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The papillary muscles are located in the ventricles of the heart. They are thick bands and ridges of endocardial-lined myocardium that project into the lumen of the cardiac ventricles. There are five total papillary muscles in the heart: three in the right ventricle and two in the left ventricle. Papillary muscles can become dysfunctional, most commonly due to ischemia, and rupture can be caused by myocardial infarction.
| Characteristics | Values |
|---|---|
| Location | Ventricles of the heart |
| Number | 5 in total (3 in the right ventricle and 2 in the left ventricle) |
| Attachment | Cusps of the atrioventricular valves (also known as the mitral and tricuspid valves) via the chordae tendineae |
| Function | Contract to prevent inversion or prolapse of the atrioventricular valves during systole (ventricular contraction) |
| Morphology | Wide variation, including number of muscle heads and basal segments |
| Blood Supply | Dependent on specific muscle group (e.g., left anterior descending artery for anterolateral muscle) |
| Dysfunction | Caused by ischemia, myocardial infarction, or trauma |
| Abnormalities | Congenital disorders, neoplasms, and variants affecting LV outflow |
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What You'll Learn
Papillary muscle rupture
The heart contains five papillary muscles originating from the ventricular walls. These muscles are essential for maintaining mitral valve function, preventing ventricular blood regurgitation by stabilising the valves during systole. The rupture of these muscles is a rare but potentially fatal complication, usually occurring after myocardial infarction or due to infective endocarditis.
Rupture of the papillary muscles can lead to severe mitral valve regurgitation, causing acute life-threatening cardiogenic shock and pulmonary edema. Urgent mitral valve replacement surgery is required to correct the hemodynamic deterioration of the patient. A case study describes an elderly woman with acute mitral regurgitation caused by a spontaneous rupture of a papillary muscle. This rupture was likely related to severe mitral annular calcification with myocardial and valvular extension.
Other documented causes of papillary muscle rupture include trauma, syphilis, periarteritis nodosa, vegetative valvulitis, myocardial abscess, iatrogenic injury, and cocaine use. Dysfunction of the papillary muscles can also be caused by ischemia, which can lead to mitral regurgitation. In addition, chronic or acute left ventricular dilatation can result in papillary muscle displacement, increasing leaflet tethering and annular dilatation.
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Papillary muscle displacement
The papillary muscles are located in the ventricles of the heart. There are five in total: 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 contraction of the papillary muscles prevents the inversion or prolapse of the valves during ventricular contraction.
In a study, anterior papillary muscle displacement was created in seven dogs, and it was found that papillary muscle displacement caused SAM in all seven dogs, with an outflow tract gradient and mitral regurgitation in six. This led to the conclusion that primary changes in the mitral apparatus can cause SAM without septal hypertrophy.
Apically displaced papillary muscles can mimic apical hypertrophic cardiomyopathy (ApHCM). However, giant negative T (GNT) waves on electrocardiograms (ECGs) may not always be specific for ApHCM, as seen in cases of apically displaced papillary muscles.
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Papillary muscle morphology
The papillary muscles are located in the ventricles of the heart and play a crucial role in cardiac valvular function. Typically, there are five papillary muscles in the heart: three in the right ventricle (anterior, posterior, and septal) and two in the left ventricle (anterolateral and posteromedial). The anterolateral papillary muscle usually consists of a single major muscle group, while the posteromedial muscle contains two or three major muscle groups.
There is significant variability in papillary muscle morphology. They can be categorized based on the number of muscle heads and whether the heads share a common basal segment or have unique basal segments. Some morphological variations are considered normal and incidental, while others can lead to functional deficits and complications such as left ventricular outflow obstruction. Significant variations include anomalous insertion, accessory muscles, antero-apical displacement, double bifid morphology, and hypermobile muscles.
Cardiovascular magnetic resonance (CMR) imaging is a valuable tool for evaluating papillary muscle morphology and function. It provides high-resolution images and multi-planar capabilities, allowing for a detailed assessment of the complex structure and function of the papillary muscles. Additionally, CMR can be enhanced with contrast agents for improved tissue characterization. Echocardiography is another imaging modality used to visualize papillary muscles and assess their function in real time, although it has limitations in terms of soft tissue contrast and field of view.
