Pericarditis is considered chronic if it lasts longer than 6 months. There are two main types of chronic pericarditis.
In chronic effusive pericarditis, fluid slowly accumulates in the pericardial space, between the two layers of the pericardium.
Chronic constrictive pericarditis, which is rare, usually results when scarlike (fibrous) tissue forms throughout the pericardium. The fibrous tissue tends to contract over the years, compressing the heart. The compression prevents the heart from filling normally and causes a form of heart failure. However, because of the compression, the heart does not enlarge as it does in most types of heart failure. Because higher pressure is needed to fill the compressed heart, pressure in the veins that return blood to the heart increases. As a result of the increased venous pressure, fluid leaks out and accumulates in other areas of the body, such as under the skin. Occasionally, constrictive pericarditis occurs more quickly (for example, within a few weeks after heart surgery) and is considered subacute.
Usually, the cause of chronic effusive pericarditis is unknown. However, it may be caused by cancer, tuberculosis, or an underactive thyroid gland (hypothyroidism), and it occasionally occurs in people with chronic kidney disease.
Usually, the cause of chronic constrictive pericarditis is also unknown. The most common known causes are viral infections, radiation therapy for breast cancer or lymphoma in the chest, and heart surgery. Chronic constrictive pericarditis may also result from any condition that causes acute pericarditis, such as rheumatoid arthritis, systemic lupus erythematosus (lupus), a previous injury, or a bacterial infection.
Previously, tuberculosis was the most common cause of chronic pericarditis in the United States, but today tuberculosis accounts for only 2% of cases. In Africa and India, tuberculosis is still the most common cause of all forms of pericarditis.
Shortness of breath and coughing occur because the high pressure in the veins of the lungs forces fluid into the air sacs.
Fatigue occurs because the abnormal pericardium interferes with the heart's pumping action, so that the heart cannot pump enough blood to meet the body's needs.
Other common symptoms are accumulation of fluid in the abdomen (ascites) and in the legs (edema). Sometimes fluid accumulates in the space between the two layers of the pleura, the membranes covering the lungs (a condition called pleural effusion). However, chronic pericarditis does not usually cause pain.
Sometimes the inflammation occurs without symptoms.
Chronic effusive pericarditis may cause few symptoms if fluid accumulates slowly. When fluid accumulates slowly, the pericardium can stretch gradually, so that symptoms caused by severe pressure on the heart (cardiac tamponade) may not develop. However, if fluid accumulates rapidly, or the pericardium is not able to stretch sufficiently, the heart can become compressed and cardiac tamponade may occur.
Symptoms provide important clues that a person has chronic pericarditis, particularly if there is no other reason for reduced heart performance—such as high blood pressure, coronary artery disease, cardiomyopathy, or a heart valve disorder.
Echocardiography is often done. It can detect the amount of fluid in the pericardial space and the formation of fibrous tissue around the heart. It can also confirm the presence of cardiac tamponade and suggest the presence of constrictive pericarditis.
Chest x-ray may detect calcium deposits in the pericardium. These deposits develop in nearly half of the people who have chronic constrictive pericarditis.
The diagnosis can be confirmed in one of two ways.
Cardiac catheterization can be used to measure blood pressure in the heart chambers and major blood vessels. These measurements help doctors distinguish chronic pericarditis from similar disorders.
Magnetic resonance imaging (MRI) or computed tomography (CT) can be used to determine the thickness of the pericardium. Normally, the pericardium is less than 1/8 inch (3 millimeters) thick, but in chronic constrictive pericarditis, it is usually about one fifth of an inch (5 millimeters) thick or more.
A biopsy may be done to help determine the cause of chronic pericarditis—for example, tuberculosis. A small sample of the pericardium is removed during exploratory surgery and examined under a microscope. Alternatively, a sample can be removed using a pericardioscope (a fiberoptic tube used to view the pericardium and to obtain tissue samples) inserted through an incision in the chest.
Laboratory tests on samples of blood and fluid from the pericardium may also be needed to help determine the cause of pericarditis.
Known causes of chronic effusive pericarditis are treated when possible. If heart function is normal, doctors take a wait-and-see approach.
For people with chronic constrictive pericarditis, restriction of salt in the diet and diuretics (drugs that increase the excretion of fluid) may relieve symptoms.
The only possible cure for chronic constrictive pericarditis is surgical removal of the pericardium. Surgery cures about 85% of people. However, because the risk of death from surgery is 5 to 15% (and is higher in people who have severe heart failure), most people do not have surgery unless the disease substantially interferes with daily activities.
Doctors usually wait until symptoms are severe—but before symptoms are so severe that they occur while the person is resting—to do the surgery. Restricting salt in the diet and taking diuretics can control the condition for months or even years and may be the only treatment required if constrictive pericarditis is subacute (for example, occurs after heart surgery).