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Power spectral analysis of heart period variability in hypertensive patients with left ventricular hypertrophy
M Petretta1, F Marciano, V Bianchi
1Institute of Internal Medicine, Cardiology and Heart Surgery, University of Naples Federico II, Italy.
Insights
Hypertensive patients with left ventricular hypertrophy show reduced vagal tone, indicating an imbalance in heart rate regulation. This reduction in parasympathetic activity correlates with increased blood pressure and left ventricular mass.
Area of Science:
- Cardiology
- Autonomic Nervous System Research
- Hypertension Studies
Background:
- Essential hypertension is often associated with left ventricular hypertrophy (LVH).
- Sympathovagal balance, assessed via heart rate variability, plays a crucial role in cardiovascular regulation.
- Power spectrum analysis of heart rate variability provides insights into autonomic nervous system activity.
Purpose of the Study:
- To characterize sympathovagal balance in hypertensive patients with LVH.
- To investigate the relationship between autonomic function, blood pressure, and left ventricular mass.
Main Methods:
- Employed 24-hour ambulatory blood pressure monitoring and electrocardiogram Holter recordings.
- Utilized fast Fourier transform algorithm for heart period power spectrum analysis.
- Compared 20 hypertensive patients with LVH to 20 age- and sex-matched controls.
Main Results:
- Hypertensive patients with LVH exhibited lower low and high frequency power compared to controls.
- A similar circadian pattern of autonomic activity was observed in both groups.
- Left ventricular mass index directly correlated with daytime systolic and diastolic blood pressure.
- Left ventricular mass index negatively correlated with low and high frequency power, indicating reduced vagal tone.
Conclusions:
- Hypertensive patients with LVH demonstrate sympathovagal imbalance, characterized by reduced vagal tone.
- The severity of hypertension and LVH is associated with a greater reduction in parasympathetic modulation.
- These findings highlight the importance of autonomic dysfunction in the pathophysiology of hypertensive heart disease.
Abstract:
This study aimed to characterize sympathovagal balance by heart period power spectrum analysis in hypertensive patients with echocardiographic evidence of left ventricular hypertrophy. Twenty ambulatory patients (11 men and 9 women), aged 50 +/- 10 years, with established essential hypertension and echocardiographic left ventricular hypertrophy, performed 24-h blood pressure monitoring and electrocardiogram Holter recording on 2 consecutive days. Twenty age- and sex-matched normal subjects comprised the control group. Power spectrum analysis, performed using the fast Fourier transform algorithm, demonstrated lower values of low and high frequency power in hypertensives than in controls, while ultralow and very low frequency power were similar in the two groups. Very low frequency, low frequency, and high frequency power increased during the night in both groups, showing a similar circadian pattern. We found a direct correlation between daytime systolic (r = 0.51; P < .05) and diastolic (r = 0.52; P < .05) blood pressure and left ventricular mass index. Moreover, negative correlations were found between left ventricular mass index and low frequency (r = -0.47; P < .05) and high frequency power (r = -0.47; P < .05). There was a direct correlation between nighttime decrease in systolic blood pressure and nighttime increase in high frequency power (r = 0.45; P < .05). As 24-h low frequency and high frequency power, obtained using the Fourier transform algorithm, both reflect the parasympathetic modulation of heart rate, our results demonstrate that hypertensive patients with left ventricular hypertrophy are characterized by a sympathovagal imbalance with a reduction of vagal tone that is more evident with increasing severity of hypertension.