Logan Steele
The papillary muscles are muscles located in the ventricles of the heart. There are five in total: three in the right ventricle and two in the left ventricle. The blood supply to the papillary muscles is segmental in distribution, and reaches the muscle from large penetrating branches originating from epicardial vessels located radially outward from the muscle. The rupture of the papillary muscle is a rare but catastrophic consequence of acute myocardial infarction. The blood supply to the papillary muscle is critical in maintaining its function, and understanding the specific arteries that supply them is important in preventing and treating myocardial infarction and its complications.
| Characteristics | Values |
|---|---|
| Location | Ventricles of the heart |
| Number | 5 in total (3 in the right ventricle, 2 in the left ventricle) |
| Names | Anterior, posterior, septal, anterolateral, posteromedial |
| Function | Attach to the cusps of the atrioventricular valves (mitral and tricuspid valves) via the chordae tendineae, control mitral valve closure during systole, participate in the ejection process during left ventricular systole |
| Blood supply | Anterolateral muscle: dual supply from left anterior descending artery and left circumflex arteries; Posterior: supplied by one or two vessels, most frequently two; Posteriomedial: single blood supply from the right coronary artery or dominant left circumflex |
| Dysfunction | Myocardial infarction may cause papillary muscle dysfunction, dysfunction can lead to mitral regurgitation |
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What You'll Learn
- The left anterior descending artery supplies the anterolateral papillary muscle
- The right coronary artery supplies the posteromedial papillary muscle
- The obtuse marginal branch of the circumflex artery supplies the posterior papillary muscle
- The papillary muscle's role in mitral valve closure
- Papillary muscle dysfunction and its link to myocardial infarction
The left anterior descending artery supplies the anterolateral papillary muscle
The papillary muscles are an integral part of the mitral valve apparatus, controlling mitral valve closure during systole and participating in the ejection process during left ventricular systole. There are five papillary muscles in the heart: three in the right ventricle and two in the left ventricle. The left ventricle papillary muscle (PM) is supplied by the left anterior descending artery.
The blood supply to the papillary muscles is segmental in distribution, with large penetrating branches originating from epicardial vessels located radially outward from the muscle. The tip, mid-portion, and base of the papillary muscles generally receive their vascular supply from separate tributaries, which have a radial arrangement. The relatively small volume and characteristic growth along the ventricular long axis of the PM help to maintain sufficient blood flow during the diastolic phase, ensuring adequate left ventricular filling.
The anterolateral papillary muscle is less frequently ruptured compared to the posteromedial papillary muscle, which has a single blood supply. Rupture of the papillary muscle can lead to mitral regurgitation (MR), which is the most immediate and predominant result of PM dysfunction. Therefore, it is critical to adequately recognise PM dysfunction and PM-derived MR in clinical interventions for MR-related diseases.
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The right coronary artery supplies the posteromedial papillary muscle
The heart contains five papillary muscles: three in the right ventricle and two in the left ventricle. The left ventricle papillary muscle (PM) is an integral part of the mitral valve apparatus, controlling mitral valve closure during systole and participating in the ejection process during left ventricular systole. The two papillary muscles in the left ventricle are the anterolateral and posteromedial muscles.
The posteromedial papillary muscle is supplied by the right coronary artery or the dominant left circumflex. The right coronary artery supplies the posterior or posteroseptal wall of the left ventricle. The right coronary artery opacified 21.1±6.1% (range, 10% to 32%) of the left ventricular myocardium in a study of 35 vein grafts.
The posteromedial papillary muscle is more frequently ruptured compared to the anterolateral papillary muscle because of its single blood supply. The anterolateral papillary muscle has a dual blood supply from the left anterior descending and left circumflex arteries. Patients typically present with an inferior infarction with the right coronary artery as the culprit.
Papillary muscle dysfunction or rupture is a rare but catastrophic consequence of acute myocardial infarction. Myocardial infarction may cause papillary muscle dysfunction when the blood supply is provided by one rather than two vessels, as is more frequently the case with the posterior rather than the anterior papillary muscle. The posterior papillary muscle is involved in about 75% of cases of papillary muscle dysfunction or rupture.
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The obtuse marginal branch of the circumflex artery supplies the posterior papillary muscle
The papillary muscles are muscles located in the ventricles of the heart. There are five in total: three in the right ventricle and two in the left ventricle. The blood supply to the papillary muscles is segmental in distribution, and they are supplied by large penetrating branches originating from epicardial vessels located radially outward from the muscle.
