The pericardium helps keep the heart in position, helps prevent the heart from overfilling with blood, and helps protect the heart from being damaged by chest infections. However, the pericardium is not essential to life. If the pericardium is removed, there is little measurable effect on the heart's performance.
Normally, the pericardium contains just enough lubricating fluid between its two layers for them to slide easily over one another. There is very little space between the two layers. However, in some disorders, extra fluid accumulates in this space (called the pericardial space), causing it to expand.
Rarely, the pericardium is missing at birth or has defects, such as weak spots or holes. These defects can be dangerous because the heart or a major blood vessel may bulge (herniate) through a hole in the pericardium and become trapped. In such cases, death can occur in minutes. Therefore, these defects are usually surgically repaired. If repair is not feasible, the whole pericardium may be removed. Other disorders of the pericardium may result from infections, injuries, drugs, or the spread of cancer.
The most common disorder of the pericardium is inflammation (pericarditis). Pericarditis may be
Acute Acute Pericarditis Acute pericarditis is inflammation of the pericardium (the flexible two-layered sac that envelops the heart) that begins suddenly, is often painful, and causes fluid and blood components such... read more
(inflammation that develops shortly after a triggering event)Subacute (inflammation that develops a few weeks to a few months after a triggering illness)
Other disorders of the pericardium include
Pericardial effusion
Constrictive pericarditis
Fibrosis of the pericardium
Pericardial effusion is accumulation of fluid in the pericardium. Cardiac tamponade Cardiac Tamponade Cardiac tamponade is pressure on the heart by blood or fluid that accumulates in the two-layered sac around the heart (pericardium). This disorder interferes with the heart's ability to pump... read more occurs when a large pericardial effusion prevents the heart from properly filling with blood and therefore prevents the heart from pumping enough blood to the rest of the body.
Constrictive pericarditis Chronic Pericarditis , which is rare, occurs when the fluid that accumulates is thick and fibrous and causes the layers of the pericardium to stick together. Constrictive pericarditis can be transient, for example if it is caused by an infection, or chronic if it occurs after a disorder that causes acute pericarditis.
Fibrosis of the pericardium may follow purulent pericarditis (pericarditis caused by an infection and in which the pericardial effusion is pus-like) or accompany a connective tissue disorder such as rheumatoid arthritis Rheumatoid Arthritis (RA) Rheumatoid arthritis is an inflammatory arthritis in which joints, usually including those of the hands and feet, are inflamed, resulting in swelling, pain, and often destruction of joints.... read more 
. In older patients, common causes are malignant tumors, heart attacks, Acute Coronary Syndromes (Heart Attack; Myocardial Infarction; Unstable Angina) Acute coronary syndromes result from a sudden blockage in a coronary artery. This blockage causes unstable angina or a heart attack (myocardial infarction), depending on the location and amount... read more 
and tuberculosis Tuberculosis (TB) Tuberculosis is a chronic contagious infection caused by the airborne bacteria Mycobacterium tuberculosis. It usually affects the lungs, but almost any organ can be involved. Tuberculosis... read more 
. Fibrosis of the pericardium differs from constrictive pericarditis in that it tends to cause less structural damage and not to impair the heart's pumping function.
Hemopericardium (accumulation of blood within the pericardium) may lead to pericarditis, pericardial fibrosis, or cardiac tamponade. Common causes include chest injury, injury as a result of medical procedures such as cardiac catheterization Cardiac Catheterization and Coronary Angiography Cardiac catheterization and coronary angiography are minimally invasive methods of studying the heart and the blood vessels that supply the heart (coronary arteries) without doing surgery. These... read more 
and pacemaker insertion Artificial Pacemakers There are many causes of abnormal heart rhythms (arrhythmias). Some arrhythmias are harmless and do not need treatment. Sometimes arrhythmias stop on their own or with changes in lifestyle,... read more 
, and rupture of a thoracic aortic aneurysm Thoracic Aortic Aneurysms Thoracic aortic aneurysms are bulges (dilations) in the wall of the aorta in the part that passes through the chest (thorax). Thoracic aortic aneurysms may not cause symptoms, or they may cause... read more 
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