1. Graduate School of Tianjin Medical University, Tianjin 300070, P.R. China
2. Department of Cardiovascular Medicine, Cangzhou Central Hospital, Cangzhou, Hebei 061001, P.R. China
3. Department of Cardiovascular Medicine, First Hospital of Hebei Medical University, Shijiazhuang, Hebei 050000, P.R. China
4. Department of Cardiovascular Medicine, Tianjin TEDA International Cardiovascular Hospital, Tianjin 300000, P.R. China