Atherosclerosis impedes coronary blood flow by which of the following mechanisms?
A. Plaques obstruct the vein.
B. Plaques obstruct the artery.
C. Blood clots form outside the vessel wall.
D. Hardened vessels dilate to allow blood to flow through.
Correct Answer: B. Plaques obstruct the artery
Atherosclerosis is a chronic inflammatory disease in which there is a build up of plaques inside arteries. These plaques are principally composed of lipids that induce an inflammatory reaction causing turbulent flow with atherosclerotic cardiovascular disease (ASCVD) as a result.
Option A: Arteries, not veins, supply the coronary arteries with oxygen and other nutrients. Atherosclerosis mainly develops through the continuous process of arterial wall lesions due to lipid retention by trapping in the intima by a matrix such as proteoglycans resulting in a modification which, in turn, aggravates chronic inflammation at vulnerable sites in the arteries and plays an important role at all phases of the atherogenic progression.
Option C: Atherosclerosis is a direct result of plaque formation in the artery. This process begins from the nascent fatty streaks in the arterial intima which evolve into fibrous plaques and emerge into complex atherosclerotic lesions that are susceptible to rupture. Also, stenosis from the inward expansion of the atheroma can result in occlusion of vessels such as the coronaries.
Option D: Hardened vessels can’t dilate properly and, therefore, constrict blood flow. Many studies indicate the role of the endoplasmic reticulum stress pathway or unfolded protein response as the chief mechanisms of macrophage cell death in plaques causing accumulation of dead macrophages. Also in comparison to early plaques, microvessel density is increased in advanced plaques by dysregulated neovascularization. In normal and atherosclerotic arteries microvessels are thin-walled and characterized with poor structural integrity and endothelial junctions.
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