Single radiofrequency application to cure atrioventricular nodal reentry: Arguments for the slow pathway origin of the high-low frequency slow potentials

Background: High-low frequency slow potentials are thought to be related to the slow AV pathway conduction, Their use was proposed to guide radiofrequ ency (RF) ablation of atrioventricular nodal reentrant tachycardia (AVNRT). The present study was designed to determine the prospective value of these high-low frequency slow potentials to guide AVNRT ablation using a single RF application. Single RF application could indeed reduce the size of the l esion created in the viciny of the specialized AV conduction system and sho rten the radiation exposure and the overall duration of the procedure. Results: Forty-one patients (14 men, 27 women, 45 +/- 16 years old) with AV NRT underwent slow pathway RF ablation guided by high-low frequency slow po tentials. High-low frequency slow potentials were found in all patients alo ng the tricuspid annulus and above the coronary sinus, Ablation was always performed in the posterior part of Koch's triangle. The mean AN amplitude r atio of the successful site was 0.43 +/- 0.59. In 32 patients (78%) AVNRT w as no longer inducible after a single RF application. Procedure and radiati on times were 35 +/- 31 and 13 +/- 12 min respectively. Five patients requi red 2, 3 patients 3, and 1 patient 6 BF applications. The mean number of RF applications was 1.4 +/- 0.9 (median = 1), In the 32 patients who required only one RF application, 24 (75%) had an obvious dual AV nodal pathways wi th a jump before ablation, wich completely disappeared in 18 of them (75%) after ablation, In the 6 remaining patients, who still had a jump after I R F application, there was no significant change in either conduction times o r refractory periods concerning both the antero-grade and retrograde AV con duction, No patient had PR interval purlongation, After a mean follow up of 11 +/- 5 months, recurrence was observed in a single patient who received 2 discontinued RF applications. Conclusion: Catheter-mediated ablation of AVNRT using high-low frequency sl ow potentials to localize the slow AV pathway is feasible and safe, Using t his technique, a single RF application was successfull in 78% of patients, and slow pathway characteristics were completely eliminated in 75% of patie nts. The radiation time and the procedure duration were short. This suggest that, in patients with AVNRT the choice of an appropriate RF target can re duce procedural duration.