Bretylium tosylate has been shown effective in the treatment of
ventricular fibrillation and in the prevention of its recurrence. However,
lidocaine is generally preferred because
bretylium could have adverse hemodynamic effects related to its antiadrenergic action. To explore further the differences between these two antiarrhythmic agents, the authors compared the effects of
bretylium,
lidocaine, and saline on a standardized dog model of
ventricular fibrillation followed by electromechanical dissociation (EMD). The protocol included three successive episodes of
cardiac arrest in each animal. Three minutes before each episode of
ventricular fibrillation, 5 mg/kg of
bretylium tosylate (n = 11), 1 mg/kg of
lidocaine (n = 9) or saline (n = 12) were administered blindly. There was no difference in the duration of
cardiac arrest (
bretylium, 8 min 18 sec;
lidocaine, 7 min 54 sec; saline, 8 min 20 sec) or the total doses of
epinephrine required to resuscitate the animals. Both
bretylium and
lidocaine appeared to preserve cardiac function 5 minutes after recovery, as stroke volume increased from 17.8 +/- 6.7 to 18.7 +/- 6.7 mL (NS) after
bretylium and from 17.7 +/- 7.7 to 19.0 +/- 7.0 mL (NS) after
lidocaine, but decreased from 19.0 +/- 5.3 to 14.6 +/- 6.0 mL (P less than .05) after saline. During the first 10 minutes of EMD,
ventricular fibrillation or
ventricular tachycardia recurred in 4 dogs treated with
lidocaine, 3 dogs treated with saline, but no dog treated with
bretylium (P less than .05 between
bretylium and saline).(ABSTRACT TRUNCATED AT 250 WORDS)