Gravitational Dose‐Response Curves for Acute Cardiovascular Hemodynamics and Autonomic Responses in a Tilt Paradigm

Whittle, Richard; Keller, Nathan; Hall, Eric A.; Vellore, Hrudayavani S.; Stapleton, Lindsay M.; Findlay, Katherine H.; Dunbar, Bonnie J.; Diaz‐Artiles, Ana

doi:10.1161/jaha.121.024175

Cited by 19 publications

(11 citation statements)

References 117 publications

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“…During the HUTT, the orthostatic changes in the hemodynamic parameters were identical to those presented in the literature [ 43 , 44 , 45 ]. A graded increase or decrease in tilt angle was accompanied by a proportional change in hemodynamic indices (except SBP) and the autonomic nervous system [ 46 ].…”

Section: Discussionmentioning

confidence: 99%

Detection of Preclinical Orthostatic Disorders in Young African and European Adults Using the Head-Up Tilt Test with a Standardized Hydrostatic Column Height: A Pilot Study

et al. 2022

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Arterial hypertension (AH) remains the most common disease. One possible way to improve the effectiveness of the primary prevention of AH is to identify and control the preclinical orthostatic disturbances that precede the development of AH. The aim of the study was to determine the feasibility of a new protocol for the head-up tilt test (HUTT) with a standardized hydrostatic column height for the detection of asymptomatic orthostatic circulatory disorders and their racial differences in young African and European adults. Methods. In total, 80 young healthy adults (40 African and 40 European) aged 20–23 years performed the HUTT with a standardized hydrostatic column height of 133 cm. The hemodynamic parameters were recorded using a Task Force Monitor (3040i). The cardio-ankle vascular index (CAVI) was measured using a VaSera VS-2000 volumetric sphygmograph. Results. The baseline and orthostatic hemodynamic changes in both racial groups were within normal limits. Orthostatic circulatory disturbances were not detected in 70% of the European participants and 65% of the African participants; however, preclinical orthostatic hypertension, which precedes AH, was detected using the new HUTT protocol in 32.5% of the African participants and 20% of the European participants. The baseline CAVI was higher in the European group compared to the African group. Conclusion. The results of this study showed the feasibility of the detection of preclinical orthostatic disturbances in young adults and the detection of their racial differences using the HUTT protocol, providing the use of a standard gravity load. Further study on the evolution of preclinical orthostatic disturbances and their relation to increased vascular stiffness is necessary among large samples.

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Section: Discussionmentioning

confidence: 99%

Detection of Preclinical Orthostatic Disorders in Young African and European Adults Using the Head-Up Tilt Test with a Standardized Hydrostatic Column Height: A Pilot Study

et al. 2022

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“…Among them, the gravitational factor is a key factor in cardiac preload and myocardial contractility. Changes in body position can cause cardiovascular reflexes, causing orthostatic venous return obstruction, which leads to reduced cardiac output ( Bergenwald et al, 1977 ; Matzen et al, 1991 ; Harms et al, 2003 ; Dorogovtsev et al, 2021 ; Whittle et al, 2022 ). During supine head-up tilt (HUT), a reduction in SV is associated with a drop in pleural fluid content, cardiac volume, central blood pressure, and hemodynamic changes ( Van Lieshout et al, 2005 ; Cheung et al, 2020 ; Dorogovtsev et al, 2021 ).…”

Section: Discussionmentioning

confidence: 99%

Effects of trunk posture on cardiovascular and autonomic nervous systems: A pilot study

et al. 2022

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Objective: Although regular and moderate physical activity has been shown to improve the cardiovascular and autonomic nervous systems, little has been done to study the effects of postural changes in the movement on the heart and autonomic nervous system. To uncover changes in cardiac function and autonomic nerves induced by different underlying posture transitions and explore which trunk postures lead to chronic sympathetic activation. Therefore, this study investigated the effects of trunk posture on the cardiovascular and autonomic nervous systems.Methods: Twelve male subjects (age 24.7 ± 1.3) underwent this study. The non-invasive cardiac output NICOM monitoring equipment and the FIRSTBEAT system are used to dynamically monitor seven trunk postures in the sitting position simultaneously (neutral position, posterior extension, forward flexion, left lateral flexion, right lateral flexion, left rotation, right rotation). Each posture was maintained for 3 min, and the interval between each movement was 3 min to ensure that each index returned to the baseline level. Repeated analysis of variance test was used to compare and analyze the differences in human cardiac function, heart rate variability index, and respiratory rate under different postures.Results: Compared with the related indicators of cardiac output in a neutral trunk position: the cardiac index (CI) was significantly reduced in forwarding flexion and left rotation (3.48 ± 0.34 vs. 3.21 ± 0.50; 3.48 ± 0.34 vs. 3.21 ± 0.46, Δ L/(min/m2)) (p = 0.016, p = 0.013), cardiac output decreased significantly (6.49 ± 0.78 vs. 5.93 ± 0.90; 6.49 ± 0.78 vs. 6.00 ± 0.96, Δ L/min) (p = 0.006, p = 0.014), the stroke volume (stroke volume)decreased significantly (87.90 ± 15.10 vs. 81.04 ± 16.35; 87.90 ± 15.10 vs. 79.24 ± 16.83, Δ ml/beat) (p = 0.017, p = 0.0003); heart rate increased significantly in posterior extension (75.08 ± 10.43 vs. 78.42 ± 10.18, Δ beat/min) (p = 0.001); left rotation stroke volume index (SVI) decreased significantly (47.28 ± 7.97 vs. 46.14 ± 8.06, Δ ml/m2) (p = 0.0003); in the analysis of HRV-related indicators, compared with the neutral trunk position, the LF/HF of the posterior extension was significantly increased (1.90 ± 1.38 vs. 3.00 ± 1.17, p = 0.037), and the LF/HF of the forward flexion was significantly increased (1.90 ± 1.38 vs. 2.85 ± 1.41, p = 0.041), and the frequency-domain index LF/HF of right rotation was significantly increased (1.90 ± 1.38 vs. 4.06 ± 2.19, p = 0.008). There was no significant difference in respiratory rate (p > 0.05).Conclusion: A neutral trunk is the best resting position, and deviations from a neutral trunk position can affect the cardiovascular and autonomic nervous systems, resulting in decreased stroke volume, increased heart rate, and relative activation of sympathetic tone.

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“…Additional information regarding the employed instrumentation, usage of devices, and environmental calibration procedure can be found in refs. 12 , 30 .…”

Section: Methodsmentioning

confidence: 99%

Linking cerebral hemodynamics and ocular microgravity-induced alterations through an in silico-in vivo head-down tilt framework

Fois,

Diaz-Artiles,

Zaman

et al. 2024

npj Microgravity

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Head-down tilt (HDT) has been widely proposed as a terrestrial analog of microgravity and used also to investigate the occurrence of spaceflight-associated neuro-ocular syndrome (SANS), which is currently considered one of the major health risks for human spaceflight. We propose here an in vivo validated numerical framework to simulate the acute ocular-cerebrovascular response to 6° HDT, to explore the etiology and pathophysiology of SANS. The model links cerebral and ocular posture-induced hemodynamics, simulating the response of the main cerebrovascular mechanisms, as well as the relationship between intracranial and intraocular pressure to HDT. Our results from short-term (10 min) 6° HDT show increased hemodynamic pulsatility in the proximal-to-distal/capillary-venous cerebral direction, a marked decrease (-43%) in ocular translaminar pressure, and an increase (+31%) in ocular perfusion pressure, suggesting a plausible explanation of the underlying mechanisms at the onset of ocular globe deformation and edema formation over longer time scales.

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Gravitational Dose‐Response Curves for Acute Cardiovascular Hemodynamics and Autonomic Responses in a Tilt Paradigm

Cited by 19 publications

References 117 publications

Detection of Preclinical Orthostatic Disorders in Young African and European Adults Using the Head-Up Tilt Test with a Standardized Hydrostatic Column Height: A Pilot Study

Detection of Preclinical Orthostatic Disorders in Young African and European Adults Using the Head-Up Tilt Test with a Standardized Hydrostatic Column Height: A Pilot Study

Effects of trunk posture on cardiovascular and autonomic nervous systems: A pilot study

Linking cerebral hemodynamics and ocular microgravity-induced alterations through an in silico-in vivo head-down tilt framework

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