Wolff-Parkinson-White Syndrome

Wolff-Parkinson-White (WPW) syndrome is a congenital abnormality in the heart’s electrical conduction system, characterized by the presence of one or more accessory conduction pathways (Kent bundles) connecting the atria and ventricles directly. WPW is rare, affecting about 0.1–0.3% of the population (1–3 in 1,000 people) and may be hereditary.

Wolff-Parkinson-White (WPW) syndrome is a congenital abnormality in the heart’s electrical conduction system, characterized by the presence of one or more accessory conduction pathways (Kent bundles) connecting the atria and ventricles directly. WPW is rare, affecting about 0.1–0.3% of the population (1–3 in 1,000 people) and may be hereditary.

In a healthy person, electrical impulses originate in the sinus node in the right atrium, then travel to the left atrium, the atrioventricular node, the His bundle, and the Purkinje network to stimulate the ventricles to contract. This conduction process ensures the heart beats in a coordinated, rhythmic manner at 60–100 beats per minute, efficiently pumping blood to the body.

In WPW syndrome, impulses can bypass the atrioventricular node via the Kent bundle, causing premature ventricular depolarization. This condition is also called pre-excitation syndrome. The ventricles receive impulses from both the normal pathway and the Kent bundle, altering ECG characteristics and potentially causing arrhythmias, especially atrioventricular reentrant tachycardia (AVRT).

Electrophysiology studies show Kent bundles can occur in various positions along the atrioventricular ring. The most common location is the left lateral heart wall (50%), followed by the posterior septal area (30%), anterior right septal area (10%), and right lateral wall (10%).

Symptoms of WPW Syndrome WPW syndrome typically first presents in adulthood or middle age but can occur at any age. The hallmark symptom is episodes of supraventricular tachycardia, primarily due to AVRT.

Patients often experience palpitations with sudden onset and termination. These rapid and regular heartbeats may last seconds to hours (rarely more than 12 hours). Other symptoms include shortness of breath, chest discomfort, or dizziness. Prolonged or severe episodes may cause fainting, though this is uncommon.

In infants, WPW may present with nonspecific signs such as rapid breathing, lethargy, poor feeding, or a noticeably fast heartbeat felt at the chest.

WPW is sometimes asymptomatic and only discovered incidentally on ECG during routine checkups. Studies estimate asymptomatic WPW in about 0.15–0.25% of the population. In those with a family history, this rate may rise to 0.55%.

Even without symptoms, WPW poses potential risks and requires proper risk assessment and follow-up.

Is WPW Syndrome Dangerous? The severity of WPW depends on the accessory pathway’s properties and the risk of dangerous arrhythmias. Many cases only cause non-life-threatening episodes of supraventricular tachycardia.

However, some patients with WPW may experience atrial flutter or fibrillation conducting rapidly to the ventricles. The estimated annual risk of atrial fibrillation is 1.5%, and sudden cardiac death is 0.1%.

If atrial fibrillation rapidly conducts to the ventricles through the accessory pathway, ventricular fibrillation may occur—a life-threatening arrhythmia that can cause sudden death. Risk factors include young age, physical exertion, history of tachycardia, multiple accessory pathways, use of drugs that block the AV node, and shortest RR interval in pre-excited atrial fibrillation ≤ 0.25 seconds.

In asymptomatic WPW patients, complications are less likely but not negligible. Additional tests like exercise stress tests, Holter monitoring, and electrophysiology studies can assess risk and guide treatment decisions.

Diagnosing WPW Syndrome Diagnosis is primarily based on ECG and electrophysiology tests. A clinical history and risk factor evaluation are also essential.

ECG shows a short PR interval (< 0.12 seconds), wide QRS complex (≥ 0.12 seconds), and a delta wave. In intermittent accessory pathway conduction (concealed WPW), more advanced testing is required.

• Holter monitoring (24–48 hours) or event recorders detect intermittent pre-excitation and assess arrhythmia risk.
• Exercise stress tests evaluate conduction changes in WPW. If the delta wave disappears during increased heart rate, the pathway has weak conduction and poses a lower arrhythmia risk.
• Electrophysiology studies locate the accessory pathway, assess conduction properties, and determine the risk of AVRT or ventricular fibrillation. Catheters are placed in the heart to stimulate and record electrical activity.

If the pathway shows rapid conduction during atrial fibrillation (RR interval ≤ 0.25 seconds), catheter ablation is recommended—even in asymptomatic patients.

Treatment of WPW Syndrome Acute Treatment The goal is to stop tachycardia episodes. In stable supraventricular tachycardia, vagal maneuvers like the Valsalva technique or carotid massage may help. If ineffective, intravenous adenosine is used to block the AV node and break the reentrant circuit. Beta-blockers or non-dihydropyridine calcium channel blockers may be considered.

In pre-excited atrial fibrillation with rapid ventricular response, AV node blockers like adenosine, beta-blockers, calcium channel blockers, or digoxin are contraindicated as they may increase conduction via the accessory pathway and raise the risk of ventricular fibrillation. Electrical cardioversion is safer for unstable cases, or class I antiarrhythmic drugs for stable patients.

Long-Term Treatment Radiofrequency ablation is the definitive treatment, eliminating the accessory pathway and preventing recurrence. Studies show a 94% success rate, 6% recurrence (often treatable with repeat ablation), and a 1% complication rate.

Ablation is recommended for:

• Symptomatic patients with recurrent episodes
• Asymptomatic patients with high-risk pathways (RR interval ≤ 0.25 seconds)
• Patients unwilling or unable to use long-term medications

Medical therapy is an alternative if ablation is not possible, using oral antiarrhythmic drugs (excluding digoxin). However, drugs only control symptoms and do not eliminate the accessory pathway, so ablation remains the preferred option.

Hanoi French Hospital is a trusted center for diagnosing and treating WPW, offering:

• Highly qualified cardiologists: Dr. Alain Lebon (European Society of Cardiology-certified electrophysiologist), Dr. Ngo Chi Hieu (26+ years of cardiology experience), and Dr. Pham Thu Thuy (advanced training at University of Paris 6, experience at major French hospitals).
• Personalized treatment protocols based on European Heart Rhythm Association guidelines.
• The latest Abbott EnSite X EP 3D cardiac mapping system—the first in Vietnam using single-use catheters imported from the USA.
• Modern DSA catheterization labs following the highest French sterilization standards.

To consult about WPW syndrome or book an appointment with leading cardiology experts at Hanoi French Hospital, please call 024 3577 1100.