1. Department of Cardiac Surgery, The Jikei University School of Medicine, Tokyo, Japan
2. Department of Cardiovascular Surgery, Hokkaido University Graduate School of Medicine, Sapporo, Japan
3. First Department of Surgery, Hamamatsu University School of Medicine, Hamamatsu, Japan
4. Department of acute and critical care medicine, Sapporo Higashi Tokushukai Hospital, Sapporo, Japan