Which one of the following is the CORRECT statement regarding coronary
blood flow?
a) Coronary blood flow is directly related to perfusion pressure and
inversely related to resistance
b) Coronary blood flow is inversely related to perfusion pressure
and directly related to resistance
c) Coronary blood flow is directly related to perfusion pressure and
also to resistance
d) Coronary blood flow is inversely related to both pressure and
resistance
Correct Answer - A
Coronary blood flow is directly related to the perfusion
pressure (aortic diastolic pressure) and the duration of
diastole. Because coronary flow drops to negligible values during
systole, the duration of diastole becomes a limiting factor for
myocardial perfusion during tachycardia.
Coronary blood flow is inversely proportional to coronary
vascular resistance. Resistance is determined mainly by intrinsic
factors—including metabolic products and autonomic activity—and
by various pharmacologic agents. Damage to the endothelium of
coronary vessels has been shown to alter their ability to dilate and to
increase coronary vascular resistance.
Ref: Katzung B.G. (2012). Chapter 12. Vasodilators & the Treatment
of Angina Pectoris. In B.G. Katzung, S.B. Masters, A.J. Trevor (Eds),
Basic & Clinical Pharmacology, 12e.