Intravenous verapamil had minimal effects on conduction times and refractory periods of the anomalous bypass, but terminated reciprocal supraventricular tachycardia in all 6 patients tested.
Does intravenous verapamil alter electrophysiological properties of the anomalous bypass and terminate supraventricular tachycardia in patients with Wolff-Parkinson-White syndrome?
Intravenous verapamil effectively terminates reciprocal supraventricular tachycardia in WPW syndrome despite having minimal or variable effects on the electrophysiological properties of the anomalous bypass itself.
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.
Spurrell et al. (Fri,) conducted a other in Wolff-Parkinson-White syndrome (n=8). Verapamil was evaluated on Conduction times and refractory periods of the anomalous bypass. Intravenous verapamil had minimal effects on conduction times and refractory periods of the anomalous bypass, but terminated reciprocal supraventricular tachycardia in all 6 patients tested.