Talman E A, Boughner D R
John P. Robarts Research Institute, University of Western Ontario, London, Canada.
Ann Thorac Surg. 1995 Aug;60(2 Suppl):S369-73. doi: 10.1016/0003-4975(95)00250-o.
Glutaraldehyde fixation noticeably alters the mechanical properties of porcine aortic valve tissue, subsequently affecting the function and durability of these tissues when used as prosthetic heart valves. Traditional uniaxial tensile testing techniques do not fully define the mechanical properties and we have devised a new approach to examine the important shear properties of the tissue. Altered shear properties would change the response of the valve tissue as it flexes open and closed. An apparatus combining a high-precision linear actuator with a gram-sensitive load cell was used to measure the shear characteristics of circular punch specimens taken from the center of each valve cusp. The tissue parameters measured showed significant differences between the fixed and fresh tissues. Glutaraldehyde-fixed tissue (n = 16) was about 100 times as stiff as fresh tissue (n = 32) between shear strain values of 0 and 0.2. The fixed tissue also had stress relaxation rates about 60% those of the fresh cusps and had about 70% of the hysteresis loss seen in fresh tissue. These results demonstrated the significant effects of glutaraldehyde fixation on the properties of porcine aortic valve cusp when tested in shear. Such changes could lead to altered tissue function and may increase internal stresses during opening and closing, contributing to valve fatigue.
戊二醛固定显著改变了猪主动脉瓣组织的力学性能，进而影响这些组织用作人工心脏瓣膜时的功能和耐久性。传统的单轴拉伸测试技术无法完全确定力学性能，我们设计了一种新方法来研究该组织重要的剪切性能。剪切性能的改变会改变瓣膜组织在开合时的反应。使用一种将高精度线性致动器与克敏感测力传感器相结合的装置来测量从每个瓣膜瓣叶中心取出的圆形冲孔试样的剪切特性。所测量的组织参数显示固定组织和新鲜组织之间存在显著差异。在0至0.2的剪切应变值之间，戊二醛固定组织（n = 16）的硬度约为新鲜组织（n = 32）的100倍。固定组织的应力松弛率也约为新鲜瓣叶的60%，滞后损失约为新鲜组织的70%。这些结果表明，在进行剪切测试时，戊二醛固定对猪主动脉瓣瓣叶的性能有显著影响。这种变化可能导致组织功能改变，并可能在瓣膜开合过程中增加内部应力，从而导致瓣膜疲劳。
