Marais Louise, Franck Grégory, Allaire Eric, Zidi Mustapha
Bioengineering, Tissues and Neuroplasticity, EA 7377, Université Paris-Est Créteil, Faculté de Médecine - Centre de Recherches Chirurgicales, 8 rue du Général Sarrail, 94010 Créteil, France.
Division of Cardiovascular Medicine, Brigham and Women׳s Hospital, Harvard Medical School, Boston, MA 02115, USA.
J Biomech. 2016 Oct 3;49(14):3467-3475. doi: 10.1016/j.jbiomech.2016.09.012. Epub 2016 Sep 15.
The purpose of this study was to evaluate the diameter and thickness-related variations in mechanical properties of degraded arterial wall. To this end, ring tests were performed on 31 samples from the rat xenograft model of abdominal aortic aneurysm (AAA) and failure properties were determined. An inverse finite element method was then employed to identify the material parameters of a hyperelastic and incompressible strain energy function. Correlations with outer diameter and wall thickness of the rings were examined. Furthermore, we investigated the changes in mechanical properties between the grafts, which consist in guinea pig decellularized aortas, native murine aortas and degraded aortas (AAAs). Decellularized aortas presented a significantly lower ultimate strain associated with a higher stiffening rate compared to native aortas. AAAs exhibited a significantly lower ultimate stress than other groups and an extensible-but-stiff behavior. The proposed approach revealed correlations of ultimate stress and material parameters of aneurysmal aortas with outer diameter and thickness. In particular, the negative correlations of the material parameter accounting for the response of the non-collagenous matrix with diameter and thickness (r=-0.67 and r=-0.73, p<0.001) captured the gradual loss of elastin with dilatation observed in histology (r=-0.97, p<0.001). Moreover, it exposed the progressive weakening of the wall with enlargement and thickening (r=-0.64 and r=-0.69, p<0.001), suggesting that wall thickness and diameter may be indicators of rupture risk in the rat xenograft model.
本研究的目的是评估退化动脉壁力学性能与直径和厚度相关的变化。为此，对来自大鼠腹主动脉瘤（AAA）异种移植模型的31个样本进行了环形测试，并确定了失效特性。然后采用逆有限元方法来识别超弹性和不可压缩应变能函数的材料参数。研究了与环的外径和壁厚的相关性。此外，我们还研究了移植物之间力学性能的变化，这些移植物包括豚鼠脱细胞主动脉、天然小鼠主动脉和退化主动脉（AAA）。与天然主动脉相比，脱细胞主动脉的极限应变显著降低，且硬化率更高。AAA的极限应力显著低于其他组，表现出可延展但僵硬的行为。所提出的方法揭示了动脉瘤性主动脉的极限应力和材料参数与外径和厚度之间的相关性。特别是，反映非胶原基质响应的材料参数与直径和厚度呈负相关（r = -0.67和r = -0.73，p < 0.001），这与组织学中观察到的随着扩张弹性蛋白逐渐丧失的情况相符（r = -0.97，p < 0.001）。此外，该方法还揭示了随着动脉瘤增大和壁增厚，其壁的逐渐弱化（r = -0.64和r = -0.69，p < 0.001），这表明在大鼠异种移植模型中，壁厚和直径可能是破裂风险的指标。
