Antiarrhythmic effects of bisaramil on triggered arrhythmias produced by intracoronary injection of digitalis and adrenaline in the dog.

Antiarrhythmic effects of bisaramil were examined by using new in vivo triggered arrhythmia models, and they were compared with those of other antiarrhythmic drugs. Bisaramil (3-10 micrograms, i.c.) suppressed triggered ventricular arrhythmias that were produced during pauses between trains of rapid ventricular stimulation (cycle length: 250 msec, train number: 15) in anesthetized open-chest dog hearts administered with subtoxic doses of digitalis or adrenaline to the anterior descending coronary artery. The potencies of bisaramil, disopyramide, lidocaine and flecainide suppressing digitalis-induced triggered ventricular arrhythmias were similar to those suppressing adrenaline-induced ones. The potency of verapamil for suppressing digitalis-induced triggered ventricular arrhythmias were weaker than that for suppressing the adrenaline-induced ones. Bisaramil was the most effective among the antiarrhythmic drugs used in the present experiment. Since bisaramil has been reported to be effective in suppressing other canine automatic ventricular arrhythmias, and the triggered ventricular arrhythmias occur in clinical situations, bisaramil may become a useful drug for the treatment of clinical arrhythmias.