Overview
Definition
A pre-excitation syndrome where electrical impulses bypass the AV node via an accessory pathway (Bundle of Kent), predisposing the patient to tachyarrhythmias.
Epidemiology
Affects ~0.1-0.3% of the population. Most patients are asymptomatic.
Etiology & Risk Factors
- Congenital presence of an accessory conduction pathway between the atria and ventricles
Clinical Symptoms
- Palpitations
- Lightheadedness
- Syncope
- Often asymptomatic (WPW pattern only on ECG)
Clinical Approach
Diagnosis
- Classic triad on resting ECG: (1) Short PR interval (< 120 ms), (2) Slurred upstroke of the QRS complex (Delta wave), (3) Widened QRS complex
- Holter monitor or Electrophysiology (EP) study
Management
- Asymptomatic: No treatment necessary
- Symptomatic (Orthodromic AVRT): Vagal maneuvers, Adenosine
- If A-Fib occurs with WPW: DO NOT USE AV nodal blockers (Adenosine, Beta-blockers, CCBs, Digoxin) as they will force all conduction down the accessory pathway, leading to V-Fib. Use Procainamide or synchronized cardioversion.
- Definitive treatment: Radiofrequency catheter ablation of the accessory pathway
Complications
- Supraventricular Tachycardia (AVRT)
- Atrial Fibrillation degenerating into Ventricular Fibrillation (Sudden Cardiac Death)