[Clinical and electrophysiological observations in a case of Romano-Ward syndrome ].

Syncope associated with atypical ventricular tachycardia of the "torsades de pointes" type was observed in a 16 year-old girl with hereditary QT prolongation. The arrhythmia occurred only during maximal prolongation of the QTc to 0.77 sec, which had possibly been aggravated by exercise and hypokalaemia. Electrophysiological studies were performed when the QTc was 0.59 sec. Incremental as well as premature ventricular pacing with single or double premature ventricular beats did not initiate ventricular arrhythmias, but revealed AV nodal and bundle branch reentry. It is postulated that these types of macroreentry are involved in the twisting of the QRS complexes in the surface ECG in torsades de pointes.