Infarction

Infarction
Micrograph of a pulmonary infarct (right of image) beside relatively normal lung (left of image). H&E stain.
Classification and external resources
Specialty	Pathology
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Infarction is tissue death (necrosis) due to inadequate blood supply to the affected area (ischemia). It may be caused by artery blockages, rupture, mechanical compression or vasoconstriction. The resulting lesion is referred to as an infarct (from the Latin infarctus, "stuffed into").

Myocardial infarction is the partial death of heart tissue commonly known as heart attack.

Infarction occurs as a result of prolonged ischemia, which is the insufficient supply of oxygen to an area of tissue due to a disruption in blood supply. The blood vessel supplying the affected area of tissue may be blocked due to an obstruction in the vessel (e.g., an arterial embolus, thrombus, or atherosclerotic plaque), compressed by something outside of the vessel causing it to narrow (e.g., tumor, volvulus, or hernia), ruptured by trauma causing a loss of blood pressure downstream of the rupture, or vasoconstricted, which is the narrowing of the blood vessel by contraction of the muscle wall rather than an external force (e.g., cocaine vasoconstriction leading to myocardial infarction).

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.

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