Mathematical modeling of the cardiovascular autonomic control in healthy subjects during a passive head-up tilt test

Abstract

A mathematical model is proposed for the autonomic control of cardiovascular system, which takes into account two separated self-exciting sympathetic control loops of heart rate and peripheral vascular tone. The control loops are represented by self-exciting time-delay systems and their tone depends on activity of the aortic, carotid, and lower-body baroreceptors. The model is used to study the dynamics of the adaptive processes that manifest in a healthy cardiovascular system during the passive head-up tilt test. Computer simulation provides continuous observation of the dynamics of the indexes and variables that cannot be measured in the direct experiment, including the noradrenaline concentration in vessel wall and heart muscle, tone of the sympathetic and parasympathetic control, peripheral vascular resistance, and blood pressure. In the supine and upright positions, we estimated the spectral characteristics of the model variables, especially in the low-frequency band, and the original index of total percent of phase synchronization between the low-frequency oscillations in heart rate and blood pressure signals. The model demonstrates good quantitative agreement with the dynamics of the experimentally observed indexes of cardiovascular system that were averaged for 50 healthy subjects.

Synchronization Of Autonomic Control Loops Of Blood Circulation In Patients With COVID-19

“…According to the results from [23], infection by different types of viruses can increase the concentration of ACE2. Additionally, similar effects can be caused by some pathologies affecting RAS (diabetes, kidney disease) [23], some pathologies of the cardiological [5] and gynecological profile [24][25], as well as changes in the physical condition [16], as was shown in our previous studies. The group-averaged values of the S index were significantly different between the groups of healthy volunteers and COVID-19 patients.…”

“…The phase analysis of CVS was shown to be a promising tool for clinical practice, in particular, for correcting the therapy in patients with hypertension and after myocardial infarction [13][14][15]. We showed that the total percentage of phase synchronization index (S index) was a sensitive index of CVS status [16,17] and was an index for specific pathologies [13][14][15].…”

Cardiovascular Response to Posture Changes: Multiscale Modeling and in vivo Validation During Head-Up Tilt

“…Transient response validation . The model is able to accurately reproduce transient responses following change of posture for the most common hemodynamic parameters—e.g.„ MAP, HR, CO, SV , and TPR refer to Critchley et al ( 1997 ); Toska and Walløe ( 2002 ); Youde et al ( 2003 ); Heldt ( 2004 ); Olufsen et al ( 2005 ); van Heusden et al ( 2006 ); Truijen et al ( 2012 ); Sundblad et al ( 2014 ); Williams et al ( 2014 ); Lau and Figueroa ( 2015 ), and Ishbulatov et al ( 2020 )—both reported in the literature and recorded in our in vivo measurements. Figure 4 shows beat-to-beat hemodynamic parameters adjustment to HUT, reaching upright posture (70°) within 17.5 s (4°/s).…”

Synchronization of the Processes of Autonomic Control of Blood Circulation in Humans Is Different in the Awake State and in Sleep Stages

“…According to a number of studies, the baroreflex and the processes of autonomic control determine the complex dynamics of blood circulation, in particular, the non-linear dynamics of heart rhythm ( Tan, 2013 ; Ernst, 2017 ; Karavaev et al, 2019 ). It is known that autonomic control loops are sensitive to changes in the physiological state of healthy subjects ( Ivanov et al, 1999 ; Valente et al, 2018 ; Ishbulatov et al, 2020 ). There is a significant change in baroreflex functions with aging ( Sharma and Goodwin, 2006 ; Schumann et al, 2010 ; Shiogai et al, 2010 ; Elliott et al, 2016 ; Parashar et al, 2016 ; Natarajan et al, 2020 ; Pietri and Stefanadis, 2021 ).…”