Pericardial effusion (per-e-KAHR-dee-ul uh-FU-zhun) is the buildup of too much fluid in the double-layered, saclike structure around the heart (pericardium).

The space between these layers typically contains a thin layer of fluid. But if the pericardium is diseased or injured, the resulting inflammation can lead to excess fluid. Fluid can also build up around the heart without inflammation, such as from bleeding, related to a cancer or after chest trauma.

Pericardial effusion can put pressure on the heart, affecting how the heart works. If untreated, it may lead to heart failure or death in extreme cases.


Pericardial effusion may not cause any noticeable signs and symptoms, particularly if the fluid has increased slowly.

If pericardial effusion signs and symptoms do occur, they might include:

  • Shortness of breath or difficulty breathing (dyspnea)
  • Discomfort when breathing while lying down
  • Chest pain, usually behind the breastbone or on the left side of the chest
  • Chest fullness
  • Lightheadedness or feeling faint
  • Swelling in the abdomen or legs

When to see a doctor

Call 911 or your local emergency number if you feel chest pain that lasts more than a few minutes, if your breathing is difficult or painful, or if you have an unexplained fainting spell.

See your health care provider if you have shortness of breath.


Pericardial effusion can result from inflammation of the pericardium (pericarditis) after an illness or injury. In some settings, large effusions may be caused by certain cancers. A blockage of pericardial fluids or a collection of blood within the pericardium also can lead to this condition.

Sometimes the cause can't be determined (idiopathic pericarditis).

Causes of pericardial effusion may include:

  • Autoimmune disorders, such as rheumatoid arthritis or lupus
  • Cancer of the heart or pericardium
  • Spread of cancer (metastasis), particularly lung cancer, breast cancer or Hodgkin's lymphoma
  • Radiation therapy for cancer if the heart was in the area of the radiation
  • Chest trauma
  • Inflammation of the pericardium following a heart attack or after heart surgery or a procedure where the heart's lining is injured
  • Underactive thyroid (hypothyroidism)
  • Use of certain drugs or exposure to toxins
  • Viral, bacterial, fungal or parasitic infections
  • Waste products in the blood due to kidney failure (uremia)


A potential complication of pericardial effusion is cardiac tamponade (tam-pon-AYD). In this condition, the excess fluid within the pericardium puts pressure on the heart. The strain prevents the heart chambers from filling completely with blood.

Cardiac tamponade results in poor blood flow and a lack of oxygen to the body. Cardiac tamponade is life-threatening and requires emergency medical treatment.