Analysis of the defibrillation efficacy for 5-ms waveforms

TitleAnalysis of the defibrillation efficacy for 5-ms waveforms
Publication TypeJournal Article
Year of Publication2004
AuthorsGuan D, Malkin R
JournalJournal of Cardiovascular Electrophysiology
Start Page447
Pagination447 - 454
Date Published01/2004

Introduction: Empirical studies have shown that biphasic defibrillation waveforms are more efficacious than monophasic waveforms. However, a more systematic approach to waveform development might be more productive. This study tested 147 multiphasic waveforms uniformly sampled from all possible 5-ms waveforms. Methods and Results: One hundred ninety-eight guinea pigs (850-1,050 g) received 30 episodes of ventricular fibrillation followed by transthoracic defibrillation. The first 10 shocks were used to determine the ED50 for a biphasic control. Then, 20 waveforms including 2 controls were tested once at the ED50. Of the 147 waveforms tested here, 21 waveforms showed equivalent or greater efficacies than the biphasic control, with one being statistically more efficacious (P < 0.05). Two fundamental assumptions were addressed: (1) similarly efficacious waveforms are analytically similar, and (2) a single optimal waveform can be described. The mean percentage of similarly efficacious waveforms with similar shapes was greater than zero in the most efficacious 21 waveforms (P = 0.023), but less efficacious waveforms showed randomly distributed shapes. Cluster analysis revealed that the best waveforms share a major phase containing most of the defibrillation energy. The optimal waveform shape extrapolated from the sample waveforms was a 2.5/1-ms biphasic-type waveform (highest correlation r = 0.701, P < 0.001). Conclusion: This work supports the assumption that efficacious waveforms are similarly shaped and the notion that one single optimum exists.

Short TitleJournal of Cardiovascular Electrophysiology