Exercise testing in children with Wolff-Parkinson-White syndrome.

Exercise testing using a modified Bruce treadmill protocol was performed by 17 children with Wolff-Parkinson-White (WPW) syndrome. All had intracardiac electrophysiology studies as well. Endurance time, heart rate and blood pressure were normal during exercise. Ventricular premature complexes were seen with exercise in 2 patients and supraventricular tachycardia with exercise testing was seen in 2. Disappearance of the delta wave with exercise correlated with a long anterograde effective refractory period of the Kent bundle (360 to 390 ms). Children with partial normalization of the QRS during exercise had a longer anterograde effective refractory period of the Kent bundle than those in whom preexcitation persisted. In 1 patient, disappearance of the delta wave with exercise confirmed the diagnosis of WPW syndrome. Preexcitation was seen only after exercise in 1 patient. Exercise testing is of value in the evaluation of children with WPW syndrome; children with WPW syndrome who have total normalization of the QRS interval during exercise and few or no symptoms of tachycardia do not require electrophysiologic study.