Endovascular coiling treatment of cerebral aneurysm: a hemodynamic analysis and a cost-efficacy analysis.

The cerebral aneurysm is a dilatation of an arterial wall and its rupture is a devastating event associated with high rates of morbidity and mortality. It's of crucial importance to investigate the alteration of mechanical properties and blood flow in the artery associated with the formation of the aneurysm. Endovascular coiling, due to its minimally invasive nature, is increasingly being used to treat brain aneurysm. Like any surgical procedure, intraprocedural complications may occur . Doctors could use Fluid-Structure Interaction (FSI) simulation, a powerful tool for studying and quantifying hemodynamic outcomes in a brain aneurysm model and the effects of endovascular treatment. FSI performed before surgery helps predict the clinical outcomes and further complications, and thus adverse outcomes could be avoided. In this work, the first goal is to numerically study the interaction between the blood and the middle cerebral artery (MCA) aneurysm wall using the FSI method. Two cases are chosen: an untreated thin wall and a treated MCA aneurysm. For each case, two subcases are examined: Newtonian and non-Newtonian blood model and the effect on the hemodynamic parameters of the blood flow such as velocity pattern, displacement, Von Mises stress and Wall shear stress (WSS). Considering the clinical results in their totality, so including in addition to the health outcomes also the clinical costs, it is equally important to conduct a cost-efectiveness analysis in order to help the decision maker, that could be a doctor, about the best clinical path to follow. This arises from the great variety of cerebral coils that can be used in endovascular treatment, and each of these types produces diferent outcomes. Work in progress aims to investigate what the most cost-efective cerebral coils choice might be. In this study, the incremental cost-utility of two macro families of cerebral coils, Spectra Bare Platinum coils (S-BP) vs the other coils, are assessed. The S-BP coils are chosen for their potential cost savings with the decreased stent request due to their particular structure. A decision-analytical study is performed with Markov modeling method to simulate patients with a cerebral aneurysm undergoing S-BP coiling or alternative coiling. Input parameters are collected from literature review, and a 1-way deterministic analysis (DSA) and probabilistic sensitivity analysis (PSA) are performed to investigate the impact of uncertainties of input parameters on the result. From the hemodynamic analysis it was found that blood flow forms a vortex in the aneurysm due to its slowing down. Newtonian model doesn't differ much to the non-Newtonian one, but it causes the overestimation of velocity blood. It was found that the blood viscosity has no signifcant effect on Von Mises stress magnitude, but there is a relation with WSS, since an increase in viscosity causes an overestimation of the WSS peak value, thus inaccurately estimating aneurysm rupture risk. It was shown that by treating the aneurysm, the vortex and the low WSS in the aneurysm are removed, which suggest the endovascular coiling as an appropriate treatment. From the cost-utility analysis endovascular treatment using S-BP coils was the more cost-effective compared with alternative coiling in the base case, and also confirmed in the DSA and PSA. So, this study indicates that S-BP coiling is the dominant strategy with a lower aneurysm retreatment rate and analogous longer lifetime survival.