Ventricular fibrillation in a conscious canine preparation of sudden coronary death and prevention by short- and long-term amiodarone administration

Abstract

The antifibrillatory properties of short-term intravenous (10 mg/kg/hr) and long-term (10 mg/kg/day for 24 days) oral amiodarone administration were examined in a conscious canine preparation of sudden coronary death. In this preparation, ventricular fibrillation was produced by electrically induced left circumflex injury and thrombosis in the presence of previous anterior myocardial infarction. On day 4 after anterior myocardial infarction animals were assigned to receive short-term intravenous or long-term oral amiodarone treatment. Animals within each group were randomly assigned to control or drug treatment. Neither short-term intravenous nor long-term oral amiodarone treatment prevented the development of ST segment changes or premature ventricular beats, but both short-term intravenous amiodarone and long-term oral amiodarone administration significantly reduced the incidence of ventricular fibrillation (short-term intravenous amiodarone [n = 10], incidence of 60% vs control [n = 10] incidence of 100%, p < .05; long-term oral amiodarone [n = 10], incidence of 20% vs control [n = 11] incidence of 91%, p < .002). Both short-term intravenous and long-term oral amiodarone administration produced increases in the PR and rate-corrected QT intervals. However, prolongation of the corrected QT interval in the group receiving long-term oral amiodarone (61 ± 18 msec) was greater than in the group receiving short-term intravenous drug (31 ± 11 msec, p