[1] Univ Pittsburgh, Med Ctr, Dept Med, Div Pulm Allergy & Crit Care Med,Pulm Vasc Dis Ct, Pittsburgh, PA 15260 USA
[2] Johns Hopkins Med Inst, Pulm Hypertens Program, Baltimore, MD 21205 USA
[3] Johns Hopkins Med Inst, Div Pulm & Crit Care Med, Baltimore, MD 21205 USA
[4] Univ Alberta, Dept Med Cardiol, Pulm Hypertens Program, Edmonton, AB, Canada
[5] Pulm Vasc Res Inst, Chicago, IL USA