Wolff-Parkinson-White (WPW) Syndrome

What is WPW syndrome?

Wolff-Parkinson-White (WPW) syndrome is a rare heart disorder, present at birth, that involves irregularities in the electrical system of the heart. The heartbeat is controlled by electrical signals that move through the heart in a highly coordinated way. A cluster of cells called the atrioventricular node conducts electrical impulses from the heart’s upper chambers (atria) to the lower chambers (ventricles). Impulses move through this node during each heartbeat, stimulating the ventricles to contract a little later than the atria. People with WPW syndrome have an extra connection in the heart called an accessory pathway. The accessory pathway allows electrical signals to bypass the atrioventricular node and move from the atria to the ventricles and back faster than normal. This extra connection results in abnormally fast heartbeat rhythms and speed. While it is present at birth, WPW syndrome may not be detected until adolescence or later. Some studies indicate that it occurs in males more than females. It is estimated to affect between 1 and 3 per 1,000 people in the United States. It often occurs with other structural abnormalities in the heart or underlying heart disease.

What are the symptoms of WPW syndrome?

Symptoms vary greatly from patient to patient, so it is important to note that each individual may not exhibit every symptom listed below. These symptoms may not become apparent until early childhood.

Episodes of irregular, fast heartbeats. These episodes can be sporadic or more irregular, and can last for a few seconds or several hours.
- Heart palpitations
- Difficulty breathing
- Lightheadedness
- Chest pain
- Decreased tolerance of exercise
- Anxiety
- Dizziness
- Fainting
Rarely, cardiac arrest

What causes WPW syndrome?

Those with WPW syndrome are born with an extra electrical pathway between their heart’s upper and lower chambers. The extra electrical impulses the accessory pathway sends are what cause the rapid heartbeat and following symptoms. The exact cause of WPW syndrome is unknown. Most cases appear randomly and for no apparent reason. A small percentage of cases seem to be caused by mutations in the PRKAG2 gene, which provides instructions for making a protein that is part of the enzyme called AMP-activated protein kinase. That enzyme helps sense and respond to energy demands within cells, and is likely involved in developing the heart before birth. Still, researchers are uncertain how exactly the PRKAG2 gene mutations lead to the development of WPW syndrome. For that small percentage in which the disease is inherited, it is done so in an autosomal dominant pattern, which means that only one parent need pass down a copy of the gene for the condition to occur.

How is WPW syndrome diagnosed?

Some patients with WPW syndrome never show the symptoms listed above, which can often mean they do not get diagnosed. For those who do exhibit symptoms, WPW syndrome is usually diagnosed using the following procedures:

Thorough clinical evaluation
Detailed patient history
Electrocardiogram (ECG), which monitors electrical signals as they travel through the heart
Holter monitor, a portable device that continuously monitors the heat’s electrical activity
Electrophysiology study, which involves insertion of a thin tube into a blood vessel and threading it to the heart, where it measures electrical activity

The goal of most diagnosing techniques is to detect the abnormal heart rhythms associated with WPW syndrome.

What are the treatments for WPW syndrome?

Specific treatment varies depending on the type of arrhythmia present, the frequency, the type and severity of symptoms, risk of cardiac arrest, and the patient’s age and general health. Treatment includes, but is not limited to:

Vagal maneuvers, or simple physical movements that can help slow rapid heartbeats
Medications
- Antiarrhythmics
- Calcium channel blockers
Cardioversion, in which a doctor uses paddles on the patient’s chest to electrically shock the heart to restore a normal rhythm
Surgery called catheter ablation, in which a small tube is inserted into the heart and guided to the abnormal pathway where high-frequency electrical energy is used to destroy the tissue making up the abnormal pathway.
Rarely, open heart surgery