Left coronary artery (LAD and circumflex)

Arteria coronaria sinistra

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What it is

Arises from the left aortic sinus as a short left main stem that passes behind the pulmonary trunk and splits into the left anterior descending (LAD) artery, running down the anterior interventricular groove round the apex, and the circumflex artery in the left atrioventricular groove.

Function

Supplies most of the left ventricle, the front two-thirds of the septum and the left atrium.

Size

Left main 4–5 mm wide and 1–2.5 cm long; LAD ~3.5 mm tapering to 1 mm, ~12–15 cm long with diagonal branches; circumflex ~3 mm with obtuse marginal branches.

Clinical note

Blockage of the proximal LAD causes large anterior infarcts and is nicknamed the "widow-maker".