Visualization of Atrioventricular Nodal Reentry Tachycardia Slow Pathways Using Voltage Mapping for Pediatric Catheter Ablation.

BACKGROUND: Catheter ablation of the slow atrioventricular (AV) pathway has been shown to be safe and effective in pediatric patients with atrioventricular nodal reentrant tachycardia (AVNRT). Despite that, acute success is not guaranteed, and safety of ablating near the AV node remains a concern. METHODS: A retrospective analysis was performed of all AVNRT ablations using the Ensite NavX voltage mapping technique at our institution. Each map was reviewed with patient and NavX computer data recorded. To account for a learning curve, each map was idealized and compared with the original map. Procedure and fluoroscopy time were compared with a control group. RESULTS: Twenty-eight patients underwent catheter ablation for AVNRT from September 2011 until December 2012 using the voltage mapping technique. The historical control group comprised 24 patients who underwent catheter ablation using the electroanatomic approach. There was 96% acute success with one recurrence in the voltage mapping group, at a mean follow-up of 24 months. The slow pathway was visualized in 86% of patients at the time of ablation, while three of four without could be found on idealization of the voltage map. Mean high- and low-voltage parameters increased with idealization, but showed no correlation with age, gender, or weight. Estimated pathway size had significant inter-patient variability. Procedure and fluoroscopy times did not vary significantly compared with controls. CONCLUSION: Visualization of the AV nodal slow pathway in a pediatric population is possible using voltage mapping technique with the potential to increase safety and efficacy. Variability exists in the voltage parameters needed to visualize individual slow pathways, which leads to a distinct learning curve.