WPW Syndrome is electrical abnormalities of the heart that are caused by electrical conduction over an accessory-wide pathway (a microscopic, hair-like electrical connection between the upper and lower chambers of the heart, atria and ventricles, respectably). This accessory pathway is in addition to the AV node, the only normal electrical conductor between the atria and ventricles.
The cause of WPW syndrome is not known. In most cases it is associated with a structurally and functionally normal heart, though occasionally can be associated with congenital heart disease or heart muscle abnormalities.
It is generally not considered to be hereditary, except in the very rare instance when associated with genetic mutation predisposing to WPW syndrome and hypertrophic cardiomyopathy (HCM).
Tachycardia presenting with palpitations and occasionally lightheadedness is the most common.
Occasionally WPW syndrome is diagnosed by the presence of the classic ECG findings on an ECG obtained for other purposes; patients may be completely asymptomatic, with no clinical palpitations or tachycardia symptoms. The most common presentation is tachycardia presenting with palpitations and occasionally lightheadedness.
The most common tachycardia is called orthodromic reentry tachycardia (ORT). This looping tachycardia travels electrically down the AV node to the ventricles and then back to the atria over the accessory pathway. In patients with an otherwise functionally normal heart this is rarely a life threatening tachycardia, but may be frequent, sustained, and symptomatic with light headedness, dizziness, and some shortness of breath or chest discomfort. This tachycardia generally starts and stops precipitously.
Cardiac catheterization with diagnostic electrophysiologic testing can be used to assess the electrical properties of the accessory pathway.
In contrast to many other types of tachycardias, WPW syndrome can be regarded as potentially “curable” with catheter ablation techniques. Radiofrequency ablation uses electrical heating to eliminate conduction over the accessory pathway, while in contrast cryoablation uses freezing to destroy the pathway.
Thanks to Dr. Robert Campbell for developing this statement.