1. From the Department of Angiology, Universitäts-Herzzentrum Freiburg Bad Krozingen, Bad Krozingen, Germany (T.Z.); Sheffield Vascular Institute, Northern General Hospital, Sheffield, United Kingdom (P.A.G.); Center for Critical Limb Care, Riverside Methodist Hospital, Columbus, OH (G.M.A.); and Department of Bioengineering, Imperial College, London, United Kingdom (C.G.C.).