The coronary arteries that run on the surface of the heart are called epicardial coronary arteries. These arteries, when healthy, are capable of autoregulation to maintain coronary blood flow at levels appropriate to the needs of the heart muscle. These relatively narrow vessels are commonly affected by atherosclerosis and can become blocked, causing angina or a heart attack. (See also: circulatory system.) The coronary arteries that run deep within the myocardium are referred to as subendocardial.
The coronary arteries are classified as "end circulation", since they represent the only source of blood supply to the myocardium: there is very little redundant blood supply, which is why blockage of these vessels can be so critical.
The exact anatomy of the myocardial blood supply system varies considerably from person to person. A full evaluation of the coronary arteries requires cardiac catheterization or CT coronary angiography.
In general there are two main coronary arteries, the left and right.
Both of these arteries originate from the beginning (root) of the aorta, immediately above the aortic valve. As discussed below, the left coronary artery originates from the left aortic sinus, while the right coronary artery originates from the right aortic sinus.
Occasionally, a coronary artery will exist as a double structure (i. e. there are two arteries, parallel to each other, where ordinarily there would be one).
Approximately 60% of the general population are right-dominant, 25% are co-dominant, and 15% are left-dominant.
The anterolateral papillary muscle more frequently receives two blood supplies: left anterior descending (LAD) artery and the left circumflex artery (LCX). It is therefore more frequently resistant to coronary ischemia (insufficiency of oxygen-rich blood). On the other hand, the posteromedial papillary muscle is usually supplied only by the PDA. This makes the posteromedial papillary muscle significantly more susceptible to ischemia. The clinical significance of this is that a myocardial infarction involving the PDA is more likely to cause mitral regurgitation.
In addition to metabolism, the coronary circulation possesses unique pharmacologic characteristics. Prominent among these is its reactivity to adrenergic stimulation. The majority of vasculature in the body constricts to norepinephrine, a sympathetic neurotransmitter the body uses to increase blood pressure. In the coronary circulation, norepinephrine elicits vasodilation, due to the predominance of beta-adrenergic receptors in the coronary circulation. Agonists of alpha-receptors, such as phenylephrine, elicit very little constriction in the coronary circulation.
Researchers Submit Patent Application, "Method and System for Multi-Scale Anatomical and Functional Modeling of Coronary Circulation", for Approval
Jun 15, 2013; By a News Reporter-Staff News Editor at Obesity, Fitness & Wellness Week -- From Washington, D.C., NewsRx journalists report that...
Wipo Publishes Patent of Siemens, Puneet Sharma, Ali Kamen, Dorin Comaniciu, Lucian Mihai Itu, Bogdan Georgescu and Viorel Mihalef for "Method and System for Multi-Scale Anatomical and Functional Modeling of Coronary Circulation" (American Inventors)
May 17, 2013; GENEVA, May 17 -- Publication No. WO/2013/071219 was published on May 16.Title of the invention: "METHOD AND SYSTEM FOR...