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February 7, 1966

Varying Waveforms May Influence Defibrillation

JAMA. 1966;195(6):49. doi:10.1001/jama.1966.03100060023011

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The type of electrical countershock (ie, the waveform) used in closed chest ventricular defibrillation is a factor influencing the success or failure of the procedure.

A waveform, for example, with a long, low amplitude tail—that is, a shock which tapers off after reaching its peak value rather than dropping rapidly to zero—may actually refibrillate the heart after the leading edge of the shock has defibrillated it.

This and other observations on the influence of varying waveforms on electrical defibrillation were reported to the 18th annual Conference on Engineering in Medicine and Biology, Philadelphia, by a group of investigators from the University of Missouri School of Medicine, Columbia.

John C. Schuder, PhD, Harry Stoeckle, MD, and Glenn A. Rahmoeller, studied the relative effectiveness of triangular and trapezoidal waveforms in defibrillating closed chest anesthetized dogs allowed to remain in experimentally induced ventricular fibrillation for 30 seconds prior to application of electrical countershock.

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