[1] Univ Rostock, Dept Cardiac Surg, Heart Ctr Rostock, Schillingallee 35, D-18057 Rostock, Germany
[2] Univ Rostock, Dept Cardiol, Heart Ctr Rostock, Rostock, Germany
[3] Univ Rostock, Dept Anesthesiol & Intens Care Med, Rostock, Germany
[4] Univ Free State Bloemfontein, Dept Cardiothorac Surg, Fac Hlth Sci, Bloemfontein, South Africa