embolism
embolism When fragments, usually of blood clot, are let loose in the bloodstream, they lodge in and obstruct the first vessels they encounter which are too narrow for them to pass. Such a fragment is known as an embolus (plural emboli) and the event as embolism. Pieces may break off from a clot (thrombus) which has formed, usually during prolonged immobility, in the deep veins of the legs or pelvis (deep vein thrombosis — DVT). The clots travel to the heart through progressively larger veins, thence from the right side of the heart to the lungs; there they obstruct branches of the pulmonary artery, where the severity of their effects depends on their size and number. Large pulmonary emboli can be fatal; very small ones lodge in microscopic vessels causing some impairment of oxygen intake. Thrombi which form on damaged lining of the left heart valves or of major arteries can release fragments which reach the brain (cerebral embolism) causing a type of stroke. There can also be fat embolism, when particles enter veins from the marrow of fractured bones, or air embolism if air is injected or sucked into an open vein.
Sheila Jennett
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embolism