ABSTRACT
Describe the coronary circulation.
The arterial blood supply to the heart comes from the right coronary artery (RCA) and the left coronary artery (LCA), which arise from the anterior and posterior aortic sinuses respectively.
The RCA supplies the right atrium, right ventricle, sinoatrial node and, in 90% of people, also the atrioventricular node.
The LCA divides into the left anterior descending (LAD) artery and the left circumflex (LCx) artery and supplies the left atrium, left ventricle and most of the interventricular septum.
In 30% of the population the LCA and RCA supply equal proportions of blood while in 50% the RCA is the dominant vessel.
Venous drainage occurs predominantly via the coronary sinus. This receives blood from the great cardiac vein (draining the anterior aspect of the heart) and the middle cardiac vein (draining the posterior aspect of the heart). In addition, there are other vessels that drain directly into the heart chambers including the thebesian veins, which contribute towards true shunt.
