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Papillary muscles are thick bands of muscle tissue that are located in the ventricles of the heart. They play a crucial role in the proper opening and closing of atrioventricular valves. There are five papillary muscles in the heart: three in the right ventricle and two in the left ventricle. Papillary muscles contract to prevent inversion or prolapse of the valves during systole (ventricular contraction). They can harbour arrhythmic substrates in structural heart disease and abnormalities can impair the heart's performance.
| Characteristics | Values |
|---|---|
| Location | Ventricles of the heart |
| Composition | Cardiac muscle tissue and connective tissue |
| Function | Preventing inversion or prolapse of atrioventricular valves |
| Contraction | Prevents regurgitation (backward flow of ventricular blood into the atrial cavities) |
| Number | 5 in total (3 in the right ventricle, 2 in the left ventricle) |
| Morphology | Thick bands and ridges of endocardial-lined myocardium |
| Abnormalities | Parachute mitral valve, Parachute-like mitral valve, Shone's anomaly |
| Rupture | Caused by myocardial infarction, ischemia, or blunt chest trauma |
| Calcification | Can occur in advanced Barlow's disease |
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What You'll Learn
- Papillary muscles are found in the ventricles of the heart
- They prevent the backward flow of blood into the heart's atrial cavities
- Papillary muscle rupture can be caused by myocardial infarction or chest trauma
- They are composed of cardiac muscle tissue and connective tissue
- Papillary muscles can harbour arrhythmic substrate in structural heart disease
Papillary muscles are found in the ventricles of the heart
The papillary muscles are thick bands and ridges of endocardial-lined myocardium that project into the lumen of the cardiac ventricles. They are found in both the left and right ventricles of the heart. There are five total papillary muscles in the heart; three in the right ventricle and two in the left ventricle.
The papillary muscles are crucial components of the cardiac muscle chambers. They attach to the cusps of the atrioventricular valves (also known as the mitral and tricuspid valves) via the chordae tendineae. Through contraction, they maintain the proportions between the valve annulus and the heads of the papillary muscles, preventing valve leaflets from prolapsing. They contract shortly before ventricular systole and maintain tension throughout, preventing the backward flow of ventricular blood into the atrial cavities.
The papillary muscles originate from the distal third of the ventricular wall in the posteromedial and anterolateral position as a single entity or a group of two to three "papillae". The muscle fibres are mostly oriented longitudinally, parallel to the muscle axis. In the peripheral region of the papillary muscles, the muscle fibres are arranged circularly.
Papillary muscle abnormalities can significantly impair the hemodynamic performance of the heart. They may become calcified in advanced Barlow's disease, and papillary muscle rupture can be caused by myocardial infarction.
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They prevent the backward flow of blood into the heart's atrial cavities
The papillary muscles are thick bands and ridges of endocardial-lined myocardium that project into the lumen of the cardiac ventricles. They are components of the cardiac muscle chambers that play a crucial role in the proper opening and closing of atrioventricular valves. There are five papillary muscles in the heart: three in the right ventricle and two in the left ventricle.
The papillary muscles attach 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 on systole (or ventricular contraction). The contraction of the papillary muscles prevents regurgitation, or the backward flow of ventricular blood into the atrial cavities, by bracing the atrioventricular valves against prolapse. This is caused by high pressure in the ventricles.
The papillary muscles of both the right and left ventricles begin to contract shortly before ventricular systole and maintain tension throughout. The contraction of the papillary muscles is essential for maintaining the proportions between the valve annulus and the heads of the papillary muscles, preventing valve leaflets from prolapsing. The longitudinal orientation of the muscle fibres results in a prevalent shortening of the long axis of the papillary muscles. Without this contraction, the longitudinal shortening of the left ventricle would result in a prolapse of the leaflets.
Papillary muscle abnormalities can significantly impair the haemodynamic performance of the heart. For example, in advanced Barlow's disease, the papillary muscle may become calcified and restrict chordae and leaflet motion. Rupture of the left ventricular papillary muscles is a rare complication of myocardial infarction, but it can lead to acute mitral regurgitation, a life-threatening condition.
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Papillary muscle rupture can be caused by myocardial infarction or chest trauma
The heart contains five papillary muscles that originate from the ventricular walls. Three of these muscles—anterior, posterior, and septal—attach to the tricuspid valve, while the remaining two—anterolateral and posteromedial—connect to the mitral valve. These muscles contract to prevent the inversion or prolapse of the valves during systole (or ventricular contraction).
Papillary muscle rupture is a rare but potentially fatal complication that can occur following a myocardial infarction or as a result of chest trauma. When a myocardial infarction occurs, the papillary muscle can become injured due to its single system of blood supply, leading to rupture. This situation usually requires urgent surgical treatment, as prognosis is favourable with early intervention.
In the case of chest trauma, the papillary muscle rupture is an uncommon complication. It typically arises from non-penetrating cardiac trauma, resulting in mitral valve rupture. The rarity of this complication is evidenced by the fact that, in a study of 546 autopsies of fatal non-penetrating cardiac injuries, only eight cases of pure mitral valve disruption were found, and these were associated with other cardiac injuries. However, the incidence of such injuries has increased due to the higher incidence of motor vehicle collisions.
