Left Circumflex ArteryEdit
The left circumflex artery (LCx) is a principal branch of the left coronary system. It arises from the left coronary artery and travels in the left atrioventricular groove (the coronary sulcus) to reach the lateral and posterior aspects of the left ventricle. Along its course, it gives off obtuse marginal branches that perfuse the lateral wall of the heart and, in certain anatomical patterns, can contribute to the posterior portion of the heart as well. The LCx plays a central role in supplying a substantial portion of the left ventricle, which is the muscular chamber responsible for pumping oxygenated blood to the systemic circulation. The artery's dominance—whether the LCx provides the posterior interventricular artery (the posterior descending artery) or whether this vessel is supplied by the right coronary artery—varies among individuals and has important clinical implications. For a broad overview of the cardiac arterial network, see Coronary circulation.
In most people, the LCx originates from the left coronary artery, then courses within the left atrioventricular groove toward the cardiac apex. Its principal branches are the obtuse marginal arteries, which run along the lateral wall of the left ventricle. In about a quarter to a third of people, the LCx also contributes to the posterior portion of the heart via branches that form or participate in the posterior interventricular system; in those cases, late branches can be involved in the formation of the posterior descending artery (PDA) depending on whether the heart is right-dominant, left-dominant, or codominant in its coronary circulation. See Left coronary artery for the origin, and dominance (cardiology) for how the LCx fits into the overall dominance pattern.
Anatomy and course
- Origin: LCx branches off the Left coronary artery just after the left coronary artery arises from the aorta.
- Path: LCx travels in the Left atrioventricular groove between the left atrium and left ventricle.
- Major branches: obtuse marginal arteries (OM1, OM2, etc.), which supply the lateral wall of the left ventricle.
- Variation: In some individuals, the LCx contributes to the posterior heart via branches that participate in the formation of the Posterior interventricular artery, influencing whether the heart is right-dominant, left-dominant, or codominant in its coronary circulation. See Coronary artery dominance for more detail.
Physiological role
The LCx delivers oxygenated blood to regions of the left ventricle responsible for pumping blood to the systemic circulation. Adequate perfusion of the lateral and, in certain patterns, posterior walls of the left ventricle is essential for maintaining contractile function and preventing ischemia in those regions. Because the left ventricle bears the greatest workload, compromised flow in the LCx can have pronounced effects on cardiac output and systemic perfusion.
Clinical relevance
Occlusion or severe narrowing of the LCx, whether from atherosclerotic plaque, thrombosis, or other pathology, can cause ischemia or infarction primarily in the lateral or posterolateral aspects of the left ventricle. Symptoms may include chest pain or pressure, shortness of breath, and other signs of myocardial ischemia. The electrocardiographic (ECG) manifestations of LCx-related events often involve lateral leads—commonly electrocardiography leads I, aVL, V5, and V6—and can occasionally be seen in adjacent or posterior leads depending on the individual’s coronary dominance and the extent of involvement. See Myocardial infarction for general information about ischemic events, and Coronary angiography for how LCx anatomy and lesions are assessed.
In the setting of a left-dominant coronary system, LCx pathology can affect not only the lateral left ventricle but also the posterior regions of the heart through its contribution to the PDA, potentially widening the clinical territory of ischemia. Conversely, in right-dominant hearts, PDA perfusion more commonly arises from the right coronary artery, while LCx disease tends to affect the lateral wall. See Dominance (cardiology) and Posterior interventricular artery for related concepts.
Clinical management of LCx disease follows established cardiology guidelines and depends on the lesion's location, severity, and the patient’s overall risk profile. Diagnostic evaluation may involve noninvasive imaging, stress testing, and definitive coronary angiography, as described in resources on Coronary angiography and related cardiovascular imaging.
Imaging and diagnosis
- Noninvasive assessment may include echocardiography to evaluate regional wall motion and function, and noninvasive ischemia testing as indicated.
- Coronary angiography is the definitive method to visualize LCx anatomy, identify stenoses, and guide treatment decisions such as percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG). See Coronary angiography.
- ECG patterns of LCx-related ischemia can be subtle and may require correlation with clinical presentation and imaging findings.