Sang-Ho Cho1, Dae Hyun Kim2, Hyo Chul Youn3. 1. Department of Thoracic and Cardiovascular Surgery, Kyung Hee University Hospital at Gangdong, Kyung Hee University School of Medicine, Seoul, South Korea. Electronic address: sinan75@khnmc.or.kr. 2. Department of Thoracic and Cardiovascular Surgery, Kyung Hee University Hospital at Gangdong, Kyung Hee University School of Medicine, Seoul, South Korea. 3. Department of Thoracic and Cardiovascular Surgery, Kyung Hee University Hospital, Kyung Hee University School of Medicine, Seoul, South Korea.