USA - Computational Evaluation of Rupture Potential of Aneurysms

An aneurysm is a local enlargement of the artery. Rupture of an aneurysm is associated with high mortality, and elective repair is recommended when the risk of rupture exceeds the risk of repair. Currently, however, there is a lack of good criteria for pr edicting rupture. The present guideline is to treat the aneurysm when its size exceeds a certain limit (55 mm for abdominal aortic aneurysms (AAA). This criterion is however inaccurate, meaning that some patients with smaller aneurysms get rupture, while other aneurysms remain intact despite of large size. The dilemma is therefore to operate the right patients at the right time. From a biomechanical point of view, the direct cause of rupture is that the load imposed on the tissue exceeds the strength of the vessel wall. Measuring the diameter gives an idealized measure of the load, since, according to Laplace equation, wall stress is proportional to diameter and blood pressure. This holds, however, only for simple geometries (cylinder, sphere). The hypot hesis is that patient specific modeling gives an improved estimate of the load imposed by the passing blood pulse, and thus a better prediction of rupture risk. The resulting model equations must be solved by numerical simulation methods with high computa tional cost. This project will try to address these issues by establishing a close collaboration with the internationally well known research group headed by Professor Thomas J. R. Hughes at the Insitute for Computational Science and Engineering (ICES), University of Texas at Austin, with focus on using advanced mathematics for improving the prediction of aneurysm rupture.