Persistent wandering atrial pacemaker after epinephrine overdosing – a case report

A 3-year-old toddler developed multifocal atrial tachycardia following an iatrogenic overdose of epinephrine accidentally administered intravenously. His ECG showed wandering atrial pacemaker (p-waves with different origins and configurations) that persisted for at least one year. This event demonstrated the sensitivity of young children to the sympathomimetic drugs, especially overdosing.Health care providers and parents should be warned of toxicities associated with sympathomimetic drug overdosing. Future studies are needed to determine whether wandering atrial pacemaker is a potential long-term complication of high-dose sympathomimetics.Sympathomimetic drugs are known to induce arrhythmias, including multifocal atrial tachycardia, re-entry tachycardia, atrial fibrillation and wandering atrial pacemaker [1,2]. The mechanism is thought to be due to sinus node and atrial tissue sensitivity to α- and β-adrenergic stimuli as well as to decreased cardio-vagal reflex. The mechanisms involve autonomic transmitters, changes in impulse formation, conduction and refractoriness [3,4]. Supraventricular tachycardia may induce left ventricular dysfunction and cardiomyopathy, which are usually reversible once the tachycardia resolves [5].Multifocal atrial tachycardia and wandering pacemaker have already been reported in association with sympathomimetic drug overdosing [2,6]. Multifocal (chaotic) atrial tachycardia is defined as multiple distinct P-wave morphologies, irregular P-P intervals and isoelectric baseline between P-waves with a rapid ventricular rate. Patients with a wandering atrial pacemaker are usually asymptomatic and have irregularly irregular rhythm. The normal heart rate in wandering atrial pacemaker differentiates this condition from multifocal atrial tachycardia [2,6]. Multifocal atrial tachycardia has been described in association with respiratory viruses [7]. The fate of the aberrant atrial electrical activity is unknown.This report describes a toddler with i