Pericardium: Structure, Function & Diseases

The pericardium is a sac of connective tissue that encases the human heart. It also bears the name pericardium.

What is the pericardium?

The pericardium is known as the pericardium, pericardum or cavitas pericardialis. With two layers of tissue, it surrounds the human heart. By providing a narrow layer of lubrication, the double-walled sac ensures that the organ can move. Serous fluid, also known as cerebrospinal fluid pericardii, in an amount of 10 to 15 milliliters serves as the lubricant. While the inner layer of the pericardium is called the visceral leaflet or epicardium, the outer layer is named the parietal pericardium.

Anatomy and structure

Composed, the pericardium is made up of two sections. These are the pericardium fibrosum and the pericardium serosum. The pericardium fibrosum represents the outer layer of the pericardium and is formed from tight connective tissue. At the basal side, there is an adhesion with the diaphragm (diaphragm) and the pleura (pleura). The pericardium serosum is composed of two sheets (laminae). These are the lamina visceralis pericardi, which lies directly on the heart and is also called the epicardium, and the lamina parietalis pericardii. The latter is fused to the pericardium fibrosum. Midway between the two sheets of the pericardium serosum is a cleft space called the pericardial cavity (cavitas pericardii). Approximately 10 to 12 milliliters of CSF pericardii are present in this cavity. The secreted fluid allows friction between the two sheets to be reduced. At the major blood vessels, the pericardial leaflets fold over so that they merge into each other. In this process, the proximal vascular segments are enveloped. Between the turnover sites, there are some hollowed structures or bulges near the vessels. Due to the allocation from the pericardium towards the heart, two spaces are formed in the pericardium: the transverse pericardial sinus and the oblique pericardial sinus. The transverse pericardial sinus separates the outgoing blood vessels, such as the pulmonary trunk and aorta, from the pulmonary veins, vena cava, and inferior vena cava, which are the feeding vessels. The oblique pericardial sinus is located between the pulmonary veins, which run toward the heart. Sensory innervation of the pericardium is provided by the small branches of the phrenic and vagus nerves. They are also referred to as the rami pericardiaci.

Function and Tasks

The functions and tasks of the pericardium are many. For example, it provides stable support for the organ in its position through the strong connections that exist on the heart as well as the diaphragm. In this way, important chest structures such as the large blood vessels, the sternum and the space between the lungs can always be in the same position relative to the heart. At the same time, the pericardium separates the heart from other chest cavity organs. The connective tissue structure of the pericardium, which can hardly be stretched, prevents the heart from overstretching during severe physical exertion. If fluctuations in ejection occur due to changes in blood pressure or respiration, the fixation of the pericardium causes an equalization of ejection between the left and right ventricles. The narrow connection between the pericardium and epicardium in the form of a narrow gap also has its benefits. Thus, in the event of heart failure, stretching of the cardiac muscle fibers is passively maintained. The fluid within the pericardial cavity has the function of reducing frictional resistance toward the heart. Basically, the pericardium serves as a displacement layer. Thus, on the one hand, it surrounds the heart for protection and, on the other hand, it provides for the contraction and expansion of the heart muscle (myocardium).

Diseases

The human pericardium can be affected by various diseases. First and foremost among these is pericarditis. Its causes are manifold. In most cases, it is caused by viruses such as adenoviruses, coxsackie viruses or echoviruses. However, in some patients, pericarditis is the result of another disease. Metabolic, autoimmune, pulmonary or renal diseases are usually considered. Inflammation of the pericardium is usually manifested by stabbing pain in the area of the sternum and increased body temperature.If the patient moves, takes a deep breath or coughs, this often leads to an increase in pain. In the further course of pericarditis, the development of a pericardial effusion is also possible. Pericarditis causes fluid to accumulate within the pericardium. If the fluid exceeds a certain amount, this can negatively affect the actions of the heart. Therefore, in the case of larger effusions, puncture is required for treatment. The therapy of pericarditis depends on the triggering causes. In addition to viruses, bacteria are also among the most common originators. Most patients receive anti-inflammatory preparations and painkillers for pericarditis caused by an infection. However, the administration of ACE inhibitors to combat heart failure and diuretics for drainage is also possible. In the case of secondary forms, the focus is on treating the underlying disease in question. Dressler’s syndrome, also known as postmyocardial syndrome, is another possible disease of the pericardium. It occurs after a heart attack and is accompanied by anginal pain. In most cases, the affected person also suffers from changes in the blood count, fever, and pericardial effusion. In very rare cases, a tumor of the pericardium may also occur.

Typical and common heart diseases

  • Heart attack
  • Pericarditis
  • Heart failure
  • Atrial fibrillation
  • Heart muscle inflammation