Wolff-Parkinson-White syndrome (WPW) is a disorder of the heart’s electrical activity. It causes the heart to beat with an irregular rhythm and faster than normal. This is called tachyarrhythmia.

In a normal heart, electrical signals that cause the heart to beat begin in the area known as the SA node, located in the right upper chamber (atrium) of the heart. The electrical signal goes from the SA node down to the AV (atrioventricular) node which is between the atria and the lower chambers of the heart (the ventricles). The AV node slows down the electrical impulse so that the ventricles have time to fill with blood before contracting.

In WPW, the electrical signals travel along an extra, abnormal pathway that go around the AV node. This causes the signals to be unregulated and to arrive at the ventricles too soon. The signals often alert the ventricles to contract abnormally. As a result, the heart beats much faster than normal.

The extra pathway is caused by abnormal growth of tissue that connects the heart’s chambers. This occurs in the embryo—during the first eight weeks after conception.

Electrical Conduction System of the Heart
Electrical conduction of heart
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