Effects of mechanical fatigue on the bending properties of the porcine bioprosthetic heart valve
Effects of mechanical fatigue on the bending properties of the porcine bioprosthetic heart valve
复制标题
DOI：
10.1097/00002480-199901000-00014
复制
发表时间：
1999-01-01
期刊：
影响因子：
4.2
通讯作者：
Sacks, MS
中科院分区：
文献类型：
--
作者：
Gloeckner, DC;Billiar, KL;Sacks, MS
猪生物人工主动脉瓣失效的机制尚不清楚。一种可能的解释是，分层瓣叶结构在弯曲过程中发生分层，导致钙化和进一步分层，最终导致瓣膜失效。我们研究了加速耐久性试验后主动脉瓣尖腹的抗弯刚度变化。我们使用三点弯曲，其中通过校准到已知载荷-位移关系的薄不锈钢棒将载荷施加到每个样本的中心。对疲劳至0、5000万、1亿和2亿次循环的瓣膜的10个环向和15个径向样本进行弯曲，弯曲方向为瓣尖曲率。应用线性梁理论作为比较组间相对弯曲刚度的手段。尽管当逆着尖瓣曲率弯曲时，与圆周方向对齐的样本更硬，但径向定向样本没有表现出弯曲方向依赖性。随着加速试验循环次数的增加，径向和周向样本的弯曲刚度均显著降低。总的来说，我们的研究结果表明，这是纤维瘤，经历了最大的刚度损失与机械诱导的疲劳损伤。
The mechanisms underlying the failure of porcine bioprosthetic aortic heart valves are not well understood. One possible explanation is that delaminations of the layered leaflet structure occur through flexion, leading to calcification and further delaminations, and finally resulting in valve failure. We investigated the changes in flexural rigidity of the belly of aortic valve cusps subjected to accelerated durability testing. We used three-point bending wherein a load was applied to the center of each specimen by a thin stainless steel bar calibrated to a known load-displacement relationship. Ten circumferential and 15 radial specimens from valves fatigued to 0, 50, 100, and 200 million cycles were flexed both with and against the curvature of the cusp. Linear beam theory was applied as a means to compare the relative bending stiffness between groups. Although specimens aligned to the circumferential direction were stiffer when bent against the cuspal curvature, the radial oriented specimens exhibited no bending directional dependence. Both the radial and circumferential specimens experienced a significant decrease in the bending stiffness with an increased number of accelerated test cycles. Overall, our results suggest that it is the fibrosa that experiences the greatest loss of stiffness with mechanically induced fatigue damage.