Time elapsed: 4 HRS

After 2 hours of non-pulsatile circulation

During muscle paralysis or paresis due to local injury, operation, or neurological deficit [f.i. Stroke, Head or spinal injury, "relaxant" surgical anaesthesia, or quasi-anaesthetic alcoholic pre-coma or coma from any cause, general debility and decubitus] the normal pattern of valve perfusion by reflux ceases and the cusps will "flutter" half open, rather than opening and closing definitively.

See : Karino T and Motomiya M ( Flow through a venous valve and its implications for thrombus formation. In:

1) Microvasc. Res. 1981 21: 247. 2) Thromb. Res. 1984; 36: 245-257)

These authors demonstrated the existence of two vortices in VVP during non-pulsatile circulation : these are a cephalad vortex which is fed from the vessel lumen and rotates to return to the main stream and a counter-rotating trapped vortex in the apical region of such VVP which does not change or exchange with the luminal stream for as long as non-pulsatile circulation persists.

Hamer JD, Malone PC, Silver IA : The PO2 in venous valve pockets: its possible bearing on thrombogenesis. Br.J. Surg., 1981, 68: 166-170.

These authors demonstrated this effect by other means.

Effects of vortex on lining endothelium
These cartoons endeavour to show the consequences of this trapped vortex as a pathophysiological feature of non-pulsatile circulation and perfusion of VVP. As time passes, the lining endothelium is shown to become "Blue" - being rendered ischaemically hypoxic by the isolated body of progressively hypoxaemic blood.