Blood clots are lifesavers when they seal a cut. They can be dangerous, even deadly, when they form inside an artery or vein. Deep vein thrombosis (sometimes called DVT) is the formation of a blood clot in a large leg vein. It can also occur in an arm vein. Deep vein thrombosis can lead to a stroke or pulmonary embolism. In the United States alone, deep vein thrombosis accounts for as many as 100,000 deaths a year. One-third of the survivors are left with long-term health problems.
Blood that circulates to the legs and feet must flow against gravity on its journey back to the heart. The trip is aided by the contraction of leg muscles during walking or fidgeting. The contractions squeeze veins, pushing blood through them. Small flaps, or valves, inside the veins keep blood flowing in the direction of the heart.
Anything that slows blood flow through the arms and legs can set the stage for a blood clot to form. This can range from having an arm or leg immobilized in a cast to prolonged sitting or being confined to bed. Things that make blood more likely to clot, such as genetic disorders and cancer, are other big triggers for deep-vein thrombosis.
Symptoms of deep vein thrombosis
Deep vein thrombosis can develop silently. It can also cause:
- pain or tenderness in a leg or arm that gets worse with time, not better
- swelling in one leg or arm
- a reddish or bluish tinge to the skin of one leg or arm
- a leg or arm that feels warm to the touch.
The symptoms of pulmonary embolism include:
- difficulty breathing
- chest pain or discomfort that worsens with a deep breath or cough
- coughing up blood
- a fast heart rate
- sudden lightheadedness or fainting
Diagnosing deep vein thrombosis
It is difficult for your doctor to diagnose deep vein thrombosis just by physical examination of the affected limb. Various tests are usually needed. The first one is usually an ultrasound of the affected leg or arm. This can visualize any clots and measure the speed of blood flow through the veins.
Some people need to have a venogram or MRI scan. A venogram involves injecting dye into the veins to look for blockages. An MRI scan can show veins high in the leg and the pelvis.
When pulmonary embolism is suspected, a blood test called the D-dimer test is usually done. It can detect high levels of blood-clot breakdown products in the bloodstream.
Treating deep vein thrombosis
The main goal for treating deep vein thrombosis is preventing pulmonary embolism. After that come easing symptoms and improving blood flow in the affected limb. Bed rest with the feet elevated, either at home or in the hospital, along with moist heat can help reduce pain and swelling.
Medications are important for controlling the clot. Heparin or other injectable blood thinners like low-molecular-weight heparin or fondaparinux (Arixtra) keeps the clot from getting larger and prevents new ones from forming. It is usually taken for five to seven days, and is then gradually replaced by warfarin (Coumadin, Jantoven, generic) or one of the newer anticoagulant drugs such as apixaban (Eliquis), dabigatran (Pradaxa), or rivaroxaban (Xarelto) for six months or longer. The use of compression stockings that squeeze the legs is also recommended.
The body's natural clot-busters gradually chip away at the clot. Sometimes it's important to speed the process along. This can be done by removing the clot with a procedure called venous thrombectomy or by injecting it with a clot-dissolving drug.
Treating pulmonary embolism is a far more urgent matter. Heparin and warfarin are used to stabilize the clot and to keep new ones from forming. Depending on the size and severity of the clot, additional treatments range from clot-dissolving drugs to physically removing the clot or placing a filter in the inferior vena cava, the large vein that carries blood from the lower half of the body to the heart.