When you are in the upright position, the blood in your leg veins must go against gravity to return to your heart. To accomplish this, your leg muscles squeeze the deep veins of your legs and feet to help move blood back to your heart. One-way flaps, called valves, in your veins keep blood flowing in the right direction. When your leg muscles relax, the valves inside your veins close. This prevents blood from flowing in reverse, back down the legs. The entire process of sending blood back to the heart is called the venous pump.
When you walk and your leg muscles squeeze, the venous pump works well. But when you sit or stand, especially for a long time, the blood in your leg veins can pool and increase the venous blood pressure. Deep veins and perforating veins are usually able to withstand short periods of increased pressures. However, sitting or standing for a long time can stretch vein walls because they are flexible. Over time, in susceptible individuals, this can weaken the walls of the veins and damage the vein valves, causing CVI.

Over the long-term, blood pressure that is higher than normal inside your leg veins causes CVI. Other causes of CVI include deep vein thrombosis (DVT) and phlebitis, both of which cause elevated pressure in your veins by obstructing the free flow of blood through the veins.
DVT occurs when a blood clot (properly called a thrombus) blocks blood from flowing toward the heart, out of a deep or perforating vein. The blood trying to pass through the blocked veins can increase the blood pressure in the vein, which, in turn, overloads your valves. Vein valves that do not work properly are called incompetent because they stretch and no longer work efficiently, and incompetent valves contribute to CVI. DVT is a potentially serious condition that causes leg swelling and requires immediate medical attention because sometimes the blood clots in the veins can break off and travel to the lungs. This condition is called a pulmonary embolus.
Phlebitis occurs when a superficial or deep vein becomes swollen and inflamed. This inflammation causes a blood clot to form, which can also lead to DVT.
Factors that can increase your risk for CVI include a family history of varicose veins, being overweight, being pregnant, not exercising enough, smoking, and standing or sitting for long periods of time. Although CVI can affect anyone, your age and sex can also be factors that may increase your tendency to develop CVI; women older than 50 most often get CVI.
You must consult your doctor for the treatment.
The information contained in this site is given to inform you and does not substitute for consulting a doctor or a pharmacist.

If you have CVI, your ankles may swell and your calves may feel tight. Your legs may also feel heavy, tired, restless, or achy. You may feel pain while walking or shortly after stopping.
CVI may be associated with varicose veins. Varicose veins are swollen veins that you can see through the skin. They often look blue, bulging, and twisted. Large varicose veins can lead to skin changes like rashes, redness, and sores.
CVI can also cause problems with leg swelling because of the pressure of the blood pooling in the veins. Your lymphatic system may also produce fluid, called lymph, to compensate for CVI. Your leg tissues may then absorb some of this fluid, which can increase the tendency for your legs to swell.