Wolff–Parkinson–White Syndrome

Overview

Wolff–Parkinson–White (WPW) syndrome is a congenital heart condition characterized by an abnormal extra electrical pathway between the atria (upper chambers) and the ventricles (lower chambers) of the heart. This extra pathway can lead to episodes of rapid heart rate (tachycardia), which may cause palpitations, dizziness, or even fainting. WPW syndrome is a type of pre-excitation syndrome, meaning electrical signals reach the ventricles prematurely, bypassing the normal route through the atrioventricular (AV) node.

First described in 1930 by Louis Wolff, Sir John Parkinson, and Paul Dudley White, WPW syndrome is one of the most common causes of supraventricular tachycardia (SVT), particularly in young people. Although many individuals with WPW live normal lives, in rare cases, it can lead to life-threatening arrhythmias such as atrial fibrillation with a rapid ventricular response or sudden cardiac arrest.

Causes

Wolff–Parkinson–White syndrome is typically congenital, meaning the abnormal electrical pathway—called an accessory pathway or bundle of Kent—is present at birth. The exact cause of this abnormal development is not fully understood, but it is believed to arise during fetal cardiac development.

Genetic Factors:

• Most cases of WPW are sporadic (not inherited), but in rare instances, it can be inherited in an autosomal dominant pattern.

• WPW syndrome has been associated with certain genetic conditions, such as familial WPW syndrome and Danon disease, a rare metabolic disorder.

Associated Conditions:

• Ebstein’s anomaly: A congenital heart defect affecting the tricuspid valve that is often linked with WPW.

Symptoms

Symptoms of Wolff–Parkinson–White syndrome can vary widely. Some individuals remain asymptomatic throughout their lives and are diagnosed incidentally during an electrocardiogram (ECG), while others experience frequent episodes of arrhythmia.

Common Symptoms:

• Palpitations: Sensation of rapid or fluttering heartbeats

• Dizziness or lightheadedness

• Shortness of breath

• Chest pain or discomfort

• Fatigue during episodes of tachycardia

• Syncope (fainting): Especially during exertion

In Infants and Young Children:

• Poor feeding

• Irritability

• Lethargy

• Pale or mottled skin

Serious Complications:

• Atrial fibrillation with rapid ventricular response: Can lead to very fast heart rates and may cause cardiac arrest if not treated promptly

• Sudden cardiac death: Extremely rare but can occur, particularly in undiagnosed or untreated cases

Diagnosis

Diagnosis of WPW syndrome is typically made through an electrocardiogram (ECG), which shows characteristic signs of pre-excitation. Further testing may be done to evaluate the risk of arrhythmias and determine the best course of treatment.

Diagnostic Tests:

• Electrocardiogram (ECG): Shows a short PR interval, delta wave (slurred upstroke of the QRS complex), and a wide QRS complex.

• Holter monitor: A 24–48-hour ECG monitoring device used to detect intermittent arrhythmias.

• Event recorder: For patients with infrequent symptoms.

• Exercise stress test: Assesses how the heart responds to physical exertion.

• Electrophysiological (EP) study: An invasive test to map electrical pathways and determine the location and characteristics of the accessory pathway.

Treatment

Treatment for Wolff–Parkinson–White syndrome depends on the severity and frequency of symptoms, as well as the risk of life-threatening arrhythmias. Some asymptomatic individuals may require no treatment but should be monitored regularly.

Acute Episode Management:

• Vagal maneuvers: Such as coughing, bearing down (Valsalva maneuver), or cold water immersion to slow the heart rate

• Medications: Intravenous adenosine, beta-blockers, or calcium channel blockers may be used to terminate supraventricular tachycardia

• Electrical cardioversion: Used in emergencies, especially for atrial fibrillation with rapid conduction

Long-term Treatment Options:

• Antiarrhythmic drugs: Such as flecainide or sotalol in selected patients

• Catheter ablation: A minimally invasive procedure that uses radiofrequency or cryoablation to destroy the accessory pathway. This is the treatment of choice for symptomatic WPW and has a high success rate (over 95%) with low risk of complications.

• Lifestyle adjustments: Avoiding triggers such as excessive caffeine or stress may help reduce episodes in some individuals

Prognosis

The overall prognosis for individuals with Wolff–Parkinson–White syndrome is excellent, especially with appropriate diagnosis and treatment. Most people with WPW can lead normal, active lives. Advances in catheter ablation have significantly improved outcomes and reduced the risk of complications.

Prognostic Factors:

• Asymptomatic patients: Often have a low risk of complications but may require periodic reevaluation

• Successful ablation: Usually results in permanent cure with minimal recurrence

• High-risk pathways: Identified through EP studies may warrant preemptive ablation even in asymptomatic individuals

With proper medical care and monitoring, WPW syndrome is a manageable condition, and life-threatening complications are rare in treated patients.