Evidence of effective cardiovascular countermeasures during spaceflights: insights from wearable monitoring

Figures

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  Fig. 1. Longitudinal evolution of some cardiac time intervals features throughout the study. A heart rate (bpm); B ratio of pre-ejection period and left ventricular ejection time (-). Measurements are taken at baseline (BDC), during the flight on day 6 ± 2, 37 ± 4, and 159 ± 4 (F6, F37, and F159, respectively), and during recovery at 3 and 8 days post-flight (R + 3 and R + 8, respectively). Results are presented as median [first quartile; third quartile]. ‡: p < 0.05 compared to supine baseline position, *: p < 0.05 compared to sitting baseline position, †: p < 0.05 compared to standing baseline position. Statistical analysis was performed using a mixed-effects model with Holm-Sidak correction for multiple comparisons.

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  Fig. 2. Longitudinal evolution of the mechanical performance and hemodynamic parameters throughout the study. A integral of kinetic energy measured during systole; B integral of kinetic energy measured during diastole; C systolic blood pressure; D diastolic blood pressure; E stroke volume computed with Kubicek formula normalized by the baseline sitting value; F cardiac output computed with Kubicek formula normalized by the baseline sitting value. Measurements are taken at baseline (BDC), during the flight on day 6 ± 2, 37 ± 4, and 159 ± 4 (F6, F37, and F159, respectively), and during recovery at 3 and 8 days post-flight (R + 3 and R + 8, respectively). Results are presented as median [first quartile; third quartile]. Statistical analysis was performed using a mixed-effects model with Holm-Sidak correction for multiple comparisons. ‡: p < 0.05 compared to supine baseline position, *: p < 0.05 compared to sitting baseline position, †: p < 0.05 compared to standing baseline position.

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  Fig. 3. Schematic representation of the different elements of CARDIOVECTOR. a Impedance cardiography (ICG) current electrodes; b ICG measuring electrodes; c Main unit (connection and amplification); d Seismocardiography (SCG) sensor at the cardiac apex (dorsoventral linear accelerations); e Plethysmography sensor (nasal thermistor); f ECG signal and its fiducial points; g SCG signal, its fiducial points (MC Mitral Closure, AO Aortic Opening, AC Aortic Closure, MO Mitral Opening), and cardiac time intervals (PEP Pre-ejection Period, LVET Left Ventricular Ejection Time, IVCT Isovolumetric Contraction Time, IVRT Isovolumetric Relaxation Time); h ICG signal and its fiducial points (B point: onset of left ventricular ejection, C point or \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\frac{{\rm{dZ}}({\rm{t}})}{{{\rm{dt}}}_{\max }}$$\end{document}dZ(t)dtmax : the maximum rate of impedance change during systole, and X point: the onset of aortic valve closure).

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  Fig. 4. Seismocardiography and impedance cardiography data collection protocol. Measurements included in this study were conducted pre-flight (BDC; 60 ± 4 days before launch), post-flight (R + 3, R + 8; 3 ± 1 and 8 ± 1 days after return, respectively), and in-flight during microgravity at three time points: the first week (F6; 6 ± 2 days), the first month (F37; 37 ± 4 days), and the fifth month (F159; 159 ± 4 days). The pre-flight and post-flight sessions included measurements in supine, sitting, and standing positions.