Byong-Ki Cha1, Kyung Hwa Kim1, Jong Bum Choi2. 1. Department of Thoracic and Cardiovascular Surgery, Chonbuk National University Medical School, 20 Geonji-Ro, Deokjin-Gu, Jeonju, Chonbuk, 561-712, South Korea. 2. Department of Thoracic and Cardiovascular Surgery, Chonbuk National University Medical School, 20 Geonji-Ro, Deokjin-Gu, Jeonju, Chonbuk, 561-712, South Korea. Electronic address: jobchoi@jbnu.ac.kr.