In the present patient, pulmonary hypertension was suspected from the chest radiograph (Fig 1), which showed clear lung fields, an enlarged heart (in particular, the right ventricle), and large pulmonary arteries. Right heart catheterization (Table 1) and confirmed pulmonary hypertension classified the condition as pulmonary arterial hypertension, and also revealed a hyperdynamic circulatory state and a substantial difference in oxygen saturation between the inferior vena cava and the superior vena cava. These findings, in combination with mild liver test result abnormalities, led us to suspect a pulmonary-hepatic vascular disorder. MRI angiography (Fig 2) showed a direct connection between the left portal vein (arrow) and the inferior vena cava (arrowhead) [ie, a persistent ductus venosus]. The right portal vein was small, and several collateral vessels were seen surrounding the spleen (Fig 2, top left, asterisk). A liver biopsy was subsequently performed to assess possible parenchymal damage and to ascertain whether a vascular reconstructive procedure should be considered. Liver biopsy (Fig 3
), however, showed abnormal portal fields with abundant hepatic arterial structures (CD31 stains endothelial cells) and a complete absence of portal venous structures. There were no signs of fibrosis or cirrhosis. Therefore, closure of the ductus in order to redirect portal flow toward the liver was not an option. Our patient was in New York Heart Association functional class I (with a 6-min walking distance of 660 m), which is generally not considered to be an indication for pulmonary vascular treatment. However, since pulmonary arterial hypertension in patients with liver disease can be rapidly progressive, we decided to treat the patient with the endothelin-1 receptor blocker bosentan under close surveillance of liver function. After 6 months of treatment, the hemodynamic profile (Table 1) and 6-min walking distance were identical. No clinical signs of liver failure have developed, and the patient remains in New York Heart Association functional class I. The development of hemoptysis and dyspnea after traveling to high altitude was probably related to a further increase in pulmonary artery pressure due to hypoxic pulmonary vasoconstriction.