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

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yurii M. Ishbulatov ◽  
Anatoly S. Karavaev ◽  
Anton R. Kiselev ◽  
Margarita A. Simonyan ◽  
Mikhail D. Prokhorov ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Cardiovascular System ◽  
Healthy Subjects ◽  
Low Frequency ◽  
Tilt Test ◽  
Peripheral Vascular ◽  
Control Loops ◽  
Head Up Tilt ◽  
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.

Age dependency of cardiovascular autonomic responses to head-up tilt in healthy subjects

2004 ◽  
Vol 96 (6) ◽  
pp. 2333-2340 ◽  
Author(s):  
Tomi Laitinen ◽  
Leo Niskanen ◽  
Ghislaine Geelen ◽  
Esko Länsimies ◽  
Juha Hartikainen
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
High Frequency ◽  
Healthy Subjects ◽  
Baroreflex Sensitivity ◽  
Low Frequency ◽  
Upright Position ◽  
Vascular Responses ◽  
Autonomic Responses ◽  
Head Up Tilt

In elderly subjects, heart rate responses to postural change are attenuated, whereas their vascular responses are augmented. Altered strategy in maintaining blood pressure homeostasis during upright position may result from various cardiovascular changes, including age-related cardiovascular autonomic dysfunction. This exploratory study was conducted to evaluate impact of age on cardiovascular autonomic responses to head-up tilt (HUT) in healthy subjects covering a wide age range. The study population consisted of 63 healthy, normal-weight, nonsmoking subjects aged 23–77 yr. Five-minute electrocardiogram and finger blood pressure recordings were performed in the supine position and in the upright position 5 min after 70° HUT. Stroke volume was assessed from noninvasive blood pressure signals by the arterial pulse contour method. Heart rate variability (HRV) and systolic blood pressure variability (SBPV) were analyzed by using spectral analysis, and baroreflex sensitivity (BRS) was assessed by using sequence and cross-spectral methods. Cardiovascular autonomic activation during HUT consisted of decreases in HRV and BRS and an increase in SBPV. These changes became attenuated with aging. Age correlated significantly with amplitude of HUT-stimulated response of the high-frequency component ( r = -0.61, P < 0.001) and the ratio of low-frequency to high-frequency power of HRV ( r = -0.31, P < 0.05) and indexes of BRS (local BRS: r = -0.62, P < 0.001; cross-spectral baroreflex sensitivity in the low-frequency range: r = -0.38, P < 0.01). Blood pressure in the upright position was maintained well irrespective of age. However, the HUT-induced increase in heart rate was more pronounced in the younger subjects, whereas the increase in peripheral resistance was predominantly observed in the older subjects. Thus it is likely that whereas the dynamic capacity of cardiac autonomic regulation decreases, vascular responses related to vasoactive mechanisms and vascular sympathetic regulation become augmented with increasing age.

scholarly journals Relation of body mass index (BMI) with cardiovascular response to head up tilt in healthy subjects

2020 ◽  
Vol 15 (1) ◽  
pp. 6-10
Author(s):  
Sadia Afrin Rimi ◽  
Shamima Sultana ◽  
Iffat Rezwana ◽  
Sultana Ferdousi
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Systolic Blood Pressure ◽  
Healthy Subjects ◽  
Cardiovascular Response ◽  
Tilt Test ◽  
Tilt Table ◽  
Chi Square ◽  
Female Head ◽  
Head Up Tilt

