Negishi, K and Borowski, AG and Popovic, ZB and Greenberg, NL and Martin, DS and Bungo, MW and Levine, BD and Thomas, JD, Effect of gravitational gradients on cardiac filling and performance, Journal of the American Society of Echocardiography, 30, (12) pp. 1180-1188. ISSN 0894-7317 (2017) [Refereed Article]
Copyright 2017 by the American Society of Echocardiography.
Methods: This was a prospective observational study with tilt-induced hydrostatic stress. Echocardiographic images were recorded at four different tilt angles in 13 astronauts, to mimic varying degrees of gravitational stress: 0° (supine, simulating microgravity of space), 22° head-up tilt (0.38 G, simulating Martian gravity), 41° (0.66 G, simulating approximate G load of a planetary lander), and 80° (1 G, effectively full Earth gravity). These images were then analyzed offline to assess the effects of preload reduction on anatomical and functional parameters.
Results: Although three-dimensional end-diastolic, end-systolic, and stroke volumes were significantly reduced during tilting, ejection fractions showed no significant change. Mitral annular e' and a' velocities were reduced with increasing gravitational load (P < .001 and P = .001), although s' was not altered. Global longitudinal strain (GLS; from -19.8% ± 2.2% to -14.7% ± 1.5%) and global circumferential strain (GCS; from -29.2% ± 2.5% to -26.0% ± 1.8%) were reduced significantly with increasing gravitational stress (both P < .001), while the change in strain rates were less certain: GLSR (P = .049); GCSR (P = .55). End-systolic elastance was not consistently changed (P = .53), while markers of cardiac afterload rose significantly (effective arterial elastance, P < .001; systemic vascular resistance, P < .001).
Conclusions: Preload modification with gravitational loading alters most hemodynamic and echocardiographic parameters including e' velocity, GLS, and GCS. However, end-systolic elastance and strain rate appear to be more load-independent measures to examine alterations in the cardiovascular function during postural and preload changes, including microgravity.
|Item Type:||Refereed Article|
|Keywords:||astronauts, gravity, NASA, preload, strain|
|Research Division:||Biomedical and Clinical Sciences|
|Research Group:||Cardiovascular medicine and haematology|
|Research Field:||Cardiology (incl. cardiovascular diseases)|
|Objective Group:||Clinical health|
|Objective Field:||Clinical health not elsewhere classified|
|UTAS Author:||Negishi, K (Dr Kazuaki Negishi)|
|Web of Science® Times Cited:||38|
|Deposited By:||Menzies Institute for Medical Research|
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