The Haemodynamic Instability Score (HIS) for assessment of cardiovascular reactivity in hypertensive and normotensive patients

Abstract

The normal response to postural challenge is characterised by maintenance of relatively stable blood pressure (BP) and heart rate (HR) after 30 sec to 30 min of headup tilt. The objective of the present study was to determine the degree of instability of cardiovascular responses to postural challenge in normotensive and hypertensive subjects. In the initial phase of the study, two groups of age and sex-matched subjects were assessed: essential hypertension (n ‫؍‬ 20) and healthy (n ‫؍‬ 37). The BP and HR were recorded at 5-min intervals during the course of the 10-min supine-30-min head-up tilt test (HUTT). We categorised 'BP-change' as the difference between individual BP measurements during HUTT and the last recumbent BP value, divided by latter value. The average and standard deviation (SD) of the recorded BP changes were calculated, and BP changes were plotted along a time curve. A computerised image analyser then calculated the outline ratio (OR) and fractal dimension (FD) values for each of the curves. An identical process evaluated measurements for HR-changes. BP-and HR-changes were then converted into absolute numbers, and the average, SD, OR, and FD were calculated. A multivariate analysis was conducted, evaluating independent predictors of hypertension. Finally, an equation for the calculation of 'haemodynamic instability score' (HIS) was deduced and a cut-off between HIS of hypertensive and normo-

Fractal analysis and recurrence quantification analysis of heart rate and pulse transit time for diagnosing chronic fatigue syndrome

“…In our results, the FD provided three out of five independent predictors that characterized the CFS group. Thus, the importance of fractal analysis in the characterization of the cardiovascular reactivity was substantiated and results of previous studies, which utilized a different technique [11,12,24,25], were confirmed.…”

An Emerging Role for Understanding Orthostatic Hyp‘er’tension in the Cardiorenal Syndrome

“…In the CARDIA study including 2,781 young adults to assess the relationship between positional BP change and incidence of hypertension over a follow-up period of 8 years, there was a significantly increased risk of developing hypertension in OHT persons [4]. The cardiovascular reactivity to orthostatic stress has been used to devise a hemodynamic instability score which has been shown to be associated with the development of hypertension [25]. Potentially, detection of OHT might help to identify a subset of pre-hypertensive patients that might have progression of their hypertension and develop hypertensive target organ damage (table 2).…”

Assessment of cardiovascular reactivity by fractal and recurrence quantification analysis of heart rate and pulse transit time

“…[28][29][30] The HIS identified a distinctive cardiovascular reactivity in patients with essential hypertension. 7 Thus, the correlation of results obtained by both the FRAS and the HIS methods supports the authenticity of reactivity phenotypes.…”

“…These include fractal analysis, 6,7 recurrence quantification analysis, 8,9 and multivariate models that consider the relation between two or more cardiovascular signals. 10 It has been suggested that joint quantification of BP and HR fluctuations, and utilization of non-Euclidean mathematic analysis may provide more reliable information on cardiovascular reactivity.…”