Epicardium

The heart consists of different layers. The outermost layer of the heart wall is the epicardium (outer skin of the heart). The epicardium is firmly attached to the underlying myocardium (heart muscle tissue).

Structure/Histology

To understand the entire structure of the layers, it is best to take another look at the entire heart. On the very inside is the endocardium, above it the thickest layer, the muscle layer (myocardium). The epicardium lies on top of this layer as a “coating”.

The entire heart is again covered by the pericardium, the pericardium, which consists of two leaves, the inner and the outer. The epicardium (outermost layer of the heart) is also the inner leaf of the pericardium (pericardium), which is also called the lamina visceralis. The outer leaf of the pericardium is the lamina parietalis.

Between the epicardium/visceral lamina and the parietal lamina there is a narrow gap, the pericardial cavity, which contains a film of fluid. The epicard/visceral lamina can itself be divided into two layers. The outermost layer facing the gap is the mesothelium.

Below this is the subserosa. It is very narrow and consists of connective tissue. Below this is the epicardial fatty tissue, where the initial part of the coronary vessels is located.

Function

The epicardium can produce the so-called liquor pericardium, which forms the fluid in the gap (cavitas pericardii) between the epicardium and the adjacent leaf of the pericardium. It is a serous fluid. The amount of pericardial CSF is about 10-12 ml. Its function is to reduce friction between the two leaves of the pericardium during cardiac activity. The epicardium is thus partly responsible for the good mobility of the heart in relation to its surroundings.

Diseases

If the small amount of liquor pericardii in the pericardial gap is exceeded, this is called pericardial effusion. This can occur in the context of pericarditis or perimyocarditis. The more fluid that accumulates, the more likely it is that the heart’s pumping function will be impaired, as the heart is no longer able to expand properly and thus fill.

In the case of large pericardial effusions, breathing difficulties (dyspnoea) are felt. If the pericardium is tamponaded, fluid accumulation can occur as early as 100-200ml. Pericardial effusion can be diagnosed by sonography. A pericardial puncture provides relief.