Oks David, Samaniego Cristóbal, Houzeaux Guillaume, Butakoff Constantine, Vázquez Mariano
Department of Computer Applications in Science and Engineering, Barcelona Supercomputing Center (BSC), Barcelona, Spain.
ELEM Biotech SL, Barcelona, Spain.
Int J Numer Method Biomed Eng. 2022 Dec;38(12):e3649. doi: 10.1002/cnm.3649. Epub 2022 Oct 11.
This work intends to study the effect of aortic annulus eccentricity and leaflet rigidity on the performance, thrombogenic risk and calcification risk in bioprosthetic aortic valve replacements (BAVRs). To address these questions, a two-way immersed fluid-structure interaction (FSI) computational model was implemented in a high-performance computing (HPC) multi-physics simulation software, and validated against a well-known FSI benchmark. The aortic valve bioprosthesis model is qualitatively contrasted against experimental data, showing good agreement in closed and open states. Regarding the performance of BAVRs, the model predicts that increasing eccentricities yield lower geometric orifice areas (GOAs) and higher normalized transvalvular pressure gradients (TPGs) for healthy cardiac outputs during systole, agreeing with in vitro experiments. Regions with peak values of residence time are observed to grow with eccentricity in the sinus of Valsalva, indicating an elevated risk of thrombus formation for eccentric configurations. In addition, the computational model is used to analyze the effect of varying leaflet rigidity on both performance, thrombogenic and calcification risks with applications to tissue-engineered prostheses. For more rigid leaflets it predicts an increase in systolic and diastolic TPGs, and decrease in systolic GOA, which translates to decreased valve performance. The peak shear rate and residence time regions increase with leaflet rigidity, but their volume-averaged values were not significantly affected. Peak solid stresses are also analyzed, and observed to increase with rigidity, elevating risk of valve calcification and structural failure. To the authors' knowledge this is the first computational FSI model to study the effect of eccentricity or leaflet rigidity on thrombogenic biomarkers, providing a novel tool to aid device manufacturers and clinical practitioners.
本研究旨在探讨主动脉瓣环偏心度和瓣叶刚度对生物人工心脏主动脉瓣置换术（BAVR）的性能、血栓形成风险和钙化风险的影响。为解决这些问题，在高性能计算（HPC）多物理场模拟软件中实现了双向浸入式流固耦合（FSI）计算模型，并与一个知名的FSI基准进行了验证。将主动脉瓣生物假体模型与实验数据进行定性对比，结果表明在关闭和开放状态下具有良好的一致性。关于BAVR的性能，该模型预测，在收缩期健康心输出量时，偏心度增加会导致几何开口面积（GOA）降低，标准化跨瓣压差（TPG）升高，这与体外实验结果一致。观察到停留时间峰值区域在主动脉窦中随偏心度增加而增大，表明偏心构型的血栓形成风险升高。此外，该计算模型用于分析不同瓣叶刚度对性能、血栓形成和钙化风险的影响，并应用于组织工程假体。对于更硬的瓣叶，它预测收缩期和舒张期TPG增加，收缩期GOA降低，这意味着瓣膜性能下降。峰值剪切率和停留时间区域随瓣叶刚度增加而增大，但其体积平均值没有显著影响。还分析了峰值固体应力，发现其随刚度增加而增加，从而增加了瓣膜钙化和结构失效的风险。据作者所知，这是第一个研究偏心度或瓣叶刚度对血栓形成生物标志物影响的计算FSI模型，为辅助设备制造商和临床医生提供了一种新工具。
