1. Department of Cardiology, Miyagi Cardiovascular and Respiratory Center, Kurihara;
2. Division of Thoracic and Cardiovascular Surgery, Niigata University, Niigata;
3. Department of Thoracic Surgery, Japanese Red Cross Ishinomaki Hospital, Ishinomaki;
4. Department of Medical Engineering and Cardiology, Tohoku University, Sendai, Japan