Wolff-Parkinson-White (WPW) syndrome is a type of arrhythmia characterized by an extra electrical pathway (circuit) in your heart. As a result, the electrical signal may arrive at the ventricles too soon. The condition can lead to episodes of rapid heart rate (tachycardia or supraventricular tachycardia). Wolff-Parkinson-White syndrome is one of the most common causes of fast heart rate disorders in infants and children, and is believed to be a congenital heart defect.