EFFECTS OF AMIODARONE ON REFRACTORY VENTRICULAR-FIBRILLATION IN ACUTEMYOCARDIAL-INFARCTION - EXPERIMENTAL-STUDY

Objectives. The aim of this study was to evaluate the efficacy of a si ngle dose of intravenous amiodarone in facilitating defibrillation of ventricular fibrillation refractory to lidocaine and epinephrine plus direct current countershocks in experimental acute myocardial infarcti on. Background. Amiodarone has been hailed as the most effective singl e antiarrhythmic drug for the treatment of ventricular arrhythmias. Ho wever, intravenous amiodarone has only sporadically been used in the d efibrillation of ventricular fibrillation in acute myocardial infarcti on. Methods. Acute myocardial infarction was induced in 60 dogs by lig ation of the proximal left anterior descending coronary artery for 2 h . Animals that developed spontaneous ventricular fibrillation were tre ated with lidocaine and epinephrine plus five direct-current countersh ocks. Dogs with ventricular fibrillation refractory to this regimen we re randomized to further treatment with additional intravenous adminis tration of epinephrine and bolus lidocaine plus less-than-or-equal-to 15 direct-current countershocks (group 1) or administration of amiodar one, 10 mg/kg body weight intravenously, followed by defibrillation wi th direct-current countershock (group II). Results. Sixteen (27%) of t he 60 dogs in which the protocol was attempted developed spontaneous v entricular fibrillation 21 min after ligation and were included in the study. Lidocaine and epinephrine plus five direct-current countershoc ks succeeded in converting ventricular fibrillation in one dog (6%). T he other 15 dogs were randomized to group I (8 dogs) or group II (7 do gs). Defibrillation was achieved in one of the eight dogs in group I a nd in six of the seven dogs in group II (p < 0.005). Conclusions. In a n experimental model of acute ischemia, intravenous amiodarone (10 mg/ kg) influences positively the response to defibrillation of ventricula r fibrillation refractory to lidocaine and epinephrine plus direct cur rent countershocks.