Piatti Filippo, Sturla Francesco, Marom Gil, Sheriff Jawaad, Claiborne Thomas E, Slepian Marvin J, Redaelli Alberto, Bluestein Danny
Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milan, Italy.
Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA.
J Biomech. 2015 Oct 15;48(13):3641-9. doi: 10.1016/j.jbiomech.2015.08.009. Epub 2015 Aug 21.
Surgical valve replacement in patients with severe calcific aortic valve disease using either bioprosthetic or mechanical heart valves is still limited by structural valve deterioration for the former and thrombosis risk mandating anticoagulant therapy for the latter. Prosthetic polymeric heart valves have the potential to overcome the inherent material and design limitations of these valves, but their development is still ongoing. The aim of this study was to characterize the hemodynamics and thrombogenic potential of the Polynova polymeric trileaflet valve prototype using a fluid-structure interaction (FSI) approach. The FSI model replicated experimental conditions of the valve as tested in a left heart simulator. Hemodynamic parameters (transvalvular pressure gradient, flow rate, maximum velocity, and effective orifice area) were compared to assess the validity of the FSI model. The thrombogenic footprint of the polymeric valve was evaluated using a Lagrangian approach to calculate the stress accumulation (SA) values along multiple platelet trajectories and their statistical distribution. In the commissural regions, platelets were exposed to the highest SA values because of highest stress levels combined with local reverse flow patterns and vortices. Stress-loading waveforms from representative trajectories in regions of interest were emulated in our hemodynamic shearing device (HSD). Platelet activity was measured using our platelet activation state (PAS) assay and the results confirmed the higher thrombogenic potential of the commissural hotspots. In conclusion, the proposed method provides an in depth analysis of the hemodynamic and thrombogenic performance of the polymer valve prototype and identifies locations for further design optimization.
对于患有严重钙化性主动脉瓣疾病的患者，使用生物假体或机械心脏瓣膜进行外科瓣膜置换仍受到限制，前者受结构瓣膜退化限制，后者受血栓形成风险限制，需要进行抗凝治疗。人工聚合物心脏瓣膜有潜力克服这些瓣膜固有的材料和设计局限性，但其研发仍在进行中。本研究的目的是使用流固相互作用（FSI）方法来表征Polynova聚合物三叶瓣瓣膜原型的血流动力学和血栓形成潜力。FSI模型复制了在左心模拟器中测试的瓣膜实验条件。比较血流动力学参数（跨瓣膜压力梯度、流速、最大速度和有效瓣口面积）以评估FSI模型的有效性。使用拉格朗日方法评估聚合物瓣膜的血栓形成足迹，以计算沿多条血小板轨迹的应力积累（SA）值及其统计分布。在瓣叶交界区域，由于最高应力水平与局部逆流模式和涡流相结合，血小板暴露于最高的SA值。在我们的血流动力学剪切装置（HSD）中模拟了感兴趣区域代表性轨迹的应力加载波形。使用我们的血小板活化状态（PAS）测定法测量血小板活性，结果证实了瓣叶交界热点具有更高的血栓形成潜力。总之，所提出的方法对聚合物瓣膜原型的血流动力学和血栓形成性能进行了深入分析，并确定了进一步设计优化的位置。
