Candidates for enrollment in this clinical trial are limited to adult patients diagnosed with severe portopulmonary hypertension (PTPH). Specifically, other causes of pulmonary hypertension (PH) such as left ventricular dysfunction, valvular heart disease, chronic lung disease, chronic thromboembolic disease, chronic hypoxemia, rheumatologic conditions, and significant untreated obstructive sleep apnea will be excluded in the usual fashion in patients with underlying portal hypertension and usually cirrhosis. The diagnosis of pulmonary hypertension will be confirmed by invasive hemodynamic measurements (i.e. right heart catheterization) and severe PH is defined as a mean pulmonary artery pressure (MPAP) >35 mmHg. If evidence of right ventricular (RV) dysfunction is present (RV dilation, reduced RV ejection fraction (EF), or elevated RV end-diastolic pressure (>10 mmHg) and the MPAP is 30-35 mmHg, then the patient may be enrolled.