Transcatheter Ablation of Posteroseptal Accessory Pathways Using a Venous Approach and Radiofrequency Energy

Background The efficacy of transcatheter ablation of atrio-ventricular (AV) accessory pathways (APs) located in the posteroseptal region using a right atrial approach and radio-frequency energy was evaluated. Methods and Results Fifty consecutive patients with APs in the posteroseptal region underwent radiofrequency catheter ablation. Manifest preexcitation was present in 36 patients and a concealed AP in 14. In 18 patients (group 1), the ventricu-loatrial (VA) interval during orthodromic tachycardia was prolonged by 21±7 milliseconds (range, 10 to 30 milliseconds) with functional left bundle-branch block. In 16 patients (group 2), functional left bundle-branch block caused no VA interval prolongation. The remaining 16 patients (group 3) had no inducible left bundle-branch block during orthodromic tachy-cardia. Functional right bundle-branch block was induced i