Case Report: Catheter ablation of atrial fibrillation in a patient with cor triatriatum sinistrum: the pivotal role of intracardiac echocardiography and electroanatomic mapping

Figures

• 

  Figure 1. Preprocedural evaluations. (A)​ Preprocedural 24-h Holter monitoring demonstrated persistent atrial fibrillation with a prolonged RR interval up to 2.47 s. Coarse fibrillatory waves are visible on the surface electrocardiogram. (B)​ Transthoracic echocardiogram views revealed cor triatriatum sinister. The fibromuscular membrane is located at the midportion of the left atrium, with a fenestration orifice measuring approximately 15.1 mm and a membrane length of 30.5 mm (consistent with Type III CTS). (C)​ Preprocedural transesophageal echocardiography confirmed the absence of intracardiac thrombi.

• 

  Figure 2. Intraprocedural findings and postablation follow-up.​ (A) left atrial geometry reconstructed using intracardiac echocardiography (ICE) integrated with the CARTO 3 system, illustrating the accessory chamber (gray), true atrium (green), and fibromuscular membrane (brown). (B) Intraprocedural ICE imaging revealed a thickened interatrial septum with the membrane located at its mid-portion. (C) Electroanatomic voltage mapping demonstrated bilateral pulmonary veins with two distinct branches each, preserved voltage in the membrane on the accessory chamber side. (D) Ablation lesions delivered following the CLOSE protocol principles (lesion spacing: 3–5 mm; ablation index targets: 350–400 for posterior walls, 450–480 for roof walls, and 480–520 for anterior walls). (E) A circular mapping catheter advanced through the membrane fenestration into the true atrium, confirming preserved anterior wall voltage. (F) At 30-month follow-up, electrocardiogram showed no recurrence of atrial tachycardia.