Corbett T J, Doyle B J, Callanan A, Walsh M T, McGloughlin T M
Centre for Applied Biomedical Engineering Research (CABER), Department of Mechanical and Aeronautical Engineering, MSSi, University of Limerick, Limerick, Ireland.
J Biomech Eng. 2010 Jan;132(1):011008. doi: 10.1115/1.4000156.
In vitro studies of abdominal aortic aneurysm (AAA) have been widely reported. Frequently mock artery models with intraluminal thrombus (ILT) analogs are used to mimic the in vivo AAA. While the models used may be physiological, their properties are frequently either not reported or investigated. This study is concerned with the testing and characterization of previously used vessel analog materials and the development of new materials for the manufacture of AAA models. These materials were used in conjunction with a previously validated injection molding technique to manufacture AAA models of ideal geometry. To determine the model properties (stiffness (beta) and compliance), the diameter change of each AAA model was investigated under incrementally increasing internal pressures and compared with published in vivo studies to determine if the models behaved physiologically. A FEA study was implemented to determine if the pressure-diameter change behavior of the models could be predicted numerically. ILT analogs were also manufactured and characterized. Ideal models were manufactured with ILT analog internal to the aneurysm region, and the effect of the ILT analog on the model compliance and stiffness was investigated. The wall materials had similar properties (E(init) 2.22 MPa and 1.57 MPa) to aortic tissue at physiological pressures (1.8 MPa (from literature)). ILT analogs had a similar Young's modulus (0.24 MPa and 0.33 MPa) to the medial layer of ILT (0.28 MPa (from literature)). All models had aneurysm sac compliance (2.62-8.01 x 10(-4)/mm Hg) in the physiological range (1.8-9.4 x 10(-4)/mm Hg (from literature)). The necks of the AAA models had similar stiffness (20.44-29.83) to healthy aortas (17.5+/-5.5 (from literature)). Good agreement was seen between the diameter changes due to pressurization in the experimental and FEA wall models with a maximum difference of 7.3% at 120 mm Hg. It was also determined that the inclusion of ILT analog in the sac of the models could have an effect on the compliance of the model neck. Ideal AAA models with physiological properties were manufactured. The behavior of these models due to pressurization was predicted using finite element analysis, validating this technique for the future design of realistic physiological AAA models. Addition of ILT analogs in the aneurysm sac was shown to affect neck behavior. This could have implications for endovascular AAA repair due to the importance of the neck for stent-graft fixation.
腹主动脉瘤（AAA）的体外研究已有广泛报道。经常使用带有腔内血栓（ILT）类似物的模拟动脉模型来模拟体内的AAA。虽然所使用的模型可能具有生理学特性，但其特性往往未被报道或研究。本研究关注先前使用的血管模拟材料的测试和表征，以及用于制造AAA模型的新材料的开发。这些材料与先前经过验证的注塑技术结合使用，以制造具有理想几何形状的AAA模型。为了确定模型特性（刚度（β）和顺应性），在逐渐增加的内部压力下研究每个AAA模型的直径变化，并与已发表的体内研究进行比较，以确定模型的行为是否符合生理学。实施了有限元分析（FEA）研究，以确定是否可以通过数值预测模型的压力 - 直径变化行为。还制造并表征了ILT类似物。在动脉瘤区域内部带有ILT类似物的理想模型被制造出来，并研究了ILT类似物对模型顺应性和刚度的影响。在生理压力（1.8 MPa（来自文献））下壁材料与主动脉组织具有相似的特性（初始弹性模量E分别为2.22 MPa和1.57 MPa）。ILT类似物的杨氏模量（0.24 MPa和0.33 MPa）与ILT中层的杨氏模量（0.28 MPa（来自文献））相似。所有模型的动脉瘤囊顺应性（2.62 - 8.01×10⁻⁴/mm Hg）在生理范围内（1.8 - 9.4×10⁻⁴/mm Hg（来自文献））。AAA模型的颈部刚度（20.44 - 29.83）与健康主动脉的刚度（17.5±5.5（来自文献））相似。在实验模型和FEA壁模型中，加压引起的直径变化之间观察到良好的一致性，在120 mm Hg时最大差异为7.3%。还确定在模型囊中包含ILT类似物可能会对模型颈部的顺应性产生影响。制造出了具有生理学特性的理想AAA模型。使用有限元分析预测了这些模型在加压时的行为，验证了该技术在未来设计逼真的生理性AAA模型中的应用。在动脉瘤囊中添加ILT类似物被证明会影响颈部行为。由于颈部对于支架移植物固定的重要性，这可能对血管内AAA修复有影响。
