The heart's blood supply comes from two main vessels that arise from the aortic root just above the aortic valve. The left coronary artery quickly divides into the left anterior descending (LAD) artery, which runs down the front of the heart in the interventricular groove, and the left circumflex (LCx) artery, which curves around the left side toward the back. The LAD supplies the anterior wall of the left ventricle, the anterior two-thirds of the interventricular septum, and the apex. The LCx supplies the lateral and posterolateral wall of the left ventricle. The right coronary artery (RCA) travels along the right side and supplies the right ventricle, the inferior (diaphragmatic) wall of the left ventricle, and — in most people — the sinoatrial and atrioventricular nodes. Because these territories are largely non-overlapping, the location of an occlusion predicts which segment of ventricular muscle loses perfusion. A proximal LAD occlusion threatens the anterior wall and septum, an RCA occlusion threatens the inferior wall, and an LCx occlusion threatens the lateral wall.
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Coronary Supply and the Myocardial Oxygen Balance
Which Artery Feeds Which Wall
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Start with the two vessels leaving the aortic root. The left coronary artery splits almost immediately into the left anterior descending artery, which runs down the front groove, and the left circumflex, which curves around the left border. The right coronary artery follows the right side and wraps toward the back. Now follow each one to the muscle it feeds. The left anterior descending covers the front wall, most of the septum, and the apex. The circumflex covers the side and back-left wall. The right coronary artery covers the right ventricle and the inferior wall. Notice that these regions barely overlap. That is the key point: if you know which vessel is blocked, you can predict which wall is starved of blood.
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