Obtuse Marginal Arteries

arteriae marginales obtusae

The obtuse marginal arteries are branches of the left circumflex artery running along the lateral and posterolateral left ventricular wall. There are typically one to three obtuse marginal branches (OM1, OM2, OM3) supplying the lateral wall of the left ventricle. In a left-dominant circulation where the LCx gives rise to the posterior descending artery, the obtuse marginals supply a larger myocardial territory.

Region: Chest

Clinical Relevance

Clinical Notes

Obtuse marginal artery occlusion produces lateral wall MI, presenting on ECG with changes in leads I, aVL, V5, and V6. Lateral MIs are sometimes called the silent MI as the ECG changes can be subtle compared to anterior or inferior patterns. Coronary angiography identifies the obtuse marginals as separate bypass targets; large OM branches are grafted with saphenous vein or radial artery during CABG. In PCI, OM branches are accessed via the LCx guide catheter and can be individually stented.

Pathology

Common Injuries & Conditions

Lateral Wall MI from Obtuse Marginal Occlusion

Acute thrombotic occlusion of an obtuse marginal artery produces lateral left ventricular wall infarction with ECG changes in high lateral or lateral leads, sometimes presenting without the dramatic anterior chest pain of LAD occlusion, requiring the same prompt PCI management as any STEMI.