Pericardium

The pericardium (pericardium) separates the heart from adjacent organs and is a thin yet dense, strong fibrous-serous sac in which the heart is located. The pericardium has two layers of different structure: the outer fibrous layer and the inner serous layer. The outer layer, the fibrous pericardium (pericardium fibrosum), passes into their adventitia near the large vessels of the heart (at its base). The serous pericardium (pericardium serosum) has two plates: the parietal (lamina parietalis), which lines the fibrous pericardium from the inside, and the visceral (lamina visceralis, s.epicardium), which covers the heart and is its outer membrane, the epicardium. The parietal and visceral plates pass into each other in the area of the base of the heart, in the place where the fibrous pericardium is fused with the adventitia of large vessels: the aorta, pulmonary trunk, and vena cava. Between the parietal plate of the serous pericardium on the outside and its visceral plate (epicardium) there is a slit-like space - the pericardial cavity (cavitas pericardialis), which surrounds the heart from all sides and contains a small amount of fluid, this fluid moistens the surfaces of the serous pericardium and ensures their sliding during cardiac contraction. The serous pericardium is a thin plate formed by dense fibrous connective tissue rich in elastic fibers. From the side of the pericardial cavity, the serous pericardium is lined with flat epithelial cells - mesothelium; these cells are located on the basement membrane. The fibrous pericardium is formed by dense fibrous connective tissue with a high content of collagen fibers.

The pericardium is shaped like an irregular cone, the base of which (the lower section) is tightly fused with the tendinous center of the diaphragm, and at the top (at the apex of the cone) it encompasses the initial sections of large vessels: the ascending aorta, the pulmonary trunk, and the superior and inferior vena cava and pulmonary veins. The pericardium is divided into three sections. The anterior sternocostal section is connected to the posterior surface of the anterior chest wall by the sternopericardial ligaments (ligamenta sternopericardiaca). It occupies the area between the right and left mediastinal pleura. The lower section is diaphragmatic, fused with the tendinous center of the diaphragm. The mediastinal section (right and left) is the most significant in length. From the lateral sides and in front, the mediastinal section of the pericardium is tightly fused with the mediastinal pleura. On the left and right between the pericardium and the pleura pass the phrenic nerve and the adjacent pericardodiaphragmatic vessels. Behind, the mediastinal part of the pericardium is adjacent to the esophagus, the thoracic part of the aorta, the azygos and hemiazygos veins, surrounded by loose connective tissue.

Pericardial sinuses

In the pericardial cavity between it, the surface of the heart and large vessels there are rather deep pockets - sinuses. First of all, this is the transverse sinus of the pericardium (sinus transversus pericardii), located at the base of the heart. In front and above it is limited by the initial section of the ascending aorta and the pulmonary trunk, and behind - by the anterior surface of the right atrium and the superior vena cava. The oblique sinus of the pericardium (sinus obliquus pericardii) is located on the diaphragmatic surface of the heart. It is limited by the base of the left pulmonary veins on the left and the inferior vena cava on the right. The anterior wall of this sinus is formed by the posterior surface of the left atrium, the posterior - by the pericardium.

It is worth characterizing the anterior inferior sinus, which is located between the sternum and ribs and between the diaphragm. This sinus is located in the form of an arc, which is located in the frontal cavity. The sinus has the form of a groove. The sinus is quite deep: the depth can reach several centimeters. In this sinus, pathological accumulation of fluid is often observed (for example, with pericarditis). Blood and serous exudate can accumulate here. Sometimes purulent-serous exudate is found.

The transverse sinus is also important. In front, this sinus is limited by the serous membrane. The length of this sinus in an adult is between 5 and 9.8 cm. The diameter depends on the side: on the right it is 5-5.6 cm, on the left – 3-3.9 cm.

The transverse sinus is designed to connect the posterior and anterior surfaces of the pericardium. The oblique sinus is located in front below. Sometimes there is a transitional fold between the pericardium and the epicardium, from which folds are formed, which are slit-like depressions.

Pericardial norms

It is necessary to know the pericardium norms, first of all, in order to draw conclusions about how correctly it functions. Pathologies can arise due to a violation of the structure, function, due to the exit of individual indicators beyond the norm. It is especially important to know the pericardium norms when conducting ultrasound, MRI, and other functional studies. It is worth noting that the norms vary significantly, depending on the individual characteristics of the body, age, and sex of the patient. The most significant differences are expressed in the shape and position of the pericardium.

