Split accessory pathway potentials in a patient with antidromic AVRT

Accessory pathway potential often indicates a highly effective ablation target in Wolff-Parkinson-White syndrome.A 27-year-old female presenting with palpitation underwent an electrophysiology study, who had mild pre-excitation in surface ECG.An accessory pathway with weak anterograde conduction was found. During isoproterenol infusion, the delta wave became prominent, an antidromic AV reentrant tachycardia was then induced. When the pathway was mapped, widely split double pathway potentials were observed at the 12 o'clock site of the tricuspid annulus during mild pre-excitation, demonstrating an example of intra-pathway conduction delay. Ablation at the site caused accelerated pathway rhythm and eliminated the pathway, rendering the tachycardia noninducible.Split pathway potentials can reflect slow conduction in patients with preexcitation.