What is the physiology of cardiac fluids relevant to pericardial effusion?

Updated: Nov 28, 2018
  • Author: William J Strimel, DO, FACP; Chief Editor: Terrence X O'Brien, MD, MS, FACC  more...
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Answer

The pericardial space normally contains 15-50 mL of fluid, which serves as lubrication for the visceral and parietal layers of the pericardium. This fluid is thought to originate from the visceral pericardium and is essentially an ultrafiltrate of plasma. Total protein levels are generally low; however, the concentration of albumin is increased in pericardial fluid owing to its low molecular weight.

The pericardium and pericardial fluid provide important contributions to cardiac function, including the following:

  • The parietal pericardium contributes to resting diastolic pressure, and is responsible for most of this pressure in the right atrium and ventricle

  • Through their ability to evenly distribute force across the heart, the pericardial structures assist in ensuring uniform contraction of the myocardium

The normal pericardium can stretch to accommodate a small amount of fluid without a significant change in intrapericardial pressure, although once this pericardial reserve volume is surpassed, the pressure-volume curve becomes steep. With slow increases in volume, however, pericardial compliance can increase to lessen the increase in intrapericardial pressure.


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