[Ventricular fibrillation under quinidine medication--quinidine syncope (author's transl)].

Ventricular fibrillation which may occur unexpected under quinidine medication--called quinidine syncope--is one of the most dangerous complications of quinidine application. These life threatening accidents occur in 0,5-4,4% treated cases. The quinidine syncope occurs mostly at the attempt to eliminate atrial fibrillation or flutter. This dangerous side effect is dose independent. The ECG shows an increased QT duration and large U-waves. It seems to be a reentry-tachycardia caused by unequal recovery times in different parts of the ventricular myocardium.