Left main coronary artery

Assoc Prof Craig Hacking and Dr Henry Knipe et al.

The left main coronary artery (LMCA) or left coronary artery (LCA) is one of the two main coronary arteries that supply the heart with oxygenated blood.

It is a branch of the ascending aorta, with its normal origin in the left aortic sinus, just superior to the aortic valve 1-2.

LMCA runs for 5-10 mm as it passes to the left and posterior to the pulmonary trunk before bifurcating 1-2.

Most hearts are right dominant where the PDA is supplied by the RCA. However up to 20% of hearts may be left dominant, where the PDA is supplied by the LAD or LCx or codominant, where a single or duplicated PDA is supplied by branches of both the RCA and LAD/LCx.

For a more in depth discussion of coronary dominance, see the article coronary arterial dominance.

Anatomical variations of the LMCA include 3:

See main article: congenital coronary artery anomalies.

Anatomy: Thoracic

Anatomy: Thoracic

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Article information

rID: 22844
System: Cardiac, Vascular
Section: Anatomy
Synonyms or Alternate Spellings:
  • Left main coronary artery
  • LCA
  • LMCA

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Cases and figures

  • Figure 1: origin of coronary arteries
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  • Case 1: anomalous origin and course LCA
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  • Case 2: anomalous septal LAD
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  • Case3: left dominant circulation
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