Merged two-way mapping technique: an alternative 3D electroanatomical mapping approach to guide challenging ablation procedures of accessory pathways with bidirectional conduction properties

Background Catheter ablation of accessory pathways (AP) with bidirectional conduction may be challenging due to issues related to anatomical course or location. Objective We describe an alternative electro-anatomical mapping technique which aims at depicting the entire anatomic course of the AP from the atrial toward the ventricular insertion in order to guide catheter ablation. Methods Twenty consecutive patients with confirmed bidirectional AP conduction and at least one previous ablation procedure or para-Hisian location were included. 3-D electro-anatomical mapping was used to depict the merged 10-ms isochrone area of maximum early activation of both the ventricular and atrial signals during sinus rhythm and ventricular pacing/orthodromic tachycardia, respectively. Catheter ablation was performed within the depicted earliest isochrone area. Results Acute bidirectional AP conduction block was achieved in all patients 4.2 ± 1.7 s after the first radiofrequency energy pulse was delivered, without reconnection during a 30 ± 10 min post-ablation observation time. No procedural complications were seen. After a mean follow-up period of 9 ± 7 months (range 3 to 16), no recurrences were documented. Conclusion This merged two-way mapping technique is a safe, efficient, and effective technique for ablation of APs with bidirectional conduction.