A 59-year-old male painter with severe chest pain is found to have atherosclerosis of his coronary arteries. What type of cells were most likely injured in the initial stage of his disease?
1.Myocytes
2.Fibroblasts
3.Neutrophils
4.Endothelial cells
5.Smooth muscle cells
sol:
'
Atherosclerosis begins with repetitive endothelial cell injury.
Endothelial cell injury (e.g. from hypertension, diabetes, smoking, etc.) results in increased permeability of the endothelium and exposure of subendothelial collagen. Monocytes, lymphocytes, and LDL cholesterol migrate into the intima, and exposure of subendothelial collagen promotes platelet aggregation. A chronic inflammatory state in the intima perpetuates the formation of an atheroma.
Atherosclerosis of the coronary arteries results in coronary artery disease (CAD), as discussed by Pflieger et al. CAD results when coronary artery plaque develops, reducing the oxygen supply to the myocardium. Almost 17 million patients in the United States have stable CAD, and annual incidence approaches 800,000.
Hansson et al. review the stages of atherosclerosis. Stage 1 consists of an atheroma, a fibrofatty plaque within the intima. Next, is the fatty streak, a subintimal collection of cholesterol-laden macrophages and smooth muscle cells. Fibrous plaques then form on the extracellular matrix and may progress to obstruction. A complex plaque including intimal ulceration or intraplaque hemorrhage can result in occlusion and emboli.
Illustration A shows the evolution an atherosclerotic plaque.
Illustration B shows a cut section of an artery with athersclerosis. Note that the atherosclerotic plaque has ruptured, leading to thrombus formation and occlusion.