1. Department of Thoracic and Cardiovascular Surgery, Seoul St. Mary's Hospital, The Catholic University of Korea, College of Medicine, Seoul, Korea.
2. Department of Thoracic and Cardiovascular Surgery, St. Mary's Hospital, The Catholic University of Korea, College of Medicine, Seoul, Korea.
3. Department of Thoracic and Cardiovascular Surgery, St. Vincent's Hospital, The Catholic University of Korea, College of Medicine, Seoul, Korea.