Quinidine Syncope; Report of a Case Successfully Treated with Lidocaine

¹ Heart Institute, The Chaim Sheba Medical Center, Tel Hashomer; and Tel-Aviv University Medical School, Israel

The case of a young woman suffering from numerous episodes of syncope due to quinidine induced ventricular tachycardia and fibrillation is reported. These were abolished by intravenous administration of a bolus of 25 to 50 mg lidocaine infusion. The paradox of one antiarrhythmic drug suppressing the toxic effects of another in this case may be explained by quantitative rather than qualitative differences between the various electrophysiologic effects of quinidine and lidocaine. Thus, prolongation of refractoriness may be more pronounced with quinidine while lidocaine may be more effective on raising the excitability threshold and in this way suppress the ventricular arrhythmias induced by quinidine. The prompt and harmless effect of lidocaine observed in this case justifies its further trial in instances of quinidine induced syncope.