Effects of headª²up tilt on heart rate variability of hypertension patients

    QIN Yun, NIU Youª²Guo, HE Zheng, WANG Shouª²Yan, WANG Yunª²Ying, ZHANG Liª²Fan

    1Department of Aerospace Physiology, 2Department of Clinical Aerospace Medicine, School of Aerospace Medicine, 3Department of Vasocardiology, Xijing Hospital, Fourth Military Medical University, Xi¡¯an 710033, China

    ¡¾Abstract¡¿ AIM: To explore the changes in cardiac autonomic regulation of hypertension patients during headª²up tilt. METHODS: Autoregressive (AR) spectral analysis was used to analyze the heart rate variability (HRV) of 17 hypertension patients and 17 ageª²matched healthy subjects during supine and +75¡ã headª²up tilting. RESULTS: ¢Ù The total power (TP), low frequency (LF), high frequency (HF), spectral indices normalized high frequency component (HFn) of HRV in hypertension patients significantly deceased (P<0.01), whereas the normalized low frequency component (LFn) and LF/HF significantly increased (P<0.01). ¢Ú With headª²up tilt for 15 min, TP, LF, HF, LF/HF and LFn significantly decreased (P<0.01), while HFn was markedly elevated (P<0.01). ¢Û With headª²up tilt for 15 min, HFn of hypertension patients significantly decreased while LFn increased, compared with that of supine control (P<0.05). CONCLUSION: The cardiovascular autonomic regulation of hypertension patients has significant changes, including an attenuated cardiac vagal, enhanced sympathetic activity in supine position and a significant impairment of cardiac autonomic response during headª²up tilting. ......