On average, the pericardium length fluctuates between 11.6 and 16.7 cm. The maximum width at the base is from 8.1 to 14.3 cm. The length from the anterior to the posterior edge is 6-10 cm. The thickness usually does not exceed 1 cm. In children, the pericardium is transparent, with age it can acquire some shades. It is also worth noting that the highest elasticity and stretchability are observed in childhood. In adults, the pericardium is less stretchable, but it can withstand high pressure (up to 2 atmospheres).

Age-related features of the pericardium

The structure of the pericardium is characterized by certain age-related features. Thus, in children, the heart, and accordingly the pericardium, grow at a rapid pace. The size of the atrium significantly exceeds the size of the ventricles. In a newborn, the heart is round, but it gradually lengthens. Also, the child's heart is highly elastic. Trabeculae are highly developed in children from 1 to 16 years old. The trabeculae reach their maximum development in adolescence, at about 17-20 years old. After this, the trabecular network undergoes gradual smoothing and straightening. The mesh pattern in the area of the apex of the heart is preserved for quite a long time. It is also worth noting that in all children, the heart valves are highly elastic, the cusps shine well. Around 20-25 years old, the valve cusps become compacted, the edges become uneven. In adulthood, the heart retains a dense structure and low elasticity.

In old and senile age, dystrophic and degenerative changes occur in the heart. In particular, partial atrophy of the papillary muscles occurs, which entails a violation of the functional state of the heart, pericardium, and its other membranes. The function of the valves is also impaired.

Pericardium in children

In a newborn, the pericardium is spherical (rounded), tightly enveloping the heart. The volume of the pericardial cavity is insignificant. The upper border of the pericardium is located very high, along the line connecting the sternoclavicular joints; the lower border corresponds to the lower border of the heart. The pericardium in a newborn is mobile, since the sternopericardial ligaments that fix the pericardium in an adult are poorly developed. By the age of 14, the borders of the pericardium and its relationship with the mediastinal organs are similar to those in an adult.

The structure of the pericardium has certain features associated with a person's age. For example, the pericardium in children differs sharply in its structure and functional state from the heart of an adult or an elderly person. Thus, in a newborn, the heart has a rounded shape. The diameter of the heart of a newborn can fluctuate between 2.7 and 3.9 cm, with the average length being 3-3.5 cm. The size from front to back is 1.7-2.5 cm. The atria are significantly larger than the ventricles, which inevitably affects the structure of the pericardium. The right atrium is significantly larger than the left. During the first year of life, the heart grows quite rapidly. Its length significantly exceeds its width; the heart grows much faster in length than in width.

The size of the heart is not the same at different ages. During the first year of life, the heart grows much faster than in other periods. At the same time, the atria grow rapidly. The ventricles grow more slowly. In the period from 2 to 5 years, the atria and ventricles do not differ in growth rates and grow at the same rate. After about 10 years, the atria begin to grow more intensively again.

The mass of the heart in a newborn is approximately 24 grams, and by the end of the first year of life it already reaches approximately 50 grams, that is, it doubles. Such ratios are maintained until the child reaches 16 years of age.

It is worth noting that the inner surface of the pericardium, mainly from the side of the ventricles, is covered with fleshy trabeculae. They appear at about 1 year and persist until 16 years.

The heart of a newborn is distinguished by its high position and transverse localization. At the end of the first year of life, a transition from the transverse position to the oblique position is observed. At about 2-3 years of age, children already have an oblique position of the heart. It is also important that the lower border of the heart in children of the first year of life is located significantly higher than in an adult. Thus, in a child of the first year of life, there is a difference in the border of the heart of one intercostal space. The upper costal border is located at the level of the second intercostal space. The projection of the apex of the heart is located in the fourth left intercostal space. The apex is located along the right edge of the sternum, or goes 1-2 cm to the right. With age, the ratio of the anterior surface of the heart to the chest wall changes.

The pericardium of a newborn is rounded in shape and has a small volume. It is worth noting that the pericardium fits tightly to the heart. The upper border is quite high (at the level of the sternoclavicular joints). The lower border corresponds to the lower border of the heart. It is also worth noting the high mobility of the pericardium of newborns and children in the first year of life, which is associated with poor development of the ligaments. The heart acquires the shape, size and structure corresponding to those of an adult child by the age of 14.

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Vessels and nerves of the pericardium

The pericardial blood supply includes the pericardial branches of the thoracic aorta, branches of the pericardiodiaphragmatic artery, and branches of the superior phrenic arteries. The pericardial veins adjacent to the arteries of the same name flow into the brachiocephalic, azygos, and hemiazygos veins. The lymphatic vessels of the pericardium are directed to the lateral pericardial, prepericardial, anterior, and posterior mediastinal lymph nodes. The nerves of the pericardium are branches of the phrenic and vagus nerves, as well as the cervical and thoracic cardiac nerves, extending from the corresponding nodes of the right and left sympathetic trunks.

