In patients with constrictive pericarditis, what occurs to hepatic vein flow during expiration?

In patients with constrictive pericarditis, the diastolic filling of the heart is impaired due to the thickened, fibrotic pericardium restricting heart movement. This limitation affects the pressures in the right atrium and consequently impacts the hepatic veins.

During expiration, the negative intrathoracic pressure that usually aids venous return is absent, leading to an increase in right atrial pressure relative to the hepatic venous pressure. This results in a reversal of the normal diastolic flow in the hepatic veins. In healthy individuals, the hepatic veins typically exhibit a forward flow during diastole, which is facilitated by the pressure gradient between the hepatic venous system and the right atrium. However, in constrictive pericarditis, this balance is disrupted, often causing a temporary reversal of flow in the hepatic veins during expiration, where the flow may shift from forward to backward due to the elevated pressures in the right atrium.

Understanding this mechanism helps in recognizing the hemodynamic abnormalities associated with constrictive pericarditis, which can be crucial for diagnosis and management.