[The effects of benzodiazepine drugs and antihistamines in experimental postinfarct arrhythmias].

Death as consequence of myocardial infarct is most frequently produced by ventricular arrhythmias. The purpose was to study if some antihistamines and benzodiazepines could reduce the incidence of these arrhythmias in the experimental myocardial infarct of the dog. The anterior descending left coronary artery was dissected and tied it twofold. Ten dogs received 150 ml of isotonic saline solution (i.v.) one hour before the occlusion, this was the control group. We integrated five more experimental groups, each one received, before the ligation, one of the following drugs (i.v.): lidocaine (2 mg/kg, n = 16), clonazepam (20 mcg/kg, n = 16), flunitrazepam (30 mcg/kg, n = 25), terfenadine (2 mg/kg, n = 11) and astemizol (1 mg/kg, n = 16). Control recordings of cardiac frequency, blood pressure and ECG were made 10 minutes before occlusion and every 5 minutes for 90 minutes after the occlusion was performed. Prevention of the presentation of ventricular fibrillation for each group was: Control 20%, lidocaine 81.24%, clonazepam 50%, flunitrazepam 76%, terfenadine 54.6%, and astemizol 75%. From this results we concluded that lidocaine, flunitrazepam and astemizol have the largest activity to prevent ventricular arrhythmias in the experimental myocardial infarct of dogs.