Left atrial access via an unroofed coronary sinus to eliminate fast/slow atypical AVNRT: A case report

Introduction Unroofed coronary sinus is a rare congenital anomaly that may alter the complex anatomy of the atrioventricular (AV) node. Arrhythmia circuits occurring among these patients may not be located in the usual position, especially those circuits involving the AV node. We report a case of the coexistence of this uncommon coronary sinus (CS) anomaly and the atypical form of atrioventricular nodal reentrant tachycardia (AVNRT) that could not be ablated by the conventional right-sided slow pathway modification but required left-sided septal ablation through an unroofed CS.