Sinoatrial Nodal Artery

arteria nodi sinuatrialis

The sinoatrial nodal artery supplies the SA node, the cardiac pacemaker situated at the junction of the superior vena cava and the right atrium. In approximately 55-60% of individuals it arises from the proximal right coronary artery; in 40-45% it arises from the left circumflex artery. It encircles the SA node in a characteristic loop and gives small terminal branches penetrating the node.

Region: Chest

Clinical Relevance

Clinical Notes

Occlusion of the SA nodal artery in the context of acute inferior STEMI (RCA occlusion) or less commonly posterolateral MI (LCx occlusion) produces sinus bradycardia, sinus arrest, and sick sinus syndrome requiring temporary pacing. The SA nodal artery origin determines which coronary territory supplies the pacemaker: in RCA-dominant individuals, inferior MI most commonly affects SA node function. Sick sinus syndrome occurring after cardiac surgery may result from SA nodal artery compromise during atriotomy or pericardial dissection.

Pathology

Common Injuries & Conditions

Sick Sinus Syndrome After Inferior MI

Proximal RCA occlusion in inferior STEMI compromises the sinoatrial nodal artery in 55% of individuals, producing sinus bradycardia, SA block, or sinus arrest requiring temporary transvenous pacing; function usually recovers within days as the RCA territory is reperfused by primary PCI.