Comparison of frequency domain measures based on spectral decomposition for spontaneous baroreflex sensitivity assessment after Acute Myocardial Infarction

Measuring the Rate of Information Exchange in Point-Process Data With Application to Cardiovascular Variability

“…In accordance with our previous research in a related database (Krohová et al, 2017), we expect an increase in PEP during orthostasis as an effect of decreased diastolic filling of the heart via the Frank-Starling mechanism leading to a lower strength of the cardiac contraction. Therefore, the decrease of the mean PAT observed during tilt should reflect mostly a decrease in PTT related to an augmented arterial stiffness caused by peripheral vasoconstriction, which is in turn evoked by the vascular baroreflex response associated with a decrease of blood pressure due to pooling of blood in the lower extremities (Czippelova et al, 2019); the concomitance of these opposite trends (i.e., increase of PEP and decrease of PTT) and the complexity of the related physiological mechanisms including autonomic reflexes and mechanical effects (Rapalis et al, 2017;Czippelova et al, 2019;Pernice et al, 2021) may -together with an increased systolic blood pressure variability associated with tilt -explain the higher variability of PAT observed during tilt. During cognitive load, induced in our protocol by the mental arithmetic task, the more prominent decrease of PAT likely reflects-in addition to vasoconstriction driven by commands stemming from the central nervous system which reduces the PTT-also a reduction of PEP associated with an increased cardiac contractility mediated by the sympathetic nervous system (Martin et al, 2016); in this case, the presence of common trends (i.e., decrease of both PEP and PTT) may explain both the lower PAT and its lower variability measured during mental arithmetic.…”

“…According to our present findings and previous research (Krohová et al, 2017;Czippelova et al, 2019;Pernice et al, 2019), the increased variability of PAT observed during postural stress arises from an increased variability of PEP related to sympathetic influence on cardiac contractility, an increased variability of systolic blood pressure leading to increased PTT variability, and an increased variability in the vascular tone related to sympathetic vasomotor control. These effects are manifested mainly in the LF band (0.04-0.15 Hz) of the spectrum, which is the frequency range where dominant oscillations of the blood pressure and the heart rate are observed during head-up tilt (Montano et al, 1994;Pernice et al, 2021). Accordingly, we ascribe the increase of cMIR observed during postural stress to the activation of the sympathetic nervous system and to the increased chronotropic baroreflex coupling occurring with tilt, which are likely responsible of the synchronous modulation of the LF variability of heart rate and PAT.…”

Spectral decomposition of cerebrovascular and cardiovascular interactions in patients prone to postural syncope and healthy controls

“…After AR identification, computation of the time-and frequency-domain interaction measures was performed from the estimated model parameters and spectra of the processes. Spectral analysis was carried out assuming the series as uniformly sampled with the mean heart period 〈HP〉 taken as the sampling period, so that the Nyquist frequency in each spectral representation was taken as (Pernice et al, 2021).…”

“…after myocardial infarction (see e.g. (La Rovere et al, 1998;Nollo et al, 2002;Pernice et al, 2021). Impairment of cardiovascular and/or cerebrovascular regulation has been also related to syncope, i.e.…”

“…This is particularly limiting for cerebrovascular and cardiovascular variability analysis, since there are several concurrent rhythms taking place within different frequency bands. In short-term cardiovascular variability, the most studied rhythms are those occurring at the frequency of the Mayer waves (~0.1 Hz), and those related to respiration, which affects the cardiovascular variables within the high-frequency (HF, 0.15-0.4 Hz) band (Cohen and Taylor, 2002), but can generate confounding effects also in lower frequencies (Krohova et al, 2019;Pernice et al, 2021). With regard to cerebrovascular variability analysis, the main regulatory mechanisms occur within several lower-frequency contiguous bands and for this reason, historically, the most often investigated frequency bands are 0.02-0.07 Hz for the very low frequency (VLF), 0.07-0.2 Hz for the low frequency (LF) and 0.2-0.5 Hz for the high frequency (HF) (Claassen et al, 2016).…”