Surrounding the heart is a sac known as the pericardium, which consists of two membranes, the outer layer being the fibrous parietal pericardium and the inner layer being the serous visceral pericardium. It is the serous visceral pericardium that secretes the pericardial fluid into the pericardial cavity, (the space between the two pericardial layers). It is similar to the serous fluid that is found in the brain for cushioning and ability to move semi-freely.
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.
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. In a healthy adult there is usually 15-50 ml of clear, straw-coloured fluid. However there is little data on the normal composition of pericardial fluid to serve as a reference.
Ischemic Heart Disease
In patients with ischemic heart disease there is an accumulation of angiogenic growth factors in the pericardial fluid. These contribute to angiogenesis (the formation of new blood vessels) and arteriogenesis (the increase in diameter of existing arterioles). This helps to prevent myocardial ischemia (lack of oxygen to the heart).
A pericardial effusion is the presence of excessive pericardial fluid, this can be confirmed using an echocardiogram. 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.
Pericardiocentesis is a procedure used to remove the pericardial fluid from the pericardial cavity. It is performed using a needle and under the guidance of an ultrasound. It can be used to relieve pressure from pericardial effusions or for diagnostic purposes, revealling the cause of abnormalities such as: Cancer, Cardiac perforation, Cardiac trauma, Congestive heart failure, Pericarditis rupture of a ventricular aneurysm.
This can also be used to treat pericardial effusion or cardiac tamponade.
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- Gray H et al. 2002, Lecture notes on cardiology 4th Edition,Blackwell publishing,p.207