11.8 Right Coronary Artery
The Right Coronary Artery supplies blood to the right ventricle and parts of the atria, originating from the coronary sinus.
Right Coronary Artery is one of the two main coronary arteries arising from the ascending aorta at the right aortic sinus. It supplies blood to the right atrium, right ventricle, sinoatrial (SA) node, atrioventricular (AV) node, part of the interventricular septum, and portions of the posterior and inferior walls of the left ventricle. The artery follows a complex course along the heart’s surface, giving off several important branches that nourish the right side of the heart and the conduction system.
Origin and Proximal Course
The Right Coronary Artery (RCA) originates from the anteromedial aspect of the right aortic sinus, just above the aortic valve. From its origin, it courses anteriorly and rightward, passing between the pulmonary trunk and the right atrium. The proximal segment is relatively short and lies in the atrioventricular (AV) groove.
Right Atrioventricular Groove Course
The RCA continues along the right AV groove (coronary sulcus), which separates the right atrium and right ventricle. This groove guides the main trunk of the artery as it travels posteriorly around the heart toward the crux, the junction where the atrioventricular groove meets the posterior interventricular groove. This course enables the artery to give off branches that supply the right atrium, right ventricle, and the conduction system.
Segments of the Right Coronary Artery
Proximal Segment
The proximal segment extends from the artery’s origin to the first significant branch, the conus artery. This segment lies adjacent to the right atrial appendage and the pulmonary trunk.
Mid Segment
The mid segment runs along the right AV groove, giving rise to several branches such as the right atrial branches and right ventricular branches. It continues toward the posterior surface of the heart.
Distal Segment
The distal segment approaches the crux of the heart, where the RCA often gives off the posterior descending artery (PDA) in right-dominant circulation. It may extend into the posterior interventricular groove.
Branches of the Right Coronary Artery
Conus Arterial Branch
The conus branch, also known as the third coronary artery, arises near the RCA origin and supplies the right ventricular outflow tract (infundibulum). It may anastomose with the left anterior descending artery.
Sinoatrial Nodal Arterial Branch
This branch arises variably from the proximal RCA (approximately 60% of individuals) or from the circumflex artery. It supplies the sinoatrial node, the primary pacemaker of the heart.
Right Atrial Arterial Branches
These small branches supply the right atrial myocardium and the sinoatrial node area. They arise along the course of the RCA in the right atrium.
Right Ventricular Arterial Branches
Arising mainly from the mid segment, these branches supply the anterior and inferior surfaces of the right ventricle.
Right Marginal Artery
The right marginal artery originates near the mid portion of the RCA and runs along the acute margin of the heart, supplying the right ventricle. It is often a large and clinically significant branch.
Right Coronary Crux Branch
At the crux of the heart, the RCA gives off branches that supply the AV node and adjacent conduction tissues. This area is critical for the conduction system’s blood supply.
Right Coronary Artery Branching Map
The RCA’s branching pattern is highly variable, but typically includes:
- Conus artery (proximal)
- Sinoatrial nodal artery (proximal)
- Right atrial branches (along course)
- Right ventricular branches (mid segment)
- Right marginal artery (mid segment)
- Posterior descending artery (distal, in right-dominant circulation)
- AV nodal artery (at crux)
Functional and Clinical Significance
The RCA is crucial for perfusing the right heart chambers and parts of the conduction system. In about 85% of hearts, the RCA is dominant, meaning it gives rise to the posterior descending artery supplying the inferior interventricular septum and parts of the left ventricle. Occlusion of the RCA can lead to right ventricular infarction, conduction abnormalities such as AV block, and inferior myocardial infarction.