Anatomy
Summary
In the human heart, coronary circulation is chiefly managed by two main arteries: the right main coronary artery (RCA) and the left main coronary artery (LCA), which further bifurcates into the left anterior descending artery (LAD) and the left circumflex artery (LCX). The RCA is essential for supplying the SA and AV nodes, and also contributes to the right ventricle via the right (acute) marginal artery. Furthermore, it commonly gives rise to the posterior descending artery (PDA), responsible for nourishing the posterior 1/3 of the interventricular septum and the posterior 2/3 of the ventricular walls. This RCA-originated PDA is often referred to as a characteristic of right-dominant circulation, which is seen in ~85% of individuals.
On the other hand, the LCA branches into the left anterior descending artery and the left circumflex artery. The LAD, often dubbed the "widow-maker" due to its frequent obstruction, irrigates the anterior two-thirds of the interventricular septum and the anterior surface of the left ventricle. The LCX focuses on the lateral and posterior walls of the left ventricle, including the anterolateral papillary muscle. It can also give rise to the obtuse marginal artery. In about 8% of people, the PDA arises from the LCX, a feature known as left-dominant circulation. In a small percentage (~7%), both the RCA and LCX contribute to the PDA, a condition known as codominant circulation. Understanding these arterial supply patterns is critical for diagnosing and managing coronary artery diseases.
Lesson Outline
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FAQs
The right and left main coronary arteries are principal vessels in coronary circulation. They both emerge from the aortic sinus and divide further to supply the heart's tissues. The right main coronary artery typically provides blood to the right side of the heart, right ventricle, and posterior descending artery. The left main coronary artery branches into the left anterior descending artery to supply the left and front part of the heart.
Heart dominance refers to whether the right or left coronary artery supplies the posterior descending artery, impacting the posterior circulation of the heart. When the right coronary artery gives rise to the PDA, the heart is considered right-dominant, which applies to the majority of people. Left dominance occurs when the left coronary artery supplies the posterior descending artery, which is less common. This knowledge helps in planning interventions and understanding certain heart diseases' pathogenesis and progression.
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