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Wolff-Parkinson-White Syndrome

Introduction
Signs and symptoms
Causes
Risk Factors
Screening and diagnosis
Treatment
Self-care

Wolff-Parkinson-White syndrome is a heart rhythm problem (arrhythmia) caused by an extra abnormal electrical pathway in the heart. In a normal heart, electrical impulses travel from the upper chambers (atria) to the lower chambers (ventricles) in an organized, rhythmic pattern through the atrioventricular node - or AV node.

In people with Wolff-Parkinson-White syndrome, there's an extra pathway between the upper and lower chambers of the heart, which allows the electrical signals to bypass the AV node. When electrical signals travel through this abnormal detour, the signals reach the ventricles too early - a condition called preexcitation. Electrical signals can also travel through the AV node and then go back up the extra pathway, which can create a short circuit and lead to fast heart rate (tachycardia).

Wolff-Parkinson-White syndrome can affect infants, children and adults. In some people, fast heart rate occurs only a handful of times. In others, it occurs as often as once or twice a week. This sensation can be scary or bothersome, but Wolff-Parkinson-White syndrome usually isn't life-threatening. Treatment for Wolff-Parkinson-White syndrome focuses on slowing fast heart rate and preventing its recurrence.

Some people with the Wolff-Parkinson-White pathway have no symptoms and only discover the extra pathway during an electrocardiogram ordered for some other, unrelated reason.

But most people with Wolff-Parkinson-White syndrome experience these signs and symptoms:

• A racing heartbeat
• A fluttering in the chest
• Dizziness
• Lightheadedness
• Fainting

If Wolff-Parkinson-White syndrome is accompanied by underlying heart disease, rapid heart rate can lead to other serious symptoms, including chest pain, chest tightness or difficulty breathing.

Your heart is made up of four chambers - two upper chambers (atria) and two lower chambers (ventricles). The rhythm of your heart is normally controlled by a natural pacemaker - the sinus node - located in the right atrium. The sinus node produces the electrical impulses that initiate each heartbeat. From the sinus node, electrical impulses travel across the atria to the atrioventricular node, which is normally the only pathway between the atria and the ventricles. From here, electrical impulses travel to the muscles of the ventricles, causing them to contract and pump blood out to your lungs and body.

In Wolff-Parkinson-White syndrome, there's an extra, abnormal conduction pathway, which directly connects the atria and ventricles. When electrical impulses use this detour through the heart, the ventricles are activated too early - a condition known as preexcitation. When electrical impulses use both pathways, it can create a repeating loop, which sends impulses to the ventricles at an abnormally high rate and causes a rapid heartbeat (tachycardia). Wolff-Parkinson-White syndrome is technically known as a supraventricular tachycardia (SVT), because the rapid heart rhythm originates in the upper chambers of the heart.

The only people who develop Wolff-Parkinson-White syndrome are those who are born with the abnormal extra pathway, known as a bundle of Kent. However, it may take years - or decades - for symptoms to occur. And, in some cases, the pathway never causes symptoms and may even resolve spontaneously over time.

Wolff-Parkinson-White syndrome is one of the most common causes of fast heart rate in infants and children. Rapid heart rate in adults is likely to be caused by some other condition.

If you or your child experiences episodes of fast heart rate, a few heart tests can often pinpoint the cause. Wolff-Parkinson-White syndrome is usually detected by the presence of specific patterns on an electrocardiogram (ECG).

Elecrocardiogram (ECG). During this test, sensors (electrodes) are attached to your chest and limbs to create a graphical record of the electrical signals traveling through your heart. An ECG can show an extra pathway or shortcut in the heart, even if you aren't experiencing rapid heart rate during the test.

• Holter monitor. This portable ECG device is carried in your pocket or worn on a belt or shoulder strap. It records your heart's activity for an entire 24-hour period, which provides your doctor with a prolonged look at your heart rhythms over time.
• Event recorder. This is a portable ECG device that you keep at home. You attach it to your body and activate it only when you experience symptoms of fast heart rate. The device is small, about the size of a portable compact disc player, and you can clip it to your belt. It has wires and sticky pads that you can apply to your chest or take off, as when you shower. When you feel symptoms, you push a button, and an ECG strip of the preceding few minutes and following few minutes is recorded. This permits your doctor to determine your heart rhythm at the time of your symptoms, to see if there's an association.

In some cases, you may need additional tests to confirm the diagnosis or to pinpoint the location of the extra pathway:

Electrophysiologic testing. During this test, thin, flexible tubes (catheters) tipped with electrodes are threaded through your blood vessels to various spots along the electrical path in your heart. Once in place, the electrodes can precisely map the spread of electrical impulses during each beat and identify the source of tachycardia.

It is possible to discover the Wolff-Parkinson-White pathway during heart tests for some unrelated reason.

If you have the Wolff-Parkinson-White pathway but you don't have any symptoms, you probably don't need treatment. In fact, in people without symptoms, the extra pathway often spontaneously disappears over time.

If you do experience fast heart rate, you may need treatments to stop the tachycardia and prevent its return.

Stopping fast heart rate
Rapid heart rate often stops on its own. If it doesn't, you may need to try some strategies to stop it or go to a hospital for help.

• Strategies to try at home. Particular maneuvers, such as coughing or bearing down as if you are having a bowel movement (Valsalva maneuver), may slow your heart rate. Talk to your doctor about how and when to use these maneuvers.
• Medications. If maneuvers don't stop the tachycardia, you may need an intravenous medication, such as adenosine or verapamil, administered at the hospital.
• Cardioversion. In this procedure, a shock is delivered to your heart through paddles or patches on your chest. The current affects the electrical impulses in your heart and restores a normal rhythm. It's typically used when maneuvers and medications aren't effective.

Preventing episodes of fast heart rate
With the following treatments, it's possible to cure Wolff-Parkinson-White syndrome in the majority of cases.

• Radiofrequency catheter ablation. This is most common treatment for Wolff-Parkinson-White syndrome. In this procedure, catheters are threaded through the blood vessels to your inner heart. Electrodes at the catheter tips are heated to destroy (ablate) a small spot of heart tissue, which blocks the extra electrical pathway. This procedure is highly effective, and complications - which can include heart injury or infection - are uncommon.
• Medications. Anti-arrhythmic medications can prevent fast heart rate when taken regularly. Medications are usually given to people who can't undergo radiofrequency catheter ablation for some reason.
• Surgery. The success rate for surgical destruction (ablation) of the extra pathway using open-heart surgery is almost 100 percent. However, because radiofrequency catheter ablation is almost as effective and less invasive, surgery for Wolff-Parkinson-White syndrome is now rare. It's typically reserved for people who are having heart surgery for other reasons.