Anatomy - Distal RCA occlusion

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Anatomy - RCA

The right coronary artery (RCA) arises from the aorta above the right cusp of the aortic valve. It then courses through the right atrioventricular sulcus, a groove between the right atrium and right ventricle. The RCA gives off several branches including:

  • SA-nodal artery
  • Acute marginal (AM) branch, also known as the right marginal artery or the RV-branch
  • Ramus Descendens Posterior
  • Right posterolateral artery (RPLA) which gives off one or more posterolateral branches (PL branches) to the left ventricle
  • AV-nodal artery

The Sino-atrial nodal artery

  • In 60% of cases, the Sino-atrial nodal artery is supplied by the proximal segment of the RCA
  • In 40% of cases, the Sino-atrial nodal artery is supplied by the RCx

This distribution is independent of the coronary circulation’s dominance.

Right marginal artery or RV-branch

The RCA supplies blood to the right ventricle through the acute marginal branch (also known as the right marginal artery or the right ventricular (RV) branch). This branch runs along the anterior aspect of the right ventricle to supply this region.

After giving off the RV-branch, the RCA continues through the right atrioventricular sulcus and winds around the right side of the heart to reach the posterior aspect of the heart.

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Ramus Descendens Posterior

In 85% of the population, the RCA gives off the RDP to supply the posterior and inferior regions of the heart and the inferoposterior segment of the interventricular septum. The RCA bifurcates into the RDP and the right posterolateral artery (RPLA) at the crux (i.e. the point of intersection of the interatrial and interventricular septa). The RDP courses through the posterior interventricular sulcus to provide septal perforators to the inferoposterior segment of the interventricular septum. In supplying blood to the interventricular septum, the RDP is a functional "mirror image" of the LAD.

In 7% of cases, the Ramus Descendens Posterior (RDP) branches from the RCx. If the RDP is a branch of the RCx, this coronary circulation is described as a left-dominant system.

In the remaining 8% of cases the coronary circulation is a co-dominant system with the RCA giving off the right RDP and the RCx supplying all the posterolateral branches to the left ventricle. In some cases the RCx may also give rise to a left RDP (or left PDA) which courses in the posterior interventricular sulcus parallel to the right RDP.

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Right posterolateral artery (RPLA) and posterolateral (PL) branches to the left ventricle:

In a right-dominant system, the RCA bifurcates into the RDP and the right posterolateral artery (RPLA) at the crux. The right posterolateral artery subsequently gives off one or more posterolateral branches (PL branches) to the left ventricle. The PL branches supply the posterior and lateral aspects of the left ventricle. In a left-dominant system, the RDP and all the posterolateral branches to the left ventricle branch off from the RCx and the blood supply of posterior wall is solely provided by the RCx.

AV nodal artery

This artery supplies blood to the AV node. In 85% of cases this artery is a branch of the dominant RCA, arising from the distal segment of the RCA just prior to the origin of the RDP. In the remaining 15% the AV nodal artery is a branch of the RCx.

Proximal RCA, mid RCA, and distal RCA

In identifying the segments of the RCA, the RV-branch is used as an anatomical landmark.

  • Proximal RCA is the segment of the RCA proximal to the origin of the RV-branch
  • Distal RCA is distal half of the segment between the origin of the RV-branch and the origin of the RDP
  • Mid RCA is the segment of the RCA between the origin of the RV-branch and the start of the distal RCA
 

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