Effusive-constrictive pericarditis (ECP) is a distinct hemodynamic syndrome in which a pericardial effusion coexists with visceral pericardial constriction. Unlike classic tamponade (where fluid alone compresses the heart) or classic constriction (where a thickened, fibrotic pericardium restricts filling), ECP involves both mechanisms simultaneously. The visceral pericardium (epicardium) becomes inflamed and fibrotic, encasing the heart in a rigid shell, while fluid accumulates in the pericardial space between the visceral and parietal layers. The pathognomonic hemodynamic finding is persistence of elevated right atrial pressure and equalization of diastolic pressures after pericardiocentesis -- when the effusion is drained, tamponade physiology resolves but constrictive physiology remains because the thickened visceral pericardium continues to restrict diastolic filling. Normal pericardiocentesis in pure tamponade normalizes intracardiac pressures; failure to normalize defines ECP. The diastolic filling pattern shows early rapid filling followed by abrupt cessation (square root sign or dip-and-plateau) due to the rigid visceral pericardium preventing further ventricular expansion. Ventricular interdependence is present: during inspiration, increased right ventricular filling shifts the interventricular septum leftward, reducing left ventricular filling and causing pulsus paradoxus. Common etiologies include tuberculosis (most common...