Selective radiofrequency ablation of the slow pathway on atrioventricular node reentry tachycardia using the inferior approach. Radiofrequency ablation on AV node reentry tachycardia

Transcatheter radiofrequency ablation using the inferior approach for selective ablation of the slow pathway was performed in 439 consecutive patients with various types of atrioventricular node reentry tachycardia. There were 163 men and 276 women with a mean age of 47 ± 16 years. All 439 patients had induction of sustained tachycardia with or without isoproterenol infusion; 391 had a common slow-fast form, 13 had an atypical fast-slow form, while 35 had a multiple form of AV node reentry tachycardia. With the inferior approach, the tip of the ablation catheter was initially manipulated to record the maximum proximal His bundle deflections from the apex of Koch's triangle. It was then curved downward and clockwise to the inferior aspect of Koch's triangle along the tricuspid annulus where His bundle deflections were no longer visible and the ratio of atrial to ventricular electrogram was < 1. The radiofrequency current was delivered from the 4 mm tip electrode. Successful ablation was achieved in 422 patients (96%) while in 8 patients (2%) ablation failed. In 9 patients, transient (2 patients or 0.5%) or persistent (7 patients or 1.5%) heart blocks developed after ablation. Successful ablation required a median of 2 applications (range of 1-39) at a power of 24 ± 4 watts and a duration of 18 ± 5 sec. The mean total fluoroscopic exposure time was 18 ± 10 min. Successful ablation resulted in selective ablation of the slow pathway (patients with slow-fast or fast-slow form tachycardia) or with the ablation of both the slow pathway and the intermediate pathway (patients with variant form of slow-fast or multiple forum tachycardia) in 89% of the patients. A follow-up electrophysiologic study was performed in the 265 patients with an initial success; no evidence of recurrence was noted in 95% while recurrence was observed in 5%. A late study was also conducted in 6 patients with an initially failed ablation and 2 showed no inducible tachycardia or echo while 4 continued to have inducible sustained AV node reentry tachycardia. Fifteen of the 18 patients with an initially failed ablation or recurrence had a successful ablation after a second attempt of ablation. In conclusion, the inferior approach is a simple, effective and safe therapeutic procedure and should be considered as a preferred approach for ablation of various types of AV node reentry tachycardia.