This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Unknown
Irreversible injury in myocardium occurs at - 
Select and explain. 
A. 2 minutes, B. 30 minutes, C. 2 hours, D. 5 hours
B: 30 minutes
Answer: B: 30 minutes 
Explanation: Ans-Bo Myocardial function is more sensitive to ischemia(loss of contractility occurs within 60 seconds) than myocardial structure (irreversible injury occurs in 20-40 minutes, thus myocardial necrosis begins at approximately 30 minutes after coronary occlusion.FeatureTimeo Onset of ATP depletiono Loss of contractilityo ATP reduced to 50%o ATP reduced to 10%o Irrversible injuryo Microvascular injurySeconds< 2 minutes10 minutes40 minutes20-40 min> 1 hr