Distribution of the geometric parameters of human aortic bifurcations.

The distribution of flow divider offset, branch angle, and angular asymmetry in a collection of 70 human aortic bifurcations are reported. A computer algorithm was used to determine these parameters objectively. The mean values with standard deviations and ranges are: 1) magnitude of flow divider offset = 1.4 +/- 1.4 mm (range = 0.04 to 8.1 mm); 2) branch angle = 35.0 degrees +/- 11.1 degrees (range = 10.4 degrees to 61.3 degrees); and 3) angular asymmetry = 15.3 degrees +/- 12.9 degrees (range 0.2 degrees to 56.1 degrees). Since these parameters have been shown to have a significant influence on hemodynamic shear, their variability suggests a corresponding variability in the fluid dynamic stresses to which the bifurcations were exposed in life.