A transient, dose-dependent cardiac depression was produced by defibrillator shocks in an isolated, working canine heart preparation perfused with oxygenated arterial blood from a support dog. Accompanying this depression was an efflux of potassium (K+ ), forced out of the myocardial cells by the passage of defibrillating current. The transient increase in extracellular K + concentration was recorded graphically in the venous outflow. It was found that 5-msec rectangular wave shocks, from three to ten times defibrillatory current threshold, released doserelated pulses of K+ . We conclude that because extracellular K + is a myocardial depressant, at least part of the myocardial depression after defibrillation is caused by the release of K+ from the myocardial cells.


This is the author accepted manuscript of Niebauer M.J., Geddes L.A., Babbs C.F., Potassium efflux from myocardial cells induced by defibrillator shock, Medical Instrumentation 20, 135-137, 1986. Copyright Elsevier, it is made available here CC-BY-NC-ND, and the version of record is available through the publisher http://www.sciencedirect.com/.


defibrillation, myocardial damage, toxicity, ventricular fibrillation, waveform

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