Centre for Applied Biomedical Engineering Research, Department of Mechanical and Aeronautical Engineering and Materials and Surface Science Institute, University of Limerick, Ireland.
Biomed Eng Online. 2009 Oct 6;8:24. doi: 10.1186/1475-925X-8-24.
Abdominal aortic aneurysms (AAA) are local dilatations of the infrarenal aorta. If left untreated they may rupture and lead to death. One form of treatment is the minimally invasive insertion of a stent-graft into the aneurysm. Despite this effective treatment aneurysms may occasionally continue to expand and this may eventually result in post-operative rupture of the aneurysm. Fluid-structure interaction (FSI) is a particularly useful tool for investigating aneurysm biomechanics as both the wall stresses and fluid forces can be examined.
Pre-op, Post-op and Follow-up models were reconstructed from CT scans of a single patient and FSI simulations were performed on each model. The FSI approach involved coupling Abaqus and Fluent via a third-party software - MpCCI. Aneurysm wall stress and compliance were investigated as well as the drag force acting on the stent-graft.
Aneurysm wall stress was reduced from 0.38 MPa before surgery to a value of 0.03 MPa after insertion of the stent-graft. Higher stresses were seen in the aneurysm neck and iliac legs post-operatively. The compliance of the aneurysm was also reduced post-operatively. The peak Post-op axial drag force was found to be 4.85 N. This increased to 6.37 N in the Follow-up model.
In a patient-specific case peak aneurysm wall stress was reduced by 92%. Such a reduction in aneurysm wall stress may lead to shrinkage of the aneurysm over time. Hence, post-operative stress patterns may help in determining the likelihood of aneurysm shrinkage post EVAR. Post-operative remodelling of the aneurysm may lead to increased drag forces.
腹主动脉瘤（AAA）是肾下主动脉的局部扩张。如果不治疗，它们可能会破裂并导致死亡。一种治疗方法是将支架移植物微创插入动脉瘤中。尽管这种治疗方法有效，但动脉瘤偶尔仍会继续扩张，最终可能导致动脉瘤手术后破裂。流固耦合（FSI）是一种特别有用的工具，可用于研究动脉瘤生物力学，因为可以同时检查壁应力和流体力。
从单个患者的 CT 扫描中重建术前、术后和随访模型，并对每个模型进行 FSI 模拟。FSI 方法涉及通过第三方软件 - MpCCI 将 Abaqus 和 Fluent 耦合。研究了动脉瘤壁的应力和顺应性，以及支架移植物上的阻力。
动脉瘤壁的应力从手术前的 0.38 MPa 降低到支架移植物插入后的 0.03 MPa。术后在动脉瘤颈部和髂骨支上观察到更高的应力。动脉瘤的顺应性也在手术后降低。术后轴向最大阻力为 4.85 N。在随访模型中，该值增加到 6.37 N。
在特定于患者的情况下，动脉瘤壁的最大应力降低了 92%。动脉瘤壁应力的这种降低可能会导致动脉瘤随时间缩小。因此，术后的应力模式可能有助于确定 EVAR 后动脉瘤缩小的可能性。动脉瘤的术后重塑可能导致阻力增加。
