Anatomy of Coronary Artery System
According to Barash chapter 10 “The left main and right coronary arteries arise from the aorta behind the left and right aortic valve leaflets. The coronary ostia remain patent throughout systole because eddy currents prevent the valve leaflets from contacting the aortic walls. The left main coronary artery divides almost immediately into the left anterior descending (LAD) artery and left circumflex coronary artery (LCCA). The LAD further divides into several branches along the anterior interventricular groove toward the apex of the heart where they supply the anterior wall of the LV and the anterior two thirds of the interventricular septum (Fig. 10-16). The LCCA marks a pathway along the base of the LV within the coronary sulcus and terminates in the left posterior descending branch. The LCCA supplies the LV lateral wall and part of the LV posterior wall. The right coronary artery (RCA) courses along the AV groove toward the right chambers of the heart and frequently extends along the posterior interventricular sulcus to give rise to the right posterior descending branch (Fig. 10-16). The RCA supplies the anterior and posterior walls of the RV except for the apex (supplied by the LAD), the right atrium including the SA node, the upper half of the atrial septum, the posterior third of the interventricular septum, the inferior wall of the LV, the AV node, and the posterior base of the LV. A branch of the LCCA occasionally supplies the SA node. Because either the RCA or the LCCA may supply the posterior descending coronary artery, the coronary circulation is described as right or left dominant, respectively, based on the source of this vessel’s blood supply.”
Coronary Blood Flow
4% of total cardiac output (250 mL/min). The right ventricle, which rarely develops pressures in excess of systemic diastolic blood pressure, receives a constant supply of blood flow (except in the setting of severe pulmonary hypertension). The left ventricle, by contrast, only receives blood flow during diastole. The healthy heart is capable of matching oxygen supply to demand, although the exact mechanism is not known – most likely an intrinsic capability, possibly related to oxygen depletion, CO2 production, or other factors such as adenosine, ATP, or [H+].