Trigonometric regressive spectral analysis: an innovative tool for evaluating the autonomic nervous system

Abstract

Biological rhythms, describing the temporal variation of biological processes, are a characteristic feature of complex systems. The analysis of biological rhythms can provide important insights into the pathophysiology of different diseases, especially, in cardiovascular medicine. In the field of the autonomic nervous system, heart rate variability (HRV) and baroreflex sensitivity (BRS) describe important fluctuations of blood pressure and heart rate which are often analyzed by Fourier transformation. However, these parameters are stochastic with overlaying rhythmical structures. R-R intervals as independent variables of time are not equidistant. That is why the trigonometric regressive spectral (TRS) analysis--reviewed in this paper--was introduced, considering both the statistical and rhythmical features of such time series. The data segments required for TRS analysis can be as short as 20 s allowing for dynamic evaluation of heart rate and blood pressure interaction over longer periods. Beyond HRV, TRS also estimates BRS based on linear regression analyses of coherent heart rate and blood pressure oscillations. An additional advantage is that all oscillations are analyzed by the same (maximal) number of R-R intervals thereby providing a high number of individual BRS values. This ensures a high confidence level of BRS determination which, along with short recording periods, may be of profound clinical relevance. The dynamic assessment of heart rate and blood pressure spectra by TRS allows a more precise evaluation of cardiovascular modulation under different settings as has already been demonstrated in different clinical studies.

Subthalamic nucleus stimulation and levodopa modulate cardiovascular autonomic function in Parkinson’s disease

“…The recorded data of RRI and systolic blood pressure (SBP) were processed by TRS analysis 3 , 31 , 32 . TRS is a newly developed and advanced analytical technique 3 , 31 . The algorithm of TRS analysis provides a pure physiological spectrum using trigonometric regression.…”

“…The algorithm of TRS analysis provides a pure physiological spectrum using trigonometric regression. In contrast to Fast Fourier Transformation, TRS does not need interpolation on non-equidistant RRIs, and can analyze a data segments as short as 25 s 3 , 31 . BRS was calculated as the slope of the regression line of coherent pairs of the detected oscillations of RRI and SBP (cross correlation coefficient >0.7) 32 .…”

“…Dysfunction of the cardiovascular autonomic nervous system (ANS) is common in Parkinson’s disease (PD), and can undermine quality of life, as well as relate to a higher mortality 1 , 2 . Spectral and baroreflex analysis are valuable tools for quantitatively evaluating the fluctuations of heart rate and blood pressure, and reflect the parasympathetic and sympathetic regulations of cardiovascular function 3 . Patients with PD showed impairment in heart rate variability and baroreflex sensitivity (BRS) in multiple studies 4 – 8 .…”

Anti-Vascular endothelial growth factor therapy impairs endothelial function of retinal microcirculation in colon cancer patients – an observational study

“…A non-artifactual global data segment of 2 min was analyzed. The local time window was set at 30 seconds and was shifted beat by beat for temporal determination of frequency and amplitude [20,21]. Two main spectral bands are usually considered: High frequency (HF) oscillations (spectral band between 0.15 and 0.4 Hz) of heart rate relate to respiratory sinus arrhythmia and, therefore, to parasympathetic cardiovagal tone.…”

Cutaneous Autonomic Pilomotor Testing to Unveil the Role of Neuropathy Progression in Early Parkinson’s Disease (CAPTURE PD): Protocol for a Multicenter Study

“…In fact, functional assessment of autonomic skin nerves has taken on increasing importance in the evaluation of autonomic neuropathy (7–9). Cutaneous unmyelinated C-fibers and lightly myelinated A-delta fibers (small fibers) are responsive to a range of physical, chemical, and mechanical stimuli that can induce an axon-reflex mediated response.…”