1. Division of Thoracic Surgery, Department of Surgery, Changhua Christian Medical Foundation Changhua Christian Hospital, Changhua 500, Taiwan, R.O.C.
2. Institute of Medicine, Chung Shan Medical University, Taichung 402, Taiwan, R.O.C.
3. School of Medicine, College of Medicine, National Taiwan University, Taipei 100, Taiwan, R.O.C.