ANTIARRHYTHMIC EFFECTS OF BISARAMIL ON TRIGGERED ARRHYTHMIAS PRODUCEDBY 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 oth er antiarrhythmic drugs. Bisaramil (3-10 mu g, i.c.) suppressed trigge red ventricular arrhythmias that were produced during pauses between t rains of rapid ventricular stimulation (cycle length: 250 msec, train number: 15) in anesthetized open-chest dog hearts administered with su btoxic doses of digitalis or adrenaline to the anterior descending cor onary artery. The potencies of bisaramil, disopyramide, lidocaine and flecainide suppressing digitalis-induced triggered ventricular arrhyth mias were similar to those suppressing adrenaline-induced ones. The po tency of verapamil for suppressing digitalis-induced triggered ventric ular arrhythmias were weaker than that for suppressing the adrenaline- induced ones. Bisaramil was the most effective among the antiarrhythmi c drugs used in the present experiment. Since bisaramil has been repor ted to be effective in suppressing other canine automatic ventricular arrhythmias, and the triggered ventricular arrhythmias occur in clinic al situations, bisaramil may become a useful drug for the treatment of clinical arrhythmias.