Portopulmonary hypertension (PPHTN) is defined as pulmonary arterial hypertension (PAH) with concomitant portal hypertension in the absence of other common causes of PAH, such as connective tissue disease or congenital heart disease. This is usually seen in patients with chronic liver disease, although it can develop in patients with non-cirrhotic portal hypertension. The pathogenesis of PPHTN involves endothelial and smooth muscle proliferation. The cause of this proliferation is unknown, but one theory is that a hormonal agent that is typically cleared by the liver enters the pulmonary blood stream via collaterals. Other theories include genetic predisposition, thromboembolic disease from portosystemic shunts, and increased blood flow through pulmonary system in patients with liver disease. PPHTN affects approximately 1%-2% of patients with portal hypertension or cirrhosis and 5%-10% of patients who are referred for liver transplantation.

Clinical presentation of PPHTN includes manifestations of portal hypertension (ascites, lower extremity edema, encephalopathy, varices, and splenomegaly) along with symptoms of PAH (dyspnea on exertion, orthopnea, fatigue, chest pain, and syncope).