The Coronary System
The coronary system is comprised of the heart's arteries, arterioles, capillaries, venules, and cardiac veins
The Coronary Arteries
The coronary arteries supply the myocardium with oxygenated blood. They originate with the right and left main coronary arteries, which exit the ascending aorta just above the aortic valve. These two branches subdivide and course over the surface of the heart (epicardium) as they traverse away from the aorta. The left main coronary artery splits into the left anterior descending artery (LAD) and the circumflex artery. The LAD supplies a large portion of the blood to the left ventricle. Hence, the LAD has been often referred to as the "the widowmaker," since a blockage within the LAD significantly reduces blood flow to the left ventricle and therefore results in high mortality rates.
Coronary arteries like others in the human body, divide into progressively smaller branches. In the heart, after branching they progress inward to penetrate the epicardium and supply blood to the transmural myocardium. More specifically, the coronary arteries branch into arterioles and these arterioles then branch into innumerable capillaries that deliver oxygenated blood to all of the heart's cells. Blood continues to flow through the capillaries and then begins its return back into the cardiac chambers through venules: they coalesce into the cardiac veins, which are also known as the coronary veins.
The Cardiac Veins
The major cardiac veins collect the deoxygenated blood (and other waste products) and return it to the right atrium through the coronary sinus (CS), where it joins the systemic deoxygenated blood entering from the superior and inferior vena cavae. Note that the anterior cardiac veins, drain deoxygenated blood from the right ventricle directly to the right atrium. One should be aware that there are several different nomenclatures that have been used to describe the major cardiac veins. The anterior interventricular vein (AIV) courses anteriorly in between the left and right ventricle. The great cardiac vein (GCV) is made up of the AIV and continues in the atrialventricular sulcus until it becomes the CS. Various landmarks have been described as the beginning of the CS: where the oblique vein of the left atrium (also known as the Marshall vein) meets the CS, the valve of Vieussens is commonly found at the ostium of this vein (at the left margin of the heart) [1,2]. The veins on the free wall of the left ventricle (LV) are commonly known as the lateral veins or left marginal veins. Veins on the posterior side of the LV free wall are typically referred to as the posterior veins of the left ventricle. Finally, the posteior interventricular vein (PIV) courses in between the left and right ventricle on the posterior/inferior side of the heart.
- Giudici M, Winston S, Kappler J, et al. Mapping the coronary sinus and great cardiac vein. Pacing Clin Electrophysiol. Apr 2002;25(4 Pt 1):414-419.
- von Ludinghausen M. The venous drainage of the human myocardium. Adv Anat Embryol Cell Biol. 2003;168:I-VIII, 1-104.