The pericardium is a membrane that covers the heart. It consists of two layers: a visceral layer (epicardium), tightly adhered to the heart muscle, and an outer parietal layer. Between these two membranes is a space, the pericardial space, which normally contains a small amount of fluid. The pericardium is not elastic and does not distend easily. When excessive fluid accumulates within the pericardial space, the heart loses its ability to beat normally and serious illness can occur.

Several illnesses can affect the pericardium. These include peritoneopericardial diaphragmatic hernia, pericardial effusion, and constrictive pericardial disease.

Peritoneopericardial Diaphragmatic Hernia

This type of hernia is present at birth and is more common in cats than dogs. Affected cats are born with an abnormality of the diaphragm that allows the abdominal contents to slip into the pericardium. In cats, the hernia often only contains fat and liver lobes. In dogs, the hernia often contains loops of intestine.

Pericardial Effusion

Pericardial effusion refers to an abnormal amount of fluid accumulating within the pericardial space. Different types of fluid, including clear fluid, pus, or blood may accumulate. As fluid accumulates, the heart's action is restricted by building pressure in the pericardial space since the pericardial sac is unable to distend. Eventually, the heart is unable to adequately pump blood to the body and the cat collapses. Without emergency treatment, death is imminent.

Constrictive Pericardial Disease

Pericardial constriction most often develops secondary to chronic inflammation, particularly from infective processes within the pericardium, or recurrent hemorrhage. Rarely, the pericardium may accumulate calcium deposits. With chronic inflammation, the pericardial space can become obliterated and the heart encased in a rigid, poorly expansive sac. As the fluid is reabsorbed, the pericardium scars and contracts, and consequently the chambers of the heart become constricted and cannot expand effectively. This condition limits the heart's ability to pump blood and can lead to right-sided heart failure.

What to Watch For

Weakness

Collapse

Difficulty breathing

Pale gums

Lack of appetite

Diagnosis

Blood work is often performed to determine the overall health of the cat. Usually, the blood work is normal, but some cat may be found anemic or to have other abnormalities.

Chest radiographs (X-rays) are performed to determine the size and shape of the heart.

Ultrasound of the heart (echocardiogram) is performed both to confirm pericardial disease and to determine the type.

Treatment

Treatment varies depending on the type of pericardial disease.

Peritoneopericardial diaphragmatic hernia is often an incidental finding and usually does not cause the cat to be ill. In such cases, the cat is simply observed for signs of illness. For cats that have clinical signs of disease associated with peritoneopericardial diaphragmatic hernia, surgery is the only treatment.

Pericardial effusion is treated by removing the fluid that has accumulated in the pericardial sac and by attempting to treat or remove the cause of the fluid accumulation.

Constrictive pericardial disease is treated by surgical removal of the pericardium.

Home Care and Prevention

There is no home care for pericardial disease. If you suspect that your pet may have pericardial disease, see your veterinarian. Prevention of pericardial disease is difficult and often not possible. Early diagnosis and treatment can help reduce the risk of serious illness.