Effects of amiodarone on cardiac electrophysiology in right ventricular rapid pacing-induced heart failure dogs
Abstract
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 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. CONCLUSION: Ami normalizes the cardiac electrophysiologic properties in CHF dogs.
Keywords:
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. CONCLUSION: Ami normalizes the cardiac electrophysiologic properties in CHF dogs.