1. Department of Cardiovascular Surgery, Saitama Medical Center, Jichi Medical University , Saitama, Japan
2. Department of Electrical and Mechanical Engineering, Nagoya Institute of Technology , Nagoya, Japan
3. Department of Medical Informatics, Center for Information, Jichi Medical University , Shimotsuke, Japan
4. Department of Cardiovascular Surgery, University Heart Centre Freiburg, University of Freiburg , Freiburg, Germany