A patient with acute myocardial infarction undergoes successful percutaneous coronary intervention with restoration of coronary flow. Paradoxically, the myocardial injury worsens in the first minutes after reperfusion. Which of the following is a key mechanism of this reperfusion injury?
- A Activation of the coagulation cascade in the coronary microvasculature
- B Generation of oxygen-derived free radicals from reintroduced molecular oxygen ✓
- C Vasospasm of the epicardial coronary artery
- D Platelet aggregation at the site of endothelial injury
Correct answer: B. Generation of oxygen-derived free radicals from reintroduced molecular oxygen
Explanation
Reperfusion injury is mediated by generation of oxygen-derived free radicals when molecular oxygen is reintroduced into ischemic tissue, calcium overload, and inflammation. These cause further myocyte death beyond the original ischemic injury. The other options describe mechanisms of ischemia or thrombosis, not the paradoxical worsening upon restoration of flow.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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