Electroanatomic mapping of entrained and exit zones in patients with repaired congenital heart disease and intra-atrial reentrant tachycardia

Background-Characterization of reentrant circuits and targeting ablation si tes remains difficult for intra-atrial reentrant tachycardias (IART) in con genital heart disease (CHD). Methods and Results-Electroanatomic mapping and entrainment pacing were per formed before successful ablation of 18 IART circuits in 15 patients with C HD. principal features of IART circuits were atrial septal defect (4 patien ts), atriotomy (3 patients), other atrial scar (3 patients, crista terminal is (3 patients), and right atrioventricular valve (5 patients). A median of 176 sites (range, 96 to 317 sites) was mapped for activation and 13 sites (range, 9 to 28 sites) for entrainment response. Postpacing intervals withi n 20 ms of tachycardia cyclo length and stimulus-to-P-wave intervals of 0 t o 90 ms (exit zones) were mapped to atrial surfaces generated by electroana tomic mapping. Criteria for entrainment were met over a median of 21 cm(2) of atrial surface (range, 2 to 75 cm(2)), 19% (range, 1% to 81%) of total a rea tested. Using integrated data? relations between activation sequence an d protected corridor of conduction could be inferred for 16 of 17 IARTs. Su ccessful ablation was achieved at a site distant from the putative protecte d corridor in 9 of 18 (50%) circuits. Conclusions-The right atrium in CHD supports a variety of IART mechanisms. Fusion of activation and entrainment data provided insight into specific IA RT mechanisms relevant to ablation.