Wolff-Parkinson-White Syndrome
Cardiology
Illness script · Cardiology
Wolff-Parkinson-White Syndrome
Pre-excitation syndrome caused by an accessory pathway (Bundle of Kent) bypassing the AV node, producing a characteristic ECG triad and predisposing to life-threatening tachyarrhythmias.
This illness script for Wolff-Parkinson-White Syndrome covers predisposing factors, classic presentation, mechanism, workup, management, and the clinical pivots that separate it from look-alikes—written for USMLE Step 1 and clerkship reasoning.
01
Predisposing factors
- Young patients, teens to young adults; male predominance
- Most cases sporadic; minority familial (PRKAG2 gene mutation)
- Associated with Ebstein's anomaly (most important structural association)
- Associated with hypertrophic cardiomyopathy
- Often discovered incidentally on routine ECG in an asymptomatic patient
02
Presentation
- Classic ECG triad: short PR (<120 ms), delta wave (slurred QRS upstroke), wide QRS (>120 ms)
- Palpitations, lightheadedness, syncope in young patient
- Orthodromic AVRT (most common ~95%): regular narrow-complex tachycardia
- Antidromic AVRT: regular wide-complex tachycardia mimicking V-tach
- WPW + A-fib: irregularly irregular wide-complex tachycardia with variable QRS morphology — extreme rate, life-threatening
- Sudden cardiac death can be the initial presentation
03
Pathophysiology
- Accessory pathway (Bundle of Kent) directly connects atria to ventricles, bypassing AV node
- Antegrade conduction over accessory pathway causes early ventricular activation → delta wave
- Re-entry circuit forms: orthodromic (anterograde via AV node, retrograde via pathway) = narrow QRS; antidromic = wide QRS
- A-fib + WPW is most dangerous: rapid unfiltered antegrade conduction → ventricular fibrillation
04
Diagnostics
- 12-lead ECG: delta wave is pathognomonic; findings may be intermittent
- Electrophysiology study (EPS): gold standard — localizes pathway, assesses risk, guides ablation
- Echocardiogram to exclude Ebstein's anomaly or HCM
- Exercise stress test: abrupt loss of delta wave at higher rates suggests low-risk pathway
- Holter/event monitor for intermittent symptomatic palpitations
05
Management
- Stable orthodromic AVRT: vagal maneuvers → IV adenosine (safe here — pathway is retrograde only)
- Unstable any tachyarrhythmia: immediate synchronized cardioversion
- WPW + A-fib: IV procainamide or ibutilide (slow accessory pathway conduction)
- AVOID AV nodal blockers in WPW + A-fib: adenosine, beta-blockers, CCBs, digoxin accelerate accessory pathway → V-fib
- Definitive treatment: radiofrequency catheter ablation (~95% curative); indicated for symptomatic patients or high-risk EPS findings
06
Clinical pivots
How to separate this script from the look-alikes that show up on exams and on the wards.
AVNRT (typical SVT)
WPW shows delta wave and short PR on baseline ECG; AVNRT baseline ECG is completely normal.
Atrial fibrillation with aberrancy (BBB)
WPW + A-fib shows irregularly irregular wide-complex tachycardia with varying QRS morphology and rates often >200 bpm; BBB-aberrant A-fib has consistent QRS morphology.
Ventricular tachycardia
Antidromic WPW is wide-complex but occurs in young patients without structural disease and has a prior ECG showing delta wave.
Lown-Ganong-Levine syndrome
LGL has a short PR interval but NO delta wave and a narrow, normal QRS complex — no ventricular pre-excitation.
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Full libraryEducational use only. This illness script is a study framework, not medical advice. Confirm decisions with current guidelines and your clinical supervisors.