What is Wolff-Parkinson-White Syndrome?
Wolff-Parkinson-White (WPW) syndrome is an abnormality of the heart's electrical conduction system which can be associated with supraventricular tachycardia (SVT). In WPW syndrome, there is an extra electrical pathway (called an "accessory pathway") in the heart which can transmit electrical impulses from the upper chambers (atria) to the lower chambers (ventricles) of the heart. In the normal conduction system, there is only one electrical conduction pathway from the atria to the ventricles. It is called the atrio-ventricular node (AV node). A WPW pathway bypasses the AV node and can transmit electrical signals through the heart faster than through the AV node This can cause SVT or other abnormal heart rhythms.
When impulses travel from the atria to the ventricles through the extra pathway, the ECG shows a pattern called a Delta wave or "pre-excitation". Each patient is different in how fast electrical impulses can be transmitted over this pathway. If the pathway is able to transmit very fast and if the patient has an arrhythmia known as atrial fibrillation (in which the atria pump from 300-600 times/minute), the extra pathway may transmit that very rapid rate.