A SIMPLE TECHNIQUE FOR SELECTIVE RADIOFREQUENCY ABLATION OF THE SLOW PATHWAY IN ATRIOVENTRICULAR NODE REENTRANT TACHYCARDIA

Objectives. A simple technique was designed for radiofrequency ablatio n therapy of atrioventricular (AV) node reentrant tachycardia. Backgro und. This technique was based on the hypothesis that slow pathway cond uction reflects conduction through the compact node and its posterior atrial input. Methods. A total of 100 consecutive patients were studie d; there were 37 men and 63 women, with a mean age of 48 +/- 15 years. All 100 patients had induction of sustained tachycardia with (51 pati ents) or without (49 patients) administration of isoproterenol or atro pine, or both. The ablation catheter was initially manipulated to reco rd the largest His bundle deflection from the apex of Koch's triangle. It was then curved downward and clockwise to the area of the compact node when His deflection was no longer visible and the ratio of atrial to ventricular electrogram was < 1. The radiofrequency current was de livered from the 4-mm tip electrode a mean of 5 +/- 7 times at a power of 25 +/- 4 W for a duration of 21 +/- 4 s. The total fluoroscopic ti me was 19 +/- 11 min. Results. Selective ablation (56 patients) or mod ification (26 patients) of the slow pathway without affecting anterogr ade and retrograde fast pathway conduction was achieved in 82 patients . Ablation or modification of both the retrograde fast pathway and the slow pathway but with preservation of anterograde fast pathway conduc tion was noted in 12 patients. Ablation or modification of the retrogr ade fast pathway alone or both anterograde and retrograde fast pathway conduction was noted in three patients. Complete AV node block occurr ed in three patients. Seventy-three patients had no induction of echo beats or tachycardia and 24 patients had induction of a single echo be at after ablation. Follow-up study was performed in 62 patients 76 +/- 18 days after ablation. Thirty-nine patients had no induction of echo beats or tachycardia, 22 had induction of echo beats alone and 1 pati ent had induction of sustained tachycardia. Conclusion. Selective abla tion of the slow AV node pathway can be achieved by a simple procedure with a high success rate and few complications.