Pericardial Effusion

Overview
  • Pericardial Effusion refers to the accumulation of excess fluid within the pericardial sac. Pericardial effusions can be caused by a number of etiologies and the fluid composing the effusion can be of varied consistency depending on its etiological basis.
Etiologies
  • Most cases of pericardial effusions are caused by inflammation associated with acute pericarditis. However, any changes in the localized Starling Forces within pericardial vasculature can also cause effusion.For example, this may result from reduced capillary oncotic pressure due to hypoalbuminemia or increased capillary hydrostatic pressure due to left heart failure.
Morphology
  • The consistency of the effused fluid varies depending on the etiology. In cases resulting from acute pericarditis the effused fluid can be serous, fibrinous, or hemorrhagic depending on the root cause of the inflammation. Cases due to deranged starling fluid typically result in a serous fluid.
Clinical Consequences
  • Pericardial Effusions are typically subclinical; however, the major clinical concern is the development of cardiac tamponade which may occur if the effusion develops rapidly and overwhelms the capacity of pericardial lymphatics to drain excess fluid. Additionally, the pericardial sac can gradually stretch with slowly developing effusions, thus accommodating larger volumes of fluid without placing pressure on the heart. As an effusion expands, heart sounds may become fainter and the pericardial friction rub associated with acute pericarditis may vanish.