The influence of the blunting of the apex on the flow in a vertebro-basilar junction model.

The apex of human vertebro-basilar junctions can be sharp-edged or blunted. In the present study, the effect of blunted apex on the flow in vertebro-basilar junction models is investigated. We compared the flow phenomena in a series of junction models with blunted apices and confluence angles 45, 85, and 125 deg with the flow phenomena in a series of junction models with sharp-edged apices and the same range of confluence angles, studied in a previous paper (Ravensbergen et al., 1996b). The blunting of the apex appears to have an effect on the size of the local recirculation area near the apex and the prevailing low velocities. Large recirculation areas are found in the models with blunted apices, especially in those with small confluence angles. In addition, the blunting of the apex has no influence on the flow further downstream, nor on the structure and strength of the secondary flow field. Furthermore, a blunted apex appears to be a geometric risk factor for atherosclerosis. This supports the hypotheses that recirculation areas and low wall shear stress influence the development of atherosclerotic plaques.