What heart anatomy is involved in acute pericarditis?

Updated: Apr 02, 2019
  • Author: Sean Spangler, MD; Chief Editor: Terrence X O'Brien, MD, MS, FACC  more...
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Answer

The pericardium (pericardial complex) serves as a protective barrier from the spread of infection or inflammation from adjacent structures. It is composed of the parietal pericardium (an outer fibrous layer) and the visceral pericardium (an inner serous membrane made of a single layer of mesothelial cells). The fibrous pericardium is a flask-shaped, tough outer sac with attachments to the diaphragm, sternum, and costal cartilage. The visceral pericardium is thin, adjacent to the surface of the heart, and attached to the epicardial fat; it reflects back on itself to form the parietal pericardium.

The pericardium normally contains as much as 20-50 mL of an ultrafiltrate of plasma. Approximately 90-120 mL of additional pericardial fluid can accumulate rapidly in the pericardium without an increase in pressure. The capacity of the atria and ventricles to fill is mechanically compromised with further fluid accumulation, which can result in marked increases in pericardial pressure, eliciting reduced stroke volume, decreased cardiac output, and hypotension (cardiac tamponade physiology). The rapidity of fluid accumulation influences the hemodynamic effect. With slow accumulation of fluid, the pericardium has time to stretch and accommodate the fluid increase so that hemodynamic compromise does not ensue. Drainage of the pericardium occurs via the thoracic duct and the right lymphatic duct into the right pleural space.


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