The blood supply to the papillary muscles is an important aspect of their morphology and function. The anterolateral papillary muscle typically receives blood from the left anterior descending artery and its diagonal branch, as well as the left circumflex artery and its obtuse marginal branch. The posteromedial papillary muscle is usually supplied by the right coronary artery, although in some cases, it may receive blood from the left circumflex artery.
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Papillary muscle abnormalities
Papillary muscles are small myocardial structures located in the ventricles of the heart. There are five papillary muscles in the heart: three in the right ventricle (anterior, posterior, and septal) and two in the left ventricle (anterolateral and posteromedial). These muscles play a crucial role in maintaining mitral valve function and preventing blood from flowing backward into the atrial cavities.
However, various abnormalities and disorders can affect the papillary muscles. One of the most common issues is papillary muscle dysfunction, which can occur due to several factors:
- Ischemia or infarction: Ischemia is a common cause of papillary muscle dysfunction. It involves a restriction of blood flow to the muscle, leading to inadequate oxygen supply. This can result in the muscle failing to shorten during the ejection phase of ventricular systole.
- Ventricular dilatation: Enlargement of the ventricles can disrupt the proper spatial relationships between the papillary muscles, chordae tendinae, and mitral valve leaflets, resulting in mitral incompetence or regurgitation.
- Rupture: Papillary muscle rupture is a rare but severe complication, often occurring after myocardial infarction or due to infective endocarditis. It can lead to acute mitral valve regurgitation, causing life-threatening cardiogenic shock and pulmonary edema.
- Inflammatory disease: Inflammation of the papillary muscles can disrupt their normal function and contribute to mitral regurgitation.
- Interventricular conduction disturbances: Abnormal electrical impulses in the heart can affect the coordination and contraction of the papillary muscles, impacting their ability to regulate blood flow effectively.
Another abnormality is the parachute mitral valve, the most common congenital abnormality of the papillary muscles. In this condition, all the chordae tendineae insert into a single papillary muscle, disrupting normal mitral valve function.
Additionally, in advanced Barlow's disease, the papillary muscle may become calcified, restricting the movement of the chordae tendineae and leaflet motion. This can further impact the proper functioning of the mitral valve complex.
Cardiovascular magnetic resonance (CMR) imaging plays a valuable role in evaluating papillary muscle abnormalities, providing detailed morphological and functional information to guide diagnosis and treatment.
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Papillary muscle dysfunction
The mitral valve has two groups of papillary muscles, namely the anterolateral and the posteromedial groups. The anterolateral papillary muscle often has a single head, while the posteromedial papillary muscle usually has two heads. These muscles provide chordae to both leaflets of the mitral valve. The anterolateral muscle has a dual blood supply, while the posteromedial muscle has a single blood supply, making it more susceptible to rupture following a myocardial infarction.
Papillary muscle rupture is a rare but potentially fatal complication of myocardial infarction or infective endocarditis. It can also be caused by blunt chest trauma, resulting from the sudden deceleration or compression of the heart. Rupture of the papillary muscles can lead to severe mitral regurgitation, causing acute life-threatening cardiogenic shock and pulmonary edema.
The dysfunction of the papillary muscles can present with varying murmurs depending on the nature of the dysfunction and the time course of activation of the muscles. Associated electrocardiographic abnormalities may also occur. Mitral insufficiency secondary to disease of the papillary muscles has been a neglected area of research, with most studies focusing on acquired or congenital valvular disease.
In conclusion, papillary muscle dysfunction is a serious condition that can lead to life-threatening complications. It is important to recognize and treat this syndrome early to prevent adverse outcomes.
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Frequently asked questions
The papillary muscles are muscles located in the ventricles of the heart. They are thick bands and ridges of endocardial-lined myocardium that project into the lumen of the cardiac ventricles.
The papillary muscles contract to prevent inversion or prolapse of the atrioventricular valves on systole (or ventricular contraction). This prevents regurgitation, or the backward flow of ventricular blood into the atrial cavities.
Papillary muscle dysfunction can refer to a murmur of mitral regurgitation that develops in the setting of myocardial ischemia. Papillary muscle rupture is a major complication of acute myocardial infarction and can also be caused by blunt chest trauma.
