1. Department of Cardiothoracic Surgery, Tianjin Hospital Affiliated to Tianjin University, Tianjin 300000, P.R. China
2. Department of Cardiology, Beichen District Hospital of Traditional Chinese Medicine, Tianjin 300400, P.R. China
3. Department of Basic Nursing, Tianjin Medical College, Tianjin 300222, P.R. China