Pericardial diseases

There are quite a few diseases of the pericardium, all of them are characterized by extremely diverse symptoms. Mostly, the course is severe. In most cases, pericardial diseases are concomitant pathologies with other diseases of the body, including systemic ones. Quite often, one has to deal with diseases such as polyserositis - a condition in which the serous membranes of the heart are involved in the inflammatory process. Pancarditis is a disease of the pericardium, in which the heart becomes inflamed, and often other membranes of the chest.

Pericarditis is an acute inflammatory disease of the heart. It often accompanies various allergic, autoimmune, infectious diseases. Many diseases of the pericardium are rheumatic in nature, or tuberculous in nature. Rheumatic forms are usually dry, and tuberculous forms are accompanied by the formation of purulent exudate.

In diseases that are accompanied by general circulatory disorders, hemorrhages and necrotic processes, conditions such as hydropericarditis and hemipericarditis often develop. As the name suggests, hydrocarditis is accompanied by the formation of watery edema, while the leading symptom of hemicarditis is the accumulation of blood. Chylopericarditis (accumulation of chylous fluid) is also observed, and a fistula develops.

Pneumopericarditis develops in severe diseases and traumatic injuries. A through cavity is formed that unites the chest cavity and the heart cavity, air penetrates from the damaged lung. This condition can also develop against the background of a ruptured lung, ruptured esophagus, stomach, or cavity. Pneumopericarditis should not be confused with an injury to the pericardium itself, which also often causes air bubbles to accumulate in the heart cavity. Gas in the pericardium can accumulate during the development of putrefactive processes in the heart cavity, during the decay of purulent exudate, and necrotic processes. This is a rather severe condition.

Pneumatosis is a condition in which air bubbles penetrate the pericardial sac. A common disease of the pericardium is anthracosis, or pneumoconiosis, in which lymph accumulates in the heart cavity. They take the form of black spots, similar to specks of black coal.

Pericardial diseases also include congenital defects. They are much more common in men than in women. Pericardial diseases also include injuries and tumor processes affecting the pericardium. Parasitic invasions are often observed, in which the parasite penetrates the pericardium and develops in it.

Anomalies of pericardial development

Abnormalities in the development of the pericardium include various forms of dystrophic processes. Most often, they develop against the background of a general metabolic disorder, primarily with a protein metabolism disorder. A disorder of salt and water metabolism can also lead to dystrophy, followed by a heart attack. Obesity is also dangerous for the pericardium, in which a huge layer of fat or subcutaneous tissue forms in the pericardium, which prevents the pericardium from performing its functions. The thickness can reach 1-2 cm. The most dangerous are fatty deposits on the right side of the heart.

Anomalies include mucus formation in the pericardium. Most often, such processes develop in old age. And are associated with the penetration of fatty deposits, serous contents, and exudate into the pericardium. This condition can also develop against the background of cachexia. In this case, the mucus is jelly-like. Gradually, the pericardium becomes saturated with mucus, and its atrophy develops, up to complete atrophy, which can end in death.

In case of parasitic damage to the pericardium, parasitic cysts may form, which are cavities filled with mucus with the parasite's waste products or eggs. It is worth noting that cysts almost always increase in size and gradually become compressed. Under the action of compression, blood circulation and trophic processes are disrupted in the surrounding tissues, which leads to the development of atrophic processes and gradual tissue death. In this case, connective or fibrous tissue may form in place of contractile tissue, which does not perform the functions assigned to the pericardium.

Parasitic cysts differ from normal cysts in that daughter vesicles and scolexes can form in the cyst cavity. After the death of the parasites contained in the cavity, it undergoes calcification. The calcification process occurs abruptly. Sometimes histoplasmosis develops - a process of calcification of surrounding tissues.

A connective tissue cyst, which is a benign tumor, develops over a long period of time. Often, not single, but multiple cysts form in the heart cavity. In this case, blood circulation, lymph flow and tissue fluid are sharply disrupted. Characteristic symptoms of the development of a cyst in the pericardium are shortness of breath, severe edema, and cyanosis.

They can be detected during an X-ray examination or during an ultrasound of the heart. Symptoms of cyst development usually include severe pain in the heart area, as well as a sharp disruption of blood circulation, including coronary circulation, which ensures the blood exchange of the heart. Often, when a cyst forms, the body's sensitization and allergization increase. Thus, eosinophilia is observed in the blood. Pleurisy and polyarthralgia often act as concomitant pathologies. Treatment of cysts is exclusively surgical intervention, surgical methods. Medication methods of treatment are not provided. It should be noted that only a single cyst can be removed. With multiple cysts, such an operation is not possible.