pericardial space
Summary
The pericardial space is the potential space between the visceral and parietal layers of the serous pericardium, normally containing 15-50 mL of lubricating fluid. Excess fluid accumulation (pericardial effusion) can lead to cardiac tamponade if it accumulates rapidly or in large volume, compressing the heart and impairing filling.
Detail
The pericardium consists of a fibrous outer layer and a serous inner layer, the latter divided into parietal (lining the fibrous pericardium) and visceral (epicardium, covering the heart) layers. The pericardial space lies between these serous layers and normally contains a small amount of serous fluid that reduces friction during cardiac contraction. Pathologic accumulation of fluid, blood, pus, or air in this space can result from various causes: pericarditis (viral, bacterial, uremic, autoimmune), malignancy, trauma, aortic dissection, or post-MI (Dressler syndrome, free wall rupture). Rapid accumulation of even small volumes (150-200 mL) can cause cardiac tamponade due to limited pericardial compliance, presenting with Beck's triad (hypotension, JVD, muffled heart sounds), pulsus paradoxus, and equalization of diastolic pressures across cardiac chambers. Chronic, slow accumulation allows the pericardium to stretch, tolerating larger volumes (up to 2L) without tamponade. Diagnosis is via echocardiography showing effusion with diastolic collapse of right atrium/ventricle. Treatment for tamponade is pericardiocentesis. Constrictive pericarditis, a related condition, involves fibrotic thickening and calcification of the pericardium, leading to impaired diastolic filling with Kussmaul's sign and pericardial knock.
Sources
- First Aid for the USMLE Step 1
- Robbins and Cotran Pathologic Basis of Disease
- Costanzo Physiology
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