Background: Tilt table test is used for the last few decades to detect cause in unexplained syncope. The response to tilting may vary physiologically with obesity. Objective: To assess the relationship of BMI to cardiovascular response to tilting. Methods: This experimental study was conducted from March 2019 to Feb 2020 on 90 healthy subjects with different BMI. Fifty one subjects of both gender with BMI 18.5-24.9 kg/m2 were included in the non-obese group and 39 subjects of both gender with BMI of 25-29.9 kg/m2 were included in overweight group and they were further subdivided into male and female. Head up tilting was done for 10 minutes at 600 by using a motorized tilt table. Systolic blood pressure (SBP), diastolic blood pressure (DBP) were recorded by an automatic sphygmomanometer. Heart rate (HR) and peripheral capillary oxygen saturation (SpO2) were measured by a pulse oximeter. For statistical analysis, Independent sample ‘t’ test, Pearson’s correlation test and Chi square tests were applied. Results: Significantly smaller rise of heart rate was observed in overweight males and greater fall of systolic blood pressure was observed in overweight females. Conclusion: This study concluded that over weight is associated with reduced orthostatic tolerance to head up tilt test in both genders. J Bangladesh Soc Physiol. 2020, June; 15(1): 6-10

Abnormal passive head-up tilt test in subjects with symptoms of anxiety power spectral analysis study of heart rate and blood pressure

1997 ◽  
Vol 60 (2) ◽  
pp. 121-131 ◽  
Author(s):  
Gianfranco Piccirillo ◽  
Santagada Elvira ◽  
Carmela Bucca ◽  
Emanuela Viola ◽  
Mauro Cacciafesta ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Spectral Analysis ◽  
Power Spectral Analysis ◽  
Tilt Test ◽  
Analysis Study ◽  
Power Spectral ◽  
Head Up Tilt ◽  
Head Up Tilt Test

scholarly journals Simultaneous Beat-To-Beat Heart Rate And Systolic Blood Pressure Variability In Patients With And Without Neurally Mediated Syncope

2021 ◽  
Author(s):  
Amirhossein Akbarzadeh ◽  
Fariborz Akbarzadeh ◽  
Babak Kazemi
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Systolic Blood Pressure ◽  
Low Frequency ◽  
Tilt Test ◽  
Control Group ◽  
Case Group ◽  
Spectral Indices ◽  
Neurally Mediated Syncope ◽  
Head Up Tilt Test

Abstract Background: Autonomic changes play an essential role in the genesis of neurally mediated syncope (NMS). The aim of this study was to compare the changes of the autonomic nervous system (ANS) by measuring spectral indices of beat-to-beat systolic blood pressure and heart rate variability (SBPV and HRV) in ranges of low frequency (LF), high frequency (HF), and the LF/HF ratio during head-up tilt test (HUTT) in patients with and without a syncope response. Methods: In this case-control study of 46 patients with a suspected history of unexplained syncope, data were recorded separately during the typical three phases of HUTT. Patients who developed syncope were designated as the case group and the rest as the control group. Results: Thirty one patients experienced syncope during HUTT. Resting HRV and SBPV indices were significantly lower in cases than controls. After tilting in the syncope group, both HF and LF powers of SBPV showed a significant and gradual decrease. LF/HF in HRV increased in both groups similarly during the test but in SBPV, mainly driven by oscilations in its LF power, it increased significantly more during the first two phases of the test in syncope patients only to paradoxically decrease during active tilt (p< 0.001). Conclusion: Our findings show an abnormal autonomic function in patients with syncope, both at rest and tilting. Fluctuations of spectral indices of beat-to-beat SBPV, a potential noval index of pure sympathetic activity, show an exaggerated response during tilt and its withdrawal before syncope.

scholarly journals Predictive Value of Blood Pressure, Heart Rate, and Blood Pressure/Heart Rate Ratio in a Chinese Subpopulation with Vasovagal Syncope

2020 ◽  
Author(s):  
Dengfeng Geng
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Vasovagal Syncope ◽  
Cost Effective ◽  
Tilt Test ◽  
Clinical Settings ◽  
Mixed Response ◽  
Head Up Tilt ◽  
Head Up Tilt Test ◽  
Mixed Pattern

