Effects of amiodarone on refractory ventricular fibrillation in acute myocardial infarction: experimental study.
OBJECTIVE
The aim of this study was to evaluate the efficacy of a single dose of intravenous amiodarone in facilitating defibrillation of ventricular fibrillation refractory to lidocaine and epinephrine plus direct current countershocks in experimental acute myocardial infarction.


BACKGROUND
Amiodarone has been hailed as the most effective single antiarrhythmic drug for the treatment of ventricular arrhythmias. However, intravenous amiodarone has only sporadically been used in the defibrillation of ventricular fibrillation in acute myocardial infarction.


METHODS
Acute myocardial infarction was induced in 60 dogs by ligation of the proximal left anterior descending coronary artery for 2 h. Animals that developed spontaneous ventricular fibrillation were treated with lidocaine and epinephrine plus five direct-current countershocks. Dogs with ventricular fibrillation refractory to this regimen were randomized to further treatment with additional intravenous administration of epinephrine and bolus lidocaine plus < or = 15 direct-current countershocks (group I) or administration of amiodarone, 10 mg/kg body weight intravenously, followed by defibrillation with direct-current counter-shock (group II).


RESULTS
Sixteen (27%) of the 60 dogs in which the protocol was attempted developed spontaneous ventricular fibrillation 21 min after ligation and were included in the study. Lidocaine and epinephrine plus five direct-current countershocks succeeded in converting ventricular fibrillation in one dog (6%). The other 15 dogs were randomized to group I (8 dogs) or group II (7 dogs). Defibrillation was achieved in one of the eight dogs in group I and in six of the seven dogs in group II (p < 0.005).


CONCLUSIONS
In an experimental model of acute ischemia, intravenous amiodarone (10 mg/kg) influences positively the response to defibrillation of ventricular fibrillation refractory to lidocaine and epinephrine plus direct current countershocks.
Anastasiou-Nana
M I
MI
Department of Clinical Therapeutics, University of Athens School of Medicine, Alexandra Hospital, Greece.
Nanas
J N
JN
Nanas
S N
SN
Rapti
A
A
Poyadjis
A
A
Stathaki
S
S
Moulopoulos
S D
SD
D000638:Amiodarone / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D000818:Animals; D004195:Disease Models, Animal; D004285:Dogs; D004558:Electric Stimulation; D004837:Epinephrine; D005260:Female; D006329:Heart Conduction System / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics; D007275:Injections, Intravenous; D008012:Lidocaine; D008297:Male; D009203:Myocardial Infarction / Q000188:drug therapy / Q000503:physiopathology*; D014693:Ventricular Fibrillation / Q000188:drug therapy*
D008012:Lidocaine; D000638:Amiodarone; D004837:Epinephrine