Department of Biomedical Engineering, The Pennsylvania State University, Chemical and Biomedical Engineering Building, 122, University Park, PA, 16802, USA.
Department of Biomedical Engineering, James T. Willerson Center for Cardiovascular Modeling and Simulation, Oden Institute for Computational Engineering Sciences, University of Texas, Austin, TX, USA.
Ann Biomed Eng. 2021 Sep;49(9):2170-2182. doi: 10.1007/s10439-021-02751-w. Epub 2021 Feb 26.
Transcatheter aortic valve replacements (TAVRs) provide minimally invasive delivery of bioprosthetic heart valves (BHVs) for the treatment of aortic valve disease. While surgical BHVs show efficacy for 8-10 years, long-term TAVR durability remains unknown. Pre-clinical testing evaluates BHV durability in an ISO:5840 compliant accelerated wear tester (AWT), yet, the design and development of AWTs and their accuracy in predicting in vivo performance, is unclear. As a result of limited knowledge on AWT environment and BHV loading, durability assessment of candidate valves remains fundamentally empirical. For the first time, high-speed particle image velocimetry quantified an ISO:5840 compliant downstream AWT velocity field, Reynolds stresses, and turbulence intensity. TAVR enface imaging quantified the orifice area and estimated the flow rate. When valve area and flow rate were at their maximum during peak systole (1.49 cm and 16.05 L/min, respectively), central jet velocity, Reynolds normal and shear stress, and turbulence intensity grew to 0.50 m/s, 265.1 Pa, 124.6 Pa, and 37.3%, respectively. During diastole, unique AWT recirculation produced retrograde flow and the directional changes created eddies. These novel AWT findings demonstrated a substantially reduced valve fully loaded period and pressure not matching in vivo or in vitro studies, despite the comparable fluid environment and TAVR motion.
经导管主动脉瓣置换术（TAVR）为主动脉瓣疾病的治疗提供了微创生物瓣心脏瓣膜（BHV）输送方式。虽然外科 BHVs 在 8-10 年内显示出疗效，但 TAVR 的长期耐久性仍不清楚。临床前测试在符合 ISO：5840 的加速磨损测试器（AWT）中评估 BHV 的耐久性，然而，AWT 的设计和开发及其在预测体内性能方面的准确性尚不清楚。由于对 AWT 环境和 BHV 加载的了解有限，候选瓣膜的耐久性评估仍然是基于经验的。这是首次使用高速粒子图像测速法对符合 ISO：5840 的下游 AWT 速度场、雷诺应力和湍流强度进行量化。TAVR 直面成像法量化了孔口面积并估计了流量。当瓣膜面积和流量在峰值收缩期达到最大值（分别为 1.49 厘米和 16.05 升/分钟）时，中心射流速度、雷诺法向和切向应力以及湍流强度分别增长到 0.50 米/秒、265.1 帕、124.6 帕和 37.3%。在舒张期，独特的 AWT 回流产生逆行流动，方向变化产生涡流。尽管流体环境和 TAVR 运动相似，但这些新型 AWT 发现表明，瓣膜完全加载周期显著缩短，压力与体内或体外研究不匹配。
