Improvement in pulmonary hemodynamics during intravenous epoprostenol (prostacyclin): a study of 15 patients with moderate to severe portopulmonary hypertension - Krowka,M.J.; Frantz,R.P.; McGoon,M.D.; Severson,C.; Plevak,D.J.; Wiesner,R.H. (Hepatology, 1999)