Wolff-Parkinson-White syndrome: A condition that is caused by an abnormality in the electrical system of the heart, which normally tells the heart muscle when to contract. Abbreviated WPW syndrome. In WPW syndrome there is an extra electrical connection inside the heart that acts as a short circuit, causing the heart to beat too rapidly and sometimes in an irregular manner. WPW syndrome can be life threatening, although that is unusual. WPW syndrome can be treated via destruction of the short circuit, using a technique termed radiofrequency catheter ablation, in which the short circuit is destroyed using radiofrequency energy.