Evaluation of blood-stasis in the left atrium using patient-specific CFD

Patients with atrial fibrillation (AF) present increased risk of systemic embolism and stroke, and are usually treated with anticoagulant therapies. Given the risk of adverse effects of these therapies, it is necessary to develop personalized quantitative tools to predict the risk of LA thrombogenesis. To that end, a computational fluid dynamics model of patient-specific LA hemodynamics has been developed, where blood stasis and thrombogenesis risk is estimated with the blood residence time (RT). The time-dependent LA geometry was obtained from computed tomography scans. In order to study the effect of atrial contractility and anatomy, simulations were performed for N=4 patients (including one with AF), considering both moving and stationary LA walls. In all subjects blood RT was highest inside the left atrial apendage (LAA). The averaged RT inside the LAA correlated inversely with LAA ejection fractions across different subjects. Furthermore, blood RT in the LAA was markedly higher in the patient with AF. However, the RT for each patient showed a weak dependence on LA wall motion, suggesting that additional factors such as atrial geometry may play a role in governing LA blood stasis.