Pathology
The pericardium is made up of all the layers right of the myocardial
tissue. The pericardial space, also called the pericardial sac,
normally holds about 25 ml of serous (serum-like) fluid. It is this
small amount of fluid between the opposing layers of the heart wall
that makes it possible for the heart to move easily without friction
when it is contracting. As little as 100 ml of fluid in the
pericardial space can cause problems.
The pressure prevents complete filling of the heart before the
next heartbeat. This lessens the amount of blood that can be pumped
by the heart. Severe pericardial fluid pressure can cause a drop in
blood pressure, shock, abnormal heart rhythms, and death. Basically,
there is just too much fluid accumulating too fast in the
pericardial space!!!
The fluid can be blood, purulence, or effusion fluid (serum leaking
out of blood vessels)...it doesn't matter. It just has to accumulate
in that space surrounding the heart, causing increased pressure on
the heart, so that the ventricles and atria cannot fill during
diastole. With rapid accumulation of fluid, 100-200 cc may be enough
to cause death. If the fluid accumulates slowly, the pericardium
will expand, and perhaps 1 liter would be necessary to cause death.
Causes
1.Hemopericardium (blood accumulation in the pericardial space)
usually from trauma or from an aortic aneurysm that dissects (chest
x-ray, 106K) into the pericardium. Or iatrogenic (condition caused
by medical treatment) like anti-coagulation therapy, use of
transvenous pacemaker, diagnostic pericardiocentesis, CPR, cardiac
catheterization or other invasive cardiac procedures can also cause
hemopericardium.
2. Neoplasm ("new growth" or cancer) can cause rapid accumulation of
serous or serosanguinous (mixture of serous and blood) fluid in the
pericardial space. 3. Pericarditis (inflammation of the pericardium)
from radiation therapy, infections, or drug reactions such as
hydralazine or procainamide can all result in pericardial effusion
that leads to tamponade.
Other Causes Of Cardiac Tamponade Include: Pericarditis, Acute
Myocardial Infarction, Tuberculosis, Radiation Damage, Bacterial,
Cardiomyopathy, Lupus, Or Dissecting Aortic Aneurysm.
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