The\xa0pericardium, also called\xa0pericardial\xa0sac, is a double-walled sac containing the heart and the roots of the great vessels. The\xa0pericardial\xa0sac has two layers, a serous layer and a fibrous layer. It encloses the\xa0pericardial\xa0cavity which contains\xa0pericardial\xa0fluid.\xa0The\xa0pericardium\xa0is a thin sac that surrounds your heart. It protects and lubricates your heart and keeps it in place within your chest. Problems can occur when the\xa0pericardium\xa0becomes inflamed or fills with fluid. The swelling can damage your heart and affect\xa0its function.\xa0The pericardium is composed of three membranous layers that encircle the exterior of the heart: the outer\xa0fibrous pericardium, the middle parietal pericardium, and the inner epicardium (also referred to as the visceral pericardium).