Effects of verapamil on electrophysiological properties of anomalous atrioventricular connexion in Wolff-Parkinson-White syndrome.

Abstract

Using intracardiac recordings of electrical activity and programmed electrical stimulation of the heart, the effect of verapamil has been studied on the conduction times and refractory periods of the anomalous bypass in 8 patients with the Wolff-Parkinson-White syndrome. A minimal effect was found on both antegrade and retrograde conduction times. The refractory period of the anomalous bypass when measured antegradely was shortened in 3 patients, unchanged in i, and lengthened in 4. There was a minimal effect on the refractory period when measured for retrograde conduction. A reciprocal supraventricular tachycardia was initiated in 6 patients and in all 6 this tachycardia was terminated after administration of intravenous verapamil. The significance of thesefindings is discussed with especial reference to the prevention and treatment of dysrhythmias complicating Wolff-Parkinson-White syndrome.