TRANSCATHETER ABLATION OF POSTEROSEPTAL ACCESSORY PATHWAYS USING A VENOUS APPROACH AND RADIOFREQUENCY ENERGY

Background The efficacy of transcatheter ablation of atrioventricular (AV) accessory pathways (APs) located in the posteroseptal region usin g a right atrial approach and radiofrequency energy was evaluated. Met hods and Results Fifty consecutive patients with APs in the posterosep tal region underwent radiofrequency catheter ablation. Manifest preexc itation was present in 36 patients and a concealed AP in 14. In 18 pat ients (group 1), the ventriculoatrial (VA) interval during orthodromic tachycardia was prolonged by 21+/-7 milliseconds (range, 10 to 30 mil liseconds) with functional left bundle-branch block. In 16 patients (g roup 2), functional left bundle-branch block caused no VA interval pro longation. The remaining 16 patients (group 3) had no inducible left b undle-branch block during orthodromic tachycardia. Functional right bu ndle-branch block was induced in 30 patients with no effect on the VA interval. In group 1, of 14 patients with manifest preexcitation durin g sinus rhythm, 10 patients had a positive delta wave in lead V-1. Of 10 group 2 patients with manifest preexcitation, only 5 had a positive delta wave in lead V-1. In group 3, of 12 patients with manifest pree xcitation, 7 exhibited a positive delta wave in lead V,. All posterose ptal APs were successfully ablated, and this was achieved via a right atrial approach in 48 patients and left ventricular approach in only 2 . Successful sites were at the posteroseptal region of the tricuspid a nnulus (30 patients), within the terminal 1 cm of the coronary sinus i ncluding its ostium (16 patients), and at the inferomedial aspect of t he right atrium posterior to the coronary sinus ostium (2 patients). T he posteroseptal region of the left ventricle was the site of successf ul ablation in 2 patients. Six patients with a recurrence of AP conduc tion required a repeat ablation, with successful results in 5. Thirty- five patients had a complete electrophysiological evaluation 2 to 3 mo nths after their successful ablation and were found to have no functio ning AP. In 49 patients with a final successful ablation, no recurrenc e of symptoms was noted during a mean follow-up period of 12+/-9 month s. Complications occurring in 3 patients were cardiac tamponade requir ing surgical drainage and repair of a right ventricular tear, pericard ial effusion with no hemodynamic consequence that spontaneously resolv ed, and a transient 2:1 atrioventricular block. Conclusions These data suggest that posteroseptal APs are amenable to successful ablation us ing a right atrial approach. Success was achieved in 47 cases (94%) in this series even though the ECG and/or electrophysiological character istics of the posteroseptal APs of some patients were suggestive of '' left-sided'' pathways.