1. Division of Vascular Surgery, Department of Surgery, Tohoku University Hospital
2. Department of Surgery, Japanese Red Cross Ishinomaki Hospital
3. Department of Surgery, Iwate Prefectural Isawa Hospital
4. Division of Cardiovascular Surgery, Tohoku Medical and Pharmaceutical University Hospital
5. Department of Surgery, Osaki Citizen Hospital
6. Department of Cardiovascular Surgery, Sendai City Hospital
7. Department of Surgery, Tohoku University Hospital