A subtle pre-excitation playing hide and seek

Abstract

24 years female presented with recurrent palpitations for one year. Sinus ECG showed preexcitation pattern suggestive of a posteroseptal accessory pathway. During the electrophysiology study, atrioventricular reciprocating tachycardia was induced with an atrial extra stimulus. Successful ablation was done in posteroseptal region. Post ablation, there was subtle preexcitation on alternate beats with mid septal pattern which showed short and fixed HV. Short fixed HV and preexcitation morphology remained the same both during atrial pacing and junctional beats. This case highlights the unusual finding of intermittent conduction in fasciculoventricular pathway.