1. Department of Cardiovascular Surgery, Sapporo Medical University School of Medicine
2. Department of Cardiovascular, Renal and Metabolic Medicine, Sapporo Medical University School of Medicine
3. Department of Cardiovascular Surgery, Hokkaido Ohno Memorial Hospital
4. Department of Cardiovascular Surgery, Sapporo Central Hospital
5. Department of Cardiovascular Surgery, Teine Keijinkai Hospital
6. Department of Cardiovascular Surgery, Otaru City General Hospital