Preexcitation syndrome

Alternative names
Wolff-Parkinson-White syndrome; WPW

Definition
Wolff-Parkinson-White syndrome involves episodes of rapid heart rate (tachycardia) and baseline abnormal ECG caused by abnormal electrical pathways (circuits) in the heart.

Causes, incidence, and risk factors

Normally, the electrical signals that coordinate the heartbeat travel through the atria (two top chambers of the heart) to the ventricles (two bottom chambers). These signals travel through the atrioventricular (AV) node, which is the electrical pathway connecting the atria and ventricles.

In people with Wolff-Parkinson-White syndrome, there is an extra (accessory) atrioventricular conduction pathway. This extra pathway bypasses the normal conduction delay of the AV node, which may cause a form of “supraventricular tachycardia” - a rapid heart rate initiated above the ventricles.

The type of supraventricular tachycardia experienced by people with Wolff-Parkinson-White syndrome is called “re-entry.” The location of the extra-electrical pathway in Wolff-Parkinson-White can often be precisely identified.

Wolff-Parkinson-White occurs in approximately 4 out of 100,000 people, and is one of the most common causes of fast heart rate disorders (tachyarrhymthmias) in infants and children.

The frequency of the episodes of rapid heart rate varies from person to person. Patients with Wolff-Parkinson-White may have isolated episodes of rapid heart rate, frequent episodes (occurring once or twice a week), or they may never have symptoms. In the latter case, the condition is often discovered accidentally when a physician is reviewing an ECG requested for some other purpose.

Symptoms

     
  • palpitations (a sensation of feeling your heart beat)  
  • light-headedness  
  • fainting  
  • dizziness  
  • shortness of breath  
  • chest pain or chest tightness

Signs and tests
An examination during the tachyarrhythmia will reveal a heart rate greater than 150 (normal is 60 to 100 beats per minute), and blood pressure that is normal or low. If a tachyarrhythmia is not present, the physical exam may be completely normal.

Wolff-Parkinson-White syndrome may be revealed by the following tests:

     
  • ECG (electrocardiogram), which looks for a finding called a “delta wave”  
  • continuous ambulatory monitoring (Holter monitor), which may record an episode of arrhythmia  
  • EPS, an intracardiac electrophysiologic study showing the accessory pathway

Treatment

The goal of treatment is to reduce symptoms by reducing the episodes of tachycardia (rapid heart rate).

Medication may be used to control or prevent rapid heart beating. These include adenosine, antiarrhythmics, and amiodarone. Digoxin, verapamil, and beta-blockers (other drugs commonly used to treat other types of tachycardia) can increase the frequency of tachycardia episodes for some people with Wolff-Parkinson-White.

Other treatments to stop a persistent episode of tachycardia may include electrical cardioversion (shock) or catheter ablation with a special type of energy called radiofrequency. This destroys the accessory pathway using a catheter (tube) inserted into the body to reach the heart.

Surgery may provide a permanent cure for Wolff-Parkinson-White. This involves ablation (destruction) of the accessory pathway using open heart surgery. Surgery may be a good approach to cure symptomatic Wolff-Parkinson-White syndrome, but it is usually only done if the patient must undergo surgery for other reasons.

Expectations (prognosis)
The outcome varies. Using a catheter to deliver radiofrequency waves to destroy the abnormal pathway usually cures Wolff-Parkinson-White. This is currently the preferred therapeutic approach to treat Wolff-Parkinson-White syndrome in the United States.

Complications

     
  • reduced blood pressure caused by sustained rapid heart rate. The most severe form of tachyarrhythmia is atrial fibrillation. It may rapidly lead to shock and thus requires emergency treatment (cardioversion).  
  • heart failure.  
  • side effects of medications used to treat Wolff-Parkinson-White (see the specific medication).  
  • complications of surgery.

Calling your health care provider
Call your health care provider if symptoms indicating Wolff-Parkinson-White develop, or if you have this disorder and symptoms worsen or do not improve with treatment.

Johns Hopkins patient information

Last revised: December 3, 2012
by Martin A. Harms, M.D.

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