Catheter Ablation of Tachycardia Involving Twin/Single Atrioventricular Node in Patients With Right Isomerism.

Aims: In addition to well-documented tachycardias involving twin atrioventricular (AV) nodes, tachycardias involving a single node have been clinically experienced in right atrial isomerism (RAI). This study aimed to characterize the AV node involvement patterns and evaluate the outcome of ablation therapy in RAI patients with tachycardias.

Methods: We retrospectively analyzed the medical records of 16 RAI patients who underwent catheter ablation of tachycardias involving twin or single AV nodes at our center between April 2006 and March 2020.

Results: A total of 22 ablation procedures were performed in 16 patients. The median age and body weight were 2 years (range 20 months-31 years) and 11.2 kg (range 7.4-42 kg), respectively. Two QRS complexes were confirmed in 11/16 patients, and a single QRS complex in 5/16. The dominant AV node was anterior in 7/16. Four patterns of tachycardias were identified: tachycardias reciprocating between two AV nodes with retrograde conduction through the anterior AV node (3/16) or through the posterior AV node (4/16); and reentrant tachycardias involving the anterior AV node only (3/16) or posterior AV node only (6/16). Ablation successfully eliminated the tachycardias in 15/16 patients (93.8%). Recurrence was reported in 7/16 (44%) during a median follow-up period of 96.5 months. Five of those 7 patients underwent additional ablation, and the tachycardias were eliminated in 3/5 patients. None of the patients developed ventricular asynchrony after ablation.

Conclusion: Transcatheter ablation was effective in RAI patients with tachycardias involving twin or single AV nodes, and deterioration of the cardiac function was rare.