We analyze left atrium haemodynamics, highlighting differences among healthy individuals and patients affected by atrial fibrillation. The computational study is based on patient-specific geometries of the left atria to simulate blood flow dynamics. We devise a novel procedure aimed at recovering the boundary conditions for the 3D haemodynamics simulations, particularly useful in absence of specific ones provided by clinical measurements. With this aim, we introduce a parametric definition of the atria displacement, and we employ a closed-loop lumped parameter model of the whole cardiocirculatory system conveniently tuned on the basis of the patient characteristics. We evaluate a number of fluid dynamics indicators for the atrial haemodynamics, validating our numerical results in terms of several clinical measurements; we investigate the impact of geometrical and clinical features on the risk of thrombosis. To analyse the correlation of thrombus formation with atrial fibrillation, coherently with the medical evidence, we propose a novel indicator, which we call age stasis and that arises from the combination of Eulerian and Lagrangian quantities. This indicator identifies regions where the slow flow cannot rinse the chamber properly, accumulating stale blood particles and creating optimal conditions for clot formation.
翻译:我们分析左心血管血液动力学,突出受性纤维化影响的健康个人和病人之间的差异。计算研究基于病人对左心室的特异性,以模拟血液流动动态。我们设计了一个新程序,旨在恢复3D血液动力学模拟的边界条件,在没有临床测量提供的具体数据的情况下特别有用。我们为此对腹膜迁移采用一个参数定义,并采用一个封闭式环状包状参数模型,根据病人的特征方便地调整整个心血管循环系统。我们评估了用于试验血液动力学的若干流体动力学指标,从几个临床测量中验证了我们的数字结果;我们调查了几何和临床特征对血栓症风险的影响。为了分析胸膜形成与酸性纤维化的相互关系,与医学证据一致,我们提出了一个新颖的指标,我们称之为年龄停滞,并且产生于Eulerian和Lagrangeian血量的组合。这个指标确定了在哪些区域形成最慢的气流和形成,以便形成最佳的血浆状状状状状状状状状,以便形成最佳的血状状状状状状状状状状状。