1. Department of Cardiovascular Surgery, Kobe University Graduate School of Medicine, 7-5-2, Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan
2. Department of Cardiovascular Surgery, Kobe University Graduate School of Medicine, Kobe
3. Department of Cardiovascular Surgery, National Cardiovascular Center, Osaka, Japan
4. Department of Orthopedic Surgery, Kobe University Graduate School of Medicine, Kobe