Para-Hisian Accessory Pathway: Mapping Using Open-Window and Ablation From the Aortic Cusp.

A 28-year-old male with palpitations and a Wolff-Parkinson-White electrocardiographic pattern was referred to our division for ablation. The previous 3 ablation attempts from the right atrioventricular annular side performed at different times in the last year were unsuccessful. His conventional 12-lead surface ECG showed highly possible para-Hisian accessory pathway (AP) localization (Figure 1, Panel A). Prior to mapping, a decapolar catheter was advanced into the coronary sinus for intracardiac reference during activation mapping if orthodromic tachycardia developed. During baseline conditions and also after isoproterenol infusion, no sustainable atrioventricular reentrant tachycardia was induced. The AP effective refractory period was 220 milli seconds during programmed atrial stimulation under isoproterenol infusion. Localization and ablation of APs using a 3D electroanatomic mapping (EAM) system and open-window strategy have been previously defined. 1 The open-window strategy using a 3D EAM system (Carto®3, Biosense Webster Inc., Diamond Bar, Calif, USA) was performed during sinus rhythm. A 20-electrode multipolar mapping catheter with 2 mm inter-electrode distance (Pentaray™ Nav, Biosense Webster Inc.) was used for high-density mapping of the right atrium, tricuspid annulus, and right ventricular. For the open-window strategy, the window-of-interest (WOI) was set according to the surface electrocardiography QRS reference including QRS duration and estimated location of atrial and ventricular intracardiac signals obtained from the multielectrode