Deep vein failure

In this page we see what happens when the DEEP VALVES of the deep veins in the leg fail.

During movement, when weight is put on the leg and the muscles contract, the blood is pumped up both deep and superficial vein systems on movement (PUMPING).

This is identical to the normal situation in the last page.

However, when the leg RELAXES during the passive phase of walking (when it is swinging forwards and all the weight is on the other leg), the pumping stops and the blood starts to flow backwards down both deep and superficial vein systems as before. This is caused by gravity.

In the superficial vein system, where the valves are still working, this back-flow of blood causes the valves to snap shut, stopping the blood from falling back down the leg veins.

BUT in the deep system, the valves are not working.

In the deep system, the valves are not working and are therefore unable to snap shut. Therefore the blood rushes back down the deep veins in the leg from above.

This blood HITS the vein wall, the lower down the leg the harder the wall is hit, as well as the smaller veins that usually feed into the main veins. This trauma to the vein wall causes INFLAMMATION of the vein and tissues surrounding the DEEP veins.

This is shown diagrammatically in the animation.