Radiofrequency catheter ablation of atypical atrioventricular nodal reentrant tachycardia.

INTRODUCTION Published reports of radiofrequency ablation of atypical atrioventricular nodal reentrant tachycardia (AVNRT) have been limited. We present our experience in 10 consecutive patients with atypical AVNRT who underwent radiofrequency ablation of the "slow" AV nodal pathway. METHODS AND RESULTS There were 9 females and 1 male; their mean age was 44 +/- 19 years (+/- SD). The mean AVNRT cycle length and ventriculoatrial (VA) interval at the His position during AVNRT were 340 +/- 50 msec and 200 +/- 70 msec, respectively. The slow pathway was successfully ablated in all patients with a mean of 10 +/- 7 radiofrequency energy applications in the posteroseptal right atrium near the coronary sinus os. The mean procedure duration was 100 +/- 35 minutes. There were no complications. In 4 patients, target sites were identified during sinus rhythm by mapping for possible slow pathway potentials. In the other 6 patients, target sites were identified by mapping retrograde atrial activation during AVNRT or ventricular pacing. The VA times at successful target sites were a mean of 45 +/- 30 msec less than the VA time at the His catheter during AVNRT. There were no differences in success rate, number of radiofrequency energy applications, or procedure duration between patients in whom mapping was guided by possible slow pathway potentials or by retrograde atrial activation. During 6 +/- 3 months of follow-up, 1 patient had a recurrence of atypical AVNRT and underwent a second ablation procedure, which was successful. CONCLUSION Radiofrequency ablation of atypical AVNRT can be safely and effectively accomplished when target sites are identified based either on possible slow pathway potentials during sinus rhythm or retrograde atrial activation times during tachycardia.