The pericardium is a sac which surrounds the heart and is filled with a viscous fluid that lubricates the outside of the heart to allow for efficient contractions. After a bout of pericarditis (inflammation of the pericardium caused by infection, autoimmune disorders, open heart surgery, etc.), the pericardium becomes thickened and can adhere to the outer surface of the heart. When this is severe, constrictive pericarditis develops which is manifest as right heart failure. In right heart failure, blood backs up into the liver causing abdominal fluid retention and distension, elevated venous pressure, and shortness of breath. Right heart failure results because blood returning to the right side of the heart does not sufficiently empty into the heart since the thickened pericardium constrains the right ventricle from expanding enough to receive the venous blood. A complete pericardiectomy can be done by a cardiac surgeon who would manually strip the entire pericardium off the outer surface of the heart. This is a major surgery however, and can be difficult to perform since the pericardium may be densely adhered to the outer surface of the heart.