Recurrent Ventricular Fibrillation Precipitated by Quinidine

Quinidine was introduced a half century ago in the treatment of certain cardiac arrhythmias,¹and it has been recognized that, in addition to its beneficial effects, it also carries some risk to the patient. Idiosyncrasy to small amounts of the drug or overdosage both lead to serious complications. Almost from the beginning of its use, there were observations made of syncopal episodes and sudden death in the course of treatment.²,³These were generally attributed to other mechanisms, most frequently to cerebral embolism, rather than to the direct action of quinidine.⁴More recently, modern monitoring documented that quinidine can sensitize the myocardium by lowering its fibrillation threshold and cause ventricular fibrillation with syncope and sudden death.⁴⁻⁸Selzer and Wray⁶described the characteristic features of this phenomenon and called it "quinidine syncope." Although the possible danger of simultaneous administration of large doses of digitalis and quinidine