Pathological-anatomical study concerning the geometry and atherosclerosis of the carotid bifurcation.

Besides metabolic factors haemodynamic elements are important in the development of obliterating athero-sclerosis. Since the geometry of a bifurcation influences the local bloodflow, we hypothesise that non-optimal geometry of a bifurcation leads to flow-disturbances, which can be a factor in atherogenesis. To verify our hypothesis that there is a correlation between non-optimal geometry of a bifurcation and the presence of atherosclerotic lesions, we studied as a parameter for the geometry of a bifurcation the area ratio defined as: the sum of the cross-sectional areas of the distal arteries divided by the cross-sectional area of the proximal artery. In this study the area ratios of 100 carotid bifurcations were studied by post-mortem examination. The mean value calculated for 60 normal carotid bifurcations was 1.47, and the mean for 40 diseased bifurcations was 0.99. The last value is significantly less than the theoretical optimal area ratio of 1.16, which was found by Womersley and Hunt as the value at which a minimum reflexion of pressure waves and a minimum of blood-flow energy loss occurs at a bifurcation. We conclude that a non-optimal area ratio of a carotid bifurcation seems to be a factor in atherogenesis.