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Heart rate variability in systemic hypertension
H V Huikuri1, A Ylitalo, S M Pikkujämsä
1Division of Cardiology and Atherosclerosis Research Group, Department of Internal Medicine and Biocenter Oulu, University of Oulu, Finland.
Insights
Long-standing hypertension reduces heart rate (HR) variability and autonomic responses. These changes are primarily linked to elevated blood pressure and obesity in hypertensive males.
Area of Science:
- Cardiology
- Autonomic Nervous System Research
- Hypertension Studies
Background:
- Low heart rate (HR) variability is a known risk factor for cardiac mortality.
- The impact of long-standing hypertension on autonomic HR modulation requires further investigation.
Purpose of the Study:
- To compare HR variability and autonomic modulation between hypertensive and normotensive males.
- To determine if hypertension is associated with altered autonomic control of HR.
Main Methods:
- Comparison of time and frequency domain measures of HR variability in 168 hypertensive and 188 normotensive males.
- Analysis of spectral components and normalized frequency components during postural changes.
- Multiple regression analysis to identify predictors of HR variability.
Main Results:
- Hypertensive subjects exhibited lower overall HR variability (reduced RR interval standard deviation and spectral components).
- Hypertensive subjects showed blunted autonomic responses to postural changes.
- Systolic blood pressure was a significant predictor of HR variability in both groups.
Conclusions:
- Long-standing hypertension is associated with reduced HR variability and impaired autonomic responses.
- Elevated blood pressure and obesity are the primary drivers of altered autonomic HR modulation in hypertensive males.
- These findings highlight the cardiovascular implications of hypertension-related autonomic dysfunction.
Abstract:
Low heart rate (HR) variability is a risk factor for cardiac mortality in various patient populations, but it has not been well established whether patients with long-standing hypertension have abnormalities in the autonomic modulation of HR. Time and frequency domain measures of HR variability were compared in randomly selected, age-matched populations of 188 normotensive and 168 hypertensive males (mean age 50 +/- 6 years for both). The standard deviation of the RR intervals was lower in the hypertensive subjects than in the normotensive ones (52 +/- 19 vs 59 +/- 20 mss; p <0.01), and the very low and low-frequency spectral components of HR variability analyzed as absolute units were reduced in the hypertensive patients relative to the normotensive controls (p <0.001 for both). Hypertensive subjects also had blunted changes of the normalized low- and high-frequency components in response to an upright (sitting) posture (NS) as compared with normotensive subjects (p <0.001 for both). Multiple regression analysis showed the standard deviation of the RR intervals to be predicted most strongly by systolic blood pressure, both in the patients with hypertension (beta--0.20, p=0.01) and in the normotensive subjects (beta--0.28, p=0.0002). After adjustment for the baseline differences in blood pressure and body mass index, none of the absolute measures of the HR variability or the responses of the normalized units of HR variability to a change in the body posture differed between the hypertensive subjects and normotensive controls. These data show that long-standing hypertension results in reduced overall HR variability and blunted autonomic responses to a change in body posture. Altered autonomic modulation of HR in hypertension is mainly due to elevated blood pressure and obesity in males with long-standing hypertension as compared with normotensive subjects.