Mean wall shear stress in the femoral arterial bifurcation is low and independent of age at rest

In elastic arteries, mean wall shear stress appears to be close to 1.5 Pa, the value predicted by the theory of minimal energy loss. This finding in e lastic arteries does not necessarily represent the situation in muscular ar teries. Elastic arteries have to store potential energy, while muscular art eries have mainly a conductive function. Therefore, we determined wall shea r stress and its age dependency in the common and superficial femoral arter ies, 2-3 cm from the flow divider in 54 presumed healthy volunteers between 21 and 74 years of age, using a non-invasive ultrasound system. Prior to t he study, the reliability of this system was determined in terms of intrasu bject variation. Mean wall shear stress was significantly lower in the comm on femoral artery (0.35 +/- 0.18 Pa) than in the superficial femoral artery (0.49 +/- 0.15 Pa). In all age categories, peak systolic wall shear stress and the maximal cyclic change in wall shear stress were not significantly different in the common and the superficial femoral arteries. Peak systolic wall shear stress in the common and the superficial femoral arteries was n ot significantly different from the value previously determined in the comm on carotid artery, but mean wall shear stress was lower in the common and s uperficial femoral arteries than in the common carotid artery by a factor o f 2-4. in both the common and the superficial femoral arteries, mean, peak systolic and maximal cyclic change in wall shear stress did not change sign ificantly with age, nor did diameter. We conclude that, as compared to elas tic arteries, mean wall shear stress is low in the conductive arteries of a resting leg, due to backflow during the first part of the diastolic phase of the cardiac cycle and the absence of flow during the rest of the diastol ic phase. Mean wall shear stress is lower in the common than in the superfi cial femoral artery due to additional reflections from the deep femoral art ery. Copyright (C) 2000 S. Karger AG, Basel.