Ablation of isthmus and non-isthmus-dependent flutters in a patient with cor triatriatum dexter

A 59-year-old man who had repair of ventricular septal defect was referred for ablation of typical atrial flutter (AFL). Due to an unusual high posterior ‘ridge’, positioning of the catheters was difficult, and medial/midline isthmus ablation with an 8 mm tip large curve catheter was unsuccessful. Ablation of the lateral isthmus with a Mullins sheath was eventually successful. Upon review of the pre-procedure transoesophageal echocardiogram, a prominent membrane was noted. The patient was brought back for ablation of another AFL originating from the right atrial (RA) posterior wall. Diagnosis of cor triatriatum dexter (CTD) was suggested by cardiac computed tomography (CT) but confirmed by cardiac magnetic resonance imaging (MRI) which delineated the membrane's insertion into the septum, and sino-atrial ostium diameter of 1.1 cm (Figure).

Cor triatriatum dexter is characterized by an anomalous membrane that partitions the RA into posterior and anterior chambers, and results from persistence of the right sinus valve which later forms the Crista terminalis, Eustachean ridge, and Thebesian. Though commonly an incidental finding, it may present with venous obstruction or supraventricular tachycardia. Our report highlights the feasibility of trans-femoral approach for ablation and the role of cardiac imaging for guiding this procedure in patients with complex anatomy.

The full-length version of this report can be viewed at: http://www.escardio.org/communities/EHRA/publications/ep-case-reports/Documents/non-isthmus-dependent.pdf