Wall Shear Stress in the Superficial Femoral Artery of Healthy Adults and its Response to Postural Changes and Exercise

Objectives: Alterations of wall shear stress (WSS) are considered to precede atherosclerosis. Local variations of WSS might contribute to the typical distribution of atherosclerotic lesions along the superficial femoral artery (SFA). We investigated the course of WSS and its response to postural changes and exercise along the SEA of healthy adults. Methods: In forty-six healthy subjects, we determined flow velocities and internal vessel diameters in five predefined segments of the SEA using duplex ultrasound; measurements were done at rest, following exercise (30 toe raises) and after postural changes (supine and sitting). Peak and mean WSS were calculated from peak systolic and mean velocities, vessel diameter and whole blood viscosity. Results: At rest, peak and mean WSS did not vary along the femoro-popliteal axis (p > 0.05); peak and mean WSS were lower in the sitting than in the supine position (p < 0.0001). After exercise, peak and mean WSS increased in all segments (p < 0.0001), showing the lowest increase in the distal Hunter's canal. Conclusion: Healthy adults do not exhibit local variations of WSS in the SEA at rest, but segmental differences in WSS occur after exercise. Whether these findings are related to the typical distribution of atherosclerotic lesions later in life requires further investigation. (C) 2011 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.