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Structure

Coronary arteries

Not medically reviewed · Content last updated · 2 min read ·

This is the date the draft was written, not a medical review date.

The right and left coronary arteries arise from the aortic root and supply the myocardium. Occlusion of specific branches produces predictable territories of infarction.

Terminologia Anatomica (Latin): Arteriae coronariae · Open in the 3D atlas

Location

The right coronary artery (RCA) runs in the right atrioventricular groove. The left main stem passes behind the pulmonary trunk and divides into the left anterior descending and circumflex arteries, which run in the anterior interventricular and left atrioventricular grooves.

Structure

The RCA arises from the right aortic sinus and gives the conus, sinoatrial nodal (about 60%), acute marginal and, in right dominance, the AV nodal and posterior descending arteries. The left main stem (about 1 to 2.5 cm) arises from the left sinus; the anterior interventricular (LAD) artery gives diagonal and septal branches, and the circumflex gives obtuse marginal branches. A ramus intermedius arises between them in a minority of people.

Blood supply

The vessel walls are nourished by vasa vasorum from the adventitia and by luminal diffusion; segments buried in myocardium (myocardial bridges) are usually spared from atherosclerosis. Venous return is by the great, middle and small cardiac veins into the coronary sinus.

Innervation

Perivascular sympathetic and vagal fibres from the cardiac plexus modulate tone, but local metabolic factors (adenosine, nitric oxide) are the dominant regulators of coronary flow.

Function

Delivers oxygenated blood to the myocardium, which extracts about 70% of arterial oxygen at rest, so increased demand must be met by increased flow. Left ventricular perfusion is predominantly diastolic.

Clinical correlations

Dominance is defined by the artery giving the posterior descending branch: right in about 70 to 90%, left in about 8 to 15%, co-dominant in the remainder. LAD occlusion causes anterior and septal infarction, circumflex occlusion lateral infarction, and RCA occlusion inferior infarction that may involve the right ventricle and the AV node. Anomalous coronary origin and myocardial bridging are recognised variants.

Common exam points

  • Right dominance (about 70 to 90%): the PDA arises from the RCA; left dominance: from the circumflex; co-dominant: from both.
  • LAD supplies the anterior wall, apex and anterior two thirds of the septum; ECG changes in V1 to V4.
  • Circumflex supplies the lateral wall (I, aVL, V5, V6); RCA supplies the inferior wall (II, III, aVF).
  • SA node artery from RCA in about 60%, from circumflex in about 40%; AV node artery from the dominant artery at the crux.
  • Great cardiac vein accompanies the LAD and middle cardiac vein the PDA; both drain to the coronary sinus.
  • Left main occlusion causes extensive anterolateral ischaemia and is life-threatening.

References

  1. Drake RL, Vogl AW, Mitchell AWM. Gray's Anatomy for Students. Elsevier — Tier 3 (textbook)
  2. Moore KL, Dalley AF, Agur AMR. Clinically Oriented Anatomy. Wolters Kluwer, 8th edition (2018) — Tier 3 (textbook)
  3. Fourth Universal Definition of Myocardial Infarction (2018). ESC / ACC / AHA / World Heart Federation (2018) — Tier 2 (guidelines / primary literature)
  4. 2023 ESC Guidelines for the management of acute coronary syndromes. European Society of Cardiology (2023) — Tier 2 (guidelines / primary literature)

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