SLL-Type CCTGA With Dual AV Conduction System: Anterior AV Node-Origin Atrial Tachycardia From RVOT.

BACKGROUND

Congenitally corrected transposition of the great arteries (ccTGA) involves atrio-ventricular/ventriculo-arterial discordance, leading to AV node-His bundle variations that complicate RVOT anterior AV node-origin atrial tachycardia (AT).

CASE SUMMARY: A 16-year-old male with 3-year paroxysmal palpitations (worsened 6 months) had narrow QRS tachycardia. Echocardiography/CTA confirmed SLL-type ccTGA. Electrophysiologic study revealed dual AV conduction system (RVOT His potentials) and RVOT as the earliest activation site. Radiofrequency ablation succeeded, with no recurrence/AV block at 12-month follow-up.

CONCLUSION

In ccTGA, pulmonary artery/RVOT is adjacent to the anteroseptum (aortic sinuses distant); redefining localization/ablation strategies ensures safety and success.