1. Graduate School of Tianjin Medical University, Tianjin 300070, P.R. China
2. Ministry of Research, Characteristic Medical Center of The Chinese People's Armed Police Force, Tianjin 300162, P.R. China
3. Department of Geriatric Medicine, Characteristic Medical Center of Chinese People's Armed Police Force, Tianjin 300162, P.R. China
4. Angiocardiopathy Institute of Characteristic Medical Center of PAP, Tianjin 300162, P.R. China