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    Differences in autonomic activity in individuals with optimal, normal, and high-normal blood pressure levels
    (2010) Doğru M.T.; Şimşek V.; Şahin Ö.; Özer N.
    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 (LF n) and high (HF n) 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 LF n (p=0.001) values, and significantly lower HF n (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, LF n, and HF n 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.
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    The relationship between serum sex steroid levels and heart rate variability parameters in males and the effect of age
    (2010) Doğru M.T.; Başar M.M.; Yuvanç E.; Şimşek V.; Şahin Ö.
    Objectives: We evaluated the relationships between sex steroid levels and heart rate variability (HRV) parameters. Study design: The study included 114 male subjects (mean age 46.6±11.3 years) presenting to our department for cardiologic evaluation. Hormonal analysis included serum levels of luteinizing hormone, prolactin, total testosterone (TT), free testosterone, estradiol (E2), and dehydroepiandrosterone sulfate (DHEA-S). Parameters of HRV were derived from 24-hour Holter monitoring. The associations between serum sex steroid levels and HRV parameters were investigated in three age groups (20-39 years; 40-59 years; >60 years). Results: All the participants had normal biochemical results. The three age groups were similar in terms of anthropometric measurements. Among sex steroids analyzed, only serum DHEA-S level was significantly different among the groups (p=0.026), showing a decreasing trend with age. In the evaluation of HRV, all parasympathetic activities decreased (for HFn, pNN50, and rMSDD: p=0.001, p=0.000, and p=0.000, respectively), while only LF/HF among sympathetic activities increased (p=0.000) with age. Partial correlation analysis with control of age and waist circumference showed that TT and DHEA-S were positively correlated with HF n (parasympathetic parameter), and were in negative correlation with LF/HF24 hours and global sympathetic index (GSI) (sympathetic parameters). Serum E2 level was negatively correlated with the parasympathetic parameter of rMSSD, and positively correlated with LF/HF24 hours and GSI. Among serum sex steroids, DHEA-S was the most correlated parameter with autonomic functions. Conclusion: Our results showed positive correlations between androgens and parasympathetic activity and between estradiol and sympathetic activity in men, independent from anthropometric factors.