Feng Wentao, Yang Xianda, Liu Yang, Fan Yubo
Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, International Research Center for Implantable and Interventional Medical Devices, Beihang University.
Beijing Key Laboratory for Optimal Design and Evaluation Technology of Implantable & Interventional Medical Devices, Beijing, 100191, China.
Artif Organs. 2017 Aug;41(8):735-743. doi: 10.1111/aor.12833. Epub 2017 Feb 24.
Clinically, the percutaneous transcatheter aortic valve (TAV) has been reported to be deformed in a noncircular configuration after its implant. The deformation is universal and various, and it leads to serious leakage and durability problems. Even in the same deformation, the leaflets made in different tissue thicknesses may cause different hydrodynamic performances. Simulating the left heart cardiac conditions by a pulse duplicator system, the present study investigated the effects of the aortic annulus deformation and the leaflet tissue thickness on the hydrodynamics of the TAV. Three 22 mm self-expanding TAV samples were fabricated with three different leaflet thicknesses (0.25, 0.4, 0.55 mm). Every sample was successively deformed to be elliptical, triangular, and undersized circular shapes. The hydrodynamics of the TAV were assessed through a quasi-physiological artery pulsatile flow duplicator system. The transvalvular pressure difference, effective orifice area, and regurgitation flow were determined. High-speed video recordings were taken to investigate the leaflet kinematics. The results showed that the triangular deformation produced the poorest valve function while the elliptical deformation led to the slightest difference from the nominal. With increasing leaflet thickness, the effect of configuration deformation on the regurgitation increased. The thinner leaflets were better than the thicker ones in adapting to the deformation but had a higher risk of deterioration.
临床上，据报道经皮经导管主动脉瓣（TAV）植入后会呈非圆形变形。这种变形普遍且多样，会导致严重的泄漏和耐久性问题。即使在相同的变形情况下，不同组织厚度制成的瓣叶可能会导致不同的流体动力学性能。本研究通过脉搏复制器系统模拟左心心脏状况，研究了主动脉瓣环变形和瓣叶组织厚度对TAV流体动力学的影响。制作了三个22毫米的自膨胀TAV样本，其瓣叶厚度分别为三种不同值（0.25、0.4、0.55毫米）。每个样本依次变形为椭圆形、三角形和尺寸过小的圆形。通过准生理动脉搏动血流复制器系统评估TAV的流体动力学。测定跨瓣压差、有效瓣口面积和反流流量。拍摄高速视频记录以研究瓣叶运动学。结果表明，三角形变形产生的瓣膜功能最差，而椭圆形变形与标称值的差异最小。随着瓣叶厚度增加，构型变形对反流的影响增大。较薄的瓣叶在适应变形方面优于较厚的瓣叶，但恶化风险更高。
