Pericardial effusion occurs when too much fluid builds up between the heart and the pericardium, which is the thin sac that covers the heart. Most pericardial effusions are not harmful, but large pericardial effusions can restrict heart function. Most pericardial effusions are caused by pericarditis, which is the inflammation of the pericardium and caused most commonly by infection. Pericardial effusions may also be caused by certain cancers, kidney failure, and tuberculosis. Pericardial effusion symptoms include shortness of breath, discomfort in breathing, chest pain, cough, low-grade fever and rapid heart rate. Imaging tests, like x-rays, can be used to diagnose pericardial effusion. Pericardiocentesis is a procedure that can be used to diagnose the cause of a pericardial effusion as well as to treat the condition. This is a procedure that uses a needle to remove pericardial fluid from around the heart, which can then be examined. Treating the underlying cause of pericardial effusion will correct the problem in most cases though. Anti-inflammatory medications can help control pericarditis contributing to a pericardial effusion. Otherwise, more invasive procedures may be necessary to drain or prevent fluids from accumulating.