Deep vein thrombosis (DVT) is a condition in which blood clots form on the inside of the deep veins and block blood flow from the leg to the heart. It most commonly develops in the veins of the legs, but occasionally occurs in the arms or, more rarely, other parts of the body.
The most common symptoms of a leg DVT are calf or thigh pain, swelling, and redness of the skin on the leg.
Besides the initial symptoms of pain and swelling, the most significant danger to people with DVT is pulmonary embolism (PE). (see below)
Unfortunately, for many people, the initial clot in the leg does not completely go away, resulting in a disease called the post-thrombotic syndrome (PTS) in that leg. 30-40% of people suffer from this condition in subsequent months to years after the acute DVT. Symptoms of PTS include pain, cramping, itching, “pins and needles,” and heaviness. The leg may appear swollen, have skin changes, and in severe cases develop ulcers. While not completely understood, PTS is caused by obstruction of blood flow through the damaged and clot-filled veins, leading to increased pressure in the leg and the symptoms described above.
A pulmonary embolism occurs when part of the blood clot breaks off from the leg or arm, travels through the veins and heart, and into the pulmonary arteries, which supply the lungs with blood. If the clot is large enough, it can compromise heart function and in some cases cause death. However, the majority of people who have PEs, especially if diagnosed and treated quickly, survive.
Chronic venous disease (CVD) can result in swelling, pain, and ulcers.
CVD is caused by increased pressure in the leg from the following: