Asymmetric features of short-term blood pressure variability

Abstract

Prolongations of cardiac cycles have a significantly larger contribution to short-term heart rate variability than shorteningsthis is called heart rate asymmetry. Our aim is to establish the existence of blood pressure asymmetry phenomenon, which has not been done so far. We used 30-min resting continuous recordings of finger pressure waveforms from 227 healthy young volunteers (19-31 years old; 97 female), and performed Poincaré plot analysis of systolic blood pressure (SBP) to quantify the effect. Median contribution of SBP increases (C i ) to short-term blood pressure variability was 52.8% (inter-quartile range: 50.9-55.1%) and median number of SBP increases (N i ) was 48.8% (inter-quartile range: 47.2-50.1%). The C i 450% was found in 82% (Po0.0001; binomial test) and N i o50% in 75% (Po0.0001) of the subjects. Although SBP increases are significantly less abundant than reductions, their contribution to short-term blood pressure variability is significantly larger, which means that short-term blood pressure variability is asymmetric. SBP increases and reductions have unequal contribution to short-term blood pressure variability at supine rest in young healthy people. As this asymmetric behavior of blood pressure variability is present in most of the healthy studied people at rest, it can be concluded that blood pressure asymmetry is a physiological phenomenon. Keywords: blood pressure asymmetry; blood pressure variability; heart rate asymmetry; heart rate variability; sympatheticparasympathetic balance INTRODUCTIONBoth heart rate variability (HRV) and blood pressure variability (BPV) are related to autonomic activity and provide some information on the mechanisms regulating the cardiovascular system. 1-6 Various physiological oscillations (for example, respiration, Mayer waves) and cardiovascular reflexes (for example, arterial and cardiopulmonary baroreflexes) are responsible for HRV and BPV. [1][2][3][4][6][7][8][9] A number of mathematical approaches like the time-domain analysis, spectral analysis, graphic or nonlinear methods have been applied in the analysis of HRV and BPV. [1][2][3][4][5][6][9][10][11][12][13] Even though heart rate and blood pressure are different cardiovascular signals, very often the same techniques are used for the quantification of both HRV and BPV. 1,[3][4][5][6][7][8][9]13 On the other hand, descriptors of baroreflex function like baroreflex sensitivity and baroreflex delay (the delay of sinus node response to a change in blood pressure) reflect the blood pressure influence on heart rate more directly. 3,9,14 Most of the methods applied to the analysis of HRV and BPV look at the changes of the duration of cardiac cycle of sinus origin (RR) intervals or blood pressure, but do not analyze their direction, that is, whether they represent increases or decreases of heart rate or blood

Asymmetry of the Variability of Heart Rate and Conduction Time Between Atria and Ventricles

“…33 Further, we have described another phenomenon of the asymmetry of systolic blood pressure variability in healthy people, and although short-term heart rate asymmetry was also present in the same persons there was no correlation between both phenomena. 35 Porta et al have reported that measures of heart rate asymmetry change according to the tilting angle during head-up tilting, that there is a significant difference in heart rate asymmetry expression between daily activity and night sleep, and that the expression of heart rate asymmetry develops with increasing age between the 16th and 40th weeks of gestation. 16, 36 Karamakar et al have shown that pharmacological autonomic modulation by atropine (parasympathetic blockade) or scopolamine (parasympathetic agitation) changes the expression of heart rate asymmetry; 37,38 that is, atropine reduces heart rate asymmetry, and scopolamine increases its expression.…”

Analysis of fetal heart rate asymmetry before and after 35 weeks of gestation

“…Both definitions have been used with popular HRA indices namely Guzki's Index (GI), Porta's Index (PI) and Ehlers' Index (EI). HRA analysis has been reported to analyse asymmetric properties of short and long-term HRV [40,42], altered parasympathetic nervous system activity [43], severity of apnea [44], blood pressure variability [45] and cardiovascular dynamics [46]. There is no study done to look at HRA in fetal heart rates.…”

Multistructure index characterization of heart rate and systolic blood pressure reveals precursory signs of syncope

“…Moreover, it has been proposed that this difference could be related to the rate 17–19 , and the pattern of breathing 20 . Also by studying BPV, differences between rises and falls in systolic blood pressure have been identified 21 . Indeed, interbeat time series do not exhibit time reversal symmetry 22 — decelerations in original time series become accelerations in the series with the inverted temporal axis/time, and vice versa.…”