Luraghi Giulia, Wu Wei, De Castilla Hector, Rodriguez Matas José Félix, Dubini Gabriele, Dubuis Pascal, Grimmé Marc, Migliavacca Francesco
Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Milan, Italy.
Department of Mechanical Engineering, University of Texas at San Antonio, San Antonio, TX, USA.
Artif Organs. 2018 Oct;42(10):E315-E324. doi: 10.1111/aor.13316. Epub 2018 Oct 9.
Heart failure is a progressive and often fatal pathology among the main causes of death in the world. An implantable total artificial heart (TAH) is an alternative to heart transplantation. Blood damage quantification is imperative to assess the behavior of an artificial ventricle and is strictly related to the hemodynamics, which can be investigated through numerical simulations. The aim of this study is to develop a computational model that can accurately reproduce the hemodynamics inside the left pumping chamber of an existing TAH (Carmat-TAH) together with the displacement of the leaflets of the biological aortic and mitral valves and the displacement of the pericardium-made membrane. The proposed modeling workflow combines fluid-structure interaction (FSI) simulations based on a fixed grid method with computational fluid dynamics (CFD). In particular, the kinematics of the valves is accounted for by means of a dynamic mesh technique in the CFD. The comparison between FSI- and CFD-calculated velocity fields confirmed that the presence of the valves in the CFD model is essential for realistically mimicking blood dynamics, with a percentage difference of 2% during systole phase and 13% during the diastole. The percentage of blood volume in the CFD simulation with a shear stress above the threshold of 50 Pa is less than 0.001%. In conclusion, the application of this workflow to the Carmat-TAH provided consistent results with previous clinical studies demonstrating its utility in calculating local hemodynamic quantities in the presence of complex moving boundaries.
心力衰竭是一种渐进性且往往致命的病症，在全球主要死因中名列前茅。可植入式全人工心脏（TAH）是心脏移植的一种替代方案。血液损伤量化对于评估人工心室的性能至关重要，并且与血流动力学密切相关，而血流动力学可通过数值模拟进行研究。本研究的目的是开发一种计算模型，该模型能够准确再现现有TAH（卡马特TAH）左泵腔内部的血流动力学，以及生物主动脉瓣和二尖瓣小叶的位移和心包制成的膜的位移。所提出的建模工作流程将基于固定网格方法的流固耦合（FSI）模拟与计算流体动力学（CFD）相结合。具体而言，通过CFD中的动态网格技术来考虑瓣膜的运动学。FSI计算的速度场与CFD计算的速度场之间的比较证实，CFD模型中瓣膜的存在对于逼真地模拟血液动力学至关重要，在收缩期的百分比差异为2%，在舒张期为13%。在CFD模拟中，剪应力高于50 Pa阈值时的血容量百分比小于0.001%。总之，将此工作流程应用于卡马特TAH得到了与先前临床研究一致的结果，证明了其在存在复杂移动边界的情况下计算局部血流动力学量方面的实用性。
