Successful Catheter Ablation of Atrial Fibrillation in a Patient With an Abnormal Septum in the Left Atrium.

A 50-year-old man underwent catheter ablation for symptomatic paroxysmal atrial fibrillation. Preprocedural cardiac computed tomography showed an abnormal septum extending from the interatrial septum to the posterior wall of the left atrium (LA) that divided the LA into 2 parts, a main chamber (MC) and an accessory chamber (AC). In addition, a fenestration was observed in the posteroinferior side of the membrane (). The right and left pulmonary veins (PVs) were connected to the AC and the MC, respectively. The fossa ovalis was mainly facing the AC. We performed trans-septal puncture at the inferior edge of the fossa ovalis facing the fenestration to access both the AC and MC. The abnormal septum had no arrhythmogenic activity in terms of conduction velocity, refractory period, and abnormal automaticity (). Ablation was performed using an irrigation catheter (SmartTouch SF®; Biosense Webster, Irvine, CA, USA). Isolation of the PVs was achieved without difficulty ().

Figure.

Horizontal plane (A–C) and inner (D) view of the membrane (red arrow) dividing the left atrium into a main chamber (MC) and an accessory chamber (AC). The blue arrow indicates the site of trans-septal puncture (TSP). (E,F) Ablation sites (red tags). LIPV, left inferior pulmonary vein; LSPV, left superior pulmonary vein; RIPV, right inferior pulmonary vein; RSPV, right superior pulmonary vein.

This case exhibited an anatomical feature that is consistent with “pseudo-cor triatriatum sinister” (p-CTS), where the membrane separating the LA has a large fenestration without any pressure gradient between the 2 chambers. To the best of our knowledge, this is the first case of PV isolation (PVI) in a patient with p-CTS. Successful PVI was achieved via a single trans-septal puncture facing the fenestration.

Disclosures

None.

Electrophysiologic Study Supplementary Figure