Abstract 25: The Use of Voltage Mapping for Slow Pathway Visualization and Ablation of Atrioventricular Nodal Reentry Tachycardia in Pediatric and Young Adult Patients

Abstract

Atrioventricular nodal reentry tachycardia (AVNRT) is a common arrhythmia in both pediatric and adult patients. Ablation of the arrhythmia substrate has typically been guided by anatomical location and electrogram morphology within the triangle of Koch. Using an anatomic approach can be challenging because of unusual pathway locations and anatomic variance. The use of voltage gradient mapping has been proposed in adults to aid in identification of the “slow pathway”, guiding placement of the ablation applications. The purpose of this study was to evaluate this novel technique of voltage guided ablation of AVNRT in a pediatric patient population, with a smaller triangle of Koch. Patients with atrioventricular nodal reentry tachycardia at the University of Iowa Children’s Hospital who underwent voltage mapping within the slow pathway area were included. Using intracardiac electrical recordings, three-dimensional voltage maps of the right atrium were created. A voltage map identified a bridge of lower voltage signals surrounded by even lower voltage tissue. This bridge was used to guide cryoablation of the slow pathway. Patient demographics, appearance of the intracardiac voltage mapping, timing of procedure, lesions to success, and total number of lesions was obtained. In this study there were 29 patients with an average age of 14 years (range 7 to 20 years) who underwent AVNRT ablation with voltage mapping. Ten were male. In these patients there was procedural success (no inducible AVNRT, single AV node echo beat or less) in all patients. In 25 of 29 patients, there was an adequate lower voltage saddle to allow guided ablation. The successful ablation site was within the first three lesions in 15/25 patients. Total lesions ranged from 5-34. There has been recurrence in 1 patient over an average follow-up period of one year (range five months - twenty months). The use of voltage guided ablation of a low voltage saddle in atrioventricular nodal reentry tachycardia is a technique that appears to be effective and safe in the pediatric population and has the advantage of allowing an electrically guided ablation therapy. Voltage guided ablation of atrioventricular nodal reentry tachycardia is a safe and effective technique for ablating AVNRT.