Wolff-Parkinson-White Syndrome (WPW)

How WPW affects the heartbeat

Normally, electrical signals travel from the upper chambers (atria) to the lower chambers (ventricles) through a single gateway, the AV node, which slows the signal slightly. In WPW, an extra pathway bypasses the AV node:

• signals reach part of the ventricles early (pre-excitation), creating the ECG pattern
• the pathway can form a loop with the AV node, letting impulses circle rapidly, causing atrioventricular reentrant tachycardia (AVRT)
• if atrial fibrillation occurs, the pathway may let very rapid impulses reach the ventricles, which can trigger ventricular fibrillation

WPW pattern vs WPW syndrome

ECG findings

• a short PR interval
• a slurred start to the QRS complex (delta wave)
• a widened QRS complex

Causes

WPW is present from birth. Most cases occur without a known cause. A small proportion run in families or are associated with congenital heart conditions such as Ebstein anomaly or with hypertrophic cardiomyopathy.

Symptoms

Episodes often start and stop suddenly:

• a very fast, regular heartbeat, often 150 to 250 beats per minute
• palpitations or pounding in the chest or neck
• dizziness or lightheadedness
• shortness of breath
• chest discomfort
• anxiety
• fainting, less commonly
• in babies: fast breathing, poor feeding, irritability, pale or sweaty skin

Symptoms may first appear in childhood, adolescence or adulthood.

Risks

• paroxysmal supraventricular tachycardia episodes, the most common problem
• atrial fibrillation with rapid conduction through the pathway
• sudden cardiac death: rare, estimated at a very small percentage per year in people with symptoms, and lower in those without

Diagnosis

• resting ECG: shows the WPW pattern
• Holter or event monitor: captures episodes
• echocardiogram: checks heart structure
• exercise test: if the pre-excitation disappears abruptly with faster heart rates, the pathway is usually lower risk
• electrophysiology study (EPS): catheters in the heart map the pathway and assess its risk, usually combined with ablation

Treatment

Stopping an episode

• vagal maneuvers: bearing down as if straining (Valsalva), or the modified Valsalva (straining then lying back with legs raised), or cold water on the face
• adenosine or other medicines in the ER, used with caution in WPW
• electrical cardioversion if unstable

Certain AV node-blocking drugs (such as digoxin, verapamil and diltiazem) can be dangerous in WPW with atrial fibrillation, so emergency teams choose medicines carefully.

Long-term treatment

• catheter ablation: a catheter delivers radiofrequency energy or freezing to destroy the pathway. Success rates are over 90% to 95% in experienced centers, with low complication rates. It is first-line for symptomatic WPW
• medicines such as flecainide or propafenone for people who cannot or prefer not to have ablation
• asymptomatic WPW pattern: risk assessment with exercise testing or an EPS, and ablation if the pathway is high risk or for people in high-risk jobs or sports

Living with WPW

After successful ablation, most people have no further restrictions. Before ablation, discuss exercise and sports with a cardiologist. Avoid stimulants such as excess caffeine, energy drinks and decongestants if they trigger episodes.

Frequently asked questions

What is Wolff-Parkinson-White syndrome?

WPW is a heart condition present from birth in which an extra electrical pathway connects the upper and lower chambers. It can cause episodes of very fast heartbeat and, rarely, dangerous rhythms.

What are the symptoms of WPW?

Symptoms include sudden episodes of a racing, pounding heartbeat, palpitations, dizziness, shortness of breath, chest discomfort and sometimes fainting. Many people with a WPW pattern on ECG never have symptoms.

Is WPW syndrome dangerous?

Most people have episodes of fast heartbeat that are uncomfortable but not life-threatening. Rarely, atrial fibrillation conducted through the extra pathway can cause sudden cardiac arrest, which is why risk assessment is recommended.

Can WPW be cured?

Yes. Catheter ablation destroys the extra pathway and cures WPW in over 90% of people, often in a single procedure with a short recovery.

What should I do during a WPW episode?

Try vagal maneuvers such as bearing down or splashing cold water on your face. If the episode does not stop within 15 to 20 minutes, or you feel faint, short of breath or have chest pain, seek emergency care.