Sinoatrial nodal artery

The sinoatrial nodal artery (or sinuatrial nodal artery or sinoatrial artery) is an artery of the heart which supplies the sinoatrial node, the natural pacemaker center of the heart, and arises from the right coronary artery in around 60% of people. In about 40% of cases, the sinoatrial artery is a branch of the left circumflex coronary artery.[1] In less than 1% of humans, the artery has an anomalous origin directly from the coronary sinus, descending aorta, or distal right coronary artery.

Sinoatrial nodal artery
Low magnification micrograph of a sinoatrial node (central on image), surrounding the sinuatrial nodal artery (on lumen in the image). H&E stain.
Arteries: RCA = right coronary AB = atrial branches SANB = sinuatrial nodal RMA = right marginal LCA = left coronary CB = circumflex branch LAD/AIB = anterior interventricular LMA = left marginal PIA/PDA = posterior descending MARG = left marginal AVN = atrioventricular nodal Veins: SCV = small cardiac ACV = anterior cardiac AIV/GCV = great cardiac MCV = middle cardiac CS = coronary sinus
Details
Identifiers
Latin	Ramus nodi sinuatrialis arteriae coronariae dextrae
TA98	A12.2.03.104 A12.2.03.212
TA2	4133
FMA	3823
Anatomical terminology

In more than 50% of human hearts, the artery actually courses close to the superior posterior aspect of the interatrial septum.[2] The origin of the sinoatrial node artery is not related to coronary artery dominance, which means the side (right or left) that provides the circulation to the back of the heart. In contrast, the atrioventricular nodal branch, that is the artery that brings blood to the atrioventricular node, depends on coronary artery dominance.

The sinoatrial node surrounds the sinoatrial artery, which can run centrally (in 70% of individuals) or off-center within the node.[3]

A left S-shaped sinoatrial artery, originating from the proximal left circumflex or LCx artery, has been described as a common variant in approximately 10% of human hearts.[4] This artery is larger than normal and supplies a good part of the left atrium, but also right-sided structures like part of the sinoatrial node and the atrioventricular nodal areas. In this variant, the artery courses in the sulcus between the left superior pulmonary vein and the left atrial appendage where it could be susceptible to injury during catheter or surgical ablation procedures on the left atrium, especially for atrial fibrillation ablation or open-heart cardiac surgery.