embolism(redirected from Microembolism)
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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).
REFERENCESChazov, 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.
V. D. TOPOLIANSKII