Pericardial effusion occurs when excess fluid accumulates in the pericardium, the protective sac that surrounds the heart. This fluid buildup can put pressure on the heart, making it harder for the heart to pump blood effectively. Some people with pericardial effusion may not have symptoms, especially if the fluid accumulates slowly, but when symptoms are present, they can include chest pain, shortness of breath, fatigue, swelling in the legs or ankles, and fast or irregular heartbeats, among others.

Pericardial effusion becomes more common with age. For example, a large study found that it affects less than 1% of people under 20 and more than 15% of those over 80. Many cases are found by chance on tests done for other reasons, such as an X-ray or ultrasound, and small fluid buildups often do not cause symptoms.

With prompt diagnosis and appropriate care, pericardial effusion can be managed effectively in many patients, depending on its cause.

In healthy people, a small amount of fluid is present in the pericardial space, the area between the two thin layers of tissue (the pericardium) that surround the heart. The fluid acts as a lubricant, allowing the heart to move smoothly as it beats. In pericardial effusion, the amount of fluid increases beyond the normal range, which can interfere with the heart’s ability to function properly.

As fluid builds up in the pericardial space, it can put pressure on the heart, making it harder for the heart to fill and pump blood with each beat. If the fluid accumulates quickly or in large amounts, it can compress the heart chambers, especially the right side of the heart, and limit the amount of blood the heart can pump to the rest of the body. This may cause symptoms such as shortness of breath, chest pain, fatigue, and swelling in the legs. In severe cases, it can lead to cardiac tamponade, a medical emergency in which the heart is unable to pump enough blood to meet the body’s needs.

Pericardial effusion may develop suddenly (acute), over a few days or weeks (subacute), or slowly over months (chronic). The impact on the body depends on how quickly the fluid accumulates and how much fluid is present. Small or slowly developing effusions may cause no symptoms, while larger or rapidly accumulating effusions can be life-threatening if not treated promptly.

Pericardial effusion can have many different causes, and in some cases, the exact cause is not known. When the cause cannot be identified, it is called idiopathic pericardial effusion. In other cases, pericardial effusion develops as a result of another medical condition or event.

Common causes include:

• Inflammation of the pericardium (pericarditis), which can be triggered by infections from viruses, bacteria, fungi, or parasites
• Autoimmune diseases such as lupus, rheumatoid arthritis, and scleroderma
• Cancer, especially lung cancer, breast cancer, and lymphoma, can cause pericardial effusion either by spreading to the pericardium or by causing inflammation
• Injury to the heart or chest (such as from surgery, trauma, or a heart attack)
• Kidney failure
• Hypothyroidism (underactive thyroid)
• Radiation therapy
• Certain medications such as blood thinners, which can increase the risk of bleeding into the pericardial space, leading to a hemorrhagic (bloody) effusion
• Tear in the heart muscle or a major blood vessel, such as the aorta (this is a rare cause)

Risk factors for pericardial effusion include:

• Autoimmune diseases such as lupus, rheumatoid arthritis, and scleroderma
• Cancer, especially lung cancer, breast cancer, lymphoma, and other metastatic cancers
• Recent heart surgery or cardiac procedures
• Heart attack
• Chest trauma or injury
• Kidney failure or uremia (high levels of waste products in the blood)
• Hypothyroidism
• Use of blood thinners (anticoagulants)
• Infections, including viral, bacterial, fungal, or parasitic infections
• Radiation therapy to the chest
• Use of certain medications, such as hydralazine or procainamide
• Aortic dissection (when a tear develops in the inner layer of the wall of the aorta, the blood vessel that carries oxygen-rich blood from the heart to the rest of the body)
• Congestive heart failure (when the heart is unable to pump enough oxygen-rich blood to the body) or pulmonary hypertension (high blood pressure in the pulmonary arteries)
• Immunosuppression, including HIV infection or organ transplantation
• Older age
• Post-cardiac injury syndromes (inflammatory heart conditions that develop after heart injury or surgery)

Some people with pericardial effusion don’t notice any symptoms. When symptoms are present, they may include:

• Chest pain or discomfort
• Shortness of breath
• Fatigue or weakness
• Swelling in the legs or ankles
• Cough
• A feeling of fullness in the chest
• Fast or irregular heartbeats (palpitations)
• Dizziness or lightheadedness
• Fainting
• Fever (especially if infection is present)
• Hoarse voice
• Hiccups
• Anxiety or confusion
• Difficulty breathing when lying flat

To diagnose pericardial effusion, your doctor will review your medical history, conduct a physical exam, and order one or more diagnostic tests.

Your doctor may ask you about your symptoms, such as chest pain, shortness of breath, fatigue, swelling, or recent infections. They may also ask about any history of heart disease, autoimmune conditions, recent surgery or trauma, cancer, kidney or thyroid disease, and use of certain medications, including blood thinners. During the physical exam, your doctor will check for signs such as muffled heart sounds, swelling of the jugular vein in the neck, low blood pressure, rapid or irregular breathing, and difficulty breathing.