Regardless of the cause, papillary muscle rupture can lead to severe mitral valve regurgitation, acute life-threatening cardiogenic shock, and pulmonary edema. Diagnosis of papillary muscle rupture is primarily done through echocardiography, which can reveal ruptured or dysfunctional papillary muscles, severe mitral regurgitation, and signs of hemodynamic instability. Management requires urgent stabilization, often followed by prompt surgical intervention, typically mitral valve repair or replacement.
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They are composed of cardiac muscle tissue and connective tissue
The papillary muscles are thick bands and ridges of endocardial-lined myocardium that project into the lumen of the cardiac ventricles. They are composed of cardiac muscle tissue and connective tissue. The connective tissue acts as a framework, uniformly organising and separating individual groups of muscle fibres. The muscle fibres are mostly oriented longitudinally, parallel to the muscle axis, although a circular arrangement of fibres is observed in the peripheral region of the papillary muscles.
The papillary muscles play a crucial role in the proper opening and closing of the atrioventricular valves. They attach to the cusps of these valves via the chordae tendineae. There are five papillary muscles in the heart: three in the right ventricle and two in the left ventricle. The right ventricle's anterior papillary muscle attaches to the chordae tendineae of the anterior and posterior cusps; the posterior papillary muscle attaches to the posterior and septal cusps' chordae tendineae; and the septal papillary muscle attaches to the chordae tendineae of the anterior and septal cusps. The left ventricle's anterior papillary muscle attaches to the chordae tendineae of the anterior and posterior cusps, while the posterior papillary muscle attaches to the same chordae tendineae.
The papillary muscles contract to prevent inversion or prolapse of the atrioventricular valves during systole (ventricular contraction). They begin contracting shortly before ventricular systole and maintain tension throughout, preventing the backward flow of ventricular blood into the atrial cavities. This action also braces the atrioventricular valves against prolapse, protecting them from being forced back into the atria by the high pressure in the ventricles.
Abnormalities in the papillary muscles can significantly impair the heart's haemodynamic performance. These abnormalities include fibrotic scarring, rupture, or congenital malformations. Rupture of the papillary muscles can be caused by myocardial infarction, and dysfunction can result from ischemia or, rarely, blunt chest trauma.
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Papillary muscles can harbour arrhythmic substrate in structural heart disease
The papillary muscles are endocardial structures located in the ventricles of the heart. They attach to the cusps of the atrioventricular valves (also known as the mitral and tricuspid valves) via the chordae tendineae. The contraction of the papillary muscles is essential for the proper functioning of the valves, i.e., the opening and closing of the atrioventricular orifice. There are five papillary muscles in total; three in the right ventricle and two in the left ventricle.
Papillary muscles can harbour arrhythmic substrates in structural heart disease and even in apparently normal hearts. In patients without a prior infarct, papillary muscles account for 4% to 12% of idiopathic ventricular arrhythmias. Both the right and left papillary muscles can be arrhythmogenic, although reported cases involving right ventricular papillary muscles are scarce. The complex anatomy of the papillary muscles and the presence of intermixed Purkinje fibres can create a substrate for idiopathic ventricular fibrillation.
The differentiation of ventricular arrhythmias originating from the papillary muscle and the fascicles is challenging and not always possible. However, it is important to distinguish between myocardial and fascicular origin as different techniques are required for the ablation of papillary arrhythmias, and potential complications may vary. Catheter ablation has a fair success rate, but the complexity of the papillary muscle anatomy and the difficulty in maintaining catheter stability pose challenges.
The morphology of papillary muscles can vary, and they can undergo changes such as fibrotic scarring, rupture, or congenital malformations. These variations may be due to developmental anomalies or neoplasms and can range from asymptomatic to life-threatening. In advanced Barlow's disease, the papillary muscle may become calcified, restricting chordae and leaflet motion. Additionally, chronic or acute left ventricular dilatation can lead to papillary muscle displacement and increased leaflet tethering.
In summary, papillary muscles play a crucial role in the proper functioning of the heart valves. However, they can also harbour arrhythmic substrates, leading to ventricular arrhythmias. The complex anatomy of papillary muscles and the presence of intermixed Purkinje fibres contribute to the development of arrhythmias. Variations and changes in papillary muscle morphology can further impact their function and may require surgical intervention in some cases.
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Frequently asked questions
Papillary muscles are thick bands and ridges of cardiac muscle tissue and connective tissue that project into the lumen of the cardiac ventricles.
They are located in the ventricles of the heart. There are two in the left ventricle and three in the right ventricle.
They contract to prevent inversion or prolapse of the atrioventricular valves on systole (or ventricular contraction).
Papillary muscle rupture is a rare complication of myocardial infarction, but it can also be caused by blunt chest trauma. It can lead to acute mitral regurgitation, which is life-threatening.
Common abnormalities include parachute mitral valve, parachute-like mitral valve, and Shone's anomaly. These abnormalities can impair the haemodynamic performance of the heart.
