Frequency-domain heart rate variability in 24-hour Holter recordings: role of spectral method to assess circadian patterns and pharmacological autonomic modulation.
Different spectral methodologies for heart rate variability were recently shown to provide the same qualitative results in the context of passive tilt test. However, the impact of the method and the use of normalized power units in long-term ECG monitoring is still debated. Autoregressive and Fast Fourier transform (FFT) spectral approaches were applied to assess circadian modulation and the effect of beta-blocker administration in mild hypertensive patients who underwent continuous ambulatory ECG recording (n = 44, 51 +/- 12 years, 30 men). Spectral analysis was applied to 5-minute sequences and spectral parameters representative of each circadian period (24 hour, day, night) were calculated. In baseline recordings, FFT spectral method provided a smaller estimate of total and very low frequency powers. On the contrary, low- and high-frequency components were systematically larger with FFT. Circadian variations were in favor of an increased overall nocturnal variability but of a reduced low frequency normalized power with both spectral methods. Chronic oral administration of beta-blocker induced an increase of all spectral components except for an unchanged low-frequency normalized power, independently from the spectral approach. In spite of quantitative differences, the qualitative assessment of circadian patterns and beta-blockade effect by autoregressive- and FFT-based spectral analyses is equivalent. The low-frequency component of heart rate variability cannot be considered a reliable direct marker of sympathetic activity in long-term ambulatory ECG recording.
Badilini
F
F
Department of Cardiology, Hôpital Lariboisière, Paris, France. badilini@aol.com
Maison-Blanche
P
P
Champomier
P
P
Provost
J C
JC
Coumel
P
P
Milon
H
H
D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D000959:Antihypertensive Agents / Q000627:therapeutic use*; D017298:Bisoprolol / Q000627:therapeutic use*; D002940:Circadian Rhythm; D015716:Electrocardiography, Ambulatory / Q000187:drug effects; D004656:Enalapril / Q000627:therapeutic use*; D005260:Female; D005583:Fourier Analysis; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D006973:Hypertension / Q000188:drug therapy / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D012815:Signal Processing, Computer-Assisted
D000319:Adrenergic beta-Antagonists; D000959:Antihypertensive Agents; D004656:Enalapril; D017298:Bisoprolol