Clin Res Cardiol (2021). 10.1007/s00392-021-01933-9

Successful pulmonary vein isolation in a patient with Cor triatriatum sinister
A. Wystrach1, A. Dietrich1
1Medizinische Klinik I - Kardiologie und Elektrophysiologie, Klinikum am Bruderwald - Sozialstiftung Bamberg, Bamberg;
Cor triatriatum sinister is a congenital abnormality  with an additional membrane in the left atrium, usually separating some or all pulmonary veins from the mitral valve. While an almost-complete separation will become evident in early childhood and mandates surgical repair, incomplete cor triatriatum with a larger inferior orifice can often be asymptomatic. However, it is associated with an increased rate of atrial fibrillation and stroke. The diagnosis is often made as an incidential finding in imaging before pulmonary vein isolation (PVI). We report a case where we could safely perform PVI in a patient with Cor triatriatum sinister using intracardiac echocardiography (ICE), 3D-Mapping and an atraumatic multipolar mapping catheter.
A 70-year old female patient suffering from drug refractory persistent atrial fibrillation presented for pulmonary vein isolation.
The preinterventional imaging included transesophageal echocardiography and a contrast enhanced computer tomography of the left atrium. Both modalities showed an accessory membrane in the left atrium in a frontal plane, separating the left atrium in two parts (Fig. 1). The membrane was located in front oft the right pulmonary veins with a small inferior opening.
The PVI procedure was performed using a 3D mapping system (Abbott Ensite Precision®).
Transseptal punction was done in a standard manner utilizing intracardiac echocardiography (ICE), accessing the interatrial septum in a distance to the additional membrane. ICE clearly visualized the additional membrane (Fig. 2). Mapping was done using an atraumatic 18polar high-density mapping catheter (Abbott HD Grid ®) to avoid potential trauma. The right pulmonary veins could be accessed through the inferior opening of the membrane. It was feasible to visualize the membrane itself  via the 3D system (Fig. 3). PVI was done in a standard manner using radiofrequency ablation by an irrigated tip catheter with contact force registration. 
Successful PVI of all 4 pulmonary veins could be performed safely; the total procedure time was 190 minutes. No complications appeared in the postprocedural course. The patient was well and discharged in sinus rhythm after 2 days of observation. 
Cor triatriatum is a rare congenital defect which is often first diagnosed in preinterventional imaging before PVI. Performing ablation in these patients can be challenging and has been reported only in a few cases before.
We demonstrated that PVI in a patient with Cor triatriatum sinister was feasible using a 18pole atraumatic mapping catheter under guidance of ICE and a 3D-Mappingsystem. The additional left atrial membrane could be well visualized by 3D-Mapping and ICE.
Fig. 1. TEE imaging using a 3D probe with biplane view. LA: left atrium. M: additional membrane

Fig. 2. ICE image during procedure. LA: left atrium. M: additional membrane. PV: right pulmonary vein. *: multipolar mapping catheter.
Fig. 3. 3D mapping image of the left atrium. Dots: ablation lines. Red: additional membrane.  Green: left atrial appendage *:Transseptal puncture site.