Intimal Hyperplasia After Aneurysm Treatment by Flow Diversion

Abstract

Flow diverter stents have become a useful tool for treatment of complex intracranial aneurysms. A serious complication is incomplete wall apposition after flow diverter placement. The aim of this study was to present a comprehensive investigation of hemodynamic changes induced by incomplete expansion of a flow diverter. A case of a patient treated for an internal carotid artery aneurysm by flow diversion with incomplete wall apposition was virtually investigated. The effect of incomplete flow diverter expansion was studied using image-based blood flow simulations under physiologically relevant flow conditions based on patient-specific clinical data. The numerical results revealed that incomplete expansion at the proximal end of the stent had minimal impact on the intra-aneurysmal blood flow alteration. A region of nonphysiologically high wall shear stress was observed near the contact area between the incompletely expanded proximal end of the flow diverter and the parent artery, which caused an intimal hyperplasia in this region. These simulation results were consistent with the real-life clinical course and outcome. The results of this study can be considered during treatment planning of complex cases where the risk of incomplete flow diverter expansion exists. Further studies are required before results can also be used to support the decision process about antiplatelet therapy and additional interventions to improve wall apposition.