1. Department of Cardiothoracic and Vascular Surgery, Westpfalz-Klinikum, Kaiserslautern, Germany
2. Department of Cardiothoracic Surgery, University Hospital of Patras, Patras, Greece
3. Cardiothoracic Services, The Newcastle upon Tyne Hospitals NHS Foundation Trust, UK
4. Department of Pathology, University Hospital of Patras, Patras, Greece