What is the correct sequence of the following in a heart attack ? I. Narrowing of the inner orifice of the vessel II. ‘Plaque’ from fibrous tissue and high cholesterol III. Inadequate supply of blood and oxygen IV. Clots of blood carried into the coronary arteries. Choose the answer from the codes given below :

The typical pathogenesis begins with formation of an atherosclerotic plaque composed of lipid and fibrous tissue (II). As plaques enlarge they narrow the arterial lumen and can become unstable; rupture or erosion can expose plaque contents and trigger thrombus formation or send embolic fragments into coronary arteries (IV), resulting in acute occlusion (I). This occlusion of a coronary vessel then produces inadequate blood and oxygen supply to myocardium, causing ischemia and infarction (III). Thus the chronological sequence is II → IV → I → III, reflecting plaque formation, clot/embolus generation, luminal occlusion, and resultant myocardial ischemia/infarction [1].

Sources

1. [1] https://www.mayoclinic.org/diseases-conditions/myocardial-ischemia/symptoms-causes/syc-20375417
2. [2] https://webpath.med.utah.edu/TUTORIAL/MYOCARD/MYOCARD.html