Changes in acute myocardial ischemia
Time after event: 1 day
Gross findings: Softening, pallor and edema.
Histopathologic findings: Eosinophilic necrosis, edema, interstitial hemorrhage, contaction band change, nuclear pyknosis, beginning neutrophil infiltration.
Time after event: 2-3 days
Gross findings: Opaque with grey-yellow center and hemorrhagic border.
Histopathologic findings: Marked neutrophil infiltrate, loss of nuclei and striations.
Time after event: 3 days to 1 week
Gross findings: Rubbery center with shrinkage
Histopathologic findings: Beginning macrophage infiltration with phagocytosis and early fibroblastic response
Time after event: 10 days
Gross findings: Thinning of myocardium with red-brown discoloration.
Histologic findings: Extensive phagocytosis, granulation tissue formation.
Time after event: 2 months.
Gross findings: Cicatrization
Histopathologic findings: Cicatrization
• If the infract preceded death by 2 to 3 hours, it is possible to highlight the area of necrosis by immersion of tissue slices in a solution of triphenyl-tetrazolium chloride . This gross histochemical stain imparts a brick-red color to intact, noninfracted myocardium where lactate dehydrogenase activity is preserved.