1. Clinical Research Unit, Russell's Hall Hospital, Dudley Group of Hospitals NHS Foundation Trust, Dudley, West Midlands, UK, a_saratzis@yahoo.gr, saratzis@doctors.net.uk
2. Heart of England NHS Foundation Trust, Birmingham, West Midlands, UK
3. 1st Department of Surgery, Aristotle University of Thessaloniki Medical School, Papageorgiou General Hospital, Thessaloniki, Greece
4. Clinical Research Unit, Russell's Hall Hospital, Dudley Group of Hospitals NHS Foundation Trust, Dudley, West Midlands, UK