Atrial branches of right coronary artery

The atrial branches of the right coronary artery (RCA) are a group of small-to-medium caliber arterial vessels that arise from the RCA as it courses along the right atrioventricular groove, providing the primary arterial blood supply to the right atrium and, in most individuals, to the sinoatrial (SA) and atrioventricular (AV) nodes.

Anatomical Description

The RCA originates from the right coronary (aortic) sinus and travels within the right atrioventricular groove between the right atrium and right ventricle. Along its course, it gives off several atrial branches that can be classified as follows:

• Right anterior atrial artery: The most constant atrial branch, present in approximately 85-96% of hearts. It arises from the proximal RCA, typically within the first 12 cm from its origin. In the majority of cases (approximately 63-66%), this vessel gives rise to the SA node artery, which courses toward the superior vena cava-right atrial junction to supply the sinus node.

• Right lateral atrial artery: Present in approximately 68-90% of hearts, this is the principal artery supplying the free wall of the right atrium. It courses along the lateral aspect of the right atrial wall and is of particular surgical significance during procedures involving right atriotomy.

• Right posterior atrial artery: Found in approximately 41% of hearts, it supplies the posterior wall of the right atrium.

• AV node artery: Arising from the distal RCA at the crux cordis (the U- or V-shaped segment at the junction of the posterior interventricular and atrioventricular grooves) in approximately 80-90% of individuals, this branch is the first and longest inferior septal perforating branch, with a mean external diameter of approximately 2 mm (range 13.5 mm). Its origin is dependent on coronary arterial dominance in left-dominant circulation, it arises from the left coronary system instead.

Clinical and Surgical Significance

These atrial branches are clinically relevant in several contexts. Occlusion of atrial branches during coronary events or percutaneous interventions can lead to atrial myocardial infarction, a frequently underrecognized entity that may contribute to atrial fibrillation and left atrial enlargement.