Pediatric Bradyarrhythmia

Definition and epidemiology

Bradyarrhythmia is a heart rate slower than the normal range for age that produces, or threatens to produce, inadequate systemic perfusion. In children the overwhelming majority of clinically significant bradycardia is secondary to hypoxia and respiratory failure rather than a primary conduction disorder — the AHA estimates roughly 80% of paediatric arrests are respiratory in origin, and bradycardia is the common pre-arrest rhythm. Primary causes (congenital or post-surgical complete heart block, sinus node dysfunction, myocarditis, channelopathy) are far less frequent but important to recognise. Other reversible drivers include raised vagal tone, hypothermia, raised intracranial pressure, electrolyte disturbance, and drug toxicity (digoxin, beta-blockers, calcium-channel blockers, organophosphates).

Clinical features

Symptomatic bradycardia presents with signs of poor cardiac output: lethargy or altered mental status, pallor or cyanosis, hypotension, cool peripheries, weak pulses, and respiratory distress. In neonates and infants apnoea, poor feeding and hypotonia may dominate. The key clinical question is whether the slow rate is accompanied by cardiopulmonary compromise — the threshold for active intervention.

Diagnosis

Confirm the rate against age-specific norms, assess perfusion, and obtain a 12-lead ECG plus continuous monitoring. Characterise the rhythm: sinus bradycardia, AV block (first/second/third degree), or junctional rhythm. Critically, always assess and support airway, oxygenation and ventilation first — most paediatric bradycardia resolves with effective oxygenation and ventilation alone.

See the full criteria: Pediatric Bradyarrhythmia Algorithm

Red flags

• Heart rate <60/min with signs of poor perfusion despite adequate oxygenation and ventilation
• Hypotension, altered mental status, or shock accompanying the bradycardia
• Complete (third-degree) AV block, especially congenital or post-cardiac-surgery
• Bradycardia in the context of suspected drug toxicity or raised intracranial pressure
• Failure to respond to ventilation and first-line pharmacological measures

Management overview

The paediatric bradycardia pathway is oxygenation-first, then escalates by perfusion status.

1. Support the ABCs: open the airway, give high-concentration oxygen, and assist ventilation — this alone corrects most paediatric bradycardia.
2. If HR <60/min with poor perfusion persists despite effective oxygenation and ventilation: start CPR (chest compressions).
3. Pharmacological support: a catecholamine/vasopressor (epinephrine class) for ongoing symptomatic bradycardia; an anticholinergic (atropine class) when the mechanism is increased vagal tone or primary AV block — atropine is less reliable in children than adults.
4. Pacing: consider transcutaneous pacing for refractory bradycardia due to complete heart block or sinus node dysfunction unresponsive to oxygenation, ventilation and drugs; transvenous/permanent pacing for established conduction disease.
5. Treat reversible causes: hypoxia, hypothermia, electrolyte derangement, raised ICP and specific toxidromes — use the appropriate antidote/strategy where a toxin is identified.
6. Disposition: urgent paediatric cardiology involvement for primary conduction abnormalities and post-arrest critical-care monitoring.

Weight-based drug doses, infusion rates and pacing thresholds are outside this overview — use a verified dosing reference and the resuscitation algorithm at the bedside.

References

• AHA PALS Guidelines 2020 — Pediatric Bradycardia With a Pulse algorithm
• AHA Pediatric Advanced Life Support post-resuscitation care
• IAP guidance on paediatric arrhythmias

Decision support for qualified clinicians only — verify against current primary guidelines and your clinical judgement.