**4. Pathology**

Histologically, constrictive pericarditis typically demonstrates fluctuating pericardial edema, inflammation and fibrin deposition similar to acute pericarditis, rather than the pericardial fibrosis and calcification more commonly seen in chronic pericardial constriction. This results in pericardial thickening in both situations leading to a loss of elasticity of the the pericardium and ultimately constrictive physiology. Although the constrictive, inelastic pericardium is typically fibrotic, calcific and thick, it is seen that the pericardium is of normal thickness at a rate of 18% in constrictive pericarditis [29].
