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May 24, 1976

Low-Energy Ventricular Defibrillation and Miniature Defibrillators

Author Affiliations

University of Virginia Medical Center 158 Charlottesville

JAMA. 1976;235(21):2284. doi:10.1001/jama.1976.03260470012006

To the Editor.—  When discussing transthoracic ventricular defibrillation, Loeb (232:845, 1975; 235:144, 1976) and Tacker et al (235:144, 1976) overlooked both direct-current (DC) countershock using low-level electrical energy and miniature defibrillators. More than 35 years ago, Wiggers1 showed that serial low-energy shocks expedite ventricular defibrillation. Recent experiments, corroborating and extending these earlier observations, indicate that only a limited critical mass of ventricle need be defibrillated for restoration of intrinsic cardiac pacemaker function.2 In humans, prospective investigation of transthoracic defibrillation showed that the stored 200 watt-second (W-sec) DC shock provided an average 3.1 (1.8-4.0) W-sec/kg. This 200 W-sec shock eliminated primary ventricular fibrillation on the first shock in 73 and on the second shock in 7 of 80 cardiac patients. Two others needed higher energy levels for defibrillation.3 Our early experience confirms this report (Table). Thus, 86 episodes of prospectively assessed human ventricular fibrillation responded to an average