PERICARDIAL EFFUSION

About the Diagnosis

Pericardial effusion refers to an accumulation of fluid around the heart, within the pericardium. The pericardium is a membranous sac that surrounds the heart. When fluid accumulates slowly, the pericardium stretches and enlarges to accommodate the fluid. More rapid accumulation can cause significant symptoms, even with relatively small amounts of fluid. The presence of the fluid causes problems because the fluid compresses the heart. During each heart cycle, there is a phase when the heart muscle relaxes; this allows the chambers to expand and fill with blood. Pressure due to pericardial effusion interferes with normal expansion of the heart. Less blood fills the heart, and therefore, less blood can be pumped to the body with each heartbeat. When pressure due to the effusion rises to the point that delivery of blood to the body is severely compromised, a condition called cardiac tamponade develops. Severe cardiac tamponade is a life-threatening condition.

Pericardial effusion is more common in older, large breed dogs. Golden retrievers are more often affected than other breeds. Cats can also develop pericardial effusions, but effusions severe enough to cause symptoms are relatively uncommon. A variety of conditions can cause pericardial effusions. Tumors of the heart, such as hemangiosarcomas or heart base tumors, tumors of the pericardium (mesotheliomas), infections, congestive heart failure, and foreign bodies can all cause accumulation of fluid within the pericardium. Trauma to the heart, rupture of the heart, or coagulation disorders (bleeding tendencies) can allow leakage of blood around the heart. Sometimes no cause can be discovered; this is called idiopathic pericardial effusion. In cats, pericardial effusion may be caused by congestive heart failure, feline infectious peritonitis infection, and tumors, particularly lymphosarcoma.

Symptoms: Symptoms can vary considerably but often include lethargy, breathing difficulty, poor appetite, episodes of collapse or fainting, and distention of the belly. In addition, your veterinarian may find muffled heart sounds when listening to the heart with a stethoscope, weak pulses, pale gums, and distention of the jugular veins on physical examination.

Diagnosis: On x-rays, the heart will commonly appear enlarged, with a round shape to the heart shadow or cardiac silhouette. Echocardiography (ultrasound examination of the heart) is the most definitive test. The fluid-filled area between the heart and pericardium can be visualized. If a tumor is present, it may be seen as well, although even large volumes of pericardial effusion can be produced by some tumors that are initially too small to be seen on ultrasound. Depending upon your pet's visible symptoms and the veterinarian's findings, additional tests may be indicated, such as electrocardiograms, blood clotting profiles, and tests for infectious diseases. A routine set of lab tests including complete blood count, biochemistry profile, and urinalysis will also be run; although these tests will often be normal, some diseases causing pericardial effusion will result in abnormalities.

Living with the Diagnosis

Prognosis for pericardial effusion depends upon the underlying cause. Some conditions, such as inoperable tumors, are incurable, and treatment is designed to extend life and keep the pet comfortable. Other underlying causes may be correctable, such as foreign bodies or coagulation disorders.

Treatment

If cardiac tamponade is present, the fluid must be drained by a procedure call pericardiocentesis. Using local anesthetic, a catheter is passed between the ribs into the pericardial sac, and the fluid is drawn off. Alleviating the fluid accumulation that presses on the heart will rapidly stabilize a pet's circulation and cardiovascular status. Treatment then depends upon the cause of the condition. If the underlying condition cannot be corrected, sometimes a procedure called pericardiectomy is performed. This is a surgery of the chest in which the pericardial sac is opened and partially removed, allowing the fluid to drain into the chest rather than building up around the heart. It is not a cure, but it does prevent the recurrence of cardiac tamponade (see above). In the case of an inoperable heart tumor, this treatment can extend the pet's life. With reoccurring idiopathic pericardial effusion, pericardiectomy can control the problem indefinitely.

DOs

• Understand that the initial symptoms can be vague and that the most accurate diagnosis requires cardiac ultrasound.

• Give all medications exactly as instructed.

When to Call Your Veterinarian

• Have your pet reexamined immediately if any signs reoccur after initial treatment.

Signs to Watch For

• Lethargy, weakness, and exercise intolerance.
• Poor appetite.
• Breathing difficulty.
• Collapse or fainting spells.
• Abdominal swelling.

Routine Follow-Up

• Monitoring depends upon the cause of the pericardial effusion. Follow-up echocardiograms will be scheduled within 2 weeks and then periodically to monitor for reoccurrence in cases of idiopathic pericardial effusion.