1. Clinical Engineer Center, Ehime University Hospital, Ehime, Japan
2. Medical Equipment Management Office, National Hospital Organization Kure Medical Center, Hiroshima, Japan
3. Division of Physiology, Hiroshima International University, Hiroshima, Japan
4. Department of Cardiology, National Hospital Organization Kure Medical Center, Hiroshima, Japan
5. Department of Cardiovascular and Thoracic Surgery, Ehime University Graduate School of Medicine, Ehime, Japan