Pericardium

About the Pericardium

The pericardium is a double walled sac that encloses the heart and the roots of the great vessels. Its tough outer fibrous layer anchors the heart to the diaphragm and sternum and limits sudden overfilling. Inside it, the serous pericardium has two thin layers, the parietal layer lining the fibrous sac and the visceral layer, or epicardium, covering the surface of the heart. Between them lies the pericardial cavity, containing a small amount of lubricating fluid that lets the heart beat with minimal friction. Inflammation of the pericardium, pericarditis, typically causes sharp chest pain that eases when sitting forward and is often due to viral infection. If fluid accumulates rapidly in the sac, it can compress the heart and impair filling, a life threatening condition called cardiac tamponade. Chronic inflammation can cause constrictive pericarditis, in which the sac becomes thickened and stiff.