The VAT 300 induces muscle contractions at 16 sites distributed on the legs and arms. The peristaltic-like contraction impulses are sequential, from distal to proximal at quarter-second intervals. This induced circulation increases blood flow toward the heart, raising venous return, preload, stroke volume and cardiac output. Through this mechanism, VAT increases blood flow and shear stress.

 

Shear stress, through mechanotransduction, activates autocrine and paracrine processes. Davies, Berk, Pan, Malek, Traub and others have documented dozens of vasoactive substances that are flow dependent. Under conditions of normal, physiological flow, such substances are increased that are mostly anticoagulent, antiinflammatory, vasodilatory, antiapoptotic, and anti-adhesive. These processes can also change endothelial cells to a quiescent phenotype. Low shear levels, on the other hand, impair most of these biochemical processes.