Infarctions

Infarction is localized tissue necrosis resulting from ischemia, usually caused by obstruction of arterial blood flow or severely reduced perfusion that persists long enough to cause irreversible cell injury. Infarction can affect any organ, but most clinically relevant are myocardial, cerebral, and pulmonary infarctions.

Infarcts are described as pale (anemic) or hemorrhagic (red). Pale infarcts occur in solid organs with a single blood supply, such as the heart, kidney, and spleen. Hemorrhagic infarcts occur in tissues with dual blood supply or loose parenchyma, such as the lungs or intestines, and after reperfusion.

Pathophysiology involves abrupt arterial occlusion by thrombosis or embolism or global hypoperfusion in shock. The extent depends on collateral circulation, tissue metabolic demand, and time to reperfusion. Histology varies by tissue: myocardial infarction shows coagulative necrosis with inflammation; cerebral infarction evolves to liquefactive necrosis.

Clinically, symptoms reflect the involved organ: chest pain and dyspnea in myocardial infarction; focal neurologic deficits in cerebral infarction; pleuritic chest pain or dyspnea in pulmonary infarction. Diagnosis uses organ-specific tests: ECG and cardiac troponins for myocardial infarction; imaging (MRI/CT) for brain infarcts; CT angiography or perfusion imaging for pulmonary infarcts.

Management focuses on addressing the cause and restoring blood flow when possible, with supportive care and prevention of complications. Outcomes vary with location, size, and timeliness of treatment.