1. From the Department of Cardiovascular Science (A.M.K.R., N.D.A., O.W., S.K.S., J.G., A.L.), Academic Unit of Radiology (A.J.S.), and INSIGNEO, Institute for Insilico Medicine (A.M.K.R., A.J.S., J.G.), University of Sheffield, Sheffield, United Kingdom; Medtronic Inc, Santa Rosa, CA (W.C.); and Sheffield Pulmonary Vascular Disease Unit, Royal Hallamshire Hospital, Sheffield, United Kingdom (R.C., C.A.E., D.G.K.).