What is pericardial effusion (PE)?

Pericardial effusion is fluid accumulation around the heart. The heart is enclosed within a protective sac within the chest (the pericardium). Several disease processes can cause fluid to build up in the pericardium. If this occurs, the extra pressure in the sac makes it hard for the heart to fill up with blood. This can cause symptoms of poor forward blood flow such as weakness, lethargy, stumbling or fainting. It can also cause back-up of blood behind the heart which causes fluid to accumulate around the lungs or in the abdomen. This may result in trouble breathing or abdominal distension. PE can be life-threatening.

Pericardial effusion is unfortunately usually due to cancer. The most commonly diagnosed cancer types include hemangiosarcoma (HSA), mesothelioma, and chemodectoma. Hemangiosarcoma is an aggressive cancer that rapidly metastasizes (spreads to other parts of the body) and has a poor prognosis even with therapy, and most patients have only weeks to months of good quality life. Hemangiosarcoma usually affects a specific part of the heart (right atrium), and since it grows rapidly it is usually detectable with echocardiography (heart ultrasound) within weeks to months of an episode of PE. Mesothelioma is a cancer of the cells lining the pericardial sac, and therefore is not visible as a discrete tumor on echocardiography. Diagnosis of mesothelioma can be difficult, and even biopsy of the pericardium may not detect it. Patients with mesothelioma can live months to years with good quality of life, though it may metastasize and recurrence of PE is possible life-long. Chemodectomas are tumors that arise from the base of the heart and are typically easily seen with echocardiography. They are slow-growing and patients with chemodectomas can live months to years with good quality of life, though recurrence of PE is possible life-long. If chemodectomas grow very large they may also cause compression of the heart making it harder to fill and beat appropriately.

Pericardial effusion may also be idiopathic. This means that despite diagnostic tests, a cause cannot be found. It can be very difficult to distinguish idiopathic effusion from mesothelioma. Patients with idiopathic effusion may or may not experience recurrence of PE.

What are treatment options for PE?

Regardless of the underlying cause, if there is a significant amount of PE it must be removed with a needle to relieve the pressure on the heart and allow it to fill. If a patient has had PE once, they are at risk for having it happen again, and careful monitoring for recurring symptoms is recommended.

If PE reoccurs frequently, your doctor may recommend a procedure called a pericardiectomy. This is a surgery to remove a portion of the sac around the heart. The purpose of this surgery is to allow drainage of any fluid that occurs and remove the risk of life-threatening PE. If fluid does develop, it instead drains out and distributes around the lungs. This space is larger, and many dogs tolerate small amounts of fluid without symptoms. In some cases, pericardiectomy is curative while in others it is palliative. If a large amount of fluid builds up, it may need to be drained with a needle. If your doctor suspects mesothelioma, placement of a chest tube may be recommended at the time of surgery to facilitate periodic drainage of large amounts of fluid long-term. Also, local chemotherapy may sometimes be given through these tubes.

Pericardiectomy sometimes requires open-chest surgery, and in other cases can be done with minimally invasive techniques. Your doctor will help you determine the best option for your pet on an individual basis.