Pacemaker therapy for the treatment of the long QT syndrome associated with long-lasting bradycardia and ventricular tachycardia. Electrophysiological characteristic and therapy.

The electrophysiological characteristics of the long QT syndrome (LQTS) associated with permanent bradycardia and ventricular tachycardiac attacks were electrophysiologically studied in 12 patients. Tachycardia could be induced by ventricular electrical stimulation in 11 cases. The following electrophysiological properties could be revealed: 1) a very short ventricular refractory period (VERP) compared with QT length; 2) inhomogeneity in VERP and QT interval in different areas of the ventricles; 3) repetitive ventricular responses on early ventricular electrical stimuli. Patients were successfully treated by pacemaker implantation and beta-blockers. In two patients a comparatively high pacing rate was required to reduce the QT interval.