1. Department of Cardiovascular and Gastroenterological Surgery, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Kagoshima, Japan
2. Department of cardiovascular surgery, National Hospital Organization Kagoshima Medical Center, Kagoshima, Kagoshima, Japan
3. Department of Cardiovascular Surgery, Graduate School of Medicine, Kyoto University, Kyoto, Kyoto, Japan