Anatomy:

Venous disease refers to all conditions related to or caused by veins that become diseased or abnormal. Venous disease is quite common -- about 15 percent of the adult population is affected. Mild venous disease is usually not a problem for patients, but as venous disease worsens, it can become crippling chronic venous insufficiency.

In the normal circulation, arteries carry oxygen rich blood from your heart to the body, and veins return the blood to your heart. Veins have one-way valves along their length to keep the blood flowing to the heart. As muscles contract, the blood is squeezed forward in the veins. When muscles relax, the valves shut to prevent blood from flowing backward.