Right coronary arteryThe right coronary artery (RCA) is one of two main coronary vessels that supply the myocardium (the other being the left coronary artery). It originates from the right aortic sinus of the ascending aorta and runs in the right atrioventricular groove (coronary sulcus) wrapping around the right side of the heart.
The right coronary artery gives rise to several cardiac arteries/heart vessels that vascularize the majority of structures located in the right aspect of the heart. These structures usually include: the right atrium, right ventricle, the interatrial and interventricular septa, atrioventricular (AV) node and sinuatrial (SA) node.
|Origin||Right aortic sinus of the ascending aorta|
|Supply||Right atrium, right ventricle, the diaphragmatic part of the left ventricle, interatrial and interventricular septa, atrioventricular node and sometimes sinoatrial node|
This article will discuss the anatomy and function of the right coronary artery.
- Branches and supply
- Anatomical variations
- Clinical relations
The right coronary artery originates immediately superior to the right coronary cusp of the aortic valve. From here, it descends inferolaterally, joining the right atrioventricular groove where it continues around the right cardiac border, crossing from the anterior (sternocostal) to the inferior (diaphragmatic) surface of the heart. From the margin, it continues towards the crux of the heart (the junction of the interventricular and interatrial septa). Around this crux, the artery can either terminate or give rise to one or two large terminal branches; the inferior interventricular artery (also commonly referred to as the posterior descending artery) and inferolateral branch. When the latter happens, the right coronary artery is considered the ‘dominant’ coronary vessel, which is the case in approximately 60-80% of the population.
Branches and supply
The right coronary artery gives rise to numerous branches that supply most of the right portion of the heart. Additionally, if the right coronary artery is dominant, the supply territory extends to the structures of the inferior left side. Keep in mind that coronary vessels can vary greatly in number, location and diameter, which is why their supply should be scrutinized individually.
In most cases, the supplied structures include:
- Right atrium
- Right ventricle
- Diaphragmatic part of the left ventricle
- Interatrial and interventricular septa
- Atrioventricular node
- Sinoatrial node
According to the location of the origins of certain vessels, the branches of the right coronary artery can be divided into three separate groups: anterior, marginal and inferior.
The conal branch is first to arise from the RCA. It runs between the base of the conus arteriosus (infundibulum) and the superior part of the right ventricle. The proximal segment of the right coronary artery also gives rise to sinuatrial nodal, anterior atrial and anterior ventricular branches that supply the sinuatrial node, as well as sternocostal aspect of the right atrium and ventricle, respectively.
The arterial segment situated in the atrioventricular groove gives off the right marginal (acute) artery. This relatively large branch supplies the surface of the right cardiac margin, as well as the right anterior and inferior surfaces of the right ventricle. Similar to other segments of the artery, in this area several small lateral atrial branches may arise.
Upon reaching the inferior aspect of the heart, the right coronary artery gives rise to the atrioventricular nodal branch that supplies the AV node. Furthermore, several small inferior atrial and ventricular branches arise to supply the diaphragmatic surface of the right atrium and ventricle, respectively. As it approaches the crux, the RCA may give off two or three inferior interventricular branches:
- The inferior interventricular (descending) branch (also commonly referred to as the posterior descending artery (PDA)) is the largest of these branches, and descends in the inferior interventricular groove. On its course, it supplies the interventricular septum and adjacent surfaces of both ventricles. When it reaches the apex of the heart it anastomoses with the anterior interventricular branch of the left coronary artery. It is important to note however that this vessel may alternatively arise from the left coronary artery, or share a joint origin with the RCA and LCA (see notes on coronary dominance below).
- In most cases, the right coronary artery terminates as it gives off another terminal branch called the right inferolateral branch. This branch continues the course of RCA in the coronary sinus supplying the diaphragmatic surface of the heart.
Learn more about the coronary arteries with our articles, videos, labeled diagrams and quizzes.
Variations of each coronary vessel are very common in the general population.
- The conal branch of RCA can originate directly from the right aortic sinus when it is referred to as the third coronary or preinfundibular artery. This is a clinically significant variation since in occlusion of primary coronary arteries, this artery can be a main source of blood supply to the right side of the heart.
- The sinoatrial nodal branch can originate from the right coronary artery, aortic sinus or left circumflex artery.
- The atrioventricular nodal and inferior interventricular branches are related to the coronary dominance. This means that they arise from the dominant coronary artery, or even from both left and right in cases of co-dominance.
The term "dominance" of either side of the coronary arterial circulation is determined by which coronary artery gives rise to the inferior (posterior) interventricular artery and supplies the diaphragmatic surface of the heart. In approximately 60-80% of cases the right coronary arises from the right coronary artery, meaning that the majority of the population has a ‘right-dominant’ coronary arterial pattern. In about 10-20% of cases, both coronary artery vessels give rise to the inferior interventricular artery, which is the case of ‘co-dominance’. The left coronary artery is dominant in the remaining 5-10%. Coronary dominance is especially critical in cardiac surgery. Research shows that left dominance is a significant risk factor for the majority of surgical interventions which is why the vessel dominance should be determined before each procedure.
It's important to keep in mind that the term ‘dominant’ is potentially misleading since it can be interpreted as the vessel which irrigates the greater portion of the myocardium. However, it is always the left coronary artery that supplies the greater myocardial portion.