Wolff-Parkinson-White Syndrome

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 travel along a single pathway called the atrioventricular node (AVN). This pathway goes from the heart’s upper chambers (atria) to its lower chambers (ventricles). The electrical signals cause the heart to contract or beat. The AVN normally slows the signal, so the atria and ventricles contract in a coordinated fashion. In WPW, the electrical signals travel along an extra, abnormal pathway. 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.

A risk factor is something that increases your chances of developing a disease or condition. There are no known risk factors for WPW.

Some people with WPW never have tachyarrhythmia and its associated symptoms. In those who do, symptoms usually begin between ages 11 and 50. 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
• Dizziness
• Fainting
• Shortness of breath

In rare cases, a person will go into cardiac arrest (the heart stops pumping) and lose consciousness.

The doctor will ask about your symptoms and medical history, and perform a physical exam. If you are having a tachyarrhythmia due to WPW, you will have normal or low blood pressure and a heart rate of 150 to 250 beats per minute. (A normal heart rate is 60 to 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 electrocardiogram will usually show a “delta wave” that signals an extra electrical pathway. An electrocardiogram is a test that records the heart's activity by measuring electrical currents through the brain.
Other tests may include:

• Monitoring with a Holter monitor for 24-48 hours to check for any episodes of irregular heart beat.
• Electrophysiology study, in which a catheter (a thin tube designed to be inserted into a blood vessel) is passed to the interior of the heart where it takes detailed measurements of its electrical activity. This will detect the extra pathway.

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:
Medication – antiarrhythmics to help coordinate your heart's electrical signals. This can help control or prevent episodes of rapid heartbeat. However, you must take the medicine carefully because it can sometimes make an abnormal heart rhythm worse.
Radiofrequency ablation – a procedure in which a catheter delivers energy at a particular radiofrequency to your heart. This destroys (ablates) the abnormal electrical pathway. In most cases ablation is successful and ends the need to take medicine.
Open-heart surgery – to destroy the abnormal pathway. This is rarely done.
Defibrillation – done in the case of cardiac arrest, which is rare. Defibrillation gives the heart a brief electric shock. This procedure converts a rapid, irregular heartbeat back into a normal heartbeat.

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