cardiac surgery, we measured mean pericardial surface pressure over the lateral . pericardial sac. . volume relationship during the first several beats after. The pericardium is a double-walled sac containing the heart and the roots of the great vessels. Here we can see its relation to the superior mediastinum a, the pleural cavities c, and the diaphragm e. organs (such as lungs); Prevents excessive dilation of the heart in cases of acute volume overload; Lubricates the heart. It is enclosed by the pericardial sac and contains the heart (Figure ). in the RV pressure or volume (e.g., severe pulmonic regurgitation or cor pulmonale) or in Searls () ascribed the relationship between the pericardial and pleural .
The pericardial fluid is a product of ultrafiltration and is considered to be drained by lymphatic capillary bed mainly.
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Under normal conditions it provides lubrication during heart beating while the mesothelial cells that line the membrane may also have a role in the absorption of the pericardial fluid along with the pericardial lymphatics.
Here, we provide a review of the the current literature regarding the physiology of the pericardial space and the regulation of pericardial fluid turnover and highlight the areas that need to be further investigated.
It is a fibrous—serosal conical sac enclosing the roots of the aorta and the pulmonary artery Chinchoy, In humans, pericardium is located inside the middle mediastinum posteriorly to the sternum and the cartilages of the third to seventh left rib. Normally, it is not in contact with the frontal wall of the thoracic cavity Frick et al.
Laterally, it is held together with the mediastinal parietal pleura. Pericardium isolates the heart from the adjacent tissues, allowing it's free movement within the boundaries of the pericardial cavity and is filled with a small amount of fluid which is called pericardial fluid Chinchoy, Anatomy and histology The pericardium consists of an external sac of fibrous connective tissue, called fibrous pericardium and an internal called serous pericardium.
The latter coats the internal surface of the fibrous pericardium and the heart. Arterial branches from thoracic aorta, right and left pericardiophrenic artery internal mammary artery branchesare responsible for the blood supply of the whole pericardium while the venous drainage is accomplished through the venae pericardiales which drain to the azygos vein, to the superior vena cava or to the brachiocephalic Chinchoy, The pericardium is innervated by the two phrenic nerves, each one giving an afferent branch pericardial branch Randall and Ardell, ; Ardell and Randall, ; Chiou et al.
The thickness of the pericardium increases proportionally to the size of the heart and the pericardial cavity, with the exception of humans who have considerably thicker pericardium compared to the mammals with the same heart size human 1—3. The serous pericardial membrane covers the outside of the heart visceral pericardiumextending a short distance beyond the atria and ventricles on the great vessels and lines the inside of the fibrous sac parietal pericardium.
The parietal lamina of the serous pericardium is composed of a monolayer of flattened, squamous-like, mesothelial cells.
Mesothelial cells rest on a thin basement membrane supported by connective tissue stroma in a narrow submesothelial space. The connective tissue stroma contains variously oriented layers of collagen fibrils and small elastic fibers Ishihara et al. The luminal surface of the mesothelial cells has well developed microvillous border with occasional cilia.
The latter bear friction and increase the surface area for fluid transport. There are junctional complexes between adjacent mesothelial cells that consist of desmosomes, which reinforce intercellular adhesion and zonulae occludentes. All of these morphological characteristics form permeability barriers.
Actin-like filaments are present in microvilli and in immediate subjacent regions of the cells. These filaments mediate changes on cell shape. Intermediate filaments are associated with desmosomes and form bundles in the perinuclear regions, which provide structural support to the cytoplasm Ishihara et al. Between the mesothelial cells of the parietal pericardium, not the epicardium, there are milky spots, similar to those in the omentum and mediastinal pleura, bulging toward the pericardial cavity.
These structures are enclosed with cuboidal mesothelial cells Takada et al. These openings provide direct access to the underlying submesothelial lymphatic system allowing rapid removal of fluid and cells from the pericardial cavity Takada et al.
Inside the pericardial cavity and submesothelial layers of the pericardium, there are resident macrophages, readily available in case of immunological response Ishihara et al. Both their stomata and lumen are covered with mesothelial cells and below them elastin and collagen fibers Fukuo et al.
The epicardium has common morphological features with the parietal pericardium but there are some functional differences. The proportion of cuboidal cells is greater in the epicardium than in the parietal pericardium Michailova and Usunoff, Underneath the basal membrane there is a dense network of collagen and elastic fibers, full of hydroxyproline, which embryologically stems from extracardiac tissue and doesn't infiltrate the underlying myocardium.
The fibers are parallel to each other, in multiple layers and crossing the heart surface from diagonally to vertically, compared to the myocardial cells Simionescu et al. When the visceral layer of serous pericardium comes into contact with heart not the great vessels it is known as the epicardium.
Pericardium - Wikipedia
The epicardium is the layer immediately outside of the heart muscle proper the myocardium. During ventricular contraction, the wave of depolarization moves from the endocardial to the epicardial surface. Anatomical relationships[ edit ] A transverse section of the thoraxshowing the contents of the middle and the posterior mediastinum.
The pleural cavity and the pericardial cavity are exaggerated since normally there is no space between the pleurae or between the pericardium and heart. Pericardium is also known as cardiac epidermis. The pericardial cavity in this image is labeled d and is part of the inferior mediastium. Here we can see its relation to the superior mediastinum a, the pleural cavities c, and the diaphragm e. Surrounds heart and bases of pulmonary artery and aorta. Deep to sternum and anterior chest wall.
The right phrenic nerve passes to the right of the pericardium. The left phrenic nerve passes over the pericardium of the left ventricle. Pericardial arteries supply blood to the dorsal portion of the pericardium. Sets heart in mediastinum and limits its motion Protects it from infections coming from other organs such as lungs Prevents excessive dilation of the heart in cases of acute volume overload Lubricates the heart Clinical significance[ edit ] Inflammation of the pericardium is called pericarditis.
This condition typically causes chest pain that spreads to the back that is worsened by lying flat.