Coronary Circulation

Key points

• Left aortic sinus → left coronary artery (LCA → LAD + circumflex); right aortic sinus → right coronary artery (RCA → posterior descending).
• RCA supplies the SA node in 60% and the AV node in 90% of patients.
• Complete heart block post-MI localises to the RCA — the AV node is supplied by the posterior interventricular artery, a branch of the RCA in the majority (otherwise the left circumflex).
• Venous drainage: coronary sinus drains into the right atrium.