A buildup of too much fluid in the sac around the heart.

Pericardial effusion is the buildup of extra fluid in the sac that contains the heart. The extra fluid presses on the heart. If untreated, it can lead to heart failure or death. Causes include chest injury, heart attack damage, some cancers and radiation therapy near the heart. Lupus, rheumatoid arthritis, kidney failure and thyroid disease also may cause it.

Symptoms include chest pain and shortness of breath. It may be difficult or uncomfortable to breathe when lying down.

Treatments include medicines and a procedure to drain the fluid. Sometimes open-heart surgery is needed.