A plaque in a coronary vessel wall will result in a decrease in the lumen diam- eter of a coronary artery and in less oxygen being delivered to the heart muscle. Why is this? A. A protruding plaque increases the distance blood needs to travel and this increases resistance to flow. B. A narrow artery restricts blood flow by increasing blood’s viscosity. C. The constricted artery causes the pressure gradient to decrease which results in lower blood flow. D. The decrease in artery radius will cause blood volume flow rate to decrease.
Option D. Poiseuille’s law states that quantity flow rate is proportional to radius the 4th power so a lower in radius consequences in a lower in flow rate and as a result much less oxygen being brought to the myocardium.
