Atrial Arrhythmia Cardioversion Pediatric Dose — Synchronized
Synchronized cardioversion is an electrical therapy used in pediatric patients to terminate hemodynamically significant atrial arrhythmias, including supraventricular tachycardia (SVT) and atrial flutter, by delivering a timed shock that coincides with the R wave of the cardiac cycle. By synchronizing to the R wave, the intervention avoids the vulnerable repolarization period and reduces the risk of inducing ventricular fibrillation. It is indicated when pharmacologic measures have failed or when the patient presents with cardiovascular compromise requiring urgent rhythm conversion.
Pediatric Dosing
The recommended dose for synchronized cardioversion of atrial arrhythmias in pediatric patients is 0.5–1 J/kg. This applies as an initial synchronized shock.
- Initial energy: 0.5 J/kg (synchronized)
- May titrate up to 1 J/kg (synchronized) if initial attempt is unsuccessful
Worked example: For a 20 kg child: 20 × 0.5 J/kg = 10 J (initial); may increase to 20 × 1 J/kg = 20 J if needed. Consult institutional protocol for further dose escalation beyond 1 J/kg if arrhythmia persists.
Indications and Clinical Context
Synchronized cardioversion is indicated for the acute management of atrial arrhythmias — including SVT refractory to vagal maneuvers or adenosine, and atrial flutter — particularly when the patient demonstrates signs of hemodynamic instability such as hypotension, altered mental status, poor perfusion, or respiratory distress. In stable patients, chemical cardioversion or rate control may be attempted first; however, synchronized cardioversion is the preferred intervention when rapid rhythm termination is necessary. These recommendations align with Pediatric Advanced Life Support (PALS) guidelines for the management of tachyarrhythmias with a pulse.
Synchronization is a critical distinction from defibrillation: the device must be placed in synchronized mode prior to shock delivery to prevent inadvertent triggering of ventricular fibrillation.
Administration and Monitoring
Deliver the shock via external defibrillator pads or paddles placed in the standard anterolateral or anteroposterior position. Confirm the device is in synchronized (SYNC) mode before each shock delivery, as some devices revert to unsynchronized mode after each discharge. Procedural sedation and analgesia should be provided in non-emergent situations. Ensure continuous cardiac monitoring, pulse oximetry, and resuscitation equipment are immediately available.
- Confirm SYNC mode is active prior to every shock attempt
- Ensure vascular access is established before the procedure when feasible
- Monitor for post-conversion arrhythmias, bradycardia, or hypotension
- Document pre- and post-shock rhythm with 12-lead ECG when possible
- Consult institutional protocol for sedation agent selection and dose escalation beyond 1 J/kg
Disclaimer: This article is an educational reference summarizing standard pediatric dosing values. It is not a substitute for clinical judgment. Always verify doses against institutional protocols, the current edition of authoritative references (e.g., Lexicomp, Harriet Lane Handbook, PALS guidelines), the patient’s accurate weight, and any patient-specific factors (renal/hepatic function, allergies, comedications) before administration.