Sugimoto Hiroatsu, Sacks Michael S
Center for Brand and Product Management, University of Wisconsin, Madison, WI, USA.
Cardiovasc Eng Technol. 2013 Mar;4(1):2-15. doi: 10.1007/s13239-013-0117-y.
Advances in the development of replacement heart valves require a deeper understanding of the valve dynamics. In the present study, dynamic aortic valve (AV) leaflet geometries were quantified using a structured laser-light imaging system (Iyengar ., ABME 29(11):963-973, 2001). Native AV leaflets were first imaged under simulated physiological flow conditions within a rigid glass conduit with simulated anatomic sinuses. Next, the valve/glass conduit combination was removed from the loop and immersed in a 0.625% aqueous glutaraldehyde solution at room temperature for 24 h to produce a bioprosthetic heart valve (BHV). The BHV leaflets were then re-imaged under identical flow conditions while kept in the same position in the glass conduit to minimize artifacts associated with removal/reinsertion of the valve. We observed that: (1) the native leaflet exhibited small, high frequency shifts in shape; (2) the BHV leaflet demonstrated a more stabile shape, as well as focal regions of prolonged, high curvature; (3) the BHV leaflet opened and closed faster by ~10 ms compared to native leaflet; (4) in both the BHV and native states, the AV opened from basal region leading to free edge (5) when closing, both the native and BHV close with both free edge and circumferential together. The high bending observed in the BHV leaflet correlated with known locations of tissue deterioration previously reported in our laboratory. Thus, in order to minimize leaflet tissue damage, methods of chemical modification utilized in BHVs that maintain leaflet flexibility are necessary to minimize the onset and progression of tissue damage. We conclude that leaflet stiffness can have a considerable effect on dynamic valve motion, and can induce deleterious bending behaviors that may be associated with tissue breakdown and valve failure. Moreover, these unique data can provide much needed quantitative information for computational simulation of heart valve leaflet stiffness on heart valve function.
人造心脏瓣膜研发的进展需要对瓣膜动力学有更深入的理解。在本研究中，使用结构化激光成像系统对动态主动脉瓣（AV）小叶几何形状进行了量化（Iyengar等人，《人工生物医学工程》29(11):963 - 973，2001）。首先，在具有模拟解剖窦的刚性玻璃管道内，在模拟生理流动条件下对天然AV小叶进行成像。接下来，将瓣膜/玻璃管道组合从回路中取出，在室温下浸入0.625%的戊二醛水溶液中24小时，以制作生物人工心脏瓣膜（BHV）。然后，在相同的流动条件下，将BHV小叶保持在玻璃管道中的相同位置进行重新成像，以尽量减少与瓣膜取出/重新插入相关的伪影。我们观察到：（1）天然小叶在形状上表现出小的高频变化；（2）BHV小叶呈现出更稳定的形状，以及延长的高曲率焦点区域；（3）与天然小叶相比，BHV小叶打开和关闭速度快约10毫秒；（4）在BHV和天然状态下，AV均从基部区域向自由边缘打开；（5）关闭时，天然小叶和BHV小叶的自由边缘和圆周同时关闭。在BHV小叶中观察到的高弯曲与我们实验室先前报道的组织退化的已知位置相关。因此，为了使小叶组织损伤最小化，在BHV中使用保持小叶柔韧性的化学修饰方法对于最小化组织损伤的发生和进展是必要的。我们得出结论，小叶刚度可对瓣膜动态运动产生相当大的影响，并可引发可能与组织破坏和瓣膜失效相关的有害弯曲行为。此外，这些独特的数据可为心脏瓣膜小叶刚度对心脏瓣膜功能的计算模拟提供急需的定量信息。
