PERICARDITIS

inflammation of the pericardium, the membranous sac that encloses the heart. Acute pericarditis may be associated with any of a number of diseases and conditions, including myocardial infarction (death of a section of heart muscle), uremia (abnormally high levels of urea and other nitrogenous waste products in the blood), allergic disorders, and infections. The pericardial infection may be syphilis, rheumatic heart disease, tuberculosis, or some other bacterial infection. It may be viral or protozoal; the protozoal organism that causes amebic dysentery, for example, may escape from a liver abscess and invade the pericardium. The infection, finally, may be fungal-infection, for example, with Histoplasma capsulatum. A person with infectious pericarditis experiences pain over the heart, neck, and shoulder. The pain is sometimes increased during breathing and is relieved by leaning forward. Lying down may accentuate the pain, which may radiate to the left arm, the shoulder, and the neck. The affected person may experience difficulty in breathing and may be weak, anxious, and depressed. His skin may be pale or bluish, and he may be feverish and delirious. The tracings of the heart's electrical activity are characteristic, and X rays may show accumulation of fluid in the pericardial sac. A rapid increase of pericardial fluid, called cardiac tamponade, may cause shock. Treatment involves slowly draining the fluid and combating the underlying infection. Acute pericarditis may result in the formation of scar tissue that contracts around the heart and interferes with its operation. This condition, called chronic constrictive pericarditis, is corrected by surgical removal of the pericardium.