Chronic venous insufficiency is a disease caused by weak, worn, or damaged valves in the veins of the legs. It can also cause sores on the legs, especially in the area of the ankles. The arteries pump blood from the heart and the veins return blood to the heart. Veins, unlike arteries, have no muscle tissue.
Veins require the muscles in our feet and legs to return the blood, against gravity, to the heart.
To help this process, the veins have a series of valves in them that prevent back flow. The valves in your veins may be weak or worn. They may have been damaged by a blood clot in one of the deep veins of your leg. When these valves are not working well, the blood has difficulty moving upward. Prolonged increased pressure in the veins causes the valves to stretch out, making them unable to close properly.