Wolff-Parkinson-White syndrome (WPW) is a syndrome of pre-excitation of the ventricles due to an accessory pathway known as the bundle of Kent. This accessory pathway is an abnormal electrical communication from the atria to the ventricles.

Unlike the AV node, which is the normal electrical pathway from the atria to the ventricles, the accessory pathway in WPW does not have slow conductive properties. This means that electrical activity that originates from the SA node with conduct to the ventricles faster via the accessory pathway than via the AV node. This causes the characteristic EKG pattern consisting of a delta wave at the beginning of the QRS complex, which manifests itself with varying degrees of subtlety. The delta wave is due to pre-excitation of the ventricle due to anterograde conduction via the accessory pathway. The EKG will exhibit a short PR interval and a widened QRS interval. Shown are two beats from a rhythm strip in V2 demonstrating these classic changes. Note the short PR interval of 0.08 seconds and the long QRS complex at 0.22 seconds.

Patients with WPW often exhibit more than one accessory pathway, and in some patients as many as eight additional abnormal pathways can be found.

Though it can be treated with medication, in the long term the treatment of choice is destruction of the abnormal electrical pathway by radiofrequency catheter ablation.

Wolff-Parkinson-White syndrome is sometimes caused by Leber hereditary optic neuropathy (LHON), a form of mitochondrial disease.