The Usefulness of Pre-procedural 3D Print of Both Atria to Plan Transseptal Puncture for the Left Atrial

All patients referred for the left atrial appendage closure will be enrolled. Before the procedure, cardiac CT (computed tomography) will be done. Using cardiac CT, segmentation procedure will be performed. The segmented 3D biatrial reconstruction will be exported in the stereolithography (STL) format and then printed out.

Before every procedure as a part of pre-procedural planning, TSP puncture will be simulated in vitro using the three-dimensional printing (3DP) models and a 12 Fr delivery sheath. Six holes (TSP locations) through the intraatrial septum will be performed from the right side of the septum by a cordless drill. The puncture sites will be localised as follows: three in the cranial part of the fossa ovalis (FO) (anteriorly just behind the aortic root, in the middle and posteriorly) and three in the caudal portion of the FO in the identical way. The delivery sheath will be inserted through each preformed hole and its distal tip was positioned in the LAA (10 - 20 mm deep). The relationship of the sheath and the proximal LAA segment will be evaluated in two orthogonal views. Two criteria had to be met in both views to classify the puncture site as optimal: (1) a central sheath position and (2) a coaxial sheath position (the angle with the LAA ostium axis not exceeding 30°).

All procedures will be done by experienced operators according to the actual guidelines. Intracardiac echocardiography (ICE) or transesophageal echocardiography (TEE) will be used. Before the procedure, each operator received a recommendation regarding the optimal puncture sites. In ICE guided cases, based on the LA anatomical structures visible in the projection plane during TSP, the puncture site was classified as posterior (left-sided pulmonary veins visible), middle (coumadin ridge visible), or anterior (LAA and mitral annulus visible). In TEE guided procedures mainly mid-oesophageal aortic valve short axis view (∼ 25-45°) and mid-oesophageal bicaval view (∼ 90-110°) will be used. Depending on in which third of the interatrial septum the puncture was performed, it will be classified as anterior, middle, or posterior (aortic valve short axis view). The bicaval projection showed the cranio-caudal localization.

The 3DP models were not used for device sizing, it was done based on the CT data and intra-procedural angiography according to the performing physicians' preferences.

The procedural difficulty will be assessed by the operator (focused on the alignment of the delivery assembly with the LAA axis). Furthermore, the number of recaptures of devices will be analyzed, as well as the number of unsuccessful procedures and procedural complications. Additional golas of the project are: to analyse the distribution of optimal puncture sites and to correlate CT 2D measurements with those findings.