NORMAL CORONARY ARTERY ANATOMY
The coronary arteries provide oxygenated blood to the myocardium and originate from the proximal aorta. There are two main branches: the left coronary artery (LCA) and the right coronary artery (RCA). The LCA branches into the left circumflex, the left marginal, and the left anterior descending arteries. The RCA branches into the right marginal artery and commonly the posterior descending artery (PDA).
Heart “dominance” is determined by which of the initial coronary arteries supplies the PDA which, in turn, supplies the AV node. The heart is right dominant (85%) if the PDA is supplied by the RCA. The heart is left dominant (7.5%) if the PDA is supplied by the circumflex branch of the LCA. If the PDA is supplied by parts of the right and left circulation, then the heart is codominant (7.5%). In a right dominant heart, the right ventricle is supplied by the right marginal branch. In a left dominant heart, the right ventricle is supplied by the circumflex artery. The left ventricle, which contains the majority of the heart’s myocardium, is supplied by both right and left circulation. Coronary arteries are considered end arteries, meaning that there is little collateralization and if blockages develop, ischemia will occur in dependent cardiac tissue.
Left coronary artery (left main), circumflex artery, left anterior descending artery, and the right coronary artery are detailed in the figure. Reproduced, with permission, from Piktel JS. Cardiac rhythm disturbances. In: Tintinalli JE, Stapczynski J, Ma O, Cline DM, Cydulka RK, Meckler GD. eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 7th ed. New York, NY: McGraw-Hill; 2011.
Cardiac catheterization demonstrating healthy left coronary arterial vasculature in a right dominant heart. (Ao, aorta; Cx, circumflex artery; LAD, left anterior descending artery; LCA, left coronary artery.)
Cardiac catheterization demonstrating healthy right coronary arterial vasculature in a right dominant heart. (Ao, aorta; Mar, marginal artery; PDA, posterior descending artery; RCA, right coronary artery.)
The coronary veins remove deoxygenated blood from the myocardium. The precise venous anatomy varies from patient to patient but commonly mirrors the arterial supply. The coronary veins drain into the coronary sinus, which empties directly into the right atrium. Below figures show the origins of the left and right coronary arteries on cardiac computed tomography (CT) scanning.
Cardiac CT demonstrating the left coronary artery arising from its source at the ascending aorta. (AAo, ascending aorta; Cx, circumflex artery; DAo, descending aorta; LAD, left anterior descending artery; LAt, left atrium; LCA, left ...