1. Department of Cardiothoracic Surgery, University Hospital Cologne, 50937 Cologne, Germany
2. Department of Vascular Surgery, Evangelical Hospital Bergisch Gladbach, 51465 Bergisch Gladbach, Germany
3. Department of Cardiothoracic Surgery, Helios Hospital Siegburg, 53721 Siegburg, Germany
4. Department of Cardiothoracic Surgery, University Hospital Tuebingen, 72016 Tuebingen, Germany
5. Department of Thoracic Surgery, University Medicine Essen—Ruhrlandklinik, University Duisburg—Essen, 45239 Essen, Germany