[Torsades de Pointes: a cause of syncope in sinus node dysfunction]

Torsade de Pointes (TdP) is an atypical ventricular tachycardia that occurs in the setting of QT interval prolongation which may be an inherited or acquired abnormality. TdP is a recognized complication of bradyarrhythmias, specifically atrioventricular block. However, sinus node dysfunction is a rare cause of syncope associated with TdP. Experimental studies have suggested that the acquired long QTU interval and TdP may be due to bradycardia or pause-dependent early after depolarizations that give rise to triggered activity. This report describes a patient with sinus bradycardia and intermittent AV nodal rhythm induced long QT interval and repetitive syncope related to TdP and successfully treated with temporal and long-term pacing.