Definition

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.

Causes

In a normal heart, electrical signals that cause the heart to beat begin in the area known as the sinoatrial (SA) node, located in the right upper chamber (atrium) of the heart. The electrical signal goes from the SA node down to the atrioventricular (AV) 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 goes 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 8 weeks after conception.

Electrical Conduction System of the Heart Copyright © Nucleus Medical Media, Inc.

Risk Factors

There are no known risk factors for WPW syndrome.

Symptoms

Some people with WPW syndrome never have tachyarrhythmia and its associated symptoms. In those who do, symptoms usually begin between ages 11-50 years old. The frequency and severity of the tachyarrhythmia varies from one person to another and may be associated with any or all of these symptoms:

• Palpitations (sensation of a pounding heartbeat)
• Chest pain or tightness
• Lightheadedness
• Fainting
• Shortness of breath

In rare cases, a person will go into cardiac arrest and lose consciousness.

Diagnosis

The doctor will ask about your symptoms and medical history. A physical exam will be done. If you are having a tachyarrhythmia due to WPW syndrome, you will have normal or low blood pressure and a heart rate of 150-250 beats per minute. (A normal heart rate is 60-100 beats per minute.)

If you are not having irregular heart rhythms during the exam, the results of the exam may be normal. In either case, an ECG (electrocardiogram—a test that records the heart's activity by measuring electrical currents through the skin) will usually show a specific wave that signals an extra electrical pathway.

Other tests may include:

• Monitoring with a Holter monitor for 24-48 hours to check for any episodes of irregular heart beat.
• Electrophysiology study —A catheter is passed to the interior of the heart where it takes detailed measurements of its electrical activity. This will detect the extra pathway.

Treatment

The goal of treatment is to reduce or eliminate episodes of tachyarrhythmia and associated symptoms. If you do not have symptoms, treatment is usually not necessary.

If you do need treatment, it may include:

Prevention

There is no known way of preventing WPW syndrome. However, symptoms can be prevented with proper treatment.