Pericardial Effusion (Fluid Around the Heart)

What pericardial effusion is

The pericardium is a two-layered sac around the heart. Between the layers is a small amount of lubricating fluid, about 15 to 50 ml, which lets the heart move smoothly as it beats. An effusion forms when the pericardium is inflamed, when fluid drains away too slowly, or when blood or other fluid leaks into the space.

Effusions are described by:

• Size: small (under 10 mm of fluid on echo), moderate (10 to 20 mm) or large (over 20 mm).
• Speed: a slow effusion can stretch the sac and grow to over a liter with few symptoms. A fast one, such as bleeding after injury, can cause tamponade with as little as 100 to 200 ml.
• Type of fluid: watery (transudate), protein-rich and inflammatory (exudate), blood (hemopericardium) or pus (purulent).

Causes

In many cases, especially small effusions in otherwise healthy people, no cause is found.

Symptoms

Small effusions usually cause no symptoms. As fluid accumulates, symptoms may include:

• Shortness of breath, especially lying flat or with exertion
• Chest pressure or fullness; sharp chest pain if pericarditis is present
• Fatigue and lightheadedness
• Cough, hoarseness or hiccups from pressure on nearby structures
• Trouble swallowing
• Swelling of the legs or belly
• Fever if infection or inflammation is the cause

Cardiac tamponade

Cardiac tamponade happens when pressure in the sac exceeds the pressure inside the heart's chambers, so the heart cannot fill and blood pressure falls. Classic signs are low blood pressure, swollen neck veins and muffled heart sounds (Beck's triad), along with a fast heart rate, breathlessness and a drop in blood pressure of more than 10 mm Hg on breathing in (pulsus paradoxus). Tamponade is fatal without urgent drainage.

Diagnosis

• Echocardiogram: the key test. It shows the size and location of the fluid and whether it is compressing the heart.
• ECG: may show low voltage or beat-to-beat changes in the size of the complexes (electrical alternans) in large effusions, or changes of pericarditis.
• Chest X-ray: an enlarged "water bottle" heart shadow with large effusions.
• CT or MRI: to look at pericardial thickening, cancer or loculated (pocketed) fluid.
• Blood tests: inflammation markers, kidney and thyroid function, blood count, autoimmune tests, troponin, and TB testing when relevant.
• Fluid analysis: fluid removed by drainage is tested for cells, infection, TB and cancer.

Treatment

Small effusions without symptoms

Often no treatment beyond addressing the cause, with a repeat echo to check the size. Many small idiopathic effusions stay stable or disappear.

Treat the underlying cause

• Pericarditis: high-dose NSAIDs or aspirin plus colchicine, under a doctor's guidance. Steroids in selected cases.
• Kidney failure: more intensive dialysis.
• Hypothyroidism: thyroid hormone replacement.
• Infection: antibiotics or TB treatment, plus drainage for pus.
• Cancer: chemotherapy or other treatment for the tumor.

Drainage

• Pericardiocentesis: a needle guided by echo is passed under the breastbone into the sac and a thin drain left in for a day or two. It is the emergency treatment for tamponade and also gives fluid for testing.
• Pericardial window: surgery to cut an opening in the sac so fluid drains into the chest or belly. Used for recurring effusions, often due to cancer.
• Pericardiectomy: removal of part of the pericardium for recurrent or constrictive disease.

Outlook

The outlook depends mostly on the cause. Effusions from viral pericarditis or after surgery usually resolve completely. Large chronic idiopathic effusions carry a small risk of later tamponade and need follow-up. Effusions caused by advanced cancer often recur and reflect a more serious prognosis.

Frequently asked questions

Is a pericardial effusion serious?

It can range from harmless to life-threatening. Small effusions found by chance are often benign and need only monitoring. Large or rapidly growing effusions can cause cardiac tamponade, which needs emergency drainage. The underlying cause, such as infection or cancer, also determines how serious it is.

What is the most common cause of fluid around the heart?

In developed countries, the most common causes are idiopathic or viral pericarditis, cancer, and effusions after heart surgery. Kidney failure, autoimmune diseases and hypothyroidism are also common. Worldwide, tuberculosis is a leading cause, especially in people with HIV.

Can a pericardial effusion go away on its own?

Yes, many do, especially small effusions and those from viral pericarditis or after heart surgery, often within weeks. Treating the cause, such as an underactive thyroid or kidney failure, also clears the fluid. Doctors usually repeat the echocardiogram to confirm it is shrinking.

How is a pericardial effusion drained?

The usual method is pericardiocentesis. Under local anesthetic, a doctor uses ultrasound to guide a needle beneath the breastbone into the sac and leaves a thin tube to drain fluid for a day or two. Recurrent effusions may need a small operation to create a permanent drainage window.

What does a small pericardial effusion mean?

A small effusion means there is slightly more fluid than normal around the heart. It is often found on an echo done for another reason and causes no symptoms. Your doctor will look for a cause, such as recent infection or thyroid or kidney problems, and may repeat the scan.