Case report: spontaneous atriofascicular pathway automaticity simulating ventricular tachycardia.

Atriofascicular pathways most commonly present electrocardiographically as an antidromic reciprocating AV reentrant tachycardia. We report the case of a child who presented in infancy with a wide QRS complex tachycardia thought to be supraventricular tachycardia with aberrant conduction, associated with tachycardia-induced cardiomyopathy. Later in life the same patient represented with episodes of palpitations secondary to a wide QRS complex tachycardia, thought to be ventricular tachycardia. Electrophysiologic mapping demonstrated the origin of the wide QRS complex tachycardia was from automatic activity originating from a right anterolateral atriofascicular pathway, which also participated in a reentrant antidromic AV reciprocating tachycardia. Radiofrequency ablation of the atriofascicular pathway successfully eliminated both arrhythmias. The mechanism of the wide QRS complex tachycardia appeared to result from spontaneous automaticity of the atriofascicular pathway.