Response of cardiac pulse parameters in humans at various inclinations via 360° rotating platform for simulated microgravity perspective

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Abstract

On the Earth, the human body is designed and adapted to function under uniform gravitational acceleration. However, exposure to microgravity or weightlessness as experienced by astronauts in space causes significant alterations in the functioning of the human cardiovascular system. Due to limitations in using real microgravity platforms, researchers opted for various ground-based microgravity analogs including head-down tilt (HDT) at fixed inclination. However, in the present study, an investigation of response of various cardiac parameters and their circulatory adaptation in 18 healthy male subjects was undertaken by using an indigenously developed 360° rotating platform. Cardiac pulse was recorded from 0° to 360° in steps of 30° inclination using piezoelectric pulse sensor (MLT1010) and associated cardiac parameters were analyzed. The results showed significant changes in the pulse shape while an interesting oscillating pattern was observed in associated cardiac parameters when rotated from 0° to 360°. The response of cardiac parameters became normal after returning to supine posture indicating the ability of the cardiovascular system to reversibly adapt to the postural changes. The observed changes in cardiac parameters at an inclination of 270°, in particular, were found to be comparable with spaceflight studies. Based on the obtained results and the proposed extended version of fluid redistribution mechanism, we herewith hypothesize that the rotation of a subject to head down tilt inclination (270°) along with other inclinations could represent a better microgravity analog for understanding the cumulative cardiac response of astronauts in space, particularly for short duration space missions.

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Recommendations for blood pressure measurement in humans and experimental animals: part 1: blood pressure measurement in humans: a statement for professionals from the Subcommittee of Professional and Public Education of the American Heart Association Council on High Blood Pressure Research.

Thomas G Pickering, John E Hall, Lawrence Appel … (2005)

Accurate measurement of blood pressure is essential to classify individuals, to ascertain blood pressure-related risk, and to guide management. The auscultatory technique with a trained observer and mercury sphygmomanometer continues to be the method of choice for measurement in the office, using the first and fifth phases of the Korotkoff sounds, including in pregnant women. The use of mercury is declining, and alternatives are needed. Aneroid devices are suitable, but they require frequent calibration. Hybrid devices that use electronic transducers instead of mercury have promise. The oscillometric method can be used for office measurement, but only devices independently validated according to standard protocols should be used, and individual calibration is recommended. They have the advantage of being able to take multiple measurements. Proper training of observers, positioning of the patient, and selection of cuff size are all essential. It is increasingly recognized that office measurements correlate poorly with blood pressure measured in other settings, and that they can be supplemented by self-measured readings taken with validated devices at home. There is increasing evidence that home readings predict cardiovascular events and are particularly useful for monitoring the effects of treatment. Twenty-four-hour ambulatory monitoring gives a better prediction of risk than office measurements and is useful for diagnosing white-coat hypertension. There is increasing evidence that a failure of blood pressure to fall during the night may be associated with increased risk. In obese patients and children, the use of an appropriate cuff size is of paramount importance.

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Long-duration bed rest as an analog to microgravity.

Alan Hargens, Laurence Vico (2016)

Long-duration bed rest is widely employed to simulate the effects of microgravity on various physiological systems, especially for studies of bone, muscle, and the cardiovascular system. This microgravity analog is also extensively used to develop and test countermeasures to microgravity-altered adaptations to Earth gravity. Initial investigations of bone loss used horizontal bed rest with the view that this model represented the closest approximation to inactivity and minimization of hydrostatic effects, but all Earth-based analogs must contend with the constant force of gravity by adjustment of the G vector. Later concerns about the lack of similarity between headward fluid shifts in space and those with horizontal bed rest encouraged the use of 6 degree head-down tilt (HDT) bed rest as pioneered by Russian investigators. Headward fluid shifts in space may redistribute bone from the legs to the head. At present, HDT bed rest with normal volunteers is the most common analog for microgravity simulation and to test countermeasures for bone loss, muscle and cardiac atrophy, orthostatic intolerance, and reduced muscle strength/exercise capacity. Also, current physiologic countermeasures are focused on long-duration missions such as Mars, so in this review we emphasize HDT bed rest studies with durations of 30 days and longer. However, recent results suggest that the HDT bed rest analog is less representative as an analog for other important physiological problems of long-duration space flight such as fluid shifts, spinal dysfunction and radiation hazards.

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Clinical measurement of arterial stiffness obtained from noninvasive pressure waveforms.

