Abstract:

Objective   To investigate the changes of linear and nonlinear heart rate variability（HRV）parameters and the correlation between HRV parameters and the number of ventricular premature beats in patients with essential hypertension and ventricular premature beats. Methods   24-hour long-term HRV parameters and 5-minute short-term HRV parameters were measured in 77 patients（group A）and 41 healthy controls（group B）. Long-term linear parameters included standard deviation of normal-to-normal RR intervals（SDNN）, standard deviation of all mean 5-minute RR intervals（SDANN）, mean of standard deviation of all 5-minute RR intervals（SDNN Index）, root mean square successive difference between adjacent RR intervals（RMSSD）and percentage of NN50 in the total number of RR intervals（pNN50）. Short-term linear parameters included normalized low frequency（LFn）, normalized high frequency（HFn）and low frequency to high frequency（LF/HF）. Short-term nonlinear parameters included center-edge ratio（CER）, cumulative energy（CE）, Lyapunov exponents（LEs）, cardiac vagus index（CVI）and cardiac sympathetic index（CSI）. The correlation between HRV parameters and the number of 24-hour ventricular premature beats in group A was analysed. Results   Compared with group B, SDNN, SDANN, SDNN Index, RMSSD, pNN50, HFn, LEs and CVI in group A were significantly lower（P<0.05）, and LFn, LF/HF, CER, CE and CSI in group A were significantly higher（P<0.05）, while both CER and LEs had increasing trends with the worsening of ventricular premature beats（P<0.05）. The number of 24-hour ventricular premature beats were positively correlated with CER, CE and CSI（P<0.05）, while negatively correlated with LEs and CVI （P<0.05）. Conclusion   In patients with essential hypertension and ventricular premature beats, HRV descends significantly and the number of ventricular premature beats increases along with the increased sympathetic tone. Nonlinear HRV parameters are more sensitive in assessing the function of automatic nerve.

Key words: Essential hypertension； Ventricular premature beat； Linear； Nonlinear； Heart rate variability