BIAXIAL MECHANICAL-BEHAVIOR OF EXCISED PORCINE MITRAL-VALVE LEAFLETS
BIAXIAL MECHANICAL-BEHAVIOR OF EXCISED PORCINE MITRAL-VALVE LEAFLETS
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DOI：
10.1152/ajpheart.1995.269.4.h1319
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发表时间：
1995-10-01
影响因子：
4.8
通讯作者：
YIN, FCP
中科院分区：
文献类型：
--
作者：
MAYNEWMAN, K;YIN, FCP
预处理后，在循环等双轴和条带双轴拉伸方案下，以 4-12%/s 的应变率对切除的猪二尖瓣的前叶和后叶进行机械测试。计算了膜和三维情况下的柯西应力和拉格朗日应变。小叶表现出非线性弹性、各向异性行为。在等双轴拉伸下，前叶和后叶在圆周方向的延展性均小于径向方向的延展性，应力比分别为 5.7 和 4.3。后叶在两个方向上表现出更大的伸展性和较低的周向移行后模量（前叶范围为 690-820，而前叶为 2,500-3,200 N/m）。这种更大的后部延伸性可能是由于更多数量的腱索附件，这为该结构提供了额外的机械稳定性。对不同拉伸方案的响应证明了径向和圆周机械行为的耦合，表明单个胶原纤维或束之间存在复杂的微观结构耦合。这些是二尖瓣的第一个双轴数据，并且是开发更详细的定量材料描述的基础。
Anterior and posterior leaflets from excised porcine mitral valves were mechanically tested under cyclic equibiaxial and strip biaxial stretch protocols at a strain rate of 4-12%/s after preconditioning. Cauchy stress and Lagrangian strain were calculated for both membrane and three-dimensional cases. The leaflets exhibited nonlinearly elastic, anisotropic behavior. Both anterior and posterior leaflets were less extensible in the circumferential than in the radial direction under equibiaxial stretch, with stress ratios of 5.7 and 4.3, respectively. The posterior leaflets exhibited greater extensibility in both directions and lower circumferential posttransitional moduli (ranges 690-820 vs. 2,500-3,200 N/m for anterior). This larger posterior extensibility may be due to the greater number of chordal attachments, which provide additional mechanical stability to this structure. Coupling of radial and circumferential mechanical behavior was evidenced by the response to different stretch protocols, indicating a complex microstructural coupling between individual collagen fibers or bundles. These are the first biaxial data for mitral valves and are a foundation far the development of a more detailed quantitative material description.