1. From the Department of Respiratory Medicine, Hannover Medical School, Hannover, Germany (M.M.H.); Department of Cardiothoracic and Vascular Surgery, Johannes Gutenberg University, Mainz, Germany (E.M.); Centre of Maladies Vasculaires Pulmonaires, Hôpital Antoine Béclère, Clamart, France (G.S.); and Pulmonary Vascular Program, University of California, San Diego (L.J.R.).