Effects of lidocaine and quinidine on post-repolarization refractoriness after the basic and premature action potentials: consideration of aim of antiarrhythmic drug therapy.

American Heart Journal
Y NakayaH Mori

Abstract

Antiarrhythmic drugs are often more effective in suppressing ventricular tachycardias than are background premature extrasystoles. The mechanism of action of these agents was examined by studies on the effects of lidocaine and quinidine on post-repolarization refractoriness of both basic and premature action potentials. In the absence of antiarrhythmic drugs, the excitability threshold was relatively constant after the end of repolarization of both basic and premature action potentials. In the presence of lidocaine or quinidine, the strength-interval curves were shifted to the right and superiorly, and the two drugs had different effects on the course of the strength-interval curve and Vmax recovery, presumably due to use-dependent V max block. Moreover, depressions of Vmax and excitability were more marked after the premature action potential than after the basic action potential. These results suggest that lidocaine and quinidine cause more depression of the excitability of second premature contractions than of first premature contractions, and also indicate that for protection against sustained ventricular tachycardias, it may not be necessary to suppress chronic premature ventricular contractions.

Citations

Oct 30, 1998·Pacing and Clinical Electrophysiology : PACE·Y MurakawaM Omata
Apr 18, 2007·Pflügers Archiv : European journal of physiology·Ian N SabirChristopher L-H Huang
Dec 28, 2010·American Journal of Physiology. Heart and Circulatory Physiology·Oleg E OsadchiiSoren Peter Olesen
Feb 14, 2007·Pflügers Archiv : European journal of physiology·Ian N SabirChristopher L-H Huang

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