Reduced parasympathetic tone in newly diagnosed essential hypertension.

Aim: The aim of the study was to compare heart rate variability (HRV) of newly diagnosed essential hypertensive subjects with controls.

Methods: The study was conducted on 120 hypertensive subjects and 120 controls.

Results: The time-domain measures, standard deviation of all RR intervals (SDNN), the square root of the mean of the sum of the squares of differences between adjacent RR intervals (RMSSD), and percentage of consecutive RR intervals that differ by more than 50ms (pNN50) which reflect parasympathetic activity were significantly less in hypertensive subjects. In frequency-domain measures, high frequency [HF (ms(2))] and [HF (nu)], which reflects parasympathetic activity, was significantly less in hypertensive subjects while LF (nu) and LF/HF (%), which reflect sympathetic activity, were comparable between the groups.

Conclusion: These findings suggest that HRV is reduced in subjects with newly diagnosed essential hypertension and the parasympathetic dysregulation is present in the early stage of essential hypertension.