Embolism

The obstruction of a blood vessel by a foreign substance or a blood clot blocking the vessel. Something travels through the bloodstream, lodges in a vessel and plugs it. Foreign substances that can cause embolism include an air bubble, amniotic fluid, a globule of fat, a clump of bacteria, chemicals (such as talc), and drugs (mainly illicit ones). Blood clots are the most common cause of embolism. A pulmonary embolus is a blood clot that has been carried through the blood into the pulmonary artery (the main blood vessel from the heart to the lung) or one of its branches, plugging that vessel. The term "embolus" refers to the plug itself obstructing the blood vessel while "embolism" refers to the process by which this happens. The word "embolus" comes from the Greek "embolos" meaning a wedge or plug. "Embolos" was derived from "en" (in) + "ballein" (to throw) so an embolus is something thrown in.

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Obstruction or occlusion of a vessel by an embolus. [G. embolisma, a piece or patch; lit. something thrust in]

- air e. an e. caused by air bubbles in the vascular system; venous air e. can result from air introduced via intravenous lines, especially central lines, and generally must be substantial to block pulmonary blood flow and cause symptoms; arterial air e. is also usually iatrogenic, caused by cardiopulmonary bypass or other intravascular interventions, rarely after penetrating lung injury; small amounts of arterial air can cause death by blockage of coronary and/or cerebral arteries; small bubbles introduced into the venous system may similarly cause symptoms if they reach the arterial side. Cf.:paradoxical e.. SYN: gas e..

- amnionic fluid e. obstruction and constriction of pulmonary blood vessel s by amniotic fluid entering the maternal circulation, causing obstetric shock. SEE ALSO: amnionic fluid syndrome.

- atheromatous e. SYN: cholesterol e..

- bland e. e. by simple nonseptic material.

- bone marrow e. obstruction of a vessel by bone marrow, usually following fracture of a bone.

- cellular e. e. due to a mass of cells transported from disintegrating tissue.

- cholesterol e. e. of lipid debris from an ulcerated atheromatous deposit, generally from a large artery to small arterial branches; it is usually small and rarely causes infarction. SYN: atheromatous e..

- cotton-fiber e. e. by cotton fibers from sterile gauze used in intravenous medication or transfusion; may form as foreign body granulomas in small pulmonary arteries.

- crossed e. SYN: paradoxical e..

- direct e. e. occurring in the direction of the blood current.

- fat e. the occurrence of fat globules in the circulation following fractures of a long bone, in burns, in parturition, and in association with fatty degeneration of the liver; the emboli most commonly block pulmonary or cerebral vessels when symptoms referable to either or both of these regions appear. SYN: oil e..

- gas e. SYN: air e..

- hematogenous e. e. occurring via a blood vessel.

- infective e. SYN: pyemic e..

- lymph e., lymphogenous e. e. occurring in a lymphatic vessel.

- miliary e. e. occurring simultaneously in a number of capillaries. SYN: multiple e. (1).

- multiple e. 1. SYN: miliary e.. 2. e. caused by the arrest of a number of small emboli.

- obturating e. complete closing of the lumen of a vessel by an e..

- oil e. SYN: fat e..

- paradoxical e. 1. obstruction of a systemic artery by an embolus originating in the venous system which passes through a septal defect, patent foramen ovale, or other shunt to the arterial system; 2. obstruction by a minute e. that passes through the pulmonary capillaries from the venous to the arterial system. SYN: crossed e..

- pulmonary e. e. of pulmonary arteries, most frequently by detached fragments of thrombus from a leg or pelvic vein, commonly when thrombosis has followed an operation or confinement to bed.

- pyemic e. plugging of an artery by an embolus detached from a suppurating source. SYN: infective e..

- retinal e. e. of an artery of the retina.

- retrograde e. e. of a vein by an embolus carried in a direction opposite to that of the normal blood current, after being diverted into a smaller vein. SYN: venous e..

- riding e. SYN: straddling e..

- saddle e. a straddling e. at any vascular bifurcation, e.g., of the aorta which occludes both common iliac arteries.

- straddling e. e. occurring at the bifurcation of an artery and blocking more or less completely both branches. SYN: riding e..

- tumor e. e. by neoplastic tissue transported from a tumor site and which may grow as a metastasis.

- venous e. SYN: retrograde e..

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em·bo·lism 'em-bə-.liz-əm n

1) the sudden obstruction of a blood vessel by an embolus

2) EMBOLUS

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n.

the condition in which an embolus becomes lodged in an artery and obstructs its blood flow. The most common form of embolism is pulmonary embolism, in which a blood clot is carried in the circulation to lodge in the pulmonary artery. An embolus in any other artery constitutes a systemic embolism. In this case a common source of the embolus is a blood clot within the heart in mitral valve disease or following myocardial infarction. The clinical features depend upon the site at which an embolus lodges (for example, a stroke may result from a cerebral embolism and gangrene caused by a limb embolism). Treatment is by anticoagulant therapy with heparin and warfarin. Major embolism is treated by embolectomy or streptokinase to remove or dissolve the embolus. See also air embolism.

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em·bo·lism (emґbə-liz-əm) [L. embolus, q.v.] the sudden blocking of an artery by a clot or foreign material which has been brought to its site of lodgment by the blood current.