Portopulmonary Hypertension and Hepatopulmonary Syndrome

Abstract

Liver disease and portal hypertension may have a deleterious effect on the pulmonary microcirculation. Vasoactive molecules damage the vascular endothelium, resulting in two clinically distinct pathologies: (1) vasodilatation and shunt formation leading to hypoxia and hepatopulmonary syndrome and (2) vasoconstriction and increased vascular resistance, which cause pulmonary hypertension. Both entities are progressive diseases and, if untreated, will lead to early mortality. Hepatopulmonary syndrome causes progressive hypoxia but may be reversed by liver transplantation. The more severe the hypoxia at the time of liver transplantation, however, the higher the risk of the procedure and the longer the recovery time. Portopulmonary hypertension is also a progressive disease with increasing resistance to flow in the pulmonary microcirculation with medial hyperplasia and eventual fibrosis. The increasing rise in pulmonary vascular resistance causes right heart dysfunction and eventual failure. Portopulmonary hypertension requires intensive medical therapy to control the hypertension and to allow the right ventricle to adjust to the extra work. Liver transplantation may reverse portopulmonary hypertension, but it may progress after transplantation or remain static. Continued medical therapy is often required after transplantation. The risk for undergoing liver transplantation increases as the pulmonary vascular resistance increases and the right ventricular function is compromised. If there is significant pulmonary fibrosis, then a double-lung transplant also may be indicated.