Pathophysiology of the Pericardium.

Pericardial heart disease includes pericarditis, (an acute, subacute, or chronic fibrinous, noneffusive, or exudative process), and its complications, constriction, (an acute, subacute, or chronic adhesive or fibrocalcific response), and cardiac tamponade. The pathophysiology of cardiac tamponade and constrictive pericarditis readily explains their respective findings on clinical examination, Doppler echocardiography, and at cardiac catheterization. The primary abnormality of cardiac tamponade is pan-cyclic compression of the cardiac chambers by increased pericardial fluid requiring that cardiac chambers compete for a fixed intrapericardial volume. Features responsible for the pathophysiology include transmission of thoracic pressure through the pericardium and heightened ventricular interdependence. Constrictive pericarditis is a condition in which the pericardium limits diastolic filling and causes dissociation of intracardiac and intrathoracic pressures, and heightened ventricular interdependence. Both conditions result in diastolic dysfunction, elevated and equal venous and ventricular diastolic pressure, respiratory variation in ventricular filling, and ultimately, reduced cardiac output.