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Related to thrombosis: embolism, cerebral thrombosis, phlebitis, Deep vein thrombosis


(thrŏmbō`sĭs), obstruction of an artery or vein by a blood clot (thrombus). Arterial thrombosis is generally more serious because the supply of oxygen and nutrition to an area of the body is halted. Thrombosis of one of the arteries leading to the heart (heart attack; see infarctioninfarction,
blockage of blood circulation to a localized area or organ of the body resulting in tissue death. Infarctions commonly occur in the spleen, kidney, lungs, brain, and heart.
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) or of the brain (strokestroke,
destruction of brain tissue as a result of intracerebral hemorrhage or infarction caused by thrombosis (clotting) or embolus (obstruction in a blood vessel caused by clotted blood or other foreign matter circulating in the bloodstream); formerly called apoplexy.
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) can result in death and, in a vessel of the extremities, may be followed by gangrenegangrene,
local death of body tissue. Dry gangrene, the most common form, follows a disturbance of the blood supply to the tissues, e.g., in diabetes, arteriosclerosis, thrombosis, or destruction of tissue by injury.
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. Acute arterial thrombosis often results from the deposition of atherosclerotic material in the wall of an artery, which gradually narrows the channel, precipitating clot formation (see arteriosclerosisarteriosclerosis
, general term for a condition characterized by thickening, hardening, and loss of elasticity of the walls of the blood vessels. These changes are frequently accompanied by accumulations inside the vessel walls of lipids, e.g.
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). A thrombus that breaks off and circulates through the bloodstream is called an embolusembolus
, foreign matter circulating in and obstructing a blood vessel. It may be a portion of a clot that has separated from the wall of a vessel (see thrombosis), a bubble of gas or air (known as an air embolus), a globule of fat, a clump of bacterial matter, or a clump of
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the formation of blood clots during life in the lumen of a blood vessel or in the heart.

Thrombogenesis is promoted by injury to the vascular wall owing to atherosclerosis or inflammation, by the slowing of the blood flow, and by an increase in the coagulability and viscosity of the blood. Peripheral venous thrombosis is most common; thrombosis in the arterial system occurs less frequently. Arterial thrombosis interferes with the blood supply to areas of tissue and often leads to necrosis of such tissue. For example, coronary thrombosis results in myocardial infarction, and cerebral thrombosis, in a stroke, or cerebrovascular accident. The thrombus may subsequently either dissolve (undergo lysis), with partial or complete restoration of the blood vessel’s patency, or it may become thickened (organized). Multiple capillary thrombosis, a syndrome involving disseminated intravascular blood coagulation, is often combined with an increased tendency for tissues to bleed. The condition may develop during shock, hemorrhage, or severe infectious diseases, or it may be a manifestation of intolerance for drugs.

Biochemical and roentgenological methods of examination are used to diagnose thrombosis. Treatment includes the administration of anticoagulants, antispasmodics, and fibrinolytic and anti-inflammatory agents, as well as surgical removal of the thrombus.


Machabeli, M. S. Koagulopaticheskie sindromy. Moscow, 1970.
Kuznik, B. I., and V. P. Skipetrov. Formennye elementy krovi, sosudistaia stenka, gemostaz i tromboz. Moscow, 1974.
Raby, C. Lokalizovannaia i rasseiannaia vnutrisosudistaia koaguliatsiia. Moscow, 1974. (Translated from French.)
Quick, A. J. Hemorrhagic Diseases and Thrombosis, 2nd ed. Philadelphia, Pa., 1966.



Formation of a thrombus.


1. the formation or presence of a thrombus
2. Informal short for coronary thrombosis
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