Fact Sheet: Deep Vein Thrombosis (DVT)

Deep vein thrombosis (DVT) is the formation of a blood clot, known as a thrombus, in the deep leg vein. It is a very serious condition that can cause permanent damage to the leg, known as post-thrombotic syndrome, or a life-threating pulomnary embolism. In the United States alone, 600,000 new cases are diagnosed each year. One in every 100 people who develops DVT dies. Recently, it has been referred to as "Economy Class Syndrome" due to the occurrence after sitting on long flights.

The deep veins that lie near the center of the leg are surrounded by powerful muscles that contract and force deoxygenated blood back to the lungs and heart. One-way valves prevent the back-flow of blood between the contractions. (Blood is squeezed up the leg against gravity and the valves prevent it from flowing back to our feet.) When the circulation of the blood slows down due to illness, injury or inactivity, blood can accumulate or "pool" which provides an ideal setting for clot formation.

Risk Factors

• Previous DVT or family history of DVT
• Immobility, such as bed rest or sitting for long periods of time
• Recent surgery
• Above the age of 40
• Hormone therapy or oral contraceptives
• Pregnancy or post-partum
• Previous or current cancer
• Limb trauma and/or orthopedic procedures
• Coagulation abnormalities
• Obesity

Symptoms

• Discoloration of the legs
• Calf or leg pain or tenderness
• Swelling of the leg or lower limb
• Warm skin
• Surface veins become more visible
• Leg fatigue

Post-thrombotic Syndrome

Post-thrombotic syndrome is an under-recognized, but relatively common sequela, or aftereffect, of having DVT if treated with blood thinners (anticoagulation) alone, because the clot remains in the leg. Contrary to popular belief, anticoagulants do not actively dissolve the clot, they just prevent new clots from forming. The body will eventually dissolve a clot, but often the vein becomes damaged in the meantime. A significant proportion of these patients develop permanent irreversible damage in the affected leg veins and their valves, resulting in abnormal pooling of blood in the leg, chronic leg pain, fatigue, swelling, and, in extreme cases, severe skin ulcers. While this use to be considered an unusual, long-term sequela, it actually occurs frequently, in as many as 60-70 percent of people, and can develop within two months of developing DVT. There is increasing evidence that clot removal via interventional catheter-directed thrombolysis in selected cases of DVT can improve quality of life and prevent the debilitating sequela of post-thrombotic syndrome.

Pulmonary Embolism

Left untreated, a deep vein thrombosis (DVT) can break off and travel in the circulation, getting trapped in the lung, where it blocks the oxygen supply, causing heart failure. This is known as a pulmonary embolism, which can be fatal. With early treatment, people with DVT can reduce their chances of developing a life threatening pulmonary embolism to less than one percent. Blood thinners like heparin and coumadin are effective in preventing further clotting and can prevent a pulmonary embolism from occurring. It is estimated that each year more than 600,000 patients suffer a pulmonary embolism. PE causes or contributes to up to 200,000 deaths annually in the United States. One in every 100 patients who develop DVT die due to pulmonary embolism. A majority of pulmonary embolism are caused by DVT. If pulmonary embolism can be diagnosed and appropriate therapy started, the mortality can be reduced from approximately 30 percent to less than ten percent.

Symptoms of Pulmonary Embolism

The symptoms are frequently nonspecific and can mimic many other cardiopulmonary events.

• Shortness of breath
• Rapid pulse
• Sweating
• Sharp chest pain
• Bloody sputum (coughing up blood)
• Fainting

^{Information provided by the Society of Interventional Radiology, www.SIRweb.org © 2005}