Heart Rate Variability in Patients with Acute Ischemic Stroke at Different Stages of Renal Dysfunction: A Cross-sectional Observational Study oleh Lin Wei, Wen-Bo Zhao, Huan-Wen Ye, Yan-Hua Chen, Xiao-Pei Zhang, Yan Huang, Ye-Feng Cai, Quan-Fu Chen, Su-Yue Pan