Arteries bring oxygen-rich blood from the heart to the rest of your body, whereas the veins are the blood vessels that return oxygen-poor blood back to the heart. There are three kinds of veins. Superficial veins lie close to the skin, and the deep veins lie in groups of muscles. Perforating veins connect the superficial veins to the deep veins with one-way valves. Deep veins lead to the vena cava, the body's largest vein, which runs directly to the heart. Deep vein thrombosis (DVT) is a blood clot in one of the deep veins. Usually, DVT occurs in the pelvis, thigh, or calf, but it can also occur less commonly in the arm, chest, or other locations.
DVT can cause sudden swelling, pain or a sensation of warmth. DVT can be dangerous because it can cause a complication known as pulmonary embolism. In this condition, a blood clot breaks free from the deep veins, travels through the bloodstream, and lodges in the lungs. This clot can block blood flow in the lungs, which can strain the heart and lungs. A pulmonary embolism is a medical emergency. A large embolism can be fatal in a short time.
About half of all DVT cases do not cause symptoms. The symptoms you feel can depend on the location and size of your blood clot. They include swelling, tenderness, leg pain that may worsen when you walk or stand, a sensation of warmth, and skin that turns blue or red.
Often, poor blood flow, or stagnation of blood flow, in your leg veins increases the risk for DVT. This poor flow can occur when you are not able to move for long periods of time. As a result, when your blood pools in your veins, clots are more likely to form. Some specific causes of DVT include:
Risks of thrombolysis include high risk of bleeding, need for additional procedures, stroke, and very small risk of death. May need to be monitored in ICU.