1. Clinical Skills Training Center, The Second Xiangya Hospital, Central South University, Changsha, Hunan, 410011, China
2. Department of Cardiovascular Medicine, The Second Xiangya Hospital, Central South University, Changsha, Hunan, 410011, China
3. Department of Surgery Labs, University of Pittsburgh, Pittsburgh, PA 15213, USA
4. Department of Stomatology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, 410011, China