1 Department of Cardiovascular Surgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, No. 277 Yanta W Rd, Xi'an, 710061, China. Electronic address: chyysh90@163.com.
2 Department of Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.
3 Faculty of Mathematics and Information Science, Shaanxi Normal University, Xi'an, China.