Saturday 21 January 2012
PERICARDIAL FLUID
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. [1] A transverse section of the thorax, showing the contents of the middle and the posterior mediastinum. The pleural and pericardial cavities are exaggerated since normally there is no space between parietal and visceral pleura and between pericardium and heart. Function 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] Composition 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
15-50ml of clear, straw-
coloured fluid. However there
is little data on the normal
composition of pericardial fluid to serve as a reference. [3] [4] 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).[5] Pericardial Effusion A pericardial effusion is the presence of excessive
pericardial fluid, this can be
confirmed using an echocardiogram.[6] 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 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.[7] 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. [4] Pericardial Window This can also be used to treat
pericardial effusion or cardiac
tamponade.
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