Effects of amiodarone on cardiac electrophysiology in right ventricular rapid pacing-induced heart failure dogs

AIM: 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 po Ami 300 mg.d(-1) for 4 - 5 wk. The electrophysiologic parameters and VET were evaluated by electric stimulation and monophasic action potential (MAP) recording. RESULTS: In CHF models, ventricular MAP duration (MAPD(90)), ventricular late repolarization duration (VLRD), and intraventricular conduction time (IVCT) were prolonged by 43 %, 318 %, and 19 %, respectively; the ratio of ventricular effective refractory period (VERP) to MAPD(90) (VERP/MAPD(90)) 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 MAPD(90), but increased VERP/MAPD(90), 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. CONCLUSION: Ami normalizes the cardiac electrophysiologic properties in CHF dogs.