left circumflex artery
Summary
The left circumflex artery (LCX) is one of the two main branches of the left main coronary artery, supplying the lateral and posterior walls of the left ventricle. Occlusion typically causes lateral wall MI with characteristic ECG changes in leads I, aVL, V5, and V6.
Detail
The left circumflex artery originates from the left main coronary artery (along with the LAD) and courses along the left atrioventricular groove. It supplies the lateral wall of the left ventricle via obtuse marginal branches and often gives rise to the posterior descending artery (PDA) in left-dominant systems (~10% of population). The LCX also supplies the left atrium and may contribute to the inferior wall. Anatomically, it's divided into proximal, mid, and distal segments. Acute occlusion presents as lateral STEMI with ST elevation in leads I, aVL, V5-V6, and reciprocal depression in leads II, III, aVF. The artery is often involved in multivessel coronary artery disease and can be challenging to visualize angiographically due to its course behind the heart. Chronic stenosis may cause exertional angina with lateral wall ischemia on stress testing.
Sources
- First Aid for the USMLE Step 1
- Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine
- Netter's Atlas of Human Anatomy
- UpToDate: Coronary artery anatomy and anomalies
Reviewed by AnkiBoss editorial — medical student review. Information here is for study reference only and is not medical advice. Spotted an error? Let us know.