1 Clinic for Cardiac Surgery, University Hospital Zürich, Zürich, Switzerland; Department of Cardiothoracic Surgery, the University of the Free State, Bloemfontein, South Africa. Electronic address: Carlos.Mestres@usz.ch.
2 Clinic for Cardiac Surgery, University Hospital Zürich, Zürich, Switzerland.
3 Department of Cardiothoracic Surgery, the University of the Free State, Bloemfontein, South Africa.