Venous disease is a term used to describe several disorders of the veins. In the body's circulatory system, arteries carry oxygen-rich blood from the heart to the tissues throughout the body, and veins carry oxygen-poor blood back to the heart and lungs. Veins include:
|Blood returns to the heart via the venous pump.|
- Superficial veins, or veins that are close to the skin;
- Communicating or perforating veins, which carry blood from the superficial veins to the deep veins; and
- Deep veins, which are located in groups of muscles and carry blood to the vena cava, the body's largest vein.
Several forces propel blood in the veins back to the heart, including contraction of the heart, gravity, and contraction of other muscles. Veins have a series of one-way valves that permit flow toward the heart, while blocking flow in the opposite direction. This is accomplished by two flaps, called cusps, that fold together and close the valves, preventing the blood from flowing backward.
If the vein walls weaken or are damaged, or if the valves malfunction, blood can pool by gravity, particularly in the lower leg. As a result, the pressure in these veins increases. This increased pressure can further damage the veins and valves, resulting in swelling, slow blood flow, and clot formation. This can in turn lead to several venous conditions.
Venous disease includes:
- Varicose veins: Varicose veins are superficial veins that are unnaturally and permanently distended, or swollen. The veins most commonly appear blue, knotted, and twisted, and usually occur on the back of the calf or the inside of the leg. Varicose veins can cause swelling in the legs and in severe cases, skin ulcers (sores). Spider veins (telangiectases) are very small, superficial veins that are easily visible but are not major contributors to serious complications.
- Superficial thrombophlebitis: This condition is inflammation that causes a blood clot, or thrombus, to form in a healthy superficial vein or a varicose vein visible on the surface of the skin. Although superficial thrombophlebitis is usually not dangerous and resolves on its own, it can recur.
- Chronic venous insufficiency (CVI): Sometimes thrombophlebitis damages the valves in the veins, particularly in the leg veins. When this happens, the valves are unable to prevent blood from flowing backward when a person stands, causing blood to pool in the vein. Varicose veins may result. However, if the leg swells because the pooling is extensive, then the condition is called venous insufficiency. The veins may no longer be able to normally pump blood out of the legs and back to the heart. CVI can affect superficial or deep veins.
- Deep vein thrombosis (DVT): This condition develops when a thrombus forms in a deeper vein, usually located in the leg or pelvis. Rarely, clots develop in the deep veins of the abdomen, chest, and arms. DVT is a primary cause of pulmonary embolism. A pulmonary embolism occurs when a blood clot dislodges from the vein wall and travels through the bloodstream to the lungs, where it becomes lodged. If an embolism is small, it may not cause much damage. However, a large embolism can block blood flow to the pulmonary artery, a potentially deadly condition that must be treated immediately. In addition, DVT can lead to CVI.