Straightening of curved pattern of collagen fibers under load controls aortic valve shape.
Straightening of curved pattern of collagen fibers under load controls aortic valve shape.
复制标题
负载下胶原纤维弯曲模式的拉直可控制主动脉瓣形状。
DOI：
10.1016/j.jbiomech.2013.11.032
复制
发表时间：
2014
影响因子：
2.4
通讯作者：
delNido,PedroJ
中科院分区：
文献类型：
--
作者：
Hammer,PeterE;Pacak,ChristinaA;Howe,RobertD;delNido,PedroJ
主动脉瓣叶中的胶原纤维网络被认为在瓣膜的强度和耐久性中起重要作用。然而，除了其应力承载作用之外，这种纤维网络还具有在压力载荷下在关闭的瓣膜中产生功能上重要的形状变化的潜力。我们测量了胶原蛋白染色后猪主动脉瓣叶中胶原蛋白网络的平均模式。然后，我们使用有限元模拟来探索这种胶原蛋白模式如何影响关闭的瓣膜的形状。我们观察到弯曲或弯曲模式，胶原纤维从连合处向下倾斜至瓣叶中心，形成朝向瓣叶自由边缘的凹面模式。模拟显示，这些弯曲的纤维轨迹在压力载荷下变直，导致关闭的瓣膜形状的功能上重要的变化。相对于平行于瓣叶自由边缘延伸的直胶原纤维模式，弯曲纤维的凹形模式产生闭合的瓣膜，中心瓣叶接合高度增加40%，瓣叶波涛减少，从而产生更符合生理学的闭合瓣膜形状。此外，模拟显示，加载瓣叶形状的这些变化反映了由于弯曲纤维拉直引起的平面内膜应力的调制而导致的瓣叶曲率的变化。这种效应似乎在正常瓣膜功能中起重要作用，并可能对人工瓣膜和组织工程置换瓣膜的设计具有重要意义。
The network of collagen fibers in the aortic valve leaflet is believed to play an important role in the strength and durability of the valve. However, in addition to its stress-bearing role, such a fiber network has the potential to produce functionally important shape changes in the closed valve under pressure load. We measured the average pattern of the collagen network in porcine aortic valve leaflets after staining for collagen. We then used finite element simulation to explore how this collagen pattern influences the shape of the closed valve. We observed a curved or bent pattern, with collagen fibers angled downward from the commissures toward the center of the leaflet to form a pattern that is concave toward the leaflet free edge. Simulations showed that these curved fiber trajectories straighten under pressure load, leading to functionally important changes in closed valve shape. Relative to a pattern of straight collagen fibers running parallel to the leaflet free edge, the concave pattern of curved fibers produces a closed valve with a 40% increase in central leaflet coaptation height and with decreased leaflet billow, resulting in a more physiological closed valve shape. Furthermore, simulations show that these changes in loaded leaflet shape reflect changes in leaflet curvature due to modulation of in-plane membrane stress resulting from straightening of the curved fibers. This effect appears to play an important role in normal valve function and may have important implications for the design of prosthetic and tissue engineered replacement valves.