RESIDUAL STRAIN IN RAT LEFT-VENTRICLE
RESIDUAL STRAIN IN RAT LEFT-VENTRICLE
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DOI：
10.1161/01.res.66.1.37
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发表时间：
1990-01-01
影响因子：
20.1
通讯作者：
FUNG, YC
中科院分区：
文献类型：
--
作者：
OMENS, JH;FUNG, YC
器官中的残余应力被定义为当所有外部载荷被移除时仍然存在的应力。在已发表的关于左心室壁应力的论文中，残余应力通常被忽略。为了在跳动心脏的应力分布分析中考虑残余应力，必须首先测量心脏无负荷状态下的残余应变。本文测量了5只钾停搏大鼠左心室赤道横截面环（1-3 mm厚）的残余应变。摩擦和外部负荷的影响，减少了浸没在液体中的标本，和一个低温，高钾的逮捕解决方案，含有硝苯地平和EGTA被用来延迟缺血性挛缩的发作。将不锈钢微球（60-100 μ m）轻轻嵌入切片表面，并穿过左心室游离壁进行径向切割。二维应变计算从一个径向切割后的切片的变形被定义为在该切片的残余应变。结果发现，主要的残余拉伸比的分布是不对称的径向切割：在大量的跨壁应变梯度存在的区域，应变分量的分布是不同的径向切割的两侧。第二径向切割产生的变形明显小于第一径向切割产生的变形。因此，具有一个径向切口的切片可以被认为是无应力的。结果表明，在拉伸比明显小于1.00的内周向区域，周向残余应变为负值，
Residual stress in an organ is defined as the stress that remains when all external loads are removed. Residual stress has generally been ignored in published papers on left ventricular wall stress. To take residual stress into account in the analysis of stress distributions in a beating heart, one must first measure the residual strain in the no-load state of the heart. Residual strain in equatorial cross-sectional rings (1-3 mm thick) of five potassium-arrested rat left ventricles were measured. The effect of friction and external loading were reduced by submersing the specimen in fluid, and a hypothermic, hyperkalemic arresting solution containing nifedipine and EGTA was used to delay the onset of ischemic contracture. Stainless steel microspheres (60-100 .mu.m) were lightly imbedded on the surface of the slices, and the radial cut was made through the left ventricular free wall. Two-dimensional strains computed from the deformation of a slice after one radial cut were defined as the residual strains in that slice. It was found that the distributions of the principal residual stretch ratios were asymmetric with respect to the radial cut: in areas where substantial transmural strain gradients existed, the distributions of strain components were different on the two sides of the radial cut. A second radial cut produced deformations significantly smaller than those produced from the first radial cut. Hence, a slice with one radial cut may be considered stress free. Our results show that the circumferential residual strain was negative in the endocardial region (stretch ratios were significantly less than 1.00, p