Wolff-Parkinson-White (WPW) syndrome

DEFINITION

In Wolff-Parkinson-White (WPW) syndrome, an extra electrical pathway between your heart’s upper chambers (atria) and lower chambers (ventricles) causes a rapid heartbeat (tachycardia).

The extra electrical pathway is present at birth and fairly rare. WPW is detected in about 4 out of every 100,000 people. People of all ages, including infants, can experience the symptoms related to Wolff-Parkinson-White syndrome. Most people with symptoms first experience them between the ages of 11 and 50.

The episodes of fast heartbeats usually aren’t life-threatening, but serious heart problems can occur. Treatment for Wolff-Parkinson-White syndrome can stop or prevent episodes of fast heartbeats. A catheter-based procedure, known as ablation, can permanently correct the heart rhythm problems.

CAUSES

In Wolff-Parkinson-White (WPW) syndrome, an extra electrical pathway between your heart’s upper chambers (atria) and lower chambers (ventricles) causes a rapid heartbeat (tachycardia). This pathway of Wolff-Parkinson-White syndrome is present at birth. An abnormal gene (gene mutation) is the cause in a small percentage of people with the syndrome. WPW also is associated with some forms of congenital heart disease, such as Ebstein’s anomaly. Otherwise, little is known about why this extra pathway develops.

Normal heart electrical system

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 the sinus node, a mass of tissue in the right atrium. The sinus node produces electrical impulses that generate each heartbeat.

These electrical impulses travel across the atria, causing muscle contractions that pump blood into the ventricles. The electrical impulses then arrive at a cluster of cells called the atrioventricular node (AV node) — usually the only pathway for signals to travel from the atria to the ventricles. The AV node slows the electrical signal before sending it to the ventricles. This slight delay allows the ventricles to fill with blood. When electrical impulses reach the ventricles, muscle contractions pump blood to the lungs and the rest of the body.

Abnormal electrical system in WPW

In Wolff-Parkinson-White syndrome, an extra electrical pathway connects the atria and ventricles, allowing electrical impulses to bypass the AV node. When the electrical impulses use this detour through the heart, the ventricles are activated too early (pre-excitation).

The extra electrical pathway can cause two major types of rhythm disturbances:

• Looped electrical impulses. In WPW, the heart’s electrical impulses travel down either the normal or the extra pathway and up the other one, creating a complete electrical loop of signals. This condition, called AV reentrant tachycardia, sends impulses to the ventricles at a very rapid rate. As a result, the ventricles pump very quickly, causing rapid heartbeat.
• Disorganized electrical impulses. If electrical impulses don’t begin correctly in the right atrium, they may travel across the atria in a disorganized way, causing the atria to beat very quickly and out of step with each other (atrial fibrillation). The disorganized signals and the extra pathway of WPW also can cause the ventricles to beat faster. As a result, the ventricles don’t have time to fill with blood and don’t pump enough blood to the body.

SYMPTOMS

Symptoms of Wolff-Parkinson-White syndrome are the result of a fast heart rate. They most often appear for the first time in people in their teens or 20s. Common symptoms of WPW syndrome include:

• Sensation of rapid, fluttering or pounding heartbeats (palpitations)
• Dizziness
• Lightheadedness
• Fainting
• Tiring easily during exercise
• Anxiety

An episode of a very fast heartbeat can begin suddenly and last for a few seconds or several hours. Episodes often happen during exercise. Caffeine or other stimulants and alcohol may be a trigger for some people. Over time, symptoms of WPW may disappear in as many as 25 percent of people who experience them.

Symptoms in more-serious cases

About 10 to 30 percent of people with Wolff-Parkinson-White syndrome occasionally experience a type of irregular heartbeat known as atrial fibrillation. In these people WPW signs and symptoms may include:

• Chest pain
• Chest tightness
• Difficulty breathing
• Rarely, sudden death

Symptoms in infants

Symptoms in infants with Wolff-Parkinson-White syndrome may include:

• Shortness of breath
• Lack of alertness or activity
• Poor eating
• Fast heartbeats visible on the chest

No symptoms

Most people who have an extra electrical pathway in the heart experience no fast heartbeat and no symptoms. This condition, called Wolff-Parkinson-White pattern, is discovered only by chance when a person is undergoing a heart exam for other reasons. Wolff-Parkinson-White pattern is harmless in many people. But doctors may recommend further evaluation before children with WPW pattern participate in high-intensity sports.

When to see a doctor

A number of conditions can cause irregular heartbeat (arrhythmia). It’s important to get a prompt, accurate diagnosis and appropriate care. See your doctor if you or your child experiences any symptoms associated with Wolff-Parkinson-White syndrome.

Call 911 or your local emergency number if you experience any of the following symptoms for more than a few minutes:

• Rapid or irregular heartbeat
• Difficulty breathing
• Chest pain