Hideyuki Shimizu1, Morihito Okada2, Akira Tangoku3, Yuichiro Doki4, Shunsuke Endo5, Hirotsugu Fukuda6, Yasutaka Hirata7, Hisashi Iwata8, Junjiro Kobayashi9, Hiraku Kumamaru10, Hiroaki Miyata11, Noboru Motomura12, Shoji Natsugoe13, Soji Ozawa14, Yoshikatsu Saiki15, Aya Saito12, Hisashi Saji16, Yukio Sato17, Tsuyoshi Taketani18, Kazuo Tanemoto19, Wataru Tatsuishi20, Yasushi Toh21, Hiroyuki Tsukihara7, Masayuki Watanabe22, Hiroyuki Yamamoto11, Kohei Yokoi23, Yutaka Okita24. 1. Department of Cardiovascular Surgery, Keio University, 35, Shinanomachi, Shinjuku-Ku, Tokyo, Japan. survey-adm@umin.net. 2. Department of Surgical Oncology, Hiroshima University, Hiroshima, Japan. 3. Department of Thoracic, Endocrine Surgery and Oncology, Institute of BioMedicine, Tokushima University Graduate School, Tokushima, Japan. 4. Department of Gastroenterological Surgery, Osaka University, Suita, Osaka, Japan. 5. Department of Thoracic Surgery, Jichi Medical University, Shimotsuke, Japan. 6. Department of Cardiac and Vascular Surgery, Dokkyo Medical University School of Medicine, Shimotsuga-gun, Tochigi, Japan. 7. Department of Cardiac Surgery, The University of Tokyo Hospital, Tokyo, Japan. 8. Department of General Thoracic Surgery, Gifu University Hospital, Gifu, Japan. 9. Department of Cardiovascular Surgery, National Cerebral and Cardiovascular Center, Suita, Japan. 10. Department of Healthcare Quality Assessment, Graduate School of Medicine, University of Tokyo, Tokyo, Japan. 11. Department of Health Policy and Management, Keio University, Tokyo, Japan. 12. Department of Cardiovascular Surgery, Toho University Sakura Medical Center, Sakura, Japan. 13. Department of Digestive Surgery, Breast and Thyroid Surgery, Kagoshima University Graduate School of Medicine, Kagoshima, Japan. 14. Department of Gastroenterological Surgery, Tokai University School of Medicine, Isehara, Japan. 15. Division of Cardiovascular Surgery, Tohoku University Graduate School of Medicine, Sendai, Japan. 16. Department of Chest Surgery, St. Marianna University School of Medicine, Kawasaki, Japan. 17. Department of Thoracic Surgery, University of Tsukuba, Tsukuba, Japan. 18. Department of Cardiovascular Surgery, Mitsui Memorial Hospital, Tokyo, Japan. 19. Department of Cardiovascular Surgery, Kawasaki Medical School, Kurashiki, Japan. 20. Division of Cardiovascular Surgery, Department of General Surgical Science, Gunma University, Maebashi, Japan. 21. Department of Gastroenterological Surgery, National Hospital Organization Kyushu Cancer Center, Fukuoka, Japan. 22. Department of Gastroenterological Surgery, Cancer Institute Hospital of Japanese Foundation for Cancer Research, Tokyo, Japan. 23. Chunichi Hospital, Nagoya, Japan. 24. Cardio-Aortic Center, Takatsuki General Hospital, Takatsuki, Japan.