Left coronary artery

At a glance

English

Left coronary artery

Latin (TA2)

Arteria coronaria sinistra

System

Heart

Region

Trunk

Side

Single, on the midline

About the left coronary artery

The left coronary artery is the first branch of the aorta on the left side. It opens from the left aortic sinus, the bulge in the aortic wall just above the left coronary cusp of the aortic valve. Its proper name is often shortened to the left main stem, or left main coronary artery, because the trunk itself is short and the term may be used either for that trunk alone or for the trunk together with all its branches.

From its opening it passes forwards and to the left between the pulmonary trunk in front and the left auricle behind. After a course of only one to two and a half centimetres it reaches the coronary sulcus and divides. The anterior interventricular artery, known clinically as the left anterior descending artery, continues down the front of the heart, while the circumflex artery turns round the left side in the atrioventricular groove. In some hearts a third vessel arises between these two, the intermediate artery or ramus intermedius, which runs over the lateral wall of the left ventricle much like a diagonal branch.

Through its branches it supplies the left atrium, most of the left ventricle, the anterior two-thirds of the interventricular septum and a strip of the right ventricle beside the anterior groove. Some descriptions add an early septal branch close to the division.

Because so much muscle depends on this one short trunk, narrowing of the left main stem is a serious finding on angiography and is usually treated by bypass surgery or stenting. Its branch, the anterior interventricular artery, has earned the nickname widow maker for the same reason.

Function and supply

Begins at

The left aortic sinus of the ascending aorta, just above the left coronary cusp of the aortic valve.

Ends at

Divides after a short course into the anterior interventricular and circumflex arteries, sometimes with an intermediate artery between them.

Function

Through its branches supplies the left atrium, most of the left ventricle, the front two-thirds of the interventricular septum and part of the right ventricle.