Effects of bretylium tosylate on the in vivo fibrillating canine ventricle.

Chemical ventricular defibrillation of the heart by intravenous or intracardiac administration of bretylium tosylate (6 to 24 mg/kg of body weight) did not occur in any dog (n = 30) given the drug 5 minutes before, immediately after, or 75 seconds after electrical induction of ventricular fibrillation. The bretylium did not appear to stabilize ventricular irritability nor facilitate resuscitation by electrical defribrillation when compared with the control group of dogs. Significant dose-dependent chronotropic or systemic pressure effects were not seen following bretylium administration.