Diagonal Arteries

arteriae diagonales

The diagonal arteries are branches arising from the left anterior descending artery at its superior-lateral surface, running diagonally across the anterolateral wall of the left ventricle. There are typically one to three diagonal branches, designated D1 (first and largest), D2, and occasionally D3. The first diagonal artery is often as large as the LAD itself and supplies a substantial portion of the anterolateral left ventricular wall.

Region: Chest

Clinical Relevance

Clinical Notes

The diagonal arteries define separate myocardial risk territories in anterior STEMI: occlusion proximal to D1 on the LAD produces a larger anterior MI involving the diagonal territory as well, while occlusion between D1 and D2 spares the first diagonal territory. Coronary angiography defines diagonal origin and calibre before bypass surgery, where large diagonal arteries are routinely grafted alongside the LAD. In PCI for anterior STEMI, the diagonal branch may be compromised by stenting across its ostium (side branch compromise), and bifurcation stenting techniques apply.

Pathology

Common Injuries & Conditions

Diagonal Branch Occlusion in Anterior STEMI

Proximal LAD occlusion before the first diagonal artery produces a large anterior MI involving the diagonal territory; recognition of the diagonal origin on angiography guides whether a bifurcation technique is needed during primary PCI to preserve the branch alongside the main LAD stent.