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The papillary muscles are thick bands and ridges of endocardial-lined myocardium that project into the lumen of the cardiac ventricles. They are located in the ventricles of the heart and play a crucial role in the proper opening and closing of atrioventricular valves. The papillary muscles contract to prevent inversion or prolapse of these valves during systole (ventricular contraction). There are five papillary muscles in the heart: three in the right ventricle and two in the left ventricle. Papillary muscle abnormalities can significantly impair the hemodynamic performance of the heart.
| Characteristics | Values |
|---|---|
| Location | Ventricles of the heart |
| Number | 5 (3 in the right ventricle and 2 in the left ventricle) |
| Function | Prevent inversion or prolapse of the atrioventricular valves on systole (or ventricular contraction) |
| Blood supply | Anterolateral muscle: left anterior descending artery - diagonal branch (LAD) and left circumflex artery; Posteromedial muscle: right coronary artery |
| Clinical aspects | Tumours, including metastases and primary lesions (benign or malignant); pathologies such as mitral stenosis; dysfunction caused by ischemia |
| Surgical procedures | Radiofrequency ablation, transcatheter valve replacement, and mitral valve repair |
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What You'll Learn
Papillary muscles are located in the ventricles of the heart
The papillary muscles are located in the ventricles of the heart. They are endocardial structures that can harbour arrhythmic substrates in structural heart disease and an apparently normal heart. Both the right and left papillary muscles can be arrhythmogenic, although reported cases involving the right ventricular (RV) papillary muscles are scarce.
There are five papillary muscles in the heart: three in the right ventricle and two in the left ventricle. The right ventricle's anterior, posterior, and septal papillary muscles attach via chordae tendineae to the tricuspid valve. The left ventricle's anterolateral and posteromedial papillary muscles attach via chordae tendineae to the mitral valve. The mitral valve papillary muscles in the left ventricle are called the anterolateral and posteromedial muscles.
The chordae tendineae, except for the tertiary chordae, arise from paired papillary muscles and extend to both mitral leaflets. There are two papillary muscles, the superolateral (anterolateral) and the inferoseptal (posteromedial), both originating from the apical to middle thirds of the LV free wall. During diastole, the papillary muscles do not protrude into the submitral space to facilitate mitral inflow. However, during systole, they bulge into the LV cavity, redirecting flow toward the aortic valve, forming part of the LV outflow tract.
The papillary muscles are integral to the mitral valve function because the annulus resides in the left atrio-ventricular groove, and the chordae tendineae are connected to the ventricle via these muscles. The papillary muscles contract to prevent inversion or prolapse of the atrioventricular valves on systole (or ventricular contraction). Without the contraction of the papillary muscles, the longitudinal shortening of the LV would result in a prolapse of the leaflets.
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They contract to prevent inversion of atrioventricular valves
The papillary muscles are endocardial structures located in the ventricles of the heart. There are five papillary muscles in the heart: three in the right ventricle and two in the left ventricle. They attach to the cusps of the atrioventricular valves (also known as the mitral and tricuspid valves) via the chordae tendineae.
The chordae tendineae, except the tertiary chordae, arise from paired papillary muscles and extend to both mitral leaflets. There are two papillary muscles, the superolateral (anterolateral) and the inferoseptal (posteromedial), both originating from the apical to middle thirds of the LV free wall. The chordae tendineae are connected to the ventricle via the papillary muscles, and mitral valve function is integrally related to the ventricle. The papillary muscles contract to prevent inversion or prolapse of the atrioventricular valves during systole (or ventricular contraction). If the papillary muscles did not contract, the longitudinal shortening of the LV would result in a prolapse of the leaflets.
The papillary muscles are well demonstrated in the short-axis view on transthoracic echocardiograms, 1–3 cm apical to the level of the mitral valve laterally. Echocardiography is the first-line imaging modality used in the evaluation of cardiac abnormalities, including papillary muscles. It allows for real-time cine depiction of papillary muscle anatomy and function through a combination of 2D and 3D grey-scale imaging for morphologic depiction, with Doppler imaging providing additional hemodynamic insights.
However, echocardiography has some limitations, including operator dependence, limited soft tissue contrast, and a restricted field of view in certain scenarios based on patient anatomy, mobility, and post-operative status. Computed tomography (CT) and magnetic resonance imaging (MRI) can also be used to evaluate papillary muscle anatomy and function, particularly in the left ventricle.
