Right Coronary Artery

The right coronary artery (RCA) is one of the two primary coronary arteries responsible for supplying blood to the myocardium. It originates from the right aortic sinus and travels through the coronary sulcus, giving off multiple branches to supply the right atrium, right ventricle, parts of the left ventricle, the interventricular septum, and components of the cardiac conduction system. Its distribution varies depending on coronary dominance.

Origin and Course

The RCA arises from the right aortic sinus of the ascending aorta, just superior to the aortic valve. It passes anteriorly and to the right, coursing between the right auricle and pulmonary trunk, then continues in the right atrioventricular (coronary) sulcus.

As it follows the sulcus, the RCA curves around the inferior border of the heart and onto the diaphragmatic surface, where it typically gives rise to the posterior interventricular artery near the crux of the heart.

Branches of the RCA

1. Atrial Branches

These small branches supply the right atrium. One of the earliest atrial branches is often the SA nodal artery, which supplies the sinoatrial node in the majority of individuals (approximately 60%).

2. Right Conus Artery

This branch supplies the conus arteriosus (infundibulum) of the right ventricle. In some cases, it anastomoses with a similar branch from the left coronary artery, forming the arterial circle of Vieussens.

3. Right Marginal Artery

This is a prominent branch that runs along the acute margin (inferior border) of the heart. It supplies the right ventricular free wall.

4. AV Nodal Artery

Usually arises near the crux of the heart and supplies the atrioventricular (AV) node. In most cases, this artery comes from the RCA (especially in right-dominant systems).

5. Posterior Interventricular Artery (Posterior Descending Artery, PDA)

In approximately 70% of individuals, the RCA gives rise to the posterior interventricular artery, which runs in the posterior interventricular sulcus. It supplies the posterior third of the interventricular septum and adjacent walls of both ventricles.

Areas Supplied by RCA

• Right atrium
• Most of the right ventricle
• Diaphragmatic (inferior) part of the left ventricle
• Posterior third of the interventricular septum
• Sinoatrial (SA) node (in ~60% of people)
• Atrioventricular (AV) node (in ~80% of people)

Coronary Artery Dominance

Dominance is defined by which coronary artery gives rise to the posterior interventricular artery (PDA):

• Right dominant: RCA gives rise to PDA (~70% of people)
• Left dominant: PDA arises from the circumflex branch of the left coronary artery (~10–15%)
• Co-dominant: PDA receives contributions from both RCA and LCA (~15–20%)

Anatomical Relations

• Anterior: Right auricle, pulmonary trunk (initial segment)
• Inferior: Right atrioventricular groove, diaphragmatic surface of the heart
• Posterior: Crux of the heart, junction with the posterior interventricular artery

Clinical Relevance (Minimal)

The RCA is a common site for atherosclerotic plaque formation. Blockage can lead to myocardial infarction affecting the inferior wall of the heart, especially in right-dominant individuals. Ischemia in the RCA distribution can also impact the conduction system, leading to arrhythmias if the SA or AV node is involved.

Topographic Summary

• Origin: Right aortic sinus
• Main course: Right atrioventricular (coronary) sulcus
• Main branches: SA nodal artery, right marginal artery, posterior interventricular artery (PDA), AV nodal artery
• Supplies: Right atrium, right ventricle, part of left ventricle, posterior septum, SA/AV nodes
• Dominance: Right-dominant if RCA gives rise to PDA