Hiroyuki Kaneda1, Tomohiro Murakawa2. 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.