrodes as said second treatment waveform.

201. A system according to claim 181, wherein said controller is configured so that said first treatment waveform is delivered through a different set of electrodes as said second treatment waveform.

202. A system according to claim 181, further comprising at least one cutaneous electrode operatively associated with said controller, and wherein said controller is configured so that said first treatment waveform is delivered by said at least one cutaneous electrode.

203. A system according to claim 181, further comprising at least one subcutaneous electrode operatively associated with said controller, and wherein said first treatment waveform is delivered by said at least one subcutaneous electrode.

204. A system according to claim 181, further comprising at least one epicardial electrode operatively associated with said controller, and wherein said first treatment waveform is delivered by at least one epicardial electrode.

205. A system according to claim 181, further comprising at least one transveneous electrode operatively associated with said controller, and wherein said first treatment waveform is delivered by said at least one transveneous electrode.

206. A system according to claim 181, further comprising at least one transveneous coronary sinus electrode operatively associated with said controller, and wherein said first treatment waveform is delivered by said at least one transveneous coronary sinus electrode.