Numerical Assessment of Geometric and Load Parameters Associated with Intracranial Aneurysm Formation

Local biomechanical effects play an important role in aneurysm formation and rupture. It is hypothesised that the main governing factors of the pathogenetic process are the temporal variation and spatial distribution of the flow induced wall shear stress (WSS). The present paper investigates the geometry of the carotid bifurcation, a typical location of cerebral aneurysms. Based on patient specific three-dimensional rotation angiography (3DRA) data a parameter study was carried out on a two-dimensional simplified model using the ANSYS commercial framework, describing the blood flow dynamics and the mechanical effects resulting from a physiologically realistic flow. While the geometry-induced surplus of the normal pressure proved to be negligible regarding even the normal diastolic pressure, the WSS and its variation showed significant deviations near the bifurcation apex. Well defined distinct geometrical properties (the lumen area ratio and the bifurcation angle) can be established describing the major impact on the pressure and the WSS enabling us to estimate the potential hazards of a healthy bifurcation.