n. obstruction of a vein by a blood clot, without preceding inflammation of its wall. It is most common within the deep veins of the calf of the leg – deep vein thrombosis (DVT) – in contrast to *thrombophlebitis, which affects superficial leg veins. Prolonged immobility, heart failure, pregnancy, injury, and surgery predispose to thrombosis by encouraging sluggish blood flow. Many of these conditions are associated with changes in the clotting factors in the blood that increase the tendency to thrombosis; these changes also occur in some women taking oral contraceptives.
The affected leg may become swollen and tender. The main danger is that the clot may become detached and give rise to *pulmonary embolism. Regular leg exercises help to prevent deep vein thrombosis, and anticoagulant drugs (such as heparin and warfarin) are used in prevention and treatment. Large clots may be removed surgically in the operation of thrombectomy to relieve leg swelling.
n. inflammation of the wall of a vein, which is most commonly seen in the legs as a complication of *varicose veins. A segment of vein becomes painful and tender and the surrounding skin feels hot and appears red. Thrombosis commonly develops (see thrombophlebitis). Treatment consists of elastic support together with drugs, such as NSAIDs, to relieve the inflammation and pain. Anticoagulants are not used (compare phlebothrombosis). Phlebitis may also complicate sepsis (see pylephlebitis) or cancer, especially of the stomach, bronchus, or pancreas. In pancreatic cancer the phlebitis may affect a variety of veins (thrombophlebitis migrans).... phlebitis
obstruction of the *pulmonary artery or one of its branches by an *embolus, usually a blood clot derived from *phlebothrombosis of the leg veins (deep vein thrombosis). Large pulmonary emboli result in acute heart failure or sudden death. Smaller emboli cause death of sections of lung tissue, pleurisy, and haemoptysis (coughing of blood). Minor pulmonary emboli respond to the *anticoagulant drugs heparin and warfarin. Major pulmonary embolism is treated by *embolectomy or by dissolution of the blood clot with an infusion of *streptokinase. Recurrent pulmonary embolism may result in *pulmonary hypertension.... pulmonary embolism
n. the condition in which a blood clot (thrombus), formed at one point in the circulation, becomes detached and lodges at another point. It is most commonly applied to the association of phlebothrombosis and *pulmonary embolism (pulmonary thromboembolic disease).... thromboembolism
n. the dissolution of a blood clot (thrombus) by the infusion of a *fibrinolytic agent into the blood. It may be used in the treatment of *phlebothrombosis, *pulmonary embolism, and coronary thrombosis.... thrombolysis
n. a condition in which the blood changes from a liquid to a solid state within the cardiovascular system during life and produces a mass of coagulated blood (thrombus). Thrombosis may occur within a blood vessel in diseased states. Thrombosis in an artery obstructs the blood flow to the tissue it supplies: obstruction of an artery to the brain is one of the causes of a *stroke and thrombosis in an artery supplying the heart – *coronary thrombosis – results in a heart attack (see myocardial infarction). Thrombosis can also occur in a vein (deep vein thrombosis; see phlebothrombosis), and it may be associated with inflammation (see thrombophlebitis). The thrombus may become detached from its site of formation and carried in the blood to lodge in another part (see embolism).... thrombosis
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