⚡ Chapter 47: Arrhythmias in Children

SVT · VT · VF · Bradyarrhythmias · JET · Long QT · AV Block · Antiarrhythmics · Defibrillation · Cardioversion

⚡ Arrhythmias in Children: Recognition and Management

📊 Epidemiology
55/100,000 paediatric ED visits. Most common: sinus tachycardia, SVT (13%), bradycardia (6%). SVT most common symptomatic paediatric arrhythmia.
🫀 Supraventricular Tachycardia (SVT)
Heart rate >220/min (infants) or >180/min (older). Narrow QRS, regular. No P waves or retrograde. Vagal manoeuvres → adenosine 0.1 mg/kg rapid push. Synchronised cardioversion if unstable.
💓 Ventricular Tachycardia (VT)
Wide QRS, monomorphic or polymorphic. Capture/fusion beats. Unstable → defibrillate 2-4 J/kg. Stable → amiodarone 5 mg/kg or lidocaine.
⚠️ Ventricular Fibrillation (VF)
Chaotic, no output. Defibrillate 2 J/kg → 4 J/kg → up to 10 J/kg. Epinephrine q3-5 min. Amiodarone after 3rd shock.
🐢 Bradyarrhythmias
Symptomatic bradycardia (hypotension, poor perfusion) → atropine 0.02 mg/kg, epinephrine infusion, or pacing. AV block: 1st degree (prolonged PR), 2nd degree Mobitz I (Wenckebach, benign), Mobitz II (unstable), 3rd degree complete heart block.
💊 Antiarrhythmics (Classes)
Ia: Procainamide, Ib: Lidocaine, Ic: Flecainide, II: Beta-blockers, III: Amiodarone, IV: Verapamil. JET (post-cardiac surgery) → cooling, amiodarone, overdrive pacing.
📌 Key Pearls: Evaluate haemodynamic status first — unstable arrhythmia requires immediate cardioversion/defibrillation. Adenosine is first-line for stable SVT. Avoid verapamil in infants (risk of cardiovascular collapse). Long QT syndrome (QTc >0.47) → beta-blockers, avoid triggers.

🩺 Step-by-Step: Approach to Paediatric Arrhythmias

1
Assess haemodynamic status
Is the child stable (normal BP, perfusion, mental status) or unstable (hypotension, poor perfusion, altered sensorium, shock)? THIS determines urgency of intervention.
2
Unstable tachycardia with pulse → immediate synchronised cardioversion
Give sedation if possible. Energy: 0.5-1 J/kg, increase to 2 J/kg. For unstable SVT, VT with pulse.
3
Pulseless arrest (VT/VF) → defibrillation
2 J/kg → 4 J/kg → up to 10 J/kg. Resume CPR immediately after shock. Give epinephrine q3-5 min. Amiodarone after 3rd shock.
4
Stable narrow-complex tachycardia (SVT) → vagal manoeuvres → adenosine
Vagal: ice to face, Valsalva. Adenosine 0.1 mg/kg rapid IV push (max 6 mg), followed by flush. If no effect, repeat 0.2 mg/kg (max 12 mg).
5
Stable wide-complex tachycardia → differentiate VT vs SVT with aberrancy
Presume VT until proven otherwise. Amiodarone 5 mg/kg IV over 20-60 min. Lidocaine 1 mg/kg alternative.
6
Symptomatic bradycardia → atropine, epinephrine, pacing
Atropine 0.02 mg/kg (min 0.1 mg, max 0.5 mg). Epinephrine infusion 0.05-0.3 mcg/kg/min. Transcutaneous or transvenous pacing if refractory.
7
Post-cardiac surgery JET (junctional ectopic tachycardia)
Cool to 34-35°C, reduce inotropes, correct Mg/K/Ca, amiodarone, overdrive atrial pacing.