Histological examination of myocardium from a patient who received successful thrombolysis shows hypercontracted sarcomeres with transverse dense eosinophilic bands across myocytes. What does this finding indicate?
- A Contraction band necrosis due to reperfusion injury ✓
- B Coagulative necrosis from unrelieved ischemia
- C Myofiber disarray typical of hypertrophic cardiomyopathy
- D Early healing with granulation tissue ingrowth
Correct answer: A. Contraction band necrosis due to reperfusion injury
Explanation
Reperfusion restores blood flow but floods lethally injured myocytes with calcium, causing hypercontraction of sarcomeres that forms dark transverse contraction bands. This pattern is characteristic of reperfused infarcts and is also seen in catecholamine injury and defibrillator shocks. Unreperfused coagulative necrosis shows wavy fibers, then eosinophilia with neutrophils, without these bands. Granulation tissue appears only after several days and myofiber disarray is unrelated to ischemia.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
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