RADIOFREQUENCY ABLATION OF ATRIOVENTRICUL AR NODAL REENTRANT TACHYCARDIAS

The first radical approach to the treatment of atrioventricular nodal reentrant tachycardia was surgical dissection of the perinodal region. This technique has been replaced by the delivery of radiofrequency en ergy by an ablation catheter to the region of the atrioventricular nod e. The aim of this report is to describe the authors' experience of at rioventricular nodal application of radiofrequency current. The study comprised 53 cases (32 women and 21 men, mean age 46 +/- 17 years) wit h frequent attacks of reciprocating tachycardia. Endocavitary electrop hysiological investigation confirmed the intranodal reentrant mechanis m. The region of application of the radiofrequency current was located radiologically and then the precise site determined by the recording of nodal electrical activity. The appearance of junctional rhythm duri ng the procedure was also used as a means of identification of the zon e of ablation. Dual conduction persisted after ablation in 35 patients . However, no episode of tachycardia could be induced after the proced ure. The AH interval increased during application of radiofrequency cu rrent in 3 cases but this abnormality regressed in the 2 months follow ing the procedure. Recurrences of nodal reentrant tachycardia were obs erved in 14 cases (26 %), 24 hours to 2 months after ablation. The rat e of recurrence was significantly higher in patients who did not have a junctional rhythm during application of the radiofrequency current ( 62 % vs 4 %, p < 0.05). The number of recurrences was also greater in the group of patients with persistence of slow intranodal conduction a fter the radiofrequency ablation (p < 0.04). A second session of radio frequency ablation was undertaken in 14 patients and a third session w as required for 2 of them. At the end of these procedures and after a minimal follow-up of 2 months per patient, there were no further recur rences of tachycardia. The only notable electrophysiological phenomeno n was the increase in the length of the cycle of appearance of the Wen ckebach phenomenon from 352 +/- 67 ms before, to 394 +/- 90 ms two mon ths after the ablation (p < 0.01). Changing the conduction properties of the atrioventricular node by application of radiofrequency current in an effective and safe technique for suppressing reciprocating intra nodal tachycardia in patients with frequent and/or invalidating attack s.