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.

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

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.

For many people, Wolff-Parkinson-White syndrome doesn't cause significant problems. But complications can occur, and it's not always possible to know your risk of serious heart-related events. If the disorder is untreated, and particularly if you have other heart conditions, you may experience:

  • Fainting spells (syncope)
  • Fast heart beats (tachycardia)
  • Rarely, sudden death

Whether you first see your family doctor or get emergency care, you'll likely be referred to a heart specialist (cardiologist). Here's some information to help you get ready for your appointment and know what to expect from your doctor.

What you can do

  • Write down your symptoms, including any that may seem unrelated to your heart.
  • Make a list of all your medications, vitamins or supplements.
  • Write down your key medical information, including other diagnosed conditions.
  • Write down key personal information, including any recent changes or stressors in your life.
  • Write down questions to ask your doctor.

Questions to ask your doctor

  • What's the most likely cause of my symptoms?
  • What kinds of tests do I need?
  • What treatments can help?
  • What risks does my heart condition create?
  • How often will I need follow-up appointments?
  • Do I need to restrict my activities?
  • How will other conditions that I have or medications I take affect my heart problem?

In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment.

What to expect from your doctor

Your doctor is likely to ask you a number of questions. Being ready to answer them may make time to go over points you want to spend more time on. You may be asked:
  • When did you first begin experiencing symptoms, and how severe are they?
  • How often have you experienced a fast heartbeat?
  • How long have the episodes lasted?
  • Does anything such as exercise, stress or caffeine seem to trigger or worsen the episodes?
  • Do you have a family history of heart disease?

Your doctor will likely start with a health history, a physical exam and laboratory tests, including:

  • Blood tests, to check thyroid hormone and potassium levels in your blood, which may lead to some heart rhythm disorders.
  • Chest X-ray, to check if your heart is enlarged.

Next, your doctor will likely recommend heart tests.

Electrocardiogram

An electrocardiogram (ECG) uses small sensors (electrodes) attached to your chest and arms to record electrical signals as they travel through your heart. Your doctor can look for patterns among these signals that indicate the presence of an extra electrical pathway in your heart. This pathway can usually be detected even when you're not currently experiencing an episode of a fast heartbeat.

Your doctor may also ask you to use portable ECG devices at home to provide more information about your heart rate. These devices include:

  • 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 24 hours, providing your doctor with a prolonged look at your heart rhythms. Your doctor will likely ask you to keep a diary during the 24 hours, describing any symptoms you experience and recording when they occur.
  • Event recorder. This portable ECG device is used to monitor your heart activity over a period of time ranging from a few weeks to a few months. You activate the recorder only when you experience symptoms of a fast heart rate.

Electrophysiological testing

This test may be used to confirm a diagnosis of Wolff-Parkinson-White syndrome or to pinpoint the location of the extra pathway. Usually, you will be awake but given medication to help you relax. Thin, flexible tubes (catheters) tipped with electrodes are threaded through your blood vessels to various spots in your heart. Once in place, the electrodes can precisely map the spread of electrical impulses during each beat and identify an extra electrical pathway.

Treatment depends on several factors, including the severity and frequency of your symptoms.

If you have the Wolff-Parkinson-White pathway but don't have any symptoms, you probably won't need treatment. If treatment is needed, the goal is to slow a fast heart rate when it occurs and to prevent future episodes. The options include:

  • Vagal maneuvers. These simple physical movements — which include coughing, bearing down as if you are having a bowel movement, and putting an ice pack on your face — affect a nerve that helps regulate your heartbeat (vagus nerve). Your doctor may recommend performing vagal maneuvers to help slow a rapid heartbeat when it occurs.
  • Medications. If vagal maneuvers don't stop the fast heartbeat, you may need an injection of an anti-arrhythmic medication. Your doctor also may recommend a medication that can slow the heart rate.
  • Cardioversion. Your doctor may use paddles or patches on your chest to electrically shock your heart and help restore a normal rhythm. Cardioversion is typically used when maneuvers and medications aren't effective.
  • Radiofrequency catheter ablation. Thin, flexible tubes (catheters) are threaded through blood vessels to your heart. Electrodes at the catheter tips are heated to destroy (ablate) the extra electrical pathway causing your condition. Radiofrequency ablation is effective in up to 95 percent of people with Wolff-Parkinson-White syndrome.

Your doctor will likely recommend follow-up appointments to monitor your heart rhythm and rate.

Mar. 19, 2014