Rapid atrial pacing: A useful technique during slow pathway ablation

Background: Catheter ablation is the treatment of choice for atrioventricular nodal reentrant tachycardia (AVNRT) with a success rate of 95-98%. The appearance of junctional rhythm during radiofrequency (RF) application to the slow pathway has been consistently reported as a marker for the successful ablation of AVNRT. Ventriculoatrial (VA) conduction during junctional rhythm has been used by many as a surrogate marker of antegrade atrioventricular nodal (AVN) function. However, VA conduction may not be an accurate or consistent marker for antegrade AVN function and reliance on this marker may leave some patients at risk for antegrade AVN injury. Objective: The purpose of this study is to describe a technique to ensure normal antegrade AVN function during junctional rhythm at the time of RF catheter ablation of the slow pathway. Methods: Retrospective review of all patients less than 21 years old who underwent RF ablation for AVNRT at our institution from January 2002 to July 2005. During RF applications, immediately after junctional rhythm was demonstrated, RAP was performed to ensure normal antegrade AVN function. Postablation testing was performed to assess AVN function and tachycardia inducibility. Results: Fifty-eight patients underwent RF ablation of AVNRT during the study period. The mean age ± SD was 14 ± 3 years (range: 5-20 years). The weight was 53 ± 15 Kg (range: 19-89 Kg). The preablation Wenckebach cycle length was 397 ± 99 msec (range: 260-700 msec). Fifty-four patients had inducible typical AVNRT, and four patients had atypical tachycardia. The mean tachycardia cycle length ± SD was 323 ± 62 msec (range: 200-500 msec). Patients underwent of 8 ± 7 total RF applications (median: 7; range 1 to 34), for a total duration of 123 ± 118 seconds (median: 78 sec, range: 20-473 sec). Junctional tachycardia was observed in 52 of 54 patients. RAP was initiated during junctional rhythm in all patients. No patient developed any degree of transient or permanent AVN block. Following ablation, the Wenckebach cycle length decreased to 364 ± 65 msec (P < 0.01). Acutely successful RF catheter ablation was obtained in 56 of 58 patients (96%). Conclusion: Rapid atrial pacing during radiofrequency catheter ablation of the slow pathway is a safe alternative approach to ensure normal AVN function.