1. Department of Geriatrics; Xijing Hospital; Fourth Military Medical University; Xi'an; China
2. Department of Physiology; Fourth Military Medical University; Xi'an; China
3. Department of Cardiology; Tangdu Hospital; Fourth Military Medical University; Xi'an; China
4. Department of Cardiac Surgery; Xijing Hospital; Fourth Military Medical University; Xi'an; China
5. Department of Pediatrics; Xijing Hospital; Fourth Military Medical University; Xi'an; China
6. Center of Teaching Experiment; Fourth Military Medical University; Xi'an; China