Venous thromboembolism, the spontaneous formation of blood clots in veins, is a significant cause of disease and death. It is estimated that approximately 350,000 to 600,000 Americans each year suffer from deep vein thrombosis (DVT) and pulmonary embolism (PE) and at least 100,000 deaths may be directly or indirectly related to these diseases. During an episode of DVT, clots usually develop in the lower leg, thigh, or pelvis, but can also occur in the arm. When DVT is present in the lower extremity, there is a 3% chance of the patient dying from PE. Although many patients who develop DVT do not have obvious symptoms, DVT in an arm or leg can cause local discoloration, warmth, tenderness, swelling, pain that is noticeable and worse when standing or walking, and/or impaired drainage of blood. Standard treatments for acute DVT include anticoagulant drugs, clotbusting
drugs, blood filters, and elastic compression stockings. Open surgical thrombectomy (clot removal) is used rarely and only in severe cases.