Effects of amiodarone on cardiac electrophysiology in right ventricular rapid pacing-induced heart failure dogs.
OBJECTIVE
To study the effects of amiodarone (Ami) on cardiac electrophysiologic properties and ventricular fibrillation threshold (VFT) in right ventricular rapid pacing-induced congestive heart failure (CHF) dogs.


METHODS
Dogs (n = 25) were randomly allocated into 3 groups: A) control group; B) CHF group induced by right ventricular rapid pacing (4 pulses.s-1) for 4-5 wk; C) CHF models p Ami 300 mg.d-1 for 4-5 wk. The electrophysiologic parameters and VFT were evaluated by electric stimulation and monophasic action potential (MAP) recording.


RESULTS
In CHF models, ventricular MAP duration (MAPD90), ventricular late repolarization duration (VLRD), and intra-ventricular conduction time (IVCT) were prolonged by 43%, 318%, and 19%, respectively; the ratio of ventricular effective refractory period (VERP) to MAPD90 (VERP/ MAPD90) and VFT were decreased by 13% and 48% respectively; the dispersion of ventricular recovery time (RT-D) was increased by 185%. In CHF models, Ami had no effects on ventricular MAPD90, but increased VERP/ MAPD90, IVCT, and VFT by 15%, 10%, and 67%, respectively, shortened VLRD by 87%; and decreased RT-D by 87%. Ami had no significant influences on the hemodynamic parameters of the CHF dogs.


CONCLUSIONS
Ami normalizes the cardiac electrophysiologic properties in CHF dogs.
Zhou
S X
SX
Department of Internal Medicine, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University of Medical Sciences, Guangzhou, China. junxig@gzsums.edu.cn
Zhang
X M
XM
Wu
W
W
Chen
X C
XC
D000200:Action Potentials / Q000187:drug effects; D000638:Amiodarone / Q000494:pharmacology*; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology*; D004285:Dogs; D004594:Electrophysiology; D005260:Female; D006333:Heart Failure / Q000503:physiopathology*; D008297:Male; D011897:Random Allocation; D012032:Refractory Period, Electrophysiological / Q000187:drug effects; D014693:Ventricular Fibrillation / Q000517:prevention & control; D016278:Ventricular Function, Right / Q000187:drug effects*
D000889:Anti-Arrhythmia Agents; D000638:Amiodarone