Biphasic waveform external defibrillation thresholds for spontaneous ventricular fibrillation secondary to acute ischemia
Gregory P. Walcott, MD*,*,
Cheryl R. Killingsworth, MD, PhD*,
William M. Smith, PhD and
Raymond E. Ideker, MD, PhD, FACC*
* Cardiac Rhythm Management Laboratory, Division of Cardiovascular Diseases, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
Cardiac Rhythm Management Laboratory, Division of Cardiovascular Diseases, Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, Alabama, USA
Cardiac Rhythm Management Laboratory, Division of Cardiovascular Diseases, Department of Physiology, University of Alabama at Birmingham, Birmingham, Alabama, USA
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Figure 1 Percent success for external defibrillation of spontaneous ventricular fibrillation (VF) with shocks from 1.5x to >2.5x the defibrillation threshold (DFT) for electrical VF (protocol 3). The x-axis indicates the energy required to defibrillate spontaneous VF as a multiple of the DFT for 60-Hz VF.
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Figure 2 Histogram of the number of arrhythmic episodes that were successfully defibrillated as a function of energy level. Arrhythmic episodes are taken from protocols 2 and 3. It appears that there are two populations of arrhythmias, one that is defibrillated at a relatively low energy level and one that is defibrillated at a much higher energy level. Open bar = reperfusion; solid bar = occlusion. ND = the ventricular fibrillation could not be defibrillated and the animal died.
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