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Heart rate variability (HRV) is used as a marker of autonomic modulation of heart rate. Nonlinear HRV parameters providing information about the scaling behaviour or the complexity of the cardiac system were included. In addition, the chaotic behaviour was quantified by means of the recently developed numerical noise titration technique. 24h Holter recordings of a large healthy population (N=276,...
Heart rate variability (HRV) measurements are used as markers of autonomic modulation of heart rate. Numerical noise titration was applied to a large healthy population to examine the influence of age. Increasing age was associated with decreasing nonlinear behaviour and this age dependency was especially prominent during daytime and was also more pronounced in the female population.
The influence of pharmacological autonomic nervous system interventions on nonlinear cardiovascular regulatory indices is nowadays still not clear. The present study assesses the effects of autonomic blockade (alpha- and beta-adrenoceptor and cholinergic) on cardiovascular function by heart rate variability (HRV) and blood pressure variability (BPV) in rats using the nonlinear numerical noise titration...
In this study we evaluated the usefulness of complex demodulation (CDM) for the assessment of baroreflex sensitivity (BRS) and time delay during dynamic changes of autonomic cardiovascular regulation induced by changing gravity during parabolic flight. BRS and time delay data assessed with CDM in the HF band are influenced by non-baroreflex coupling of heart rate and blood pressure variations. LF...
The aim of this study was to evaluate the usefulness of complex demodulation (CDM) in assessing frequency components of heart rate variability (HRV) in the setting of dynamic amplitude variations. First, analysis of simulated data showed that the upper limit of rapid amplitude variations corresponded to a period of less than 16 s in order to allow a 95% reliable LF and HF estimation. Second, in terms...
Non-invasive assessment of the atrial cycle length can be obtained through QRST-cancellation algorithms. The main spectral component of the QRST-cancelled ECG gives an indication of the atrial cycle length. Due to QRS amplitude variations (eg caused by respiration) small residuals of QRS complexes can remain in the final ECG. We applied a QRST scaling algorithm to minimize these effects. Standard...
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