Right coronary artery

Arteria coronaria dextra

Also known as: RCA

The right coronary artery arises from the right aortic sinus and runs in the right atrioventricular groove to the crux of the heart. It supplies the right atrium, most of the right ventricle, the SA node in about 60% of people and the AV node in about 80–90%. In right-dominant hearts it also supplies the inferior wall of the left ventricle through the posterior interventricular artery.

Overview

OriginRight aortic sinus

Right dominance≈70–80% of hearts

Supplies SA node≈60%

Supplies AV node≈80–90%

Course. The RCA leaves the right aortic sinus and runs forward between the pulmonary trunk and the right auricle. It then descends in the right coronary (atrioventricular) sulcus and curves around the acute margin of the heart onto the diaphragmatic surface. It continues to the crux, where the atrioventricular and posterior interventricular grooves meet.

Dominance. In about 70–80% of people the RCA gives rise to the posterior interventricular (posterior descending) artery, making the heart "right-dominant". In about 5–10% this artery comes from the circumflex (left dominance). In the remaining 10–20% both arteries contribute (codominance). The dominant artery also supplies the AV node.

Nodal arteries. The SA nodal artery arises from the proximal RCA in about 60% of hearts. It runs up between the right auricle and the aorta to the junction of the SVC and right atrium. The AV nodal artery arises at the crux.

Anatomy

Course

It starts in the right aortic sinus and passes between the pulmonary trunk and right auricle. It then runs in the right coronary sulcus around the acute margin to the crux, where it usually turns down as the posterior interventricular artery.

Branches

In order from proximal to distal: the conus artery (which anastomoses with the LAD around the infundibulum), the SA nodal artery (≈60%), right atrial branches, the right marginal (acute marginal) artery along the inferior border, the AV nodal artery at the crux (≈80–90%), the posterior interventricular artery (in right-dominant hearts) and the posterolateral (right posterior ventricular) branches.

Relations

It lies in the epicardial fat of the right AV groove, next to the small cardiac vein, and is covered anteriorly by the right auricle.

Clinical significance

Inferior myocardial infarction

Occlusion of the RCA causes ST elevation in leads II, III and aVF. Ischaemia of the AV node and increased vagal tone often cause bradycardia and AV block, which is usually transient. A proximal occlusion can also infarct the right ventricle, producing hypotension and a raised JVP with clear lungs.

Coronary dominance

The artery that gives rise to the posterior interventricular artery is called dominant. In a left-dominant heart, an occlusion of the circumflex can therefore infarct the lateral and inferior walls together.

Test yourself

In most people, the atrioventricular (AV) node is supplied by a branch of which artery?

Left anterior descending artery
Circumflex artery
Right coronary artery
Left main coronary artery

Answer: Right coronary artery

The AV nodal artery arises from the dominant coronary artery at the crux of the heart. That is the RCA in about 80–90% of people. This is why inferior MIs from RCA occlusion are often complicated by bradycardia and AV block.

A patient has ST elevation in leads II, III and aVF. Which territory is infarcting, and which artery is usually responsible?

Anterior wall — LAD
Lateral wall — circumflex
Inferior wall — right coronary artery
Septum — left main stem

Answer: Inferior wall — right coronary artery

Leads II, III and aVF look at the inferior (diaphragmatic) wall. In right-dominant hearts this wall is supplied by the posterior interventricular branch of the RCA. Leads V1–V4 correspond to the LAD, and leads I, aVL, V5 and V6 to the circumflex.