The left coronary artery (LCA) is another major coronary blood vessel. Overall, it supplies oxygenated blood to the left side of the heart. The LCA also arises from the proximal ascending aorta but from its left aspect. It is typically larger than the RCA and divides into two branches.

Origin

The LCA starts from the left coronary ostium, which is located in the left coronary sinus (left sinus of Valsalva). The opening is found in the left wall of the root of the ascending aorta immediately above the left coronary cusp of the aortic valve.

Course

The left coronary artery has a relatively short trunk (0.2 - 0.4 inches or 5 - 10 mm long) that divides into two branches soon after the artery arises.

After the LCA originates from the ascending aorta, it passes between the left auricle and the left aspect of the pulmonary trunk. Further, it goes into the left half of the anterior coronary sulcus and, upon reaching the anterior interventricular sulcus, splits into two terminal branches - the left anterior descending artery (LAD) and left circumflex artery (LCx).

The left anterior descending artery (LAD) travels within the anterior interventricular sulcus toward the apex of the heart. The left circumflex artery (LCx) continues to pass within the coronary sulcus and, close to the cardiac crux, it anastomoses with the right coronary artery (RCA).

If the LCA is a dominant artery, before the LCx anastomoses with the RCA, it gives rise to the posterior descending artery (PDA) that travels within the posterior interventricular sulcus.

Supply

Overall, the LCA supplies the following structures of the heart:

Left atrium
Left ventricle
Part of the anterior surface of the right ventricle
Anterior two-thirds of the interventricular septum
Atrioventricular bundle
Sinoatrial (SA) node (in some cases)
Anterior papillary muscle of the left ventricle

Note: The 3D model shows a right dominant circulation. In a left dominant circulation, the LCA also supplies the posterior and inferior aspects of the left ventricle, as well as the posterior one-third of the interventricular septum.

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Left coronary artery (LCA)