[1] Univ Pittsburgh, Med Ctr, Heart Lung & Esophageal Inst, Pittsburgh, PA USA
[2] Univ Pittsburgh, Med Ctr, Cardiovasc Inst, Pittsburgh, PA USA
[3] Univ Michigan, Sect Cardiac Surg, Ann Arbor, MI 48109 USA
[4] Johns Hopkins Univ Hosp, Dept Med, Baltimore, MD 21287 USA
[5] Univ Minnesota, Div Cardiothorac Surg, Minneapolis, MN USA
[6] Washington Hosp Ctr, Dept Cardiovasc Med, Washington, DC 20010 USA
[7] Univ Rochester, Div Cardiac Surg, Rochester, NY USA
[8] Duke Univ, Med Ctr, Div Cardiovasc & Thorac Surg, Durham, NC USA
[9] Washington Univ, Sch Med, Div Cardiothorac Surg, St Louis, MO 63110 USA
[10] Thoratec Corp, Pleasanton, CA USA