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There are five papillary muscles in the heart
The heart contains five papillary muscles, which are pillar-like muscles found within the cavity of the ventricles, attached to their walls. They play a crucial role in ensuring the proper functioning of the cardiac valves. The development of these muscles begins at around five weeks of embryonic development and concludes at approximately week nineteen.
Three of the five papillary muscles are found in the right ventricle, and the remaining two are found in the left ventricle. The anterior, posterior, and septal papillary muscles of the right ventricle are each attached to the tricuspid valve via chordae tendineae. The anterolateral and posteromedial papillary muscles of the left ventricle are attached to the mitral valve via chordae tendineae. The mitral valve papillary muscles in the left ventricle are specifically called the anterolateral and posteromedial muscles.
The papillary muscles are responsible for contracting to prevent the inversion or prolapse of the valves during systole or ventricular contraction. They receive nerve impulses from the AV node, which are then transmitted to the ventricles from the base of the papillary muscles. The proper functioning of the papillary muscles is vital, as their rupture can be life-threatening and may occur due to myocardial infarction or blunt chest trauma.
The papillary muscles are susceptible to various abnormalities and conditions. For instance, in advanced Barlow's disease, the papillary muscle may become calcified, restricting chordae and leaflet motion. Additionally, papillary muscle fibrosis or necrosis can occur without rupture, commonly caused by coronary atherosclerosis or other factors such as shock, infective endocarditis, acute valvar regurgitation, and anemia.
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Papillary muscle abnormalities can impair the heart's performance
The heart contains five papillary muscles, three in the right ventricle and two in the left ventricle. These muscles attach to the tricuspid and mitral valve leaflets through the chordae tendineae, preventing ventricular blood regurgitation by stabilising the valves during systole.
Papillary muscle dysfunction is another abnormality that can impair the heart's performance. This can occur as a result of ischemia or infarction of a papillary muscle, ventricular dilatation (including aneurysm), rupture of a papillary muscle, inflammatory disease of a papillary muscle, or interventricular conduction disturbances. Dysfunction of the papillary muscles can cause blood to regurgitate through the valves, leading to a backflow of blood that can result in left- or right-sided heart failure.
In addition, the failure of one or both papillary muscles to shorten during the ejection phase of ventricular systole, fibrosis, and atrophy of a papillary muscle or centrifugal migration due to left ventricular dilatation can result in mitral incompetence. This can lead to a worsening of mitral regurgitation and further impair the heart's performance.
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Papillary muscle rupture can be caused by myocardial infarction
The heart contains five papillary muscles: three in the right ventricle and two in the left ventricle. These muscles are attached to the cusps of the atrioventricular valves (also known as the mitral and tricuspid valves) via the chordae tendineae. They contract to prevent inversion or prolapse of these valves during ventricular contraction.
Papillary muscle rupture is a rare but potentially fatal complication following myocardial infarction. Myocardial infarction refers to the occlusion of a coronary artery, which can lead to papillary muscle rupture in about 1% of patients. This is most common in the case of an inferior wall infarction due to the occlusion of either the RCA (right coronary artery) or the left circumflex artery. The rupture usually occurs within a week after myocardial infarction, particularly as an evolution of inferior AMI.
Mitral regurgitation (MR) after myocardial infarction is a common complication, with an incidence of around 50%. Papillary muscle rupture is one cause of MR after myocardial infarction, and this situation usually requires urgent surgical treatment. The prognosis is favourable with early surgical intervention, so early diagnosis of the underlying cause of mitral regurgitation is important.
The postero-medial papillary muscle is the most common site of rupture, and the rupture is often partial or incomplete (head rupture). Patients most commonly undergo mitral valve replacement (MVR), although mitral valve repair (MVr) may lead to a better outcome due to greater preservation of post-operative left ventricular function.
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Frequently asked questions
Papillary muscles are components of the cardiac muscle chambers. They are thick bands and ridges of endocardial-lined myocardium that project into the lumen of the cardiac ventricles.
They are located in the ventricles of the heart. There are five total papillary muscles in the heart; three in the right ventricle and two in the left ventricle.
They play a crucial role in the proper opening and closing of atrioventricular valves. They contract to prevent inversion or prolapse of these valves on systole (or ventricular contraction).
Papillary muscle abnormalities can significantly impair the haemodynamic performance of the heart. Some common abnormalities include fibrotic scarring, rupture, congenital malformations, and calcification.
