Veins are blood vessels that return deoxygenated (the oxygen content has been used up) blood to the heart from all parts of the body. The capillaries (tiny blood vessels) deliver deoxygenated blood from the tissues to the venules (small veins), which join together to form the veins. The veins carry the blood to the venae cavae (the two largest veins in the body), which deliver the blood to the right atrium of the heart. In the heart, the blood travels from the right atrium to the right ventricle, which pumps the blood through the pulmonary artery into the lungs. In the lungs, the blood is reoxygenated (gives up carbon dioxide and receives oxygen) and is returned through the pulmonary veins to the left atrium of the heart. The blood then travels from the left atrium to the left ventricle, which pumps the blood through the aorta (the body's main artery). From the aorta, the blood travels back to the tissues through the arteries, arteri-oles (tiny arterial branches), and capillaries.
Blood pressure in the veins is much lower than it is in the arteries. Also, the walls of the veins are thinner, weaker, and much less elastic than the walls of the arteries. Because of this, the veins need help to move the blood along. To keep blood flowing toward the heart, the linings of the veins have folds that work as
Heart, Blood, and Circulation one-way valves. Each valve has two halves (cusps) with edges that meet, like a pair of swinging doors. As blood travels through the veins back to the heart, it pushes these valves open. Surrounding muscles contract and press against the vessel walls, which helps keep blood flowing toward the heart.
Your legs contain two types of veins—superficial veins, which are located in the fatty layer beneath the skin, and deep veins, which are located in the muscles. Short veins connect the deep veins with the superficial veins. The leg veins depend on the powerful calf muscles to help move blood up toward the heart. Three common problems that can affect the leg veins are deep vein thrombosis, varicose veins, and superficial phlebitis.
A clot that forms in a blood vessel is called a thrombus. Deep vein thrombosis is formation of blood clots in the deep veins in the legs. The condition is not always life-threatening. However, if a piece of blood clot breaks loose, it can travel through the bloodstream and lodge in an artery in the lung, obstructing blood flow. This is called a pulmonary embolism (see page 249), which is a potentially life-threatening condition. For this reason, all cases of deep vein thrombosis are considered serious.
Factors that contribute to deep vein thrombosis include:
• an increased tendency to form blood clots, which occurs, for example, after an injury or surgery
• sluggish blood flow in the veins, which occurs, for example, when a person is inactive or immobilized for long periods
Occasionally, deep vein thrombosis occurs as a complication of superficial phlebitis (see page 238). Thrombosis also can occur in healthy people who sit for long periods while driving or flying.
Warning Signs of Deep Vein Thrombosis
About half of all people with deep vein thrombosis do not experience symptoms. Others may experience some or all of the following:
• inflammation of the calf, with swelling, warmth, and tenderness
• swelling of the ankle, foot, or thigh
• edema (fluid accumulation) in the ankles that is worse toward the end of the day
• brownish skin, usually above the ankle, that breaks open easily
If you experience any of these symptoms, talk to your doctor as soon as possible.
Imaging techniques such as radionuclide scanning (see page 213) and Doppler ultrasound (an imaging technique that provides motion pictures of blood flow) can be used to diagnose deep vein thrombosis. These tests can reveal important information about blood flow and the condition of the veins deep inside the legs.
Treatment may not be necessary if the blood clots are small and confined to the calf. If you walk a lot, the clots may dissolve on their own. People at risk for deep vein thrombosis (such as those recovering from surgery, and long-distance travelers) should flex and extend their ankles about 10 times every 30 minutes to keep the blood flowing. Support hosiery can help by putting pressure on the legs, causing the veins to narrow slightly, which makes the blood flow faster and clotting less likely. (Warning: If not worn correctly, support hose may aggravate the problem by obstructing blood flow in the legs. Ask your doctor or nurse to show you the correct way to wear support hose.) For more serious cases of thrombosis, a doctor may prescribe anticoagulant (blood-thinning) medication or throm-bolytic (clot-dissolving) drugs to reduce the risk of pulmonary embolism. In some cases surgery to remove the clots may be necessary.
Heart, Blood, and Circulation
Varicose veins are enlarged, twisted veins just beneath the skin that result from weakening of the valves in the veins. Over time, the veins lose their elasticity and stretch, becoming longer and wider. Because of limited space, the elongated veins start to curve, form twisted, snakelike patterns, and bulge up into the skin. As the veins widen, the edges of the valves separate and the veins lose their ability to keep blood flowing toward the heart. Consequently, blood pools (collects) in the veins, causing them to enlarge even more. Although varicose veins are most common in the legs, they also can occur in the esophagus, and in the rectal area as hemorrhoids (see page 271).
Varicose veins appear blue and swollen, just beneath the skin, usually on the inside of the leg or the back of the calf. The affected area may ache, and your legs may feel tired. Your feet and ankles may swell, and your skin may become dry and itchy. However, many people, even those who have large varicose veins, have no discomfort. A small percentage of people have complications such as superficial phlebitis (see page 238), or bleeding, which can result from injury or scratching.
Treatment focuses on relieving symptoms, improving appearance, and preventing complications. Elevating your legs is one of the best ways to relieve symptoms. Treatment also includes wearing elastic support hose, taking regular walks, avoiding standing for long periods, and controlling your weight.
Very painful or unsightly veins may be surgically removed by a process called stripping. The procedure is performed using a local anesthetic and takes about half an hour per leg. Healthy veins take over the work of the veins that have been removed. After surgery, new varicose veins may develop elsewhere.
Although stripping relieves symptoms and prevents complications, the procedure also can leave scars.
Sclerotherapy is an alternative to stripping. An irritant solution is injected into the varicose vein, causing the vein's walls to stick together and block the blood flow through the vein. Other veins take over the work of the treated veins. After the procedure there is a chance that new varicose veins will develop.
Superficial phlebitis (also called phlebitis or thrombophlebitis) is inflammation and thrombus (blood clot) formation in a superficial vein. This condition can affect any vein in the body but usually affects the leg veins. Phlebitis can occur after minor injury to a vein or as a complication of varicose veins. Although phlebitis occurs in people with varicose veins, most people with varicose veins do not develop phlebitis.
Symptoms include redness, swelling, and tenderness in the affected area. Some people may experience fever and a vague feeling of being ill. Deep vein thrombosis (see page 236) is a possible, though uncommon, complication.
Superficial phlebitis usually is treated by gently wrapping the leg with a compression bandage and by taking a nonsteroidal anti-inflammatory drug such as ibuprofen. The blood clot usually dissolves on its own. The affected area may remain tender for several weeks. In severe cases the doctor may inject a local anesthetic, make a small cut in the leg, and remove the thrombus. He or she will recommend wearing a compression bandage for several days and taking aspirin or ibuprofen to relieve pain and inflammation.
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