1. Department of Cardiovascular Medicine, Chiba University Graduate School of Medicine, Japan
2. Department of Cardiovascular Surgery, Chiba University Graduate School of Medicine, Japan
3. Department of Cardiovascular Surgery, Toho University Sakura Medical Center, Japan
4. Department of Surgical Pathology, Toho University Sakura Medical Center, Japan
5. Department of Diagnostic Pathology, Chiba University Graduate School of Medicine, Japan