Heart - LO 8

8. Describe the arterial supply of the heart.

The epicardium and myocardium are supplied by the right and left coronary aa. (RCA & LCA), which are the first (most proximal) branches of the ascending aorta.

Right coronary a. (RCA): 

• Originates in the right aortic sinus (of Valsalva)

• Typically travels between the ascending aorta and the R. auricle as it enters the coronary sulcus

• Branches include:

  • Sinu-atrial (SA) nodal br.: branches near the ascending aorta toward the SA node located near the junction of the R. atrium and superior vena cava

    • A branch of the RCA in 60% of individuals

    • In 40% of cases, it is a branch of the circumflex br. of the LCA (Moore et al., 2014)

  • R. marginal br.: located along the inferior border of the heart and is typically the last anterior branch of RCA

  • Atrioventricular (AV) nodal br.: arises near the posterior interventricular br., and dives deep and superior toward the AV node

    • Arises from RCA in 67% of individuals, and circumflex br. of LCA in 33% of cases

  • Posterior interventricular (posterior descending) br.: located in posterior interventricular sulcus

    • Arises from RCA in 67% of individuals, and circumflex br. of LCA in 33% of cases

    • Heart dominance

      • Determined by which coronary artery supplies the crux of the heart (e.g. the origin of the posterior interventricular branch, but also the AV nodal br.)

        • Right dominance = source is RCA

          • Typical

        • Left dominance = source is LCA

        • Codominance = source is both RCA and circumflex branch of LCA

Left coronary artery (LCA): located between the pulmonary trunk and L. auricle as it enters the coronary sulcus

• Branches include:

  • Anterior interventricular (left anterior descending) br.: located in the anterior interventricular sulcus

    • Typically anastomoses with posterior IV br.

    • The most common site of artery occlusion in the heart

  • Circumflex br.

    • Often referred to as a continuation of the LCA, continuing through the coronary sulcus to the base of the heart (posterior aspect)

    • L. marginal a., follows the left border of the heart

    • In left and/or codominant hearts:

      • AV nodal br

      • Posterior interventricular brs.