Catheter Ablation of an Anteroseptal Accessory Pathway Guided by Three-dimensional Electroanatomical Mapping in Symptomatic Wolff-Parkinson-White Syndrome

OBJECTIVE: To report a case of a successful anteroseptal accessory pathway ablation in a 32-year old male with symptomatic Wolf-Parkinson-White (WPW) syndrome with the guidance of three-dimensional (3D) electroanatomical mapping. CLINICAL PRESENTATION: This is the case of a 32-year old male with symptomatic WPW syndrome presenting as frequent episodes of palpitations since 2002 despite being maintained on flecainide 100 mg twice daily. He was initially admitted in another institution for electrophysiological study (EPS), which showed orthodromic tachycardia using an anteroseptal pathway. Due to the proximity of the accessory pathway to the bundle of His, ablation was not attempted. He was referred to our institution and eventually underwent successful radiofrequency (RF) ablation of the anteroseptal accessory pathway with the guidance of 3D electroanatomical mapping. At baseline, the His proximal electrodes appeared to have the earliest ventricular activation in sinus rhythm, and the earliest His bundle activation with ventricular pacing as well. During tachycardia, there was concentric ventriculo-atrial (VA) conduction via the accessory pathway, with the earliest VA conduction at the His electrode essentially fused. The accessory pathway was mapped to the anteroseptal region of the tricuspid annulus that was 2 to 3 mm from the Bundle of His. RF application in this area during sinus rhythm with 3D electroanatomical guidance resulted in loss of the delta wave after 2 seconds of energy application of 30 watts at 35° (right antero-oblique), which persisted after the ablation. SIGNIFICANCE: EPS with RF ablation is the first-line treatment for symptomatic WPW syndrome. However, due to the potential for atrioventricular block especially in the anteroseptal accessory pathway ablation because of its close proximity to the His bundle, precise mapping of the tract is essential and can be accomplished using 3D electroanatomical mapping.