1. Department of Surgery, Yonsei University College of Medicine, Seoul, Korea
2. Department of Surgery, Yonsei University Wonju College of Medicine, Wonju, Korea
3. Department of Cardiology, Yonsei University Wonju College of Medicine, Wonju, Korea
4. Department of Thoracic and Cardiovascular Surgery, Yonsei University Wonju College of Medicine, Wonju, Korea