Successful Pacemaker Setting Using Treadmill Exercise Test in a Child with Fontan Circulation.

The usefulness of a treadmill exercise test for determining optimal pacemaker settings remains unknown. An 8-year-old boy with Fontan circulation and a dual-chamber pacemaker for a rate-dependent advanced atrioventricular block suffered from dullness and poor school attendance. Although the pacemaker log showed an atrial tachycardia/fibrillation episode, treadmill exercise testing revealed sinus tachycardia, which converted to a 2:1 atrioventricular block. The pacemaker setting was optimized, with improvement in the patient's condition.Treadmill exercise testing helps optimize dual-chamber pacemaker settings in children with complex congenital heart disease involved in energy-consuming physical activities and having a wide working range in sinus rate.