1. Department of Cardiology, West China Hospital, Sichuan University , No.37 Guoxue Street, Chengdu 610041 , P. R. China
2. Machine Intelligence Laboratory, College of Computer Science, Sichuan University , No.24 South Section 1, Yihuan Road, Chengdu 610065 , P. R. China
3. Department of Information Science and Technology, Tibet University, No.10 Zangda East Road, Lhasa 850000, Tibet, P. R. China