Impact of calcifications on patient-specific wall stress analysis of abdominal aortic aneurysms
Impact of calcifications on patient-specific wall stress analysis of abdominal aortic aneurysms
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DOI：
10.1007/s10237-010-0191-0
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发表时间：
2010-10-01
影响因子：
3.5
通讯作者：
Wall, W. A.
中科院分区：
文献类型：
--
作者：
Maier, A.;Gee, M. W.;Wall, W. A.
腹主动脉瘤（abdominal aortic aneurysms，AAA）是一种发生于老年患者的退行性和炎症性疾病，约80%的AAA瘤壁钙化。钙化对AAA计算壁应力分析的影响在文献中很少被处理。钙化是不均匀分布的非纤维性硬斑块，最常见于血管壁的内膜和中层之间的管腔表面附近。因此，在这项研究中，我们调查钙化作为单独的AAA成分对有限元模拟结果的影响。因此，三个AAA重建管腔内血栓（ILT），钙化和血管壁。每个患者特定AAA模拟两次，一次包括所有三个AAA成分，一次忽略钙化，因为它在文献中仍然很常见。由此，从作者进行的实验中获取用于钙化的本构建模的参数，表明钙化表现出几乎线性的应力-应变行为，杨氏模量Ea为千分之40 MPa。仿真结果表明，钙化表现出显着的承载效果，并减少在相邻的血管壁的应力。血管壁内的平均应力降低了9.7%至59.2%。对于三分之二的AAA，考虑钙化时，峰值壁应力降低（8.9%和28.9%）。对于一个AAA，由于钙化边界附近的应力峰值，模拟的峰值壁应力增加了5.5%。然而，这种应力奇异性，由于突然刚度跳跃是生理上值得怀疑的。可以进一步观察到，大的钙化大多位于AAA壁的凹形区域中。我们推断，AAA形状的影响，存在的钙化，因此，严重的错误发生，如果它们被忽略在计算壁应力分析。钙化AAA破裂风险的普遍增加值得怀疑。
As a degenerative and inflammatory desease of elderly patients, about 80% of abdominal aortic aneurysms (AAA) show considerable wall calcification. Effect of calcifications on computational wall stress analyses of AAAs has been rarely treated in literature so far. Calcifications are heterogeneously distributed, non-fibrous, stiff plaques which are most commonly found near the luminal surface in between the intima and the media layer of the vessel wall. In this study, we therefore investigate the influence of calcifications as separate AAA constituents on finite element simulation results. Thus, three AAAs are reconstructed with regard to intraluminal thrombus (ILT), calcifications and vessel wall. Each patient-specific AAA is simulated twice, once including all three AAA constituents and once neglecting calcifications as it is still common in literature. Parameters for constitutive modeling of calcifications are thereby taken from experiments performed by the authors, showing that calcifications exhibit an almost linear stress-strain behavior with a Young's modulus E a parts per thousand yen 40 MPa. Simulation results show that calcifications exhibit significant load-bearing effects and reduce stress in adjacent vessel wall. Average stress within the vessel wall is reduced by 9.7 to 59.2%. For two out of three AAAs, peak wall stress decreases when taking calcifications into consideration (8.9 and 28.9%). For one AAA, simulated peak wall stress increases by 5.5% due to stress peaks near calcification borders. However, such stress singularities due to sudden stiffness jumps are physiologically doubtful. It can further be observed that large calcifications are mostly situated in concavely shaped regions of the AAA wall. We deduce that AAA shape is influenced by existent calcifications, thus crucial errors occur if they are neglected in computational wall stress analyses. A general increase in rupture risk for calcified AAAs is doubted.