Coronary Artery Disease
The coronary circulation is formed by the right coronary artery (RCA), left coronary artery (LCA) and various branches. Coronary dominance refers to which vessel (RCA, circumflex) supplies the posterior interventricular (PIV) or posterior descending artery (PDA) branch to the inferior septum. Majority of hearts are right dominant (85% RCA) with the remainder either circumflex 8% or co-dominant 7%.
The LCA supplies blood to the left heart, including the LA and LV. The left main coronary artery divides early into the left anterior descending (LAD), circumflex (Cx) and intermediate (15%) arteries. The LAD runs in the anterior interventricular groove and supplies the anterior and lateral LV walls (diagonal branches), anterior septum (septal perforators) and atrioventricular (A-V) bundle. The Cx artery runs in the left A-V groove around the posterior heart to supply the infero-lateral LV wall (obtuse marginal branches). In 10–15% of patients the Cx continues as the PIV.
Most of the coronary blood flow to the RV is from the acute marginal branch of the RCA. The first septal perforator supplies the moderator band and the posterior septal perforators from the RCA supply the inferior (posterior) 1/3 of the IVS. In 30% of patients a separate conus artery branch supplies the infundibulum. Under normal conditions the RV is well perfused during both systole and diastole.