[1] Univ Chicago, Dept Surg, Sch Med, Chicago, IL 60637 USA
[2] Stanford Univ, Sch Med, Stanford, CA USA
[3] Northwestern Univ, Sch Med, Chicago, IL 60611 USA
[4] Massachusetts Gen Hosp, Boston, MA 02114 USA
[5] Harvard Univ, Sch Med, Cambridge, MA 02138 USA
[6] NYU, Med Ctr, New York, NY USA
[7] Klinikum Sud Nurnberg, Nurnberg, Germany
[8] John Radcliffe Hosp, Oxford OX3 9DU, England
[9] Guidant Corp, Indianapolis, IN 46244 USA