Abstract
Flow-diverting stents (FDSs) show considerable promise for the treatment of cerebral aneurysms by diverting blood flow away from the aneurysmal sacs, however, post-treatment complications such as failure of occlusion and subarachnoid haemorrhaging remain and vary with the FDS used. Based on computational fluid dynamics (CFD), this study aimed to investigate the performance of a new biodegradable stent as compared to two metallic commercially available FDSs. CFD models were developed for an idealized cerebral artery with a sidewall aneurysmal sac treated by deploying the aforementioned stents of different porosities (90, 80, and 70 % ) respectively. By using these models, the simulation and analysis were performed, with a focus on comparing the local hemodynamics or the blood flow in the stented arteries as compared to the one without the stent deployment. For the comparison, we computed and compared the flow velocity, wall shear stress (WSS) and pressure distributions, as well as the WSS related indices, all of which are of important parameters for studying the occlusion and potential rupture of the aneurysm. Our results illustrate that the WSS decreases within the aneurysmal sac on the treated arteries, which is more significant for the stents with lower porosity or finer mesh. Our results also show that the maximum WSS near the aneurysmal neck increases regardless of the stents used. In addition, the WSS related indices including the time-average WSS, oscillatory shear index and relative residence time show different distributions, depending on the FDSs. Together, we found that the finer mesh stents provide more flow reduction and smaller region characterized by high oscillatory shear index, while the new stent has a higher relative residence time.
Highlights
A cerebral aneurysm, known as a brain aneurysm, is an abnormal blood-filled bulge or dome of a blood vessel, typically an artery, caused by weakening of the blood vessel due to cerebrovascular diseases/disorders
We investigated how the fine mesh stent affects the reduction of the WSS related indices including time average wall shear stress (TAWSS) and oscillatory shear index (OSI) distribution
We presented a simplified computational fluid dynamics (CFD) model consisting of a spherical aneurysm on a straight artery, where three different stents - a new design and two commercial devices, were deployed, respectively, for treatment
Summary
A cerebral aneurysm, known as a brain aneurysm, is an abnormal blood-filled bulge or dome of a blood vessel, typically an artery, caused by weakening of the blood vessel due to cerebrovascular diseases/disorders. The degree of flow modification necessary to induce a complete aneurysm occlusion among patients is not yet clear due to the complexity involved in the changed hemodynamics upon the use of stents. Studies have been recently published regarding this topic and it is generally accepted that the success of FDS treatment with a satisfactory aneurysm occlusion depends on the changed hemodynamics [5,6]. It is recognized the porosity of stents plays an important role in the changed hemodynamics; lower porosity can reduce the blood flow into the aneurysm, increasing the likelihood of aneurysm occlusion. The FDA-approved endovascular stents for cerebral applications have porosities between 80% and
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