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High Voltage Shock Induced Cellular Electrophysiological Effects: Transient Refractoriness and Bimodal Changes in Action Potential Duration
Author(s) -
LI HUAGUI G.,
JONES DOUGLAS L.,
YEE RAYMOND,
KLEIN GEORGE J.
Publication year - 1995
Publication title -
pacing and clinical electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.686
H-Index - 101
eISSN - 1540-8159
pISSN - 0147-8389
DOI - 10.1111/j.1540-8159.1995.tb06962.x
Subject(s) - refractory period , medicine , electrophysiology , shock (circulatory) , ventricular fibrillation , effective refractory period , defibrillation , stimulation , cardiology , refractory (planetary science) , fibrillation , membrane potential , biophysics , atrial fibrillation , materials science , biology , composite material
LI, H.G., et al .: High Voltage Shock Induced Cellular Electrophysiological Effects: Transient Refractoriness and Bimodal Changes in Action Potential Duration . The cellular electrophysiological effects of defibrillation shocks on the myocardium during ventricular fibrillation are not clear. The present study investigated the effects of high voltage shocks on membrane potentials of isolated guinea pig and pig papillary muscles during rapid activations simulating ventricular fibrillation. High voltage shocks induced an action potential with a prolonged duration, followed by a transient refractory state. Subsequent action potentials following this refractory state had shortened durations. The duration of the transient refractory state varied in proportion to shock intensity and stimulation rate, whether the shock was biphasic or monophasic. Shock induced prolonged depolarization was not a consistent finding and mainly observed with slow stimulation rates. In conclusion, high voltage shocks induce bimodal changes of the action potential duration associated with a transient refractory state during rapid activation. The rate dependency of this refractory state suggests that the duration of the shock induced refractory state may be longer in the fibrillating than the normal beating heart, and may contribute to successful defibrillation.