| Coronary circulation | |
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| An anterior view of the heart shows the right coronary artery and the anterior descending branch of the left coronary artery. The heart is a muscular organ in all Vertebrates responsible for pumping Blood through the Blood vessels by repeated rhythmic The right coronary artery (RCA originates above the right cusp of the Aortic valve. The left coronary artery, abbreviated LCA and also known as the left main coronary artery (often abbreviated LMCA) arises from the aorta above the | |
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| Base and diaphragmatic surface of heart. | |
| MeSH | Coronary+Vessels |
Coronary circulation is the circulation of blood in the blood vessels that supply blood to and from the heart muscle itself. Medical Subject Headings ( MeSH) is a huge Controlled vocabulary (or metadata system for the purpose of indexing journal articles and books The blood vessels are part of the Circulatory system and function to transport Blood throughout the body Blood is a specialized Bodily fluid that delivers necessary substances to the body's cells such as nutrients and oxygen—and transports Waste products The heart is a muscular organ in all Vertebrates responsible for pumping Blood through the Blood vessels by repeated rhythmic Although blood fills the chambers of the heart, the muscle tissue of the heart, or myocardium, is so thick that it requires coronary blood vessels to deliver blood deep into it. Myocardium is the muscular tissue of the Heart. Relationship to other layers The other tissues of the heart are the Endocardium The vessels that deliver oxygen-rich blood to the myocardium are known as coronary arteries. The vessels that remove the deoxygenated blood from the heart muscle are known as cardiac veins.
The coronary arteries that run on the surface of the heart are called epicardial coronary arteries. Arteries are Blood vessels that carry blood away from the Heart. These arteries, when healthy, are capable of autoregulation to maintain coronary blood flow at levels appropriate to the needs of the heart muscle. Myocardium is the muscular tissue of the Heart. Relationship to other layers The other tissues of the heart are the Endocardium These relatively narrow vessels are commonly affected by atherosclerosis and can become blocked, causing angina or a heart attack. Atherosclerosis is a Disease affecting arterial Blood vessels It is a chronic inflammatory response in the walls of arteries in large part due to the accumulation Angina pectoris, commonly known as angina, is severe Chest pain due to Ischemia (a lack of blood and hence Oxygen supply of the heart Myocardial infarction ( MI or AMI for acute myocardial infarction) also known as a heart attack, occurs when the blood supply (See also: circulatory system. This is an article about the rock music band "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.
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Coronary anatomy
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. Cardiac catheterization ( heart cath) is the insertion of a Catheter into a chamber or vessel of the Heart. Computed tomography (CT is a Medical imaging method employing Tomography.
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. The right coronary artery (RCA originates above the right cusp of the Aortic valve. The left coronary artery, abbreviated LCA and also known as the left main coronary artery (often abbreviated LMCA) arises from the aorta above the As discussed below, the left coronary artery originates from the left aortic sinus, while the right coronary artery originates from the right aortic sinus.
Variations
Four percent of people have a third, the posterior coronary artery. In rare cases, a person will have one coronary artery that runs around the root of the aorta.
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).
Coronary artery dominance
The artery that supplies the posterior descending artery (PDA) and the posterolateral artery (PLA) determines the coronary dominance. The posterior interventricular artery (PIV (or posterior descending artery(PDA) is typically a branch of the Right coronary artery (80% known as right dominance The "LCX" or left circumflex artery (or circumflex artery, or circumflex branch of the Left coronary artery) is an Artery of the
- If the right coronary artery (RCA) supplies both these arteries, the circulation can be classified as "right-dominant". The right coronary artery (RCA originates above the right cusp of the Aortic valve.
- If the circumflex artery (CX), a branch of the left artery, supplies both these arteries, the circulation can be classified as "left-dominant". The "LCX" or left circumflex artery (or circumflex artery, or circumflex branch of the Left coronary artery) is an Artery of the
- If the RCA supplies the PDA and the CX supplies the PLA, the circulation is known as "co-dominant".
