[1] The pericardial fluid reduces friction within the pericardium by lubricating the epicardial surface allowing the membranes to glide over each other with each heart beat.
[2] Ben-Horin et al. (2005) studied the composition of pericardial fluid in patients undergoing open heart surgery.
They found that the fluid is made up of a high concentration of lactate dehydrogenase (LDH), protein and lymphocytes.
[7] Small effusions are not necessarily dangerous and are commonly caused by infection such as HIV or can occur after cardiac surgery.
Large and rapidly accumulating effusions may cause cardiac tamponade, a life-threatening complication, that puts pressure on the heart preventing the ventricles from filling correctly.