Determination of the mechanical properties of normal and calcified human mitral chordae tendineae
Determination of the mechanical properties of normal and calcified human mitral chordae tendineae
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DOI：
10.1016/j.jmbbm.2012.03.016
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发表时间：
2012-09-01
影响因子：
3.9
通讯作者：
Gutierrez-Solana, F.
中科院分区：
文献类型：
--
作者：
Casado, J. A.;Diego, S.;Gutierrez-Solana, F.
本研究的目的是确定人类二尖瓣钙化对其边缘腱索力学性能的影响。该研究是在从13个人二尖瓣中获得的边缘腱索上进行的，这些二尖瓣在手术中被固定，包括6个非钙化瓣膜、4个中度钙化瓣膜和3个强烈钙化瓣膜。通过准静态拉伸试验确定非钙化和中度钙化瓣膜的腱索的机械响应（严重钙化瓣膜的不良状况使其无法进行机械表征）。获得并分析的材料参数（杨氏模量、割线模量、比例极限应力、极限强度、断裂应变和最大载荷下储存的能量密度）显示两组二尖瓣腱索之间的机械行为存在显著差异。在所有情况下都获得了大的分散，然而，考虑到平均值，观察到正常的腱比中度钙化的腱硬3到7倍或更有抵抗力。相反，断裂应变的结果显示了相当不同的情况，因为在这种情况下，两个弦家族之间没有观察到显着差异。扫描电子显微镜研究进行，以找出钙化腱索中存在的钙沉积的相关功能。此外，应力-应变曲线中的一般方面与显微镜下确定的胶原形态证据相关。最后，通过原子吸收光谱法定量测定了三组腱索中的钙含量;然后，获得了正常和中度钙化腱索的力学性能与其钙含量的关系。该分析证实了钙含量与刚度或阻力之间存在强相关性，而对延展性的影响似乎可以忽略不计。(C)2012爱思唯尔有限公司保留所有权利。
The aim of the present research is to determine the influence of the calcification of human mitral valves on the mechanical properties of their marginal chordae tendineae. The study was performed on marginal chords obtained from thirteen human mitral valves, explanted at surgery, including six non-calcified, four moderately calcified and three strongly calcified valves. The mechanical response of the chords from the non-calcified and moderately calcified valves was determined by means of quasi-static tensile tests (the poor condition of the strongly calcified valves prevented them from being mechanically characterised). The material parameters that were obtained and analysed (the Young's modulus, the secant modulus, the proportional limit stress, the ultimate strength, the strain at fracture and the density of energy stored up to maximum load) revealed noticeable differences in mechanical behaviour between the two groups of mitral chordae tendineae. Large scatter was obtained in all cases, nevertheless, considering the mean values, it was observed that the normal chords are between three and seven times stiffer or more resistant than the moderately calcified ones. On the contrary, the results obtained for the strain at fracture showed a rather different picture as, in this case, no significant differences were observed, between the two families of chords. A scanning electron microscopy study was conducted in order to find out the relevant features of the calcium deposits present in the calcified chordae tendineae. In addition, the general aspects appreciated in the stress vs. strain curves were correlated with the collagen morphological evidences determined microscopically. Finally, the calcium content present in the three groups of chords was quantitatively determined through atomic absorption spectroscopy; then, the relation between the mechanical properties of normal and moderately calcified chords as a function of its calcium content was obtained. This analysis confirmed the existence of a strong correlation between calcium content and stiffness or resistance whereas the influence on the ductility seems to be negligible. (C) 2012 Elsevier Ltd. All rights reserved.