Recurrences in cardiovascular dynamics: supine vs. orthostasis

37th Congress of IUPS (Birmingham, UK) (2013) Proc 37th IUPS, PCC036

Poster Communications: Recurrences in cardiovascular dynamics: supine vs. orthostasis

Z. Turianikova1, M. Javorka1, K. Javorka1, M. Baumert2

1. Department of Physiology, Comenius University, Jessenius Faculty of Medicine, Martin, Slovakia. 2. School of Electrical & Electronic Engineering, The University of Adelaide, Adelaide, South Australia, Australia.

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New nonlinear methods are continuously developed to quantify novel aspects of heart rate variability (HRV) and blood pressure variability (BPV) with a potential to reveal subtle changes in the cardiovascular control system. Recurrence is a basic feature of many dynamical systems – it is defined as the repeated occurrence of a given state of the system in time. Recurrence plot (RP) is a graphical representation of such recurrences in a dynamical system. The structures exhibited by RP reveal information on system properties and can be described quantitatively by recurrence quantification analysis (RQA). The aim of this study was to assess the effect of orthostatic challenge on RQA measures of HRV and BPV in healthy young subjects. The change from supine to standing position is a well-described autonomic stress paradigm that is characterised by an immediate reduction in vagal outflow to the sinus node and an increase in sympathetic nerve activity. HRV and BPV were assessed in 28 healthy subjects over 15 minutes in the supine and standing positions. Complexity of HRV and BPV was assessed by recurrence quantification analysis from RPs constructed using fixed percentage of recurrences.The magnitude of oscillations was quantified by linear time and frequency domain measures. We found high sensitivity of RQA measures to the change in autonomic balance accompanying orthostasis. We have also demonstrated the positive properties of RPs with fixed percentage of recurrence points in detection of qualitative change in cardiovascular dynamics. The different behavior of complexity and variability indices was observed: HRV complexity was reduced along with HRV magnitude after changing from supine to standing position; contrary, the BPV magnitude increased and BPV complexity decreased upon standing. We conclude that RQA of HRV and BPV are sensitive to orthostatic challenge and might therefore be suited to assess changes in autonomic neural outflow to the cardiovascular system. Since analysis of variability and complexity can provide independent information on cardiovascular system control, it is beneficial to use both groups of measures simultaneously in the studies demanding the application of HRV and BPV analysis as a noninvasive tool for the assessment of cardiovascular autonomic nervous system function. We suggest that simultaneous use of both groups of measures can increase the information value and thus improve the sensitivity and reliability of the detection and monitoring of the cardiovascular system dysregulation during various pathological conditions.



Where applicable, experiments conform with Society ethical requirements.

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