The bovine pericardial xenograft: III. Effect of uniaxial and sequential biaxial stress during fixation on the tensile viscoelastic properties of bovine pericardium.
The bovine pericardial xenograft: III. Effect of uniaxial and sequential biaxial stress during fixation on the tensile viscoelastic properties of bovine pericardium.
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牛心包异种移植物：III。
DOI：
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发表时间：
1989
期刊：
影响因子：
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通讯作者：
S. Haberer
中科院分区：
文献类型：
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作者：
J. M. Lee;M. Ku;S. Haberer
我们之前的两篇文章已经表明，戊二醛固定牛心包几乎是各向同性的，无论是固定无约束，系带，或压力。在这项研究中，我们在固定过程中使用单轴应力来生产具有明显拉伸各向异性的牛心包材料。矩形和十字形心包样本在四种处理之一后进行了机械检查：(i)在88千帕单轴应力下固定，（ii）在176千帕单轴应力下固定，（iii）在176千帕单轴应力下固定3小时，然后在相同的应力下固定24小时，（iv）在176千帕单轴应力下固定，然后在176千帕应力下垂直于第一次方向进行第二次固定。在与初始应力方向0度、30度、60度和90度处切割材料条，测试材料对循环加载的响应、应力松弛、塑性变形和断裂性能。在单轴应力下固定产生与猪主动脉瓣小叶相似的异向异性；然而，材料的整体延伸性取决于施加的应力和应力样品的纵横比。虽然在盐水中加载没有产生变化，但顺序双轴应力使各向异性减少，这表明暴露了额外的交联位点。固定过程中的单轴应力可能是构造各向异性心脏瓣叶的有效方法。
Our previous two articles have shown that glutaraldehyde-fixed bovine pericardium is nearly isotropic, whether fixed without constraints, with tethering, or with pressure. In this study, we have used uniaxial stress during fixation to produce bovine pericardial material with marked tensile anisotropy. Rectangular and cruciate pericardial samples have been mechanically examined after one of four treatments: (i) fixation under 88-kPa uniaxial stress, (ii) fixation under 176-kPa uniaxial stress, (iii) 3 h of 176-kPa uniaxial stress in saline followed by 24-h fixation under the same stress, (iv) fixation under 176-kPa uniaxial stress followed by a second fixation under 176-kPa stress in a direction normal to the first. Strips of material were cut at 0 degree, 30 degrees, 60 degrees, and 90 degrees to direction of the initial stress, and tested for response to cyclic loading, stress relaxation, plastic deformation, and fracture properties. Fixation under uniaxial stress produced anistropy similar to that seen in porcine aortic valve leaflets; however, the overall extensibility of the material depended on the applied stress and the aspect ratio of the stressed sample. While loading in saline produced no change, the sequential biaxial stressing produced a reduction in anisotropy, suggesting exposure of additional crosslinking sites. Uniaxial stress during fixation may be a useful method for construction of anisotropic heart valve leaflets.