1. Department of Cardiovascular Surgery, Kobari General Hospital, 29-1 Yokouchi, Noda City, Chiba, 278-8501, Japan
2. Department of Cardiovascular Surgery, Kobari General Hospital, Chiba, Japan
3. Department of Cardiovascular Surgery, Showa University, Yokohama City Northern Hospital, Kanagawa, Japan
4. Department of Cardiovascular Surgery, Shin-Tokyo Hospital, Chiba, Japan