Termination of paroxysmal junctional tachycardia by right ventricular stimulation.

This report documents the use of right ventricular stimulation in the termination of a rapid junctional tachycardia. The tachyeardia developed in the background setting of heart block and bradycardia. Right ventricular stimulation was effective at 94/min, a rate considerably slower than that of the tachycardia. Analysis of pacemaker stimuli during the tachycardia defined ventricular refractory and excitable periods. Within the ventricular excitable period there was a critical time interval during which stimulation produced premature ventricular depolarization and abrupt termination of the tachycardia. These findings support the hypothesis that junctional tachyeardias in the absence of the Wolf-Parkinson-White syndrome may be sustained by reentry mechanisms. Moreover, right ventricular stimulation may be a valuable therapeutic adjunct in the treatment of such tachyeardias.