奎尼丁和胺碘酮对犬心室电生理效应的影响差异探讨

A study on discrepancy of ventricular electrophysiologic effects between quinidine and amiodarone in canine models

应用心脏电刺激技术和单相动作电位记录技术，从心室复极化时程、时相及复极化离散性和心室肌电稳定性的角度，研究口服奎尼丁和胺碘酮４周后对心室电生理效应的影响及其差异。结果表明，奎尼丁和胺碘酮有相似的心室电生理效应，包括延长心室有效不应期和心室复极化时程。但是奎尼丁对延长复极化后期的作用尤为突出，且使复极化离散性增加，对心室纤颤阈值无显著影响；而胺碘酮均一同步地延长复极化时程，不影响复极化离散性，且使心室纤颤阈值上升，提高心室肌电稳定性。

Abstract Department of Internal Medicine,3rd Hospital Affiliated to Sun Yat-sen University of Medical c,Sciences Department of Cardiology,Sun Yat-sen Memorial Hospital,Sun Yat-sen University of Medical Sciences The ventricular electrophysiologic effects of chronically orally administered quinidine and amiodaronewere studied in canine models with the techniques of electric stimulation and monophasic action potential(MAP)recording, Twenty-two adult mongrel dogs were randomizedly allocated into 3 groups :Group 1(n=8)served as normal controls. Group 2(n= 7)were given quinidine orally 400mg a day for 4 weeks. Group 3(n=7)were given amiodarone orally 400mg a day for 4 weeks. The results showed that in anes-thetized,open-chest dogs :(1)The general ventricular electrophysiologic effects of quinidine were similarto those of amiodarone; both increased ventricular effective refractory period(VERP. Quinidine :192±30to 135±12, P<0.01 ; Amiodarone: 205±26 to 135±12, P<0. 01)and ventricular repolarization(QT in-terval.Quinidine:332±35 to 210± 19,P<0.01;Amiodarone:341±17 to 210±19, P<0. 01);(2)Quini-dine lengthened ventricular repolarization unsynchronously and inhomogeneously and the lengthening is ob-served mainly in phase 3 of action potential;whereas, amiodarone lengthened ventricular repolarizationsynchronously and homogeneously;(3)Amiodaronie increased ventricular electric stability characterized byan elevation of ventricular fibrillation threshold (VFT,38±6 to 25±6, P<0.01),while quinidine had nosignificant effect on VFT(26±8 to 25±6,P>0.05).This study might explain why clinically quinidine andamiodarone lengthened QT interval to a simillar extent, but amiodarone had a higher cardiac safety thanquinidine.