Wolff-Parkinson-White syndrome (WPW) is a paroxysmal tachycardia or atrial fibrillation associated with a preexcitation syndrome, characterized by a short P-R interval and a wide QRS complex with an early QRS vector or delta wave.

WPW sydrome is estimated to affect approximately 0.15% to 0.2% of the general population. Males are more frequently affected than females.

WPW syndrome results from accessory electrical connections between the atria and ventricles produced by anomalous embryonic myocardial tissue development bridging the septa. The connections produced allow electrical conduction via sites other than the atrioventricular node (AV node). Bypass tracts may be numerous, including atriofascicular, fasciculoventricular, intranodal, and nodoventricular. The most common bypass is an accessory AV pathway called a Kent bundle. Kent bundle conduction can occur anterograde and/or retrograde.