Objectives: We sought to characterize re-entry circuits causing intra-atrial re-entrant tachycardias (IARTs) late after the repair of congenital heart disease (CHD) and to define an approach for mapping and ablation, combining anatomy, activation sequence data and entrainment mapping.
Background: The development of IARTs after repair of CHD is difficult to manage and ablate due to complex anatomy, variable re-entry circuit locations and the frequent co-existence of multiple circuits.
Methods: Forty-seven re-entry circuits were mapped in 20 patients with recurrent IARTs refractory to medical therapy. In the first group (n = 7), ablation was guided by entrainment mapping. In the second group (n = 13), entrainment mapping was combined with a three-dimensional electroanatomic mapping system to precisely localize the scar-related boundaries of re-entry circuits and to reconstruct the activation pattern.
Results: Three types of right atrial macro-re-entrant circuits were identified: those related to a lateral right atriotomy scar (19 IARTs), the Eustachian isthmus (18 IARTs) or an atrial septal patch (8 IARTs). Two IARTs originated in the left atrium. Radiofrequency (RF) lesions were applied to transect critical isthmuses in the right atrium. In three patients, the combined mapping approach identified a narrow isthmuses in the lateral atrium, where the first RF lesion interrupted the circuit; the remaining circuits were interrupted by a series of RF lesions across a broader path. Overall, 38 (81%) of 47 IARTs were successfully ablated. During follow-up ranging from 3 to 46 months, 16 (80%) of 20 patients remained free of recurrence. Success was similar in the first 7 (group 1) and last 13 patients (group 2), but fluoroscopy time decreased from 60 +/- 30 to 24 +/- 9 min/procedure, probably related to the increasing experience and ability to monitor catheter position non-fluoroscopically.
Conclusions: Entrainment mapping combined with three-dimensional electroanatomic mapping allows delineation of complex re-entry circuits and critical isthmuses as targets for ablation. Radiofrequency catheter ablation is a reasonable option for treatment of IARTs related to repair of CHD.