Effect of antihypertensive treatment on daytime and nighttime power spectral analysis of heart rate.
Power spectral analysis of heart rate may provide useful information about cardiac neural activity. The aim of this study was to evaluate cardiac sympathetic and parasympathetic activity, as assessed by power spectral analysis of heart rate, in hypertensive patients before and after antihypertensive treatment. In 14 hypertensive patients and in 7 normotensive subjects 24 h Holter electrocardiogram monitoring was performed under basal conditions and after 6 months of treatment with nifedipine (n = 7) or enalapril (n = 7). Sequences of 512 RR intervals were taken for the evaluation of power spectral analysis (autoregressive method); absolute and normalized power spectral density of the peak at 0.10 Hz (low frequency peak: LF) and at 0.25 Hz (high frequency peak: HF), as well as their ratio (index of sympatovagal interaction: SVI) were calculated. Under basal conditions SVI was significantly decreased from daytime to nighttime in normotensives, while no change was observed in hypertensive patients. In all hypertensive patients a reduction of SVI during nighttime in respect to basal values was observed after treatment. SVI during nighttime was significantly reduced with both nifedipine and enalapril, while SVI during daytime was slightly increased during nifedipine treatment, and significantly reduced during enalapril treatment. Systolic and diastolic arterial pressure as well as left ventricular mass index were significantly reduced with both treatments. In conclusion, long term treatment with nifedipine or enalapril seems to be able to restore an impaired daytime to nighttime SVI modulation in hypertensive patients, even considering the potential limitations of power spectral analysis of heart rate.
Rizzoni
D
D
Cattedra di Medicina Interna, University of Brescia, Italy.
Muiesan
M L
ML
Zulli
R
R
Castellano
M
M
Bettoni
G
G
Porteri
E
E
Agabiti-Rosei
E
E
D000328:Adult; D000959:Antihypertensive Agents / Q000627:therapeutic use*; D002940:Circadian Rhythm; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D006973:Hypertension / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D008722:Methods; D008875:Middle Aged; D013997:Time Factors
D000959:Antihypertensive Agents