Changes in electrophysiologic properties of the conductive system of the heart in children with atrioventricular nodal reentrant tachycardia after 2–8 years following radiofrequency catheter ablation of the slow pathway

Radiofrequency ablation of the slow pathway is an effective method of treatment in children with atrioventricular nodal reentrant tachycardia. The aim of our study was to evaluate anterograde conduction properties in children before and after radiofrequency ablation of the slow pathway and to determine the efficacy and safety of this method.
Material and methods. Noninvasive transesophageal electrophysiological examination was performed in 30 patients at the follow-up period (mean duration, 3.24 years) after radiofrequency ablation of the slow pathway.
Results. The slow pathway function was observed in 13 patients one day after ablation, in 26 patients during the follow-up period, and in 28 patients after administration of atropine sulfate. Atrioventricular node conduction was significantly decreased the following day after ablation and at the follow-up versus the preablation (165.2 [30.2] bmp and 146.3 [28.5] bpm versus 190.9 [31.4] bpm; P<0.001). The atrioventricular node effective refractory period prolonged significantly the following day after ablation and at the follow-up versus the preablation (319.3 [55.3] ms and 351.0 [82.1] ms versus 248.3 [36.6] ms; P<0.001). Effective refractory period of the fast pathway prolonged significantly as compared with the preablation (from 408.0 [60.4] ms to 481.2 [132.9] ms; P=0.005). The prolongation of effective refractory period of the slow pathway was more significant than effective refractory period of the fast pathway at the follow-up (P<0.001). Two late recurrences occurred; one patient had atrial tachycardia.
Conclusion. Children with atrioventricular nodal reentrant tachycardia can be effectively and safety cured by ablative therapy. The end-point during slow pathway ablation should be the abolition of tachycardia with preservation of dual atrioventricular nodal physiology.