“…Furthermore, the changed electrocardiographic pattern-namely, block, idioventricular rhythm and standstill-is very reminiscent of the action of quinidine on isolated dog hearts and intact dogs. In a previous paper (Fawaz, 1955) it was shown that doses of quinidine ranging between 30 and 140 mg, and which were sufficient to depress the myocardium as judged by a decreased output and increased right atrial pressure, did not influence the lethal dose of ouabain in the dog heart-lung preparation but that in all cases the terminal arrhythmia was indeed ventricular fibrillation. Benfey & Varma (1966) working on the isolated guinea-pig atrium reported that pronethalol and propranolol possess an anti-fibrillatory property equal to that of quinidine and that it is not directly related to their /3-blocking action.…”