Left coronary artery
Synonyms and keywords: LCA

# Overview
The left coronary artery normally arises from the aortic sinus above the left cusp of the aortic valve.  The origin of the left coronary artery is called the left main coronary artery, and it bifurcates into the left anterior descending and the left circumflex artery.  This artery supplies the majority of the blood flow to the left ventricle, the pumping chamber of the heart.  In fact, the LCA supplies the posterolateral side of the left ventricle as well as the anterior part of the left ventricle which includes the anterolateral myocardium, the apex, the anterior interventricular septum and the anterolateral papillary muscle.

# Branches
The left coronary artery typically courses for 1 to 25 mm as the left main artery, and then bifurcates into the anterior interventricular artery (also called left anterior descending (LAD)) artery and the left circumflex artery (LCX).
If an artery arises from the left main between the LAD and LCX, it is known as the ramus intermedius.  The ramus intermedius occurs in 37% of the general population, and is considered a normal variant.

## LCA with Median Ramus and Marginal Branches
Shown below is an image depicting the LCA and its branches in particular the marginal arteries, the diagonal arteries and the median ramus.  Please refer to the table at the bottom for more details about the LCA segments.
LM= Left main; L1= Proximal left anterior descending artery ; L2= Mid left anterior descending artery; L3= Distal left anterior descending artery; L4= The left anterior descending artery terminus on the inferior wall; D1= First diagonal artery; D2= Second diagonal artery; D3= Third diagonal artery; S1, S2, S3= Septal arteries; MR= Median ramus; C1= Proximal circumflex artery; C2= Mid circumflex artery; C3= Distal circumflex artery; C4= Left posterolateral artery; M1, M2, M3 = Marginal arteries ; OM1-OM3= Obtuse marginal arteries.  For a full description of the labels, refer to the table at bottom of the page.

## LCA with Obtuse Marginal Branch
Shown below is an image depicting the LCA and its branches in particular the obtuse marginal branch.  Please refer to the table at the bottom for more details about the LCA segments.
M1= Marginal artery; OA= Anterior branch of the obtuse marginal artery ; OM2= Obtuse marginal artery; OP= Posterior branch of the obtuse marginal artery; OT= Obtuse marginal trunk.  For a full description of the labels, refer to the table at bottom of the page.

## Left Coronary Artery Anatomic Classification Scheme
In order to objectively characterize the location of coronary obstructions, the left coronary artery segments can be classified according to their location.  Shown below is a classification scheme developed by the PERFUSE study group which lists all the segments of the LCA in terms of corresponding numbers, labels, locations and anatomic descriptions.

# Coronary Angiography of the Left Coronary Artery

# Additional images
- A coronary angiogram that shows the LMCA, LAD and LCX
- A coronary angiogram that shows the LMCA, LAD and LCX
- A coronary angiogram that shows the LMCA, LAD and LCX
- A coronary angiogram that shows the LMCA, LAD and LCX
- A coronary angiogram that shows the LMCA, LAD and LCX