1. Department of Cardiothoracic Surgery, Heart, Center, University of Cologne, Faculty of Medicine and University Hospital Cologne , Cologne, Germany
2. School of Medicine, University of Cologne, Cologne, Germany Albertus-Magnus-Platz , Cologne, Germany
3. Department of Otorhinolaryngology, Head and Neck Surgery, University of Cologne, Faculty of Medicine and University Hospital Cologne , Cologne, Germany