[1] Univ Penn, Sch Med, Dept Surg, Div Cardiovasc Surg, Philadelphia, PA 19104 USA
[2] Indiana Univ, Sch Med, Dept Surg, Div Cardiothorac Surg, Indianapolis, IN 47405 USA
[3] Stanford Univ, Sch Med, Dept Cardiothorac Surg, Falk Bldg CV 235,300 Pasteur Dr, Stanford, CA 94305 USA