Bradycardia-associated torsade de pointes and the long-QT syndromes: a case report and review of the literature.

We report a case of bradycardia-associated torsade de pointes in which the underlying long-QT syndrome appeared to be attributable to primary cardiac conducting system disease. Our patient presented complaining of presyncope and syncope. Serial electrocardiograms obtained over a period of 10 years demonstrated slowly progressive conduction system abnormalities, and evaluation revealed no other cause. The patient's dysrhythmia was refractory to magnesium but abated with cardiac pacing at a moderate rate. A review of the relevant literature on congenital and acquired long-QT syndrome is included.