Pericardial effusion is a buildup of fluid in the space between the heart and the sac around the heart (pericardium).

Pericardial effusion can be caused by pericarditis, an inflammation of the pericardium. Pericarditis may be caused by heart attack, kidney failure, bacterial or viral infection, or cancer treatment.

Pericarditis can also cause chest pain and, rarely, increased pressure on the heart (cardiac tamponade).

Pericardial effusion may be drained in a procedure called pericardiocentesis, which involves using a needle and sometimes a thin tube called a catheter to drain the fluid. If the fluid buildup is gradual and the heart is tolerating the increased fluid around it, treatment of the underlying cause may be tried first.