Saccular aneurysm formation in curved and bifurcating arteries.

BACKGROUND AND PURPOSE

Distinguishing whether forces resulting from the impingement of central blood flow streams at a curved arterial segment or at the apex of an intracranial bifurcation could be important for the understanding of aneurysm formation. Using finite element models, our purpose was to investigate the hemodynamics related to intracranial saccular aneurysm formation through computer simulations.

METHODS

We present two-dimensional finite element models describing several distinct stages of aneurysm formation in both curved and bifurcating arteries. For each model, a description of the numeric solutions and results are presented.

RESULTS

Our results suggest that the pressures and shear stresses that develop along the outer (lateral) wall of a curved artery and at the apex of an arterial bifurcation create a hemodynamic state that promotes saccular aneurysm formation. The impingement of the central stream results in greatly increased velocity/pressure gradients and high shear stresses at the apex compared with those in the proximal parent or distal daughter branches. The results also indicate that the maximal pressure generated at the apex of the arterial bifurcation ranges from two to three times the peak luminal pressure in the proximal parent artery.

CONCLUSION

These data suggest that, in the absence of any underlying disease process, aneurysm development is a mechanically mediated event. These models offer a plausible hypothesis regarding the initiation, growth, and subsequent rupture of saccular intracranial aneurysms as they relate to the hemodynamics of intracranial arterial blood flow.