Overview of venous thromboembolism.

Thrombosis occurs at sites of injury to the vessel wall, by inflammatory processes leading to activation of platelets, platelet adherence to the vessel wall and the formation of a fibrin network. A thrombus that goes on to occlude a blood vessel is known as a thromboembolism. Venous thromboembolism begins with deep vein thrombosis (DVT), which forms in the deep veins of the leg (calf) or pelvis. In some cases, the DVT becomes detached from the vein and is transported to the right-hand side of the heart, and from there to the pulmonary arteries, giving rise to a pulmonary embolism (PE). Certain factors predispose patients toward the development of venous thromboembolism (VTE), including surgery, trauma, hospitalization, immobilization, cancer, long-haul travel, increased age, obesity, major medical illness and previous VTE; in addition, there may also be a genetic component to VTE. VTE is responsible for a substantial number of deaths per annum in Europe. Anticoagulants are the mainstay of both VTE treatment and VTE prevention, and many professional organizations have published guidelines on the appropriate use of anticoagulant therapies for VTE. Treatment of VTE aims to prevent morbidity and mortality associated with the disease, and any long-term complications such as VTE recurrence or post-thrombotic syndrome. Generally, guidelines recommend the use of low molecular weight heparins (LMWH), unfractionated heparin (UFH) or fondaparinux for the pharmacological prevention and treatment of VTE, with the duration of therapy varying according to the baseline characteristics and risk profile of the individual. Despite evidence showing that the use of anticoagulation prevents VTE, the availability of several convenient, effective anticoagulant therapies and the existence of clear guideline recommendations, thromboprophylaxis is underused, particularly in patients not undergoing surgery. Greater adherence to guideline-recommended therapies, such as LMWH, which can be administered on an outpatient basis, should reduce the mortality associated with this preventable disease.