VASC Echo (2015-2019)
CARDIAC AND VESSEL STRUCTURE AND FUNCTION WITH LONG-DURATION SPACE FLIGHT AND RECOVERY.
PI Pr Richard Hughson (Univ Waterloo Canada), 2 CoI Pr K Shoemaker (London Canada) & Pr Ph Arbeille (Tours France).
PI Pr Richard Hughson (Univ Waterloo Canada), 2 CoI Pr K Shoemaker (London Canada) & Pr Ph Arbeille (Tours France).
Background
Cardiovascular health is influenced by many factors in normal daily life on the International Space Station. The microgravity environment dramatically changes the normal head-to-foot blood pressure gradient, causing crew to experience much higher sustained BP at the brain. Normal daily life on ISS involves much lower physical activity levels, and together with the BP gradient changes are responsible for microgravity-specific structural adaptations of the heart and blood vessels compared to daily life on Earth.
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Changes in cardiac mass have been identified with space flight as well as bed rest and there is recent evidence of functional change in cardiac contraction as well as relaxation from bed rest studies. Arterial and venous blood vessel wall architectural properties are changed with bed rest and a recent observation indicated that arteries are stiffer during and for at least 6-days after prolonged spaceflight on ISS. These observations collectively have functional significance in terms of performance of physical work tasks or return to an upright posture after 6-months on ISS, and they might also indicate long-term or permanent cardiovascular health consequences. This is particularly relevant for future interplanetary exploration as well as on Earth where many cultures are tending to adopt increasingly sedentary lifestyles.
Therefore, it is essential to gain a thorough knowledge