Saccular aneurysm formation in curved and bifurcating arteries

BACKGROUND AND PURPOSE: Distinguishing whether forces resulting from the im pingement of central blood how streams at a curved arterial segment or at t he apex of an intracranial bifurcation could be important for the understan ding of aneurysm formation, Using finite element models, our purpose was to investigate the hemodynamics related to intracranial saccular aneurysm for mation through computer simulations. METHODS: We present two-dimensional finite element models describing severa l distinct stages of aneurysm formation in both curved and bifurcating arte ries, For each model, a description of the numeric solutions and results ar e presented. RESULTS: Our results suggest that the pressures and shear stresses that dev elop along the outer (lateral) wall of a curved artery and at the apex of a n arterial bifurcation create a hemodynamic state that promotes saccular an eurysm formation, The impingement of the central stream results in greatly increased velocity/pressure gradients and high shear stresses at the apex c ompared with those in the proximal parent or distal daughter branches. The results also indicate that the maximal pressure generated at the apex of th e arterial bifurcation ranges from two to three times the peak luminal pres sure in the proximal parent artery. CONCLUSION: These data suggest that, in the absence of any underlying disea se process, aneurysm development is a mechanically mediated event. These mo dels offer a plausible hypothesis regarding the initiation, growth, and sub sequent rupture of saccular intracranial aneurysms as they relate to the he modynamics of intracranial arterial blood how.