Cryoablation in pediatric atrioventricular nodal reentry: electrophysiologic effects on atrioventricular nodal conduction.

BACKGROUND: Cryoablation for treatment of atrioventricular nodal reentrant tachycardia (AVNRT) is safe and efficacious. Information on the effects of cryoablation on atrioventricular (AV) nodal conduction is limited. OBJECTIVES: The purpose of this study was to evaluate the effects of cryoablation on AV nodal conduction in pediatric patients with AVNRT. METHODS: We retrospectively analyzed electrophysiologic studies before and after successful cryoablation. Patients were divided into two groups: group 1 (n = 22, age 14 +/- 3 years) had baseline discontinuous atrial-to-His interval (AH) conduction curves; and group 2 (n = 13, age 12 +/- 4 years, P = .054) had continuous curves. RESULTS: At baseline, group 1 had longer measurements of maximal AH with A1A2, AV nodal effective refractory period, and AV block cycle length. Postcryoablation, both group 1 and group 2 showed decreases in maximal AH with A1A2 pacing or atrial overdrive pacing and in the finding of PR > or = RR with atrial overdrive pacing (group 1: 55% vs 5%, P < .001; group 2: 69% vs 0%, P < .001). A significant increase in overall AV effective refractory period and a decrease in AV block cycle length were found in group 1 but not group 2. Fifty percent of group 1 patients had complete abolition of slow pathway conduction. CONCLUSION: Successful cryoablation for treatment of AVNRT is associated with a reduction in PR > or = RR and with decreases in maximal AH with A1A2 pacing or atrial overdrive pacing. Further study is needed to determine the usefulness of these parameters for assessment of ablation efficacy or as proxies for AVNRT inducibility.

Catheter ablation in children and adolescents.

Adult and pediatric interventional electrophysiology practices have been diverging for the past 10 years, and so we review current pediatric ablation practice. Radiofrequency ablation (RFA) is safe and efficacious as documented by recent prospective, multi-center pediatric studies. Computer assisted mapping systems used for complex arrhythmias in adult patients have been successfully deployed in selected pediatric substrates. With increased computational power, decreased catheter size, and increased maneuverability, we expect increased use in the pediatric population. Finally, cryoablation has demonstrated efficacy and safety in locations traditionally associated with increased risk when using RFA, particularly around the AV node. As larger, multi-institutional studies are undertaken, the benefits of this technology in pediatric patients will be better defined.