Abstract
We show here the data suggesting that enhanced hemodynamics in the asymmetric-shaped circle of Willis initiates cerebral aneurysm (CA) formation, using CA-inducing model and CFD analysis. CA develops at the circle of Willis, where blood flow is increased by a carotid ligation and hypertension. The number of induced CA was significantly smaller in knockout mice of P2X4 purinoceptor, the endothelial shear-sensor, than wild types. Endothelium may sense an enhanced wall shear stress (WSS), which initiates CA formation. In CFD, flow velocities derived from individual physiological data, but not commonly used assumed ones calculated with the average in healthy adults, should be used as inlet boundary conditions. In CFD analyses in the human MCA aneurysm, we virtually reconstructed the arterial geometry just before CA induction, and compared hemodynamics between CA-induced side and normal side. Normalized transverse WSS is significantly larger at CA side than normal side, suggesting that WSS temporal fluctuations in transverse direction to flow are involved in CA formation. To clarify mechanisms of CA enlargement and rupture, the prospective clinical trial, CFD ABO Study was launched.
