Montano N, Ruscone T G, Porta A, Lombardi F, Pagani M, Malliani A
Centro Ricerche Cardiovascolari, CNR, Ospedale L. Sacco, Università degli Studi di Milano, Milano, Italy.
Circulation. 1994 Oct;90(4):1826-31. doi: 10.1161/01.cir.90.4.1826.
The powers of the low-frequency (LF) and high-frequency (HF) oscillations characterizing heart rate variability (HRV) appear to reflect, in their reciprocal relationship, changes in the state of the sympathovagal balance occurring during numerous physiological and pathophysiological conditions. However, no adequate information is available on the quantitative resolution of this methodology.
We studied 22 healthy volunteers (median age, 46.5 years) who were subjected after a rest period to a series of passive head-up tilt steps randomly chosen from the following angles: 15 degrees, 30 degrees, 45 degrees, 60 degrees, and 90 degrees. From the continuous ECG, after appropriate analog-to-digital conversion, a personal computer was used to compute, with an autoregressive methodology, time and frequency domain indexes of RR interval variability. Spectral and cross-spectral analysis with the simultaneously recorded respiratory signal excluded its contribution to LF. Age was significantly correlated to variance and to the absolute values in milliseconds squared of very-low-frequency (VLF), LF, and HF components. The tilt angle was correlated to both LF and HF (expressed in normalized units [nu]) and to the LF-to-HF ratio (r = .78, -.72, and .68; respectively). Lower levels of correlation were found with HF (in ms2) and RR interval. No correlation was present between tilt angle and variance, VLF, or LF (in ms2). Individual analysis confirmed that the use of nu provided the greatest consistency of results.
Spectral analysis of HRV, using nu or LF-to-HF ratio, appears to be capable of providing a noninvasive quantitative evaluation of graded changes in the state of the sympathovagal balance.
表征心率变异性（HRV）的低频（LF）和高频（HF）振荡的功率，在其相互关系中，似乎反映了在众多生理和病理生理状况下发生的交感迷走神经平衡状态的变化。然而，关于该方法的定量分辨率尚无充分信息。
我们研究了22名健康志愿者（年龄中位数为46.5岁），在休息一段时间后，让他们接受一系列从以下角度随机选取的被动头高位倾斜步骤：15度、30度、45度、60度和90度。从连续心电图经适当的模数转换后，使用个人计算机通过自回归方法计算RR间期变异性的时域和频域指标。对同时记录的呼吸信号进行频谱和互谱分析，排除了其对LF的贡献。年龄与方差以及极低频（VLF）、LF和HF成分以毫秒平方为单位的绝对值显著相关。倾斜角度与LF和HF（以归一化单位[nu]表示）以及LF与HF的比值相关（r分别为0.78、-0.72和0.68）。与HF（以ms²为单位）和RR间期的相关性较低。倾斜角度与方差、VLF或LF（以ms²为单位）之间无相关性。个体分析证实，使用nu可使结果具有最大的一致性。
使用nu或LF与HF的比值对HRV进行频谱分析，似乎能够对交感迷走神经平衡状态的分级变化进行无创定量评估。
