Ascending Defibrillation Waveform Significantly Reduces Myocardial Morphological Damage and Injury Current.

Abstract

OBJECTIVES: This study tested the hypothesis that a biphasic defibrillation waveform with an ascending first phase (ASC) causes less myocardial damage by pathology and injury current than a standard biphasic truncated exponential (BTE) waveform in a swine model. BACKGROUND: Although lifesaving, defibrillation shocks have significant iatrogenic effects that reduce their benefit for patient survival. METHODS: An ASC waveform with an 8-ms linear ramp followed by an additional positive 0.5-ms decaying portion with&#xa0;amplitudes of 20&#xa0;J (ASC 20J) and 25&#xa0;J (ASC 25J) was used. The control was a 25-J BTE conventional waveform (BTE&#xa0;25J) RESULTS: The ASC 20J and ASC 25J shocks were both successful in 6 of 6 pigs, but the BTE 25J was successful in only 6&#xa0;of 14 pigs (p&#xa0;<&#xa0;0.05). Post-shock ST-segment elevation (injury current) in the right ventricular electrode was significantly greater with BTE 25J than with ASC 20J and ASC 25J. With a blinded pathology reading, hemorrhage, inflammation, thrombi, and necrosis 24&#xa0;h post-shock were significantly greater with BTE 25J than with ASC 20J and ASC 25J. Troponin levels were also markedly lower at 3, 4, 5, and 6&#xa0;h post-shock. CONCLUSIONS: Defibrillation shocks cause electrophysiological, histological, and biochemical signs of myocardial damage and necrosis. These signs of damage are markedly less for an ASC waveform than for a conventional BTE&#xa0;waveform.