Objective: The head-up tilt test (HUTT) is widely used but is time-consuming and not cost-effective to evaluate patients with vasovagal syncope (VVS). The present study aims to verify the hypothesis that ambulatory blood pressure (BP) monitoring (ABPM) and the simplistic tilt test may be potential alternatives to the HUTT.Methods: The study consecutively enrolled 360 patients who underwent the HUTT to evaluate VVS. BP), heart rate(HR), and BP/HR ratios derived from ABPM and the simplistic tilt test were evaluated to predict the presence, pattern, and stage of syncope during the HUTT.Results: Mixed response was the commonest pattern, and syncope occurred frequently with infusion of isoproterenol at a rate of 3 μg/min. During the simplistic tilt test, the cardioinhibitory group had higher tilted BP/HR ratios than the vasodepressor group, while the vasodepressor group had a faster tilted HR and a larger HR difference than the cardioinhibitory group. The higher the BP/HR ratio in the titled position, the higher the isoproterenol dosage needed to induce a positive response. During ABPM, BP/HR ratios were significantly higher in the cardioinhibitory group than in the vasodepressor group. The higher the ABPM-derived BP, the higher the dosage of isoproterenol needed to induce syncope. There were significant correlations in BP/HR ratios between ABPM and the supine position in the vasodepressor group, while significant correlation was found only for the diastolic BP/HR ratio between ABPM and the tilted position in the cardioinhibitory group. The mixed pattern shared correlative features of the other two patterns.Conclusion: ABPM and the simplistic tilt test might be used as promising alternatives to the HUTT in VVS evaluation in clinical settings.

scholarly journals Effect of Global Postural Reeducation on cardiovascular system of healthy subjects

2014 ◽  
Vol 27 (3) ◽  
pp. 389-397 ◽  
Author(s):  
Elizângela Márcia de Carvalho Abreu ◽  
Tatiana Sousa Cunha ◽  
Alderico Rodrigues de Paula Júnior ◽  
Marco Antonio de Oliveira
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
Wavelet Transform ◽  
Cardiovascular System ◽  
High Frequency ◽  
Sympathetic Activity ◽  
Healthy Subjects ◽  
Low Frequency ◽  
Healthy Men

Objective To evaluate the effect of Global Postural Reeducation (GPR) on cardiovascular system by heart rate variability (HRV), blood pressure (BP) and heart rate (HR). Materials and methods Seventeen healthy men (22.47 ± 3.02 years) were submitted to the postures frog on the floor, frog on the air, sitting, standing against the wall and inclined standing, two postures per session. The systolic and diastolic blood pressure (SBP and DBP) and HR were recorded. The intervals between heartbeats were collected during the whole session (Polar S810i). The frequency domain was analyzed (Wavelet Transform), the low frequency (LF) and high frequency (HF) were obtained. The data were analyzed by ANOVA and Tukey (p < 0.05). Results Increased LF/HF ratio was observed in the frog on the floor (1 ± 0.1 vs. 2 ± 0.3 p < 0.05) and on the air postures (1 ± 0.1 vs. 2 ± 0.2 p < 0.01). There was an increase in SBP in the postures frog on the floor (123 ± 2 vs. 136 ± 4 p < 0.05), frog on the air (122 ± 2 vs. 133 ± 3 p < 0.05), standing against the wall (123 ± 2 vs. 136 ± 4 p < 0.05), inclined standing (124 ± 3 vs. 146 ± 5 p < 0.05). There was increase of DBP in the postures frog on the floor (69 ± 2 vs. 81 ± 2 p < 0.01), frog on the air (72 ± 2 vs. 83 ± 3 p < 0.05), sitting (85 ± 2 vs. 102 ± 3 p < 0.01). There was increase in HR in the postures frog on the air (67 ± 2 vs. 77 ± 3 p < 0.05) and inclined standing (88 ± 3.5 vs. 101 ± 3 p < 0.05). Conclusion The increase in LF/HF ratio and also the BP and HR indicates high sympathetic activity, possibly related to the work isometric developed during GPR method. [P]

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