Oxygen supply Cardiovascular Physiology Web Resource Richard E. Klabunde, Ph.D. Oxygen Supply Oxygen is supplied to the myocardium by the coronary circulation . Coronary blood flow is determined by hemodynamic factors such as perfusion pressure and vascular resistance. Ordinarily, the oxygen content of arterial blood changes relatively little. Therefore, the primary determinant of oxygen delivery in the absence of hypoxemia is coronary blood flow. In coronary artery disease, a number of factors can alter coronary blood flow.
Stenotic lesions cause a narrowing of an epicardial vessel.
The stenosis may be at a specific site, or it may diffuse along the length of the vessel. Diseased coronary vessels are more susceptible to vasospasm which can lead to stress-induced temporary restriction of coronary flow at rest and during exercise. Finally, thrombus formation particularly at the site of a ruptured atherosclerotic plaque can partially or completely occlude a coronary vessel causing unstable angina or myocardial infarction .