Left marginal branch of circumflex artery of heart
Ramus marginalis sinister arteriae circumflexae cordis
- Latin synonym: Ramus marginalis sinister arteriae coronariae sinistrae
- Synonym: Left marginal branch of left coronary artery; Left marginal artery of heart
- Related terms: Left marginal artery
Definition
The left marginal branch of the circumflex artery (Obtuse marginal artery) is a branch of the left circumflex artery (LCx), which itself arises from the left main coronary artery. It courses along the left (obtuse) margin of the heart, supplying the lateral wall of the left ventricle.
Anatomical Overview
The left circumflex artery travels in the left atrioventricular groove and gives off one or more marginal branches. The left marginal branch often referred to as the obtuse marginal (OM) artery descends over the obtuse margin of the heart toward the apex. There may be one to three obtuse marginal branches (OM1, OM2, OM3), with OM1 being the most proximal and typically the largest.
Territory of Supply
The lateral wall of the left ventricle is the primary territory perfused by this vessel.
In some anatomic variants, it may also contribute blood supply to the posterolateral wall and, to a lesser extent, the anterolateral papillary muscle.
Clinical Significance
Occlusion of the left marginal branch can result in a lateral myocardial infarction, which may manifest as ST-segment elevation in leads I, aVL, V5, and V6 on electrocardiography.
During coronary angiography, the obtuse marginal branches are important landmarks for assessing the extent of circumflex artery disease.
In coronary artery bypass grafting (CABG), the obtuse marginal artery is a common target vessel for bypass conduits (e.g., saphenous vein graft or left internal mammary artery sequential grafting).
Anatomic Variants
The size and number of obtuse marginal branches are variable and inversely related to the dominance of the right coronary artery. In a left-dominant circulation (approximately 10-15% of individuals), the circumflex artery and its marginal branches supply a larger territory, including the posterior descending artery territory. In a right-dominant circulation (approximately 85% of individuals), the obtuse marginal branches are relatively smaller but remain the principal supply to the lateral left ventricular wall.
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