What is CVI?
Chronic venous insufficiency (CVI) is a common cause of leg pain and swelling, and is commonly associated with varicose veins. It occurs when the valves of the veins do not function properly, and the circulation of blood in the leg veins is impaired. CVI may affect up to 20% of adults. CVI can be caused by damaged valves in the veins or vein blockage. Both may be a result of deep-vein thrombosis (DVT) or blood clots in the deep veins of the legs. If a clot does form in the superficial veins, there is a very low risk of DVT occurring. Over time, CVI may result in varicose veins, swelling and discoloration of the legs, itching and the development of ulcers near the ankles.
Vein problems are among the most common chronic conditions in North America. In fact, more people lose work time from vein disorders than from artery disease. By the age of 50, nearly 40 percent of women and 20 percent of men have significant leg vein problems. Although varicose veins are thought to be slightly more frequent in men than in women, that could be, in part, because many men delay evaluation and treatment until a later stage of the vein disorder. Spider veins occur much more frequently in women. It is estimated that at least 20 to 25 million Americans have varicose veins.
What is the cause of chronic venous insufficiency?
The cause of CVI is related either to poorly functioning vein valves or blockage in the veins. Vein valves are designed to allow blood to flow against gravity from the legs back to the heart. When the values fail to close properly, gravity wins and the flow reverses. This is called venous reflux. Vein valves may fail to close due to either:
- vein wall weakness that causes the vein to enlarge so that the valves can’t close,
- a history of blood clots or deep vein thrombosis in the vein that damage the valve, or
- an absence of vein valves since birth.
Varicose veins are hereditary most of the time and generally occur in several members of the same family. Much less commonly, varicose veins develop after a trauma or injury. Regardless of the cause, defective valves cause a build up of pressure of the blood in the leg, leading to venous hypertension or high blood pressure in the vein. This may result in enlargement of the varicose veins and an increased likelihood of other symptoms such as swelling, skin changes and ulcers at the ankles or lower leg. Valve failure and venous reflux can also occur in the veins that are unseen, such as the saphenous veins (which run from the foot to the thigh), or in the deep veins. Reflux in these veins is often the underlying cause of painful varicose veins. Venous reflux is a condition that is progressive. If left untreated, it can worsen and cause more advanced symptoms of CVI. On occasion, the cause of the problem isn’t even in the legs, but is in the pelvis. Here, blockage of the veins may severely aggravate the symptoms of varicose veins, thus requiring separate treatment.