Approximately 60% of the general population are right-dominant, 25% are co-dominant, and 15% are left-dominant. [1]
Blood supply of the papillary muscles
The papillary muscles tether the mitral valve (the valve between the left atrium and the left ventricle) and the tricuspid valve (the valve between the right atrium and the right ventricle) to the wall of the heart. In Anatomy, the papillary muscles of the Heart serve to limit the movements of the mitral and Tricuspid valves These muscles contract to tighten The miter valve (also known as the bicuspid valve or left atrioventricular valve) is a dual flap (bi = 2 valve in the Heart that lies between The left atrium is one of the four chambers in the Human Heart. The left ventricle is one of four chambers (two atria and two ventricles in the Human Heart. The tricuspid valve (also known as the right atrioventricular valve) is on the right side of the heart between the Right atrium and the Right ventricle The right atrium (in older texts termed the "right auricle" is one of four chambers (two atria and two ventricles in the Human The right ventricle is one of four chambers (two atria and two ventricles in the Human Heart. If the papillary muscles are not functioning properly, the mitral valve leaks during contraction of the left ventricle. This causes some of the blood to travel "in reverse", from the left ventricle to the left atrium, instead of forward to the aorta and the rest of the body. This leaking of blood to the left atrium is known as mitral regurgitation. Mitral regurgitation ( MR) a Valvular heart disease also known as mitral insufficiency, is the abnormal leaking of blood through the Mitral valve
The anterolateral papillary muscle more frequently receives two blood supplies: left anterior descending (LAD) artery and the left circumflex artery (LCX). The "LAD" or left anterior descending artery (or anterior interventricular branch of the Left coronary artery, or anterior descending branch) The "LCX" or left circumflex artery (or circumflex artery, or circumflex branch of the Left coronary artery) is an Artery of the [2] It is therefore more frequently resistant to coronary ischemia (insufficiency of oxygen-rich blood). In Medicine, ischemia ( Greek ισχαιμία, isch- is restriction hema or haema is Blood) is a restriction On the other hand, the posteromedial papillary muscle is usually supplied only by the PDA. [2] 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. Myocardial infarction ( MI or AMI for acute myocardial infarction) also known as a heart attack, occurs when the blood supply
Coronary flow
During contraction of the ventricular myocardium (systole), the subendocardial coronary vessels (the vessels that enter the myocardium) are compressed due to the high intraventricular pressures. In the Heart, a ventricle is a heart chamber which collects Blood from an atrium (another heart chamber that is smaller than a ventricle and However the epicardial coronary vessels (the vessels that run along the outer surface of the heart) remain patent. Because of this, blood flow in the subendocardium stops. As a result most myocardial perfusion occurs during heart relaxation (diastole) when the subendocardial coronary vessels are patent and under low pressure. Diastole is the period of time when the heart fills with blood after systole (contraction This contributes to the filling difficulties of the coronary arteries. compression remains the same. Failure of oxygen delivery via increases in blood flow to meet the increased oxygen demand of the heart results in tissue ischemia, a condition of oxygen debt. Brief ischemia is associated with intense chest pain, known as angina. Angina pectoris, commonly known as angina, is severe Chest pain due to Ischemia (a lack of blood and hence Oxygen supply of the heart Severe ischemia can cause the heart muscle to die of oxygen starvation, called a myocardial infarction. Myocardial infarction ( MI or AMI for acute myocardial infarction) also known as a heart attack, occurs when the blood supply Chronic moderate ischemia causes contraction of the heart to weaken, known as myocardial hibernation.
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. Norepinephrine ( INN) (abbreviated norepi or NE) or noradrenaline ( BAN) (abbreviated NA or NAd) is a In the coronary circulation, norepinephrine elicits vasodilation, due to the predominance of beta-adrenergic receptors in the coronary circulation. Norepinephrine ( INN) (abbreviated norepi or NE) or noradrenaline ( BAN) (abbreviated NA or NAd) is a Agonists of alpha-receptors, such as phenylephrine, elicit very little constriction in the coronary circulation.
See also
References
- ^ Kaimkhani ZA, Ali MM, Faruqi AM (2005). Cardiology (from Greek grc καρδίᾱ kardiā, "heart" and grc -λογία -logia) is the branch of Internal medicine "Pattern of coronary arterial distribution and its relation to coronary artery diameter". Journal of Ayub Medical College, Abbottabad : JAMC 17 (1): 40-3. PMID 15929526.
- ^ a b Voci P, Bilotta F, Caretta Q, Mercanti C, Marino B (1995). "Papillary muscle perfusion pattern. A hypothesis for ischemic papillary muscle dysfunction". Circulation 91 (6): 1714–8. PMID 7882478.
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