Wolff-Parkinson-White Syndrome

Wolff-Parkinson-White syndrome, or WPW, is named after the three doctors who described it in 1930. People with WPW are born with an extra electrical pathway, often called the bundle of Kent, that connects the upper chambers (atria) and lower chambers (ventricles) of the heart. Normally, every signal from the atria must pass through the AV node, a gate that holds the signal back briefly before passing it on to the ventricles. The extra pathway bypasses that gate, so part of the ventricles receives the signal early. WPW is a commonly seen type of pre-excitation, covered on the Pre-Excitation Syndrome page.

WPW Pattern and WPW Syndrome

On an ECG, the extra pathway shows up as a short PR interval, a delta wave (a slurred start of the ventricular wave), and a widened ventricular wave. If these signs are present without symptoms, doctors call it a WPW pattern. If they come with episodes of tachycardia, it is called WPW syndrome. The WPW pattern is found in about 1 to 3 of every 1,000 people, and some of them never have an episode.

How Episodes Happen

The common type of episode is called AVRT. The signal travels down through the AV node and then back up through the extra pathway, forming a loop that keeps circling. The heart then beats fast and regularly, often 150 to 250 times per minute, in episodes that start and stop suddenly. This type of tachycardia is also covered on the Supraventricular Tachycardia page.

A less common situation, but the main concern, is atrial fibrillation in people with WPW. The chaotic rhythm of the atria can be conducted very rapidly through the extra pathway because it is not filtered by the AV node. In a small number of cases, this can turn into ventricular fibrillation and cause cardiac arrest, sometimes without any earlier symptoms. That is why everyone with a WPW pattern or WPW syndrome should have their risk assessed by a cardiologist.

Treatment

The extra pathway can be disabled with catheter ablation. The 2019 ESC guidelines recommend ablation for people with WPW syndrome who have repeated episodes, and in many patients the episodes do not come back afterward. For people with a WPW pattern and no symptoms, the decision is made after assessing the risk of the extra pathway, taking into account age, occupation, and the sports they play.

WPW is often first discovered on an ECG, either during an episode or at a routine checkup. Your doctor will ask about any history of a racing heartbeat, dizziness, or fainting, and about heart disease in your family. The ECG between episodes is distinctive enough to show an extra pathway, and the shape of the delta wave helps estimate where it is.

Next, your doctor assesses the risk of the extra pathway. A pattern that comes and goes on a Holter monitor, or that disappears suddenly during a treadmill test, usually means a pathway that cannot conduct signals very rapidly. Echocardiography looks for any accompanying structural abnormalities. If you have episodes, or if you are an athlete or a worker for whom fainting would be dangerous, your doctor may recommend an electrophysiology study. This catheter-based test precisely measures what the extra pathway can do and maps its location, so ablation can be done in the same session.

A WPW pattern on your ECG needs to be assessed by a cardiologist, even if you have never had an episode. This assessment determines whether your extra pathway only needs monitoring or should be treated with ablation. Make an appointment if any of the following applies to you, and go to the emergency room right away if warning signs appear.

• Your ECG report mentions a WPW pattern, pre-excitation, or a delta wave
• Episodes of a racing heartbeat that start and stop suddenly
• Your child has been diagnosed with WPW and is going to take part in competitive sports
• You work as a driver or pilot, or at heights
• Fainting, chest pain, or a very fast, irregular heartbeat: go to the emergency room right away