[1] Univ British Columbia, Dept Surg, Div Cardiovasc Surg, Vancouver, BC, Canada
[2] Baylor Coll Med, Michael E DeBakey Dept Surg, Div Cardiothorac Surg, Houston, TX USA
[3] Texas Heart Inst, Dept Cardiovasc Surg, Houston, TX USA
[4] Univ Virginia Hlth, Dept Cardiothorac Surg, Charlottesville, VA USA
[5] Texas Heart Inst, Dept Cardiovasc Surg, 6770 Bertner Ave,MC 1-194, Houston, TX 77030 USA