Coronary Artery AnatomyEdit

Coronary artery anatomy concerns the vessels that deliver oxygenated blood to the myocardium, the muscular tissue of the heart. The epicardial arteries originate at the aortic root, run along the surface of the heart in the coronary sulci, and give off branches that supply the atria, ventricles, and the conducting system. The left coronary artery largely feeds the anterior wall and lateral left ventricle, while the right coronary artery predominantly supplies the right heart and inferior aspects of the left ventricle. Understanding the typical patterns, common variants, and potential anomalies is essential for interpreting imaging, planning interventions, and assessing risk in ischemic heart disease.

Major vessels and normal patterns

The primary sources are the right coronary artery Right coronary artery and the left coronary artery Left coronary artery.
The left coronary artery typically divides soon after its origin into the left anterior descending artery Left anterior descending artery and the left circumflex artery Left circumflex artery. These branches distribute blood to the anterior wall of the left ventricle, the anterolateral papillary muscle, and the lateral and posterior aspects of the left ventricle.
The right coronary artery runs in the right atrioventricular groove and furnishes branches such as the acute marginal arteries and often the posterior interventricular artery, also called the posterior descending artery Posterior descending artery.
Coronary arteries are organized into a system of epicardial arteries that feed a rich network of intramural vessels. The main epicardial vessels give rise to perforating branches that penetrate toward the endocardium to perfuse the myocardial layers.
Coronary arterial dominance describes which artery supplies the posterior descending artery Posterior descending artery and influences which vessel is most critically involved in certain ischemic patterns. Right-dominant circulation is most common, with the posterior interventricular artery arising from the RCA in the majority of individuals; left-dominant circulation occurs when the LCx contributes the posterior interventricular artery; codominance is a blend of both sources.
The course of these arteries lies within the coronary sulcus (also called the atrioventricular groove), where they are most accessible to imaging and intervention. The sulcus also houses related venous drainage structures such as the great cardiac vein Great cardiac vein and the coronary sinus Coronary sinus.
Variants in branching patterns are common. A ramus intermedius is an additional diagonal branch that can arise from the left main or the LAD, adding to the complexity of supply to the anterior wall. Some individuals may have an anomalous origin or course of a coronary artery, which can be clinically important in certain circumstances. See Coronary artery anomaly for a broader discussion.

Branch patterns and regional supply

The LAD supplies the anterior left ventricle, the anterior two-thirds of the interventricular septum, and often the apex. It is a frequent focus in ischemic disease and can be the target of percutaneous or surgical interventions. The LAD is sometimes referred to by its segmental branches rather than as a single vessel in practical discussions.
The LCx travels in the left atrioventricular groove and distributes to the lateral and posterior walls of the left ventricle, with obtuse marginal branches supplying the lateral free wall.
The RCA provides the right-sided structures, portions of the inferior left ventricle, and often the posteroinferior septum. In many people, the RCA also gives rise to the sinoatrial nodal artery, which supplies the SA node in a large fraction of individuals; variations exist where the nodal supply comes from the LCx or the LAD.
The posterior interventricular (posterior descending) artery may originate from the RCA (right-dominant pattern) or from the LCx (left-dominant pattern), with the codominant arrangement reflecting contributions from both territories.
The perfusion of the conduction system is tightly linked to coronary anatomy. The SA node and AV node have arterial sources that can vary by dominance pattern; these arteries are important considerations during procedures that risk nodal ischemia.

Variants, anomalies, and development

Anatomic variants in coronary branching are common and range from accessory branches to unusual origins. While most variations are clinically silent, certain origins (such as anomalous takeoff from the opposite aortic sinus) can be associated with clinical risk, particularly during exertion or in the setting of congenital heart disease. See Coronary artery anomaly for a comprehensive review.
Coronary arteries may display embryologic variations that persist into adulthood, influencing the distribution of blood flow and the pattern of collateral networks in response to disease.
Myocardial bridging is a phenomenon in which a band of myocardium overlies a segment of a coronary artery, usually the LAD, producing systolic compression. This is typically considered a benign variant but can be implicated in rare cases of angina or myocardial ischemia.

Microanatomy, physiology, and clinical relevance

The arterial wall consists of layers—the intima, media, and adventitia—with the endothelium lining the luminal surface. The coronary circulation is designed to respond to myocardial metabolic demand, adjusting flow according to perfusion pressure and vascular resistance.
Atherosclerosis affects the coronary arteries with formation of plaques in the tunica intima, potentially narrowing the lumen and reducing flow. Plaque rupture or erosion can precipitate acute coronary syndromes, including myocardial infarction. See Atherosclerosis and Myocardial infarction for related topics.
Imaging and diagnostics: coronary angiography directly visualizes the lumen and branch patterns; computed tomography (CT) coronary angiography provides a noninvasive view of calcium burden and vessel anatomy; magnetic resonance imaging (MRI) and other modalities can assess perfusion and cardiac function. See Coronary angiography and CT coronary angiography for details.
Variants in dominance and branch distribution can influence the presentation and interpretation of ischemic events. For example, occlusion of the RCA in a right-dominant system may produce infarction in territories supplied by the RCA, while a left-dominant system may shift the affected region to the LCx territory.

Pathophysiology and clinical considerations

Coronary artery disease is driven by risk factors such as age, hypertension, hyperlipidemia, diabetes, smoking, and family history. The anatomical distribution of disease can affect prognosis and the choice of intervention, including percutaneous coronary intervention (PCI) or bypass surgery.
In planning procedures, awareness of dominant pattern, branch anatomy, and potential anomalies helps minimize risk to the conduction system and to critical branches. The venous anatomy, including the coronary sinus and great cardiac vein, also informs certain approaches to imaging and ablation.
Anatomical knowledge supports interpretation of electrocardiographic changes during ischemia and guides the localization of infarct-related arteries in acute care settings.