Altered pattern of circadian neural control of heart period in mild hypertension.
We addressed the problem of the circadian changes in neural control of heart period in ambulant hypertensive subjects. A running spectral analysis of R-R variability from Holter tapes provided markers of sympathetic, i.e. low-frequency component (LF) almost equal to 0.10 Hz, and vagal, i.e. high-frequency component (HF) almost equal to 0.25 Hz, controlling activities for the 24-h period of the recording. Significant circadian differences were observed in LF between the two groups of subjects: during night-time rest (0300-0400 h), LF was greater in hypertensives than in normotensives (56 +/- 2 and 48 +/- 2 nu, respectively; P less than 0.05). Furthermore, the difference between daytime and night-time LF values was progressively reduced with increasing severity of the hypertensive state, as assessed by resting arterial pressure levels. Spectral analysis of R-R variability suggests that essential hypertension may be characterized by a reduced day-night oscillation in sympathetic activity than can be quantified non-invasively using this approach.
Guzzetti
S
S
Istituto Ricerche Cardiovascolari, Ospedale L. Saccó, Università Milano, Italy.
Dassi
S
S
Pecis
M
M
Casati
R
R
Masu
A M
AM
Longoni
P
P
Tinelli
M
M
Cerutti
S
S
Pagani
M
M
Malliani
A
A
D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology*; D004562:Electrocardiography; D015716:Electrocardiography, Ambulatory; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D012016:Reference Values; D012044:Regression Analysis; D015203:Reproducibility of Results