1. Department of Vascular Surgery, “Democritus” University of Thrace, University Hospital of Alexandroupolis, Alexandroupolis, Greece
2. Department of Surgery, Vascular Surgery Unit, Medical School, University of Ioannina, Ioannina, Greece
3. Department of Vascular Surgery, St. Franziskus Hospital and University Clinic Münster, Münster, Germany
4. Department of Mathematics, University of Ioannina, Ioannina, Greece