The obtuse marginal branch is a smaller branch of the circumflex artery. The circumflex artery, in turn, is a branch of the left coronary artery. The number of circumflex artery branches varies from person to person, and there may be up to three obtuse marginal branches. These smaller branches typically travel along the outside margin of the left ventricle toward its tip or apex.
The left anterior descending artery - diagonal branch (LAD) supplies the anterolateral muscle, which is one of the mitral valve papillary muscles in the left ventricle.
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The papillary muscle's role in mitral valve closure
The human heart has four valves, one of which is the mitral valve, which connects the left atrium (LA) and the left ventricle (LV). The mitral valve opens during diastole to allow blood to flow from the LA to the LV. During ventricular systole, the mitral valve closes and prevents backflow to the LA. The mitral valve is composed of three layers: the fibrosa, spongiosa, and atrialis. The normal function of the mitral valve depends on its six components: the left atrial wall, annulus, leaflets, chordae tendineae, papillary muscles, and left ventricular wall.
The papillary muscles are located in the ventricles of the heart. There are five in total, with three in the right ventricle and two in the left ventricle. The mitral valve papillary muscles in the left ventricle are called the anterolateral and posteromedial muscles. The anterolateral muscle has a dual arterial supply, while the posteromedial papillary muscle has a single arterial supply. The left circumflex or right coronary artery (depending on dominance) provides the blood supply to the posteromedial papillary muscle. The anterolateral papillary muscle blood supply is from the left anterior descending and the diagonal or a marginal branch of the circumflex artery.
The papillary muscles play an important role in the functioning of the mitral valve. The chordae tendineae are fibrous strings that play a crucial role in the function of the mitral valve by connecting the valve leaflets to the papillary muscles within the LV. These structures prevent prolapse of the valve leaflets during systole, ensuring proper closure and preventing regurgitation. The chordae tendineae can be classified based on their origin, insertion, and structure. True chordae tendineae originate from the papillary muscles and insert into the valve leaflets. These are crucial for maintaining valve integrity by preventing leaflet prolapse. False chordae tendineae are not involved in valve function but may connect papillary muscles to each other or to the ventricular wall.
During systole, the papillary muscles contract before LV wall contraction, which results in apposition of the mitral valve leaflets, limiting the retrograde flow of blood from the LV back into the left atrium. If an ectopic ventricular beat results in contraction of the LV wall before the papillary muscles, an element of mitral regurgitation will be present. Papillary muscle dysfunction or rupture is a rare but catastrophic consequence of acute myocardial infarction.
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Papillary muscle dysfunction and its link to myocardial infarction
The papillary muscles are muscles located in the ventricles of the heart. There are five in total, three in the right ventricle and two in the left ventricle. The blood supply to the papillary muscles is segmental in distribution, and reaches the muscle from large penetrating branches originating from epicardial vessels located radially outward from the muscle. The tip, mid-portion, and base generally receive their vascular supply from separate tributaries.
Papillary muscle dysfunction is a well-recognized feature of acute myocardial infarction (AMI). The systolic murmur of papillary muscle dysfunction appears transient in most cases, but its presence is associated with prior infarction, persistent pain, heart failure, and greater mortality despite small infarct size. The presence of systolic murmur may also represent a subset of patients at high risk for early reinfarction. Mitral regurgitation after myocardial infarction is the result of multifactorial processes involving local and global left ventricular remodelling. The prevalence of mitral regurgitation varies from 11% to 59%. Mitral regurgitation after myocardial infarction carries an adverse prognosis, with an increased risk of death and heart failure.
Papillary muscle rupture is a rare but severe mechanical complication that can occur following an acute myocardial infarction, affecting 0.07% to 0.26% of patients. Despite the condition's rarity, it contributes to 5% of post-myocardial infarction mortality. Rupture occurs more frequently with ST-segment elevation myocardial infarction compared to non–ST-segment elevation infarction. Papillary muscle rupture leads to severe mitral valve regurgitation, often resulting in cardiogenic shock and pulmonary edema, necessitating immediate medical intervention. The posterior papillary muscle is involved in about 75% of cases, and this is due to the fact that it is supplied by one vessel, the posterior descending coronary artery, rather than two.
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Frequently asked questions
The blood supply to the papillary muscles is segmental in distribution, and reaches the muscle from large penetrating branches originating from epicardial vessels located radially outward from the muscle. The tip, mid-portion, and base generally receive their vascular supply from separate tributaries.
The anterolateral papillary muscle has a dual blood supply from the left anterior descending artery and the left circumflex arteries.
The posteromedial papillary muscle is supplied by the right coronary artery or the left circumflex artery.
