Pacemapping the Triangle of Koch Reveals Unusual Atrioventricular Nodal Fast Pathway Inputs in Pediatric Patients

Pacemapping the triangle of Koch determines the location of atrioventricular (AV) nodal fast pathway inputs in adults. This study aims to evaluate the technique in pediatrics. A retrospective, single-center study of pediatric patients who underwent ablation for atrioventricular nodal reentrant tachycardia (AVNRT) was performed. Pacemapping was performed from the posteroseptal (PS), midseptal (MS), and anteroseptal (AS) locations. The stimulation to His bundle (SH) times were recorded in milliseconds (ms). The usual fast pathway position was defined as progressive decrease from PS to MS to AS. An abnormal response was defined as SH time in the MS or PS location that was less than that from the AS. Fifty-six ablation procedures were reviewed in 56 patients. The usual fast pathway position was documented in 53 of 56 patients (94.6%), with SH times measured in the PS of 97 ms (63-189 ms), MS of 82 (50-166 ms), and AS of 71 (35-161 ms). Unusual fast pathway inputs were observed in three patients (5.4%). Seven of 56 patients (12.5%) sustained transient AV nodal injury that resolved within minutes. Unusual fast pathway inputs were observed in 5.4 % of pediatric patients undergoing slow pathway ablation for AVNRT. Transient AV nodal injury was documented in 12.5% of cryoablations. No patients with unusual fast pathway inputs had transient AV nodal injury.