Atrioventricular dissociation due to pheochromocytoma in a young adult.

Atrioventricular dissociation can be a manifestation of an underlying noncardiac disease.We present a patient who underwent pacemaker implantation because of intermittent atrioventricular dissociation and medically untreatable supraventricular arrhythmias, which could not be induced by electrophysiological testing. The arrhythmias proved to be due to a pheochromocytoma. After left adrenalectomy, both the supraventricular arrhythmias and the atrioventricular dissociation disappeared. Adequate recognition and treatment of pheochromocytoma can reverse atrioventricular dissociation and may avoid unnecessary procedures such as electrophysiological testing and pacemaker implantation.