LCx

The left circumflex artery (LCx) is one of the main branches of the left coronary artery. It arises from the left coronary ostium and travels in the left atrioventricular groove (coronary sulcus) around the left heart, typically following the margin between the left atrium and left ventricle.

The LCx supplies blood to the lateral and posterior aspects of the left ventricle and, variably, portions of the left atrium. Its branches include obtuse marginal arteries that extend to the lateral wall of the left ventricle and, in some individuals, posterior left ventricular branches that reach the posterior surface of the heart. The extent of its perfusion is influenced by coronary dominance: in most hearts (right-dominant circulation), the posterior descending artery arises from the right coronary artery, while in left-dominant circulation the LCx gives rise to the posterior descending artery, and in codominant patterns both arteries contribute.

Clinical significance centers on the LCx as a potential source of myocardial ischemia. Occlusion or critical narrowing can cause lateral or posterior left ventricular ischemia or infarction. Electrocardiographic changes may include ST-segment elevations or depressions in lateral leads (eg, I, aVL, V5–V6) and, depending on dominance, posterior involvement may be inferred from reciprocal changes. Diagnosis is typically via coronary angiography, with treatment options including percutaneous coronary intervention or coronary artery bypass grafting based on anatomy and extent of disease.

See also: coronary artery disease, myocardial infarction, coronary dominance, coronary angiography.