[1] Toronto Gen Hosp, Div Thorac Surg, Toronto, ON M5G 2C4, Canada
[2] Queen Elizabeth Hosp, Birmingham B15 2TH, W Midlands, England
[3] Freeman Rd Hosp, Newcastle Upon Tyne, Tyne & Wear, England
[4] Univ Minnesota, Minneapolis, MN USA
[5] Univ Alabama Birmingham, Birmingham, AL USA
[6] Univ Calif Berkeley, Berkeley, CA 94720 USA
[7] Mayo Clin Jacksonville, Jacksonville, FL 32224 USA
[8] Univ Leuven Hosp, Louvain, Belgium