W. Nichols (2005)

Aortic pulse wave velocity (PWV) and augmentation index are independent predictors of adverse cardiovascular events, including mortality. In hypertension and aging, central elastic arteries become stiffer, diastolic pressure decreases, and central systolic and pulse pressures are augmented due to increased PWV and early return of reflected waves to the heart from the periphery. Valuable information on arterial properties such as stiffness can be obtained from both central (aortic) and peripheral (radial artery) pressure waveforms, but absolute values of wave reflection amplitude and wasted left ventricular (LV) pressure energy can only be obtained from the central arterial pressure waveform. As the arterial system becomes stiffer, there is a marked increase in central systolic and pulse pressures and wasted LV energy, along with a decrease in pulse pressure amplification. The increase in aortic systolic and pulse pressures are due primarily to increases in PWV and wave reflection amplitude with a small increase in incident wave amplitude. In individuals with very stiff elastic arteries (eg, in older persons with isolated systolic hypertension), there is a decrease in diastolic pressure. These changes in pressure components increase LV afterload and myocardial oxygen demand and therefore cause an undesirable mismatch between ventricle emptying and arterial pulse wave transmission, which promotes ventricular hypertrophy. High systolic and pulse pressures resulting from advanced age or hypertension increase circumferential arterial wall stress, which likely causes breakdown of medial elastin and increases the possibility of local fatigue, endothelial damage and development of atherosclerosis. Vasodilator drugs may have little direct effect on large central elastic arteries, but at the same time, their effects on peripheral muscular arteries reduce wave reflection amplitude and markedly lower systolic and pulse pressures and ventricular afterload. These beneficial effects on central arterial pressure can occur with or without a reduction in cuff blood pressure (BP) and may explain the apparent "pressure-independent" effects of drugs such as angiotensin-converting enzyme inhibitors and angiotensin receptor blockers. Therefore, optimal treatment of high BP and its complications should include consideration of arterial stiffness, augmentation of aortic pressure, and LV wasted energy, all of which should be reduced to the lowest possible level.

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Author and article information

Contributors

Sagar Jagtap:

ORCID: http://orcid.org/0000-0002-0749-1434

ssjagtap83@gmail.com

Ajay Kumar:

ORCID: http://orcid.org/0000-0002-8839-2998

a.kajay541@gmail.com

Pandit Vidyasagar:

ORCID: http://orcid.org/0009-0001-9900-8285

prof_pbv@yahoo.com

Journal

Journal ID (nlm-ta): NPJ Microgravity

Journal ID (iso-abbrev): NPJ Microgravity

Title: NPJ Microgravity

Publisher: Nature Publishing Group UK (London )

ISSN (Electronic): 2373-8065

Publication date (Electronic): 18 July 2023

Publication date PMC-release: 18 July 2023

Publication date Collection: 2023

Volume: 9

Electronic Location Identifier: 54

Affiliations

[1 ]Department of Physics, Haribhai V. Desai College, Pune, MS 411002 India

[2 ]GRID grid.417643.3, ISNI 0000 0004 4905 7788, Physical and Materials Chemistry Division, CSIR-National Chemical Laboratory, ; Dr. Homi Bhabha Road, Pune, MS 411008 India

[3 ]GRID grid.469887.c, ISNI 0000 0004 7744 2771, Academy of Scientific and Innovative Research (AcSIR), ; Ghaziabad, 201002 India

[4 ]GRID grid.32056.32, ISNI 0000 0001 2190 9326, Department of Electronics, , Savitribai Phule Pune University, ; Pune, MS 411007 India

[5 ]GRID grid.32056.32, ISNI 0000 0001 2190 9326, Department of Microbiology, , Savitribai Phule Pune University, ; Pune, MS 411007 India

[6 ]GRID grid.32056.32, ISNI 0000 0001 2190 9326, Department of Physics, , Tuljaram Chaturchand College, ; Baramati, Dist., Pune, 413102 MS India

[7 ]GRID grid.32056.32, ISNI 0000 0001 2190 9326, Department of Physics, , Savitribai Phule Pune University, ; Pune, MS 411007 India

Author information

Sagar Jagtap http://orcid.org/0000-0002-0749-1434

Ajay Kumar http://orcid.org/0000-0002-8839-2998

Jyotsana Dixit http://orcid.org/0000-0001-9498-3682

Rajesh Kanawade http://orcid.org/0000-0002-9298-585X

Pandit Vidyasagar http://orcid.org/0009-0001-9900-8285

Article

Publisher ID: 301

DOI: 10.1038/s41526-023-00301-3

PMC ID: 10354073

PubMed ID: 37463938

SO-VID: b9900986-3880-4b6c-b92e-31dfcb2bffac

License:

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

History

Date received : 28 July 2022

Date accepted : 2 July 2023

Funding

Funded by: FundRef https://doi.org/10.13039/501100001413, Indian Space Research Organisation (Indian Space Research Organisation, Department of Space);

Award ID: GOI-A-597

Award Recipient : Pandit Vidyasagar

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Keywords: biophysics,physiology

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Keywords: biophysics, physiology

Response of cardiac pulse parameters in humans at various inclinations via 360° rotating platform for simulated microgravity perspective

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Most cited references 58

Recommendations for blood pressure measurement in humans and experimental animals: part 1: blood pressure measurement in humans: a statement for professionals from the Subcommittee of Professional and Public Education of the American Heart Association Council on High Blood Pressure Research.

Long-duration bed rest as an analog to microgravity.

Clinical measurement of arterial stiffness obtained from noninvasive pressure waveforms.

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