Atrioventricular dissociation during paroxysmal junctional tachycardia.

We describe the rare occurrence of atrioventricular dissociation in three patients during paroxysmal junctional tachycardia. The mechanism of tachycardia was atrioventricular nodal reentry in to patients. The third patient had reentrant tachycardia that utilized the AV node for at least part of the reentrant circuit. This patient also had a nodoventricular pathway that may have participated in the reentrant circuit. In two patients, ventricular tachycardia was diagnosed prior to electrophysiologic assessment and medication to prevent tachycardia was not successful. After electrophysiological studies, treatment directed at suppressing AV nodal reentry prevented recurrent tachycardia. These case studies demonstrate the importance of detailed electrophysiological assessment of tachycardia in patients whose arrhythmia does not respond to empirical antiarrhythmic therapy.