Differences in autonomic activity in individuals with optimal, normal, and high-normal blood pressure levels [Turk Kardiyol Dern Ars]
Turk Kardiyol Dern Ars. 2010; 38(3): 182-188

Differences in autonomic activity in individuals with optimal, normal, and high-normal blood pressure levels

M Tolga Doğru, Vedat Şimşek, Ömer Şahin, Nurtaç Özer
Department of Cardiology, Kirikkale University Faculty of Medicine, Kırıkkale, Turkey


OBJECTIVES
We investigated differences in autonomic activity in normotensive individuals having optimal, normal and high-normal blood pressure (BP) levels according to the guidelines of the European Society of Hypertension and European Society of Cardiology (ESH/ESC).

STUDY DESIGN
The study included 294 normotensive subjects (135 males, 159 females; age range 16 to 75 years) with similar clinical, morphometric, biochemical, electrocardiographic, and echocardiographic features. The subjects were classified into the following BP groups: group 1 (n=113) with optimal BP (<120/80 mmHg); group 2 (n=104) with normal BP (120-129/80-84 mmHg), and group 3 (n=77) with high-normal BP (130-139/85-89 mmHg). All the subjects underwent 24-hour Holter monitoring to obtain heart rate variability (HRV) parameters of 24-hour, daytime, and nighttime periods. Normalized low (LFn) and high (HFn) frequency powers, and logarithmic (Log) values of HRV parameters were also calculated.

RESULTS
On 24-hour Holter monitoring, heart rates were similar in three groups. Compared to group 1 and 2, group 3 exhibited significantly higher LF/HF (p<0.001) and LFn (p=0.001) values, and significantly lower HFn (p=0.001), pNN50 (p=0.001), and rMSSD (p=0.005) values. There were no significant differences between the groups with respect to daytime HRV parameters; however, nighttime LF/HF, LFn, and HFn values were significantly different between the groups. Log LF/HF values obtained during the 24-hour and nighttime periods showed significant differences between group 1 and group 3 (for 24 hours, p<0.001; for night, p=0.001) and between group 2 and group 3 (for 24 hours, p<0.001; for night, p=0.009), but group 1 and group 2 did not differ significantly in this respect (p>0.05).

CONCLUSION
These findings suggest that subjects with high-normal BP have increased sympathetic activity and decreased parasympathetic activity, possibly making them more liable to hypertension.

Keywords: Autonomic nervous system, blood pressure, electrocardiography, ambulatory; heart rate; hypertension

How to cite this article
M Tolga Doğru, Vedat Şimşek, Ömer Şahin, Nurtaç Özer. Differences in autonomic activity in individuals with optimal, normal, and high-normal blood pressure levels. Turk Kardiyol Dern Ars. 2010; 38(3): 182-188

Corresponding Author: M Tolga Doğru, Türkiye
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