Boundary-Condition Analysis of an Idealized Left Atrium Model.

The most common type of cardiac arrhythmia is atrial fibrillation (AF), which is characterised by irregular and ineffective atrial contraction. This behaviour results into the formation of thrombi, mainly in the left atrial appendage (LAA), responsible for thromboembolic events. Very different approaches are considered as therapy for AF patients. Therefore, it is necessary to yield insight into the flow physics of thrombi formation to determine which is the most appropriate strategy in each case. Computational Fluid Dynamics (CFD) has proven successful in getting a better understanding of the thrombosis phenomenon, but it still requires validation by means of accurate flow field in vivo atrial measurements. As an alternative, in this paper it is proposed an in vitro flow validation, consisting in an idealised model that captures the main flow features observed in the human LA which, once combined with Particle Image Velocimetry (PIV) measurements, provides readily accessible, easy to emulate, detailed velocity fields. These results have been used to validate our laminar and Large Eddy Simulation (LES) simulations. Besides, we have run a parametric study of different boundary conditions sets previously employed in the literature. These data can be used as a benchmark for further development of LA CFD models.