Wolff-Parkinson-White (WPW) syndrome
Overview
Wolff-Parkinson-White (WPW) syndrome is a congenital pre‑excitation disorder caused by an accessory atrioventricular pathway (the bundle of Kent) that bypasses the AV node. Antegrade conduction over this pathway produces premature ventricular activation (a delta wave) and permits re‑entrant tachyarrhythmias.
WPW is an important cause of supraventricular tachycardia (SVT) in the emergency department; recognition is essential because some commonly used AV‑nodal blocking therapies are hazardous when atrial fibrillation conducts over an accessory pathway.
Epidemiology and clinical relevance
- Incidence is approximately 1-3 per 1 000 population, with more diagnoses in men and a peak presentation in the third to fourth decades of life.
- Most patients are asymptomatic. Symptomatic presentations include palpitations, light‑headedness, presyncope, syncope, chest pain, dyspnoea and, rarely, cardiac arrest.
- Long‑term risk of sudden cardiac death is low but present: approximately 0.1% per year in asymptomatic patients and approximately 0.3% per year in symptomatic patients.
- Associations include Ebstein’s anomaly and, rarely, PRKAG2 mutations; congenital structural heart disease may coexist.
Pathophysiology (concise)
- An accessory pathway can conduct anterogradely (atria → ventricles), retrogradely (ventricles → atria) or bidirectionally.
- When anterograde conduction occurs, part of the ventricle is activated early producing a short PR interval and a slurred initial QRS upstroke (delta wave).
- The effective refractory period of the accessory pathway determines how rapidly atrial impulses can be transmitted to...