Pediatric Tachyarrhythmia
Definition and epidemiology
A tachyarrhythmia is a heart rate faster than the upper limit of normal for age arising from an abnormal or accelerated rhythm. The clinically decisive first step is separating sinus tachycardia (a physiological response to fever, pain, hypovolaemia, anaemia or sepsis) from a primary tachyarrhythmia that needs rhythm-directed therapy. Supraventricular tachycardia (SVT) is the commonest symptomatic non-sinus arrhythmia of childhood, with an estimated incidence of roughly 1 in 250–1000 children; most paediatric SVT is re-entrant (accessory pathway or AV-nodal). Ventricular tachycardia (VT) is far less common and usually signals structural heart disease, channelopathy, myocarditis, electrolyte derangement or toxin exposure.
Clinical features
Presentation depends on rate, duration and underlying cardiac reserve. Infants tolerate fast rates poorly and often present late with feeding difficulty, pallor, irritability, sweating or frank heart failure after hours of unrecognised SVT. Older children report palpitations, chest discomfort, dizziness or syncope.
- Sinus tachycardia: rate usually <220/min (infants) or <180/min (children), variable beat-to-beat rate, normal P waves, an identifiable cause and a compatible history.
- SVT: abrupt onset/offset, fixed non-variable rate, rate generally ≥220/min (infants) or ≥180/min (children), P waves absent or abnormal, narrow QRS.
- VT: wide-QRS tachycardia, often with haemodynamic compromise; assume VT until proven otherwise in any wide-complex tachycardia.
Diagnosis
Assess perfusion and obtain a 12-lead ECG and continuous monitoring early. The pivotal branch point is QRS width: narrow (≤0.09 s) points to sinus tachycardia or SVT, while wide (>0.09 s) is treated as VT. Then judge whether the rhythm is causing cardiopulmonary compromise (hypotension, altered mental status, signs of shock), which dictates urgency.
See the full criteria: Pediatric Tachyarrhythmia Algorithm
Red flags
- Hypotension, poor perfusion, altered consciousness or signs of shock with the tachycardia
- Wide-complex tachycardia in any child (treat as VT)
- Infant with sustained rate ≥220/min and feeding failure or heart-failure signs
- Syncope or chest pain during palpitations, or a family history of sudden death/channelopathy
- Failure to respond to initial vagal/pharmacological measures
Management overview
Management is driven by perfusion status and QRS width, not by rate alone.
- Sinus tachycardia: do not attempt to slow the rhythm — search for and treat the underlying cause (fever, hypovolaemia, sepsis, pain, anaemia).
- Stable SVT (narrow QRS, adequate perfusion): vagal manoeuvres first (ice to the face in infants, Valsalva in older children), then a rapidly-acting AV-nodal blocking agent (adenosine) by rapid IV/IO push if access is immediate.
- Unstable SVT or VT (cardiopulmonary compromise): synchronised cardioversion without delay; adenosine may be tried only if it does not delay cardioversion and access is already in place.
- Wide-complex/VT, stable: expert paediatric cardiology/electrophysiology consultation before antiarrhythmic therapy; treat reversible causes (electrolytes, toxins, ischaemia).
- Throughout: correct hypoxia, electrolyte abnormalities and toxic exposures; obtain a 12-lead ECG before and after conversion to document the mechanism, and arrange cardiology follow-up for definitive management (including consideration of ablation in recurrent SVT).
Drug selection, energy doses and infusion rates are weight-based and beyond the scope of this overview — use a verified dosing reference and the resuscitation algorithm at the point of care.
References
- AHA PALS Guidelines 2020 — Pediatric Tachycardia With a Pulse algorithm
- AHA/ESC paediatric supraventricular tachycardia statements
- IAP guidance on paediatric arrhythmias
Decision support for qualified clinicians only — verify against current primary guidelines and your clinical judgement.