Wolff-Parkinson-White Syndrome

Preexcitation is based on an accessory conduction pathway between the atrium and ventricle. In the human embryo, there are three to four atrioventricular (AV) connections. Normally, all pathways, with exception of the AV node/His system, undergo hypoplasia or fibrosis and lose conduction function. However, in approximately 3 of every 1000 people, one so-called accessory pathway (AP) persists and can support antegrade and retrograde conduction. Generally, the electrocardiogram (ECG) in these individuals shows, constantly or more rarely intermittently, the typical pattern of preexcitation with a shortened PQ interval and a delta wave. Approximately 40% of the people with an AP experience tachycardias in which this pathway is used. The term Wolff-Parkinson-White (WPW) syndrome is used for patients with the preexcitation/WPW pattern associated with AP-related tachycardias.