Blood clots in the blood vessels

The two major types of blood vessels are veins and arteries. Arteries carry blood from the heart to the body; veins carry blood back to the heart.

Usually the causes of blood clots in the veins are very different from the causes of the blood clots in the arteries. In the short term, serious problems can result from clots in both veins and arteries. However, a blood clot (thrombus) in an artery generally carries more long-term risks of complications than a blood clot in a vein. Arterial blood clots are associated with other chronic diseases, such as atherosclerosis. These conditions can lead to further serious complications like heart attack or stroke.

The major risk of deep vein thrombosis is when the clot breaks off and blocks blood flow in a blood vessel of the lung (pulmonary embolism). Other complications, such as postthrombotic syndrome, can also be serious. However, proper treatment most often prevents these problems, and a person can generally expect a normal life span with few long-term complications.

Having a blood clot in a vein does not mean you are at increased risk for blood clots in the arteries. A venous thrombosis is a blood clot in a vein. A blood clot generally develops in damaged blood vessels or in places where the blood flow stops or slows down, such as the calves of the legs.