Additional tests are necessary to make a diagnosis. They may include the following:

• Transthoracic echocardiogram (TTE): This ultrasound test is the primary tool for diagnosing pericardial effusion. It shows the presence, size, and location of fluid around the heart and can help detect signs of pressure on the heart.
• Electrocardiogram (ECG or EKG): This test records the electrical activity of the heart and can show changes that suggest pericardial effusion or pericarditis.
• Chest X-ray: This imaging test can reveal an enlarged heart silhouette if a large amount of fluid is present, but it is less sensitive for small effusions.
• Computed tomography (CT) scan: A CT scan provides detailed images of the heart and surrounding structures, helping to identify the amount and location of fluid, as well as possible causes such as tumors or aortic dissection.
• Magnetic resonance imaging (MRI): MRI offers detailed pictures of the heart and pericardium and can help distinguish between different types of fluid and identify inflammation or masses.
• Blood tests: These may be used to look for signs of infection, inflammation, kidney or thyroid problems, or markers of autoimmune disease.
• Pericardiocentesis (fluid sampling): In some cases, a sample of the fluid from the pericardium may be removed with a needle for laboratory analysis to check for infection, cancer cells, or other causes.
  

Treatment for pericardial effusion depends on the cause, the amount of fluid, and the severity of symptoms. Some small effusions that do not cause symptoms may only require monitoring, while larger effusions or effusions that cause symptoms may need urgent intervention. The main treatments include:

• Observation and monitoring: Small, stable effusions without symptoms may be monitored with regular checkups and repeat imaging to watch for changes.
• Medications: These may include:
  • Nonsteroidal anti-inflammatory drugs (NSAIDs): Used to reduce inflammation and relieve pain, especially if the effusion is related to pericarditis.
  • Colchicine: An anti-inflammatory medication, sometimes used in combination with NSAIDs, to reduce symptoms and prevent recurrence in cases of pericarditis.
  • Corticosteroids: Only used in certain cases, such as autoimmune disease or when colchicine and NSAIDs are not effective or cannot be used.
  • Antibiotics or antifungal medications: Prescribed if the effusion is caused by a bacterial or fungal infection.
  • Other medications: Treatment of underlying conditions, such as thyroid hormone replacement for hypothyroidism or stopping blood thinners if they are contributing to bleeding.
• Pericardiocentesis: A procedure in which a needle and catheter are used to drain fluid from the pericardial sac, often guided by ultrasound. This is used for large, symptomatic, or rapidly accumulating effusions, or when cardiac tamponade is present.
• Surgical procedures:
  • Pericardial window: A surgical procedure that creates an opening in the pericardium to allow continuous drainage of fluid, often used for recurrent or difficult-to-treat effusions.
  • Pericardiectomy: Removal of part or all of the pericardium in rare, severe, or recurrent cases.
• Sclerosing therapy (sclerotherapy): In some cases, especially with recurrent malignant effusions, medications may be injected into the pericardial space to help prevent fluid from building up again.

People with pericardial effusion may be at increased risk for certain complications, including:

• Cardiac tamponade: A life-threatening condition where fluid buildup puts pressure on the heart, preventing it from filling and pumping blood properly.
• Shock: A sudden drop in blood pressure and inadequate blood flow to organs, which can occur if the heart cannot pump effectively.
• Arrhythmias: Abnormal heart rhythms, which may develop due to pressure on the heart.
• Recurrent pericardial effusion: Fluid may build up again after initial treatment, requiring further intervention.
• Infection: Procedures to drain fluid, such as pericardiocentesis or surgery, can increase the risk of infection.
• Death: If severe complications such as cardiac tamponade are not treated promptly, pericardial effusion can be fatal.

The outlook for people with pericardial effusion can vary depending on several factors, including the underlying cause, the amount and speed of fluid buildup, the presence of other health conditions, and how quickly treatment is started. In many cases, especially when the effusion is small, develops slowly, or is caused by a treatable condition such as a viral infection or mild inflammation, people recover well with appropriate care and monitoring. Chronic, large effusions that do not cause symptoms may also have a good outlook if they are closely monitored and do not progress.

However, the outlook may be more serious if the effusion is related to cancer, HIV, or a fungal or bacterial infection of the pericardium, or if it leads to complications such as cardiac tamponade. Rapidly accumulating or large effusions can be life-threatening if not treated promptly.

“At Yale, we have a wide range of specialists who can help to diagnose, image, and treat pericardial effusion and its related diagnoses,” says S. Elissa Altin, MD, a Yale Medicine interventional cardiologist. “Often, a diagnosis of pericardial effusion represents a cardiac manifestation of more systemic disease states, and we bring together specialists who can treat this from every approach.”