[1] Univ Hosp Halle Saale, Dept Cardiac Surg, D-06120 Halle, Germany
[2] Heidelberg Univ Hosp, Dept Cardiac Surg, D-69120 Heidelberg, Germany
[3] Ruhr Univ Bochum, St Josef Hosp, Dept Anaesthesiol, D-44791 Bochum, Germany
[4] Furtwangen Univ, Fac Med & Life Sci, D-78054 Villingen Schwenningen, Germany