The mechanical role of thrombus on the growth rate of an abdominal aortic aneurysm
The mechanical role of thrombus on the growth rate of an abdominal aortic aneurysm
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DOI：
10.1016/j.jvs.2009.08.075
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发表时间：
2010-01-01
影响因子：
4.3
通讯作者：
Jacobs, Michael H.
中科院分区：
文献类型：
--
作者：
Speelman, Lambert;Schurink, Geert Willem H.;Jacobs, Michael H.
目的：在腹主动脉瘤(AAA)的外科治疗中，最大直径是最主要的因素。多项研究已经得出结论，直径可能不是作为个体患者破裂风险标准的可靠标准，并且发现壁应力具有较高的敏感性和特异性。AAA、壁应力也可能是AAA生长的影响因素。本研究在壁应力计算中使用理想化AAA模型和患者特有的AAA模型来研究腔内血栓对壁应力和动脉瘤生长速度的影响。血栓被模拟为不可压缩的线弹性材料，并固定在壁上。计算了一定范围内血栓体积和剪切模数的壁应力减少量。对于30个具有不同血栓体积的患者特定的AAA模型，计算有无血栓时的壁应力。比较血栓体积较大和较小的AAA的直径生长率。结果：血栓引起壁应力降低，血栓越大、弹性模数越高，这种作用越明显。发现有大血栓的AAA比有小血栓的动脉瘤直径增长更明显(P<；.01)。血栓引起的应力降低在理想化模型和患者特定模型中显示出相同的趋势，尽管理想化模型高估了这种效果，并且患者之间观察到了相当大的差异。结论：AAA中较大的血栓与较高的AAA生长率相关，但也与较低的壁应力有关。因此，在血栓的影响下，AAA壁的弱化在AAA的生长过程中可能起着比作用于壁上的应力更直接的作用。(《外科杂志》2010；51：19-26。)
Objectives: In the decision for surgical repair of abdominal aortic aneurysms (AAAs), the maximum diameter is the main factor. Several studies have concluded that the diameter may not be reliable as rupture risk criterion for the individual patient and wall stress was found to have a higher sensitivity and specificity. The AAA, wall stress may also be an influential factor in growth of the AAA. This study investigates the effect of intraluminal thrombus on the wall stress and growth rate of aneurysms, using both idealized and patient-specific AAA models in wall stress computations.Methods: Idealized AAA models were created for wall stress analysis. Thrombus was modeled as an incompressible linear elastic material and was fixed to the wall. The reduction in wall stress for a range of thrombus volumes and shear moduli was computed. For 30 patient-specific AAA models with varying thrombus volumes, the wall stress was computed with and without thrombus. The diameter growth rate was compared for AAAs with a small and large thrombus volume. The results were compared between the idealized and patient-specific models.Results: The thrombus caused a reduction in wall stress, which was stronger for larger thrombi and higher elastic moduli. Any AAAs with a large thrombus were found to have significant stronger growth in diameter than aneurysms with a small thrombus (P < .01). The stress reduction due to the thrombus showed the same trend for the idealized and patient-specific models, although the effect was overestimated by the idealized models and a considerable variation between patients was observed.Conclusion: A larger thrombus in AAA was associated with a higher AAA growth rate, but also with a lower wall stress. Therefore, weakening of the AAA wall, under the influence of thrombus, may play a more imminent role in the process of AAA growth than the stress acting on the wall. (J Vasc Surg 2010;51:19-26.)