Atrial anastomotic branch of circumflex artery of heart

The atrial anastomotic branch of the circumflex artery (also known as Kugel's artery or the arteria anastomotica auricularis magna) is a small but clinically significant atrial vessel that arises from the proximal portion of the left circumflex coronary artery (LCx). First described by Kugel in the early 20th century, this artery runs in the inferior part of the interatrial septum and serves as a backup collateral pathway for the blood supply to the sinoatrial (SA) node and the atrioventricular (AV) node.

Anatomical course and relationships

The vessel arises from the proximal LCx, near the origin of the sinus node artery, and travels posteriorly along the base of the interatrial septum. It establishes communications between branches of the right coronary artery and the left circumflex artery within the atrial walls and septum. In some anatomical variants, it may also connect with the right Kugel artery arising from the right coronary artery, forming a complete anastomotic ring.

Functional significance

This branch plays a role as a collateral channel that can provide alternative perfusion to the cardiac conduction system particularly the SA and AV nodes in the setting of coronary artery disease or occlusion of the dominant nodal artery. Occlusion of atrial coronary branches during percutaneous coronary interventions has been associated with periprocedural myocardial infarction, atrial arrhythmias (including atrial fibrillation), and intra-atrial conduction delay.

Variability and clinical considerations

The existence and prominence of this vessel are highly variable. Most studies report difficulty demonstrating Kugel's artery both postmortem and angiographically, and current evidence suggests that the interatrial septum is not vascularized by a single large connecting artery but rather by a network of several small branches from both coronary arteries coursing posteriorly to the base of the septum. This vessel becomes vulnerable during aortic root and mitral valve surgical procedures, where inadvertent injury may compromise the blood supply to the conduction system.