Hypoxia is the most common cause of pediatric bradycardia. Oxygenation and ventilation should be prioritized before medications.

SVT is the most common pediatric tachyarrhythmia, often presenting with a heart rate >180 bpm in children or >220 bpm in infants, with no distinct P waves.

Atropine (0.02 mg/kg IV, min 0.1 mg, max 1 mg) is used for bradycardia caused by increased vagal tone or AV block when epinephrine fails.

Hyperkalemia presents with peaked T waves first, then progresses to widened QRS, loss of P waves, and eventually a sine wave pattern.

A prolonged QT interval (>460 ms in infants, >440 ms in children) increases the risk of Torsades de Pointes and sudden cardiac arrest.

The first defibrillation dose in pediatrics is 2 J/kg, increasing to 4 J/kg if needed, up to a max of 10 J/kg or adult dose.

Amiodarone (5 mg/kg IV over 20-60 min) is preferred for stable VT. Adenosine is ineffective for VT unless it is aberrantly conducted SVT.

SVT is common in infants, often with rates >220 bpm and absent or abnormal P waves. Sinus tachycardia is usually <220 bpm and has normal P waves.

PEA requires CPR, epinephrine every 3-5 minutes, and treating reversible causes (H’s & T’s). Defibrillation is only for VF/pVT.

Epinephrine (0.01 mg/kg IV/IO every 3-5 min) is the first-line drug for bradycardia due to hypoxia or shock. Atropine is only used for bradycardia caused by increased vagal tone or AV block.

Unstable SVT (with poor perfusion, hypotension, altered mental status) requires synchronized cardioversion (0.5-1 J/kg, increasing if necessary).

Wide-complex tachycardia without a pulse is pulseless VT, which requires immediate defibrillation (2 J/kg, then 4 J/kg).

Adenosine (0.1 mg/kg IV push, max 6 mg first dose) is first-line for stable SVT, causing transient AV node blockade to restore sinus rhythm.

PEA is the most common arrest rhythm in children due to respiratory failure or shock leading to cardiac arrest. Asystole is also common, while VF is rare in pediatrics.