1 Department of Thoracic and Cardiovascular Surgery, Kansai Medical University 2-5-1 Shinmachi, Hirakatashi, Osaka, 573-1010 Japan. Electronic address: kanedah@hirakata.kmu.ac.jp.
2 Department of Thoracic and Cardiovascular Surgery, Kansai Medical University 2-5-1 Shinmachi, Hirakatashi, Osaka, 573-1010 Japan.