Wolff–Parkinson–White syndrome

Background

Orthodromic (~95%)
- Accessory pathway (Kent bundles) is used for retrograde reentry conduction
  - QRS narrow (delta wave absent)
  - May see ST depression, TWI
  - Rate 150-250 bpm
Antidromic (~5%)
- Accessory pathway used for anterograde conduction
  - QRS wide, delta wave present

Short PR interval - <0.12sec
1. Due to loss of normal AV node conduction delay
2. Differentiate from premature junctional complex
Delta wave / slurred upstroke
1. Due to early activation of ventricular myocardium
QRS duration > 0.10 sec
1. Represents a fusion beat

Orthodromic
- Treat like paroxysmal SVT:
  - Unstable
    - Cardioversion (synchronized)
      - Adult: 50-100 J
      - Peds: 0.5-2 J/kg
  - Stable
    - CCBs, BBs, procainamide, or adenosine
      - Procainamide safe irrespective of type of pathway conduction
Antidromic
- Treat like ventricular tachycardia:
  - Synchronized cardioversion
    - Adult: 50-100 J
    - Peds: 0.5-2 J/kg
  - Procainamide
    - 17mg/kg IV over 30min (up to 50mg/kg or 50% widening of QRS complex)
  - Amiodarone
  - Contraindicated: 'ABCD' drugs ie adenosine, BBs, CCBs, digoxin
Wide-complex, irregular (presumed preexcited A-fib)
- Unsynchronized cardioversion (200J)

Discharge:
- Consider if dysrhythmia was easily terminated and can arrange outpt EP study with poss RF catheter ablation
- C/w with cardiologist regarding outpt beta-blockers vs. more potent medications (amiodarone, sotalol, flecainide, etc.)
Admit or transfer to center with electrophys^[1]:
- Pts with chest pain, CHF, electrolyte imbalance, or required cardioversion
- Syncope
- Uncertain dx (wide-complex tachycardia)
- Significant associated structural heart disease (MVP, cardiomyopathy)
- Family hx of Sudden cardiac death
- Atrial flutter or atrial fibrillation