Infarction

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").

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

Causes

The supplying artery can be blocked by an obstruction (e.g., an arterial embolus, thrombus, or atherosclerotic plaque), may be mechanically compressed (e.g., tumor, volvulus, or hernia), ruptured by trauma (e.g., atherosclerosis or vasculitides), or vasoconstricted (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.