What histologic findings indicate a myocardial infarction with reperfusion?

What histologic findings indicate a myocardial infarction with reperfusion?

• A. Contraction bands and late scar formation in previously necrotic tissue.
• B. Granulomatous inflammation.
• C. Contraction bands and early neutrophil infiltration in previously necrotic tissue; hemorrhage and capillary hyperemia.
• D. Lymphocytic infiltration without necrosis.

Answer: (C)

Reperfusion after a myocardial infarction triggers an acute injury pattern in the necrotic area, combining signs of both tissue damage and a rapid inflammatory response. The most telling features are contraction bands, which are hypercontraction of the myocytes due to a surge of calcium when blood flow returns. Along with this, you see hemorrhage and capillary hyperemia as the now-reperfused vessels leak and become engorged. In addition, there is early neutrophil infiltration as part of the acute inflammatory reaction to the sudden reperfusion of necrotic tissue. These findings distinguish reperfusion injury from other MI histology. Granulomatous inflammation would point to a granulomatous process rather than acute reperfusion. Lymphocytic infiltration without necrosis suggests a different pattern, such as a chronic or viral myocarditis. Late scar formation reflects healing weeks later, not the immediate reperfusion changes.

Reperfusion after a myocardial infarction triggers an acute injury pattern in the necrotic area, combining signs of both tissue damage and a rapid inflammatory response. The most telling features are contraction bands, which are hypercontraction of the myocytes due to a surge of calcium when blood flow returns. Along with this, you see hemorrhage and capillary hyperemia as the now-reperfused vessels leak and become engorged. In addition, there is early neutrophil infiltration as part of the acute inflammatory reaction to the sudden reperfusion of necrotic tissue.

These findings distinguish reperfusion injury from other MI histology. Granulomatous inflammation would point to a granulomatous process rather than acute reperfusion. Lymphocytic infiltration without necrosis suggests a different pattern, such as a chronic or viral myocarditis. Late scar formation reflects healing weeks later, not the immediate reperfusion changes.