Constrictive pericarditis is the result of scarring and consequent loss of the normal elasticity of the pericardial sac. This leads to impairment of ventricular filling in mid and late diastole. As a result, the majority of ventricular filling occurs rapidly in early diastole and the ventricular volume does not increase after the end of the early filling period.
Restrictive cardiomyopathy is characterized by a nondilated rigid ventricle, resulting in severe diastolic dysfunction and restrictive filling that produces hemodynamic changes similar to those in constrictive pericarditis.
Constrictive pericarditis and restrictive cardiomyopathy both lead to diastolic heart failure with normal (or near normal) systolic function, and characteristically abnormal ventricular filling that results in similar clinical and hemodynamic features. However, because of their markedly different treatments, differentiating between the two conditions is critical. In some patients, the correct diagnosis may be readily suggested from the history or routine diagnostic testing. In others, however, this differentiation cannot be diagnosed before biopsy or even surgical exploration.