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1. the occlusion of a blood vessel by an embolus
2. Botany the blocking of a xylem vessel by an air bubble
3. RC Church a prayer inserted in the canon of the Mass between the Lord's Prayer and the breaking of the bread
4. another name (not in technical use) for embolus



disruption of the blood supply to an organ or tissue owing to blockage of a blood vessel by any type of particle transported by the blood or lymph stream but not normally circulating therein.

Circulatory disorders are aggravated by reflex vasospasms and secondary thrombosis. In the case of obstruction of small vessels, blood circulation can be quickly restored by collateral circulation, so that the embolism may be described as incomplete. Thromboembolism, which is caused by a thrombus or part of a thrombus that has broken free, is the type that is most important in practical terms. Emboli from peripheral veins usually lodge in the basin of the pulmonary artery. If there are defects in the septa of the heart, the emboli may reach the arterial system, bypassing the pulmonary circulation; this is called a paradoxical embolism. Embolism in the systemic circulation arteries is usually caused by the breaking away of thrombotic material from the left ventricular valves or walls, as in endocarditis, in heart diseases, and in aneurysm of the left ventricle.

Other possible types are tissue and fat embolisms (especially after extensive and severe injuries or fractures of the long tubular bones), air or gas embolisms (as in the case of open heart surgery, injuries to the large veins of the neck and chest, and decompression sickness), bacillary embolisms (obstruction by aggregations of microbes), and embolisms caused by foreign bodies—mainly by small fragments in gunshot wounds—which are sometimes moved by the force of gravity against the direction of the blood stream (retrograde, or venous, embolism).

Treatment includes the use of anticoagulants, thrombolytic and spasmolytic agents, antibiotics, therapeutic recompression (for decompression sickness), and surgical removal of the embolus (embolectomy).


Chazov, E. I. Trombozy i embolii v klinike vnutrennikh boleznei. Moscow-Warsaw, 1966.
Tregubenko, A. I. Trombozy i embolii v khirurgii. Kiev, 1972.
Perlick, E. Antikoagulanten. Leipzig, 1964.



The blocking of a blood vessel by an embolus.
References in periodicals archive ?
Some of the clinical features of inadvertent intravenous injections may be explained by the microembolism of fat globules, water-insoluble particles, and an immune response to foreign antigens (Table 1) (1, 10).
While thromboembolism has been frequently described in the medical literature as a source of stroke, cholesterol microembolism also occurs.
The indications section includes the statement that it "should only be used in patients who require testosterone replacement therapy and in whom the benefits of the product outweigh the serious risks of pulmonary oil microembolism and anaphylaxis." The drug will be available, with restrictions, through the Aveed Risk Evaluation and Mitigation Strategy (REMS), according to the manufacturer, Endo Pharmaceuticals, which is marketing the product as Aveed.
In the study of Borger and colleagues [71], a similar significant linear relationship between the performance on nonverbal memory tests and intraoperative cerebral microembolism was observed.
Apart from venous thrombosis, SPS has been associated with various other clinical entities, including acute coronary syndrome with normal coronary angiography findings (6), transient ischemic attack 121, recurrent miscarriage syndrome (7), peripheral arterial microembolism (8), ischemic optic neuropathy (9), (10) and transplant thromboembolic events (11), (12).
In the CRL, the FDA has requested information from the company to address the agency's concerns regarding very rare but serious adverse events, including post-injection anaphylactic reaction and pulmonary oil microembolism. The letter also specified that the proposed Risk Evaluation and Mitigation Strategy (REMS) is not sufficient.
Microembolism during cardiopulmonary bypass is common but macroembolism is rare, with an incidence less than 0.1% (23).
(16) Researchers in this small study used doppler ultrasound to see if combination therapy would lead to a reduction in asymptomatic microembolism from the carotid plaques.
Retinal microembolism and neuropsychological deficit following clinical cardiopulmonary by-pass.
Time course of haemodynamic, respiratory and inflammatory disturbances induced by experimental acute pulmonary polystyrene microembolism. Eur J Anaesthesiol 2010;27:67-76.
Thus, in AS, PE impairs blood oxygenation, although frequent microembolism in hypercholesterolemia, as well as a decreased oxygen binding capacity due to a cholesterol layer around the red blood cells may contribute to this impairment [23, 24].

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