The endocardium, the innermost layer of the heart, is constantly in contact with the blood flowing through it.

The heart is made up of different layers. The innermost layer is the endocardium. As the innermost layer, it comes into direct contact with the blood flowing through the heart. On the endocardium (from the inside to the outside) lie the myocardium (the heart muscle layer) and the epicardium (the outer skin of the heart). The pericardium, known as the pericardium, is on the outside and surrounds the entire heart.

Structure / histology

The endocardium is also divided into different layers. It's about 0.5 to 1.0 millimeters thick. From the inside out, the layers consist of that of the innermost layer, the Endothelium. The endothelium is a continuous, monolayer squamous epitheliumwhich forms the smooth surface of the inner lining of the heart. It's on her Subendothelial stratumwhich from loose connective tissue, in which elastic fibers are embedded, consists. That follows Stratium myoelasticumwhich from smooth muscles and Collagen fibers consists. There are also some here Blood vessels and Nerve fibers. The outermost layer of the endocardium is the Tela subendocardialewho the Connection to the myocardium (Heart muscle tissue) maintains. It also consists of loose connective tissue.


The endocardium clothes the whole heart, that means the Chambers of the heart as well as the Papillary muscles and Tendon threads from within. It also forms the four heart valves(Aortic valve, pulmonary valve, mitral valve, tricuspid valve) that in a sense Duplicates of the endocardium are. The heart valves are in turn suspended from the heart skeleton.

Since the endocardium is a very smooth surface represents, thereby becomes the proper and efficient blood flow in the heart promoted. The formation of Thrombi (= Accumulation of blood platelets) is thus prevented. As soon as the surface of the endocardium shows small bumps, for example by a Endocarditis can arise is that Risk of thrombus increasedwhich one Heart attack can trigger.

Blood supply

The endocardium itself hardly has its own blood vesselssince it is from the bloodwhich by the heart, flows is also supplied. However, there is still one subendocardial capillary networkthat helps.


The inflammation of the inner lining of the heart is called endocarditis. If left untreated, this disease is usually fatal, but is nowadays easily treatable with antibiotics. Other diseases are Löffler's endocarditis and endomyocardial fibrosis.

Learn more about: Endocarditis prophylaxis


To display the endocardium, Echocardiography used. With that you can especially examine the heart valves very well.