Micrograph of a pulmonary infarct (right of image) beside relatively normal lung (left of image). H&E stain.
In medicine, infarction is tissue death (necrosis) caused by a local lack of oxygen, due to an obstruction of the tissue's blood supply. The resulting lesion is referred to as an infarct (from the Latin infarctus, "stuffed into").
Hypertension and atherosclerosis are risk factors for both atherosclerotic plaques and thromboembolism. In atherosclerotic formations, a plaque develops under a fibrous cap. When the fibrous cap is degraded by metalloproteinases released from macrophages or by intravascular shear force from blood flow, subendothelial thrombogenic material (extracellular matrix) is exposed to circulating platelets and thrombus formation occurs on the vessel wall occluding blood flow. Occasionally, the plaque may rupture and form an embolus which travels with the blood-flow downstream to where the vessel narrows and eventually clogs the vessel lumen.
Infarctions can also involve mechanical blockage of the blood supply, such as when part of the gut or testicles herniates or becomes involved in a volvulus.
Infarction of the lung due to a pulmonary embolism
Infarctions are divided into 2 types according to the amount of blood present:
Brain: Cerebral infarction is the ischemic kind of stroke due to a disturbance in the blood vessels supplying blood to the brain. It can be atherothrombotic or embolic. Stroke caused by cerebral infarction should be distinguished from two other kinds of stroke: cerebral hemorrhage and subarachnoid hemorrhage. Cerebral infarctions vary in their severity with one third of the cases resulting in death.
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