Veins in the lower leg are divided into superficial and deep veins and these are connected by perforator veins. The deep veins are found between the muscle groups and are responsible for carrying most of the blood leaving the leg. Valves are found in the superficial perforator and deep veins, these ensure that blood flows in one direction only. Chronic venous insufficiency occurs when the valves do not function properly and venous drainage is impaired. This valve failure may occur as a result of trauma, varicose veins or thrombosis allowing blood into the section of the vein below. Obesity, sedentary lifestyle or pregnancy can impede venous flow leading to back pressure and consequent valve failure. The valve failure prevents the reduction of venous pressure that normally occurs during exercise resulting in venous hypertension.
Chronic venous hypertension causes abnormalities in the capillaries in the leg tissues that make them more permeable. This allows fluids, proteins, and blood cells to leak into the tissues. Venous hypertension may also be associated with an increased inflammatory response, changes in the structure of the microvasculature and reduced skin and tissue oxygenation. Venous ulceration occurs when the valves are compromised and calf muscle pump is inefficient in facilitating blood flow to the heart. If this remains unmanaged, venous hypertension increases in the lower limb due to prolonged and worsening venous stasis.