Figure 6. Oscillatory flow in the venous valve sinus is stimulated by muscular activity but not pneumatic compression of the calf.

(A) 2D color Doppler studies of venous flow at the site of valves (V, green dashed line) and valve sinuses (S) in human femoral, popliteal, and saphenous veins were performed in healthy individuals. The images are representative of 3 femoral veins, 7 popliteal veins, and 7 saphenous veins studied in distinct individuals. Blood flow in the direction of circulation is shown in blue, and reverse/oscillatory flow in red and orange. Flow measured when the individual was immobile (top) was compared with flow measured during muscular activity stimulated by a single toe curl (bottom). A, adjacent artery. (B) Representative images of valve sinus (S) flow in healthy individuals in the saphenous and femoral veins during immobility, after a toe curl, and during the compression phase of a calf intermittent compression device (ICD). The images are representative of 3 saphenous veins and 4 femoral veins.