What?
Pericardial Effusion is an abnormal amount of fluid between the heart and the pericardium, which is the sac surrounding the heart. Pericardial effusions are associated with many different medical conditions. Most pericardial effusions are not harmful, but large pericardial effusions can cause problems by impairing heart functions.
WHY?
Most pericardial effusions are caused by inflammation of the pericardium, a condition called pericarditis. As the pericardium becomes inflamed, extra fluid is produced, leading to a pericardial effusion.