Central volume expansion is pivotal for sustained decrease in heart rate during seated to supine posture change

Pump, Bettina; Kamo, Tsutomu; Gabrielsen, Anders; Bie, Peter; Christensen, Niels Juel; Norsk, Peter

doi:10.1152/ajpheart.2001.281.3.h1274

Cited by 16 publications

(19 citation statements)

References 27 publications

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“…The subjects were seated in an adjustable chair, whereby the upper body was manually tilted from upright vertical to horizontal supine and back to vertical again by moving the back support of the chair. During the test the legs were kept horizontal (22)(23)(24)(25). Each posture lasted 15 min.…”

Section: Methodsmentioning

confidence: 99%

“…In previous studies, we have shown that during a moderate anti-orthostatic tilt maneuver, which on an average better reflect the usual ambulatory human body posture changes than passive whole body tilting, HR decreases simultaneously with increases in SV and APP (21)(22)(23)(24)(25). Increases of the latter can be considered to reflect the pulsatile stimuli to the arterial baroreflexes for adjusting HR (21-24, 27).…”

Section: Mechanisms Of Bh Effects On Cardiovascular Variables During mentioning

confidence: 99%

“…Results of earlier studies, where subjects went from the seated to supine posture but with cardiac filling kept constant by simultaneous lower body negative pressure to prevent changes in SV and APP, indicate that the acute decrease in HR is accomplished by acute static stimulation of the carotid baroreceptors. The subsequent maintenance of a lower HR than in the seated position is accomplished by the pulsatile stimuli to the arterial baroreceptors and/or the static inputs to the cardiopulmonary (21)(22)(23)(24). Thus, during a posture change from upright seated with legs kept horizontal to supine, the stimuli to the baroreceptors, which are necessary for maintaining MAP and HR decreased, consist of 1) a static pressure input to the carotid baroreceptors, 2) a pulsatile (increased APP) input to both the carotid and aortic baroreceptors, and 3) static stimulation of the cardiopulmonary receptors (21)(22)(23)(24).…”

Section: Mechanisms Of Bh Effects On Cardiovascular Variables During mentioning

confidence: 99%

“…We have in several previous studies shown that tilting the upper body from vertical to supine while keeping the legs horizontal induces cardiac distension and increases in stroke volume (SV) and arterial pulse pressure (APP) with simultaneous decreases in mean arterial pressure (MAP) and HR (21)(22)(23)(24)(25). We therefore tested the hypothesis that the cardiovascular system in tall individuals is more affected by gravity than in short so that the baroreflex-induced changes in cardiovascular variables during the anti-orthostatic tilt are more pronounced.…”

mentioning

confidence: 99%

“…Second, upper body tilting better represents cardiovascular effects of a posture change during ambulatory conditions than whole body tilting. Third, applicability of the model has been extensively tested by us (21)(22)(23)(24)(25). Finally, stimulation of local vascular reflexes in the legs is virtually absent during selective upper body tilting so that effects of hydrostatic gradients on baroreflexes can be investigated without intervening disturbances from other reflexes.…”

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confidence: 99%

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Body height and blood pressure regulation in humans during anti-orthostatic tilting

Arvedsen

Damgaard

Norsk

2012

American Journal of Physiology-Regulatory, Integrative and Comp

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Arvedsen SK, Damgaard M, Norsk P. Body height and blood pressure regulation in humans during anti-orthostatic tilting. Am J Physiol Regul Integr Comp Physiol 302: R984 -R989, 2012. First published February 15, 2012 doi:10.1152/ajpregu.00036.2011.-The hypothesis was tested that the cardiovascular changes during an upper body anti-orthostatic maneuver in humans are more pronounced in tall than in short individuals, because of the larger intravascular hydrostatic pressure gradients. In 34 males and 41 females [20 -30 yr, body height (BH) ϭ 147-206 cm], inter-individual multiple linear regression analyses adjusted for gender and body weight were conducted between changes in cardiovascular variables versus BH during tilting of the upper body from vertical to horizontal while keeping the legs horizontal. In all the subjects, tilting induced increases in stroke volume and arterial pulse pressure and a decrease in heart rate, which each correlated significantly with BH. In males (n ϭ 51, BH ϭ 163-206 cm), 24-h ambulatory mean arterial pressure increased significantly with BH (P ϭ 0.004, r ϭ 0.40, ␣ ϭ 0.15 mmHg/cm) so that systolic/diastolic blood pressure increased by 2/2 mmHg per 15 cm increase in BH. There was no significant correlation between mean arterial pressure and BH in females (n ϭ 53, BH ϭ 147-193 cm). In conclusion, a larger BH induces larger cardiovascular changes during anti-orthostatic tilting, and in males 24-h ambulatory mean arterial pressure increases with BH. The lack of a mean arterial pressure to BH correlation in females is probably because of their lower BH and greater variability in blood pressure. cardiovascular system; hydrostatic pressure; gravity; orthostasis WHEN HUMANS CHANGE POSITION from supine to upright, blood is redistributed from the upper to the lower body. This results in a reduction in blood pressure (BP) in the upper body and an increase in the lower body. To ensure an adequate venous return and appropriate blood flow to the brain, baroreflexes originating from the carotid sinus, aorta, and atria of the heart induce contraction of the arterial resistance vessels and an increase in heart rate (HR) and cardiac contractility (1, 27). During anti-orthostatic maneuvers from upright to supine, the opposite changes occur.Because hydrostatic pressure gradients in upright individuals impede venous return to the heart and inhibit the carotid baroreceptors, it is possible that body height (BH) is a determinant of BP at heart level. That this might be the case is indicated by the giraffe, which exhibits the highest BP than any other creature (2, 10, 11). It is possible that to ensure an adequate perfusion of the brain in the giraffe, the high BP at heart level of more than 200 mmHg is required to overcome the high hydrostatic pressure gradient from head to heart. Therefore, it is possible that also in humans, however, much weaker BH and thereby the distance from the heart to the brain is one of the determinants of BP at heart level.It is known that BP during childhood is correlated to BH a...

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Section: Methodsmentioning

confidence: 99%

Section: Mechanisms Of Bh Effects On Cardiovascular Variables During mentioning

confidence: 99%

Section: Mechanisms Of Bh Effects On Cardiovascular Variables During mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Body height and blood pressure regulation in humans during anti-orthostatic tilting

Arvedsen

Damgaard

Norsk

2012

American Journal of Physiology-Regulatory, Integrative and Comp

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Conditions of autonomic reciprocal interplay versus autonomic co-activation: Effects on non-linear heart rate dynamics

Mourot¹,

Bouhaddi²,

Gandelin³

et al. 2007

Autonomic Neuroscience

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Portable single-lead electrocardiogram device is accurate for QTc evaluation in hospitalized patients

Muñoz

et al. 2021

Heart Rhythm O2

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BACKGROUND Many commonly used drugs can prolong the QTc interval (QTc), which can lead to potentially life-threatening arrhythmias. In the current era of COVID-19 pandemic, it is worth mentioning that the disease itself and several drugs used for its treatment have been associated with QTc prolongation. OBJECTIVE To evaluate the agreement and clinical precision of a portable single-lead ECG device to measure the QTc interval compared to the standard 12-lead ECG. METHODS In sequential tests, QTc of ECG recordings obtained with the device KardiaMobile (KM-1L) (AliveCor®) were compared to QTc obtained with conventional 12-lead ECG. Agreement was evaluated using Bland-Altman plots and the Lin's concordance coefficient. Consistency between the two devices in determining QTc prolongation (QTc ≥470 ms in males, or ≥480 ms in females), was evaluated with kappa statistics. RESULTS 128 patients with a presumed or confirmed diagnosis of COVID-19 admitted to a University Hospital were included. QTc intervals measured with KM were similar to QTc measured with conventional ECG (442.45±40.5 vs. 441.65±40.3 ms, p :0.15). Bland–Altman analysis showed no significant difference in QTc values (average difference of -0.797, 95% Limits Of Agreement:-13.179;11.585). Lin's concordance coefficient showed an excellent agreement (0.988, p <0.001). Concordance between the two devices for determining QTc prolongation was excellent (Kappa>0.90). CONCLUSION ECG recordings obtained with KM-1L allow an accurate QTc interval assessment. Considering its simplicity of use, this approach has advantages over conventional ECG and can provide an alternative for the evaluation of QTc in hospitalized patients, during the current time of pandemic by COVID-19 and beyond.

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Central volume expansion is pivotal for sustained decrease in heart rate during seated to supine posture change

Cited by 16 publications

References 27 publications

Body height and blood pressure regulation in humans during anti-orthostatic tilting

Body height and blood pressure regulation in humans during anti-orthostatic tilting

Conditions of autonomic reciprocal interplay versus autonomic co-activation: Effects on non-linear heart rate dynamics

Portable single-lead electrocardiogram device is accurate for QTc evaluation in hospitalized patients

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