What it is
What it does
Who gets it?
How do we look at it?
What do we do about it?
What’s going to happen?
Pericardial Effusion is a disease seen mostly in large breed dogs, and also affects smaller dogs, and very rarely cats. Pericardial effusion is a disease where fluid accumulates in the heart sac around the heart.
In order to understand how the fluid in the heart sac affects your pet, a brief synopsis of normal blood flow is helpful. Normally, blood is ejected from the main pumping chamber of the heart (the left ventricle) into the aorta and then to the body. Blood returns from the body to the right heart (first the right atrium, through the tricuspid valve and into the right ventricle) where it is pumped into the pulmonary artery and into the lungs for oxygenation. Blood from the lungs then returns to the left heart (into the left atrium, through the mitral valve and back into the left ventricle).
As fluid and pressure build up within the sac, the right side of the heart is compressed, and blood cannot get into the right heart. Blood then backs up into body cavities, and also is not pumped forward into the left heart and to the body. Fluid in the body cavities is called right congestive heart failure; fluid in the chest is called pleural effusion, and fluid in the abdomen is called ascites. Animals with pleural effusion breath heavily and cannot exercise, animals with ascites often do not eat well. Animals will also be weak and not eat well or faint with exercise or excitement.
Causes of the fluid in the heart sac are tumors (there are three different common tumors causing fluid in the sac: hemangiosarcoma, aortic body tumor, and mesothelioma), it just occurs for unknown reasons (idiopathic), or infections (bacterial or fungal). Hemangiosarcoma carries a poor prognosis, with some dogs dying within days to weeks (although I have had some animals live for up to eight or nine months with chemotherapy). Aortic body tumors are very slow growing, and these dogs can live for years with this problem (though they may need to have the heart sac removed). About 30% of dogs with idiopathic pericardial effusion will never recur once they have had the fluid removed, about 30% will require multiple fluid removals, and about 30% will require surgery. Mesothelioma is difficult to diagnose, and may not be definitely diagnoses until surgery. Dogs with this disease rarely survive longer than six months, even with chemotherapy.
Therapy is by removing fluid from the heart sac with a long catheter (called pericardiocentesis). Medications are not useful in removing the fluid, and diuretics can make an animal feel even worse. If an animal has a large amount of ascites, diuretics after a pericardiocentesis may be useful. Pericardiocentesis is very safe in the hands of an experienced cardiologist, and complications are rare. Some animals with recurring pericardial effusions require surgery to remove the heart sac. A cardiologist will be able to tell you the risk benefit ration for a given animal.
There are certain diagnostic tests that are necessary to accurately diagnose pericardial effusion, to tell you how bad the problem is, what can be done about the problem, and what you can expect in the future for your pet. An echocardiogram (or heart ultrasound) is used to look within the heart, confirm the diagnosis, and to look for the cause of the effusion. Radiographs show congestive heart failure (pleural effusion), and are often taken prior to an echocardiogram being performed. Radiographs are rarely repeated, since ultrasound is much more sensitive in monitoring the disease. An electrocardiogram (EKG or ECG) may be used to check for rhythm disturbances, and again may be performed prior to the echocardiogram to try to give more evidence of effusion. Labwork is also run to look for other diseases. The fluid may be submitted for analysis, though not in every case.
Monitoring at home consists of monitoring eating and activity, and to note breathing and coughing patterns. Dogs will first start to act lethargic and not want to exercise, and then not want to eat. Fluid in the chest causes increased breathing rates, and breathing rates can increase. Breathing rates in animals can only be accurately assessed when they are asleep and it is cool out (they pant at other times, which cannot be used for accurate determinations). Their sleeping breathing rates should be about 30 breaths a minute or less (about a breath every other second). If congestive heart failure is developing, sleeping breathing rates increase to about 60 breaths a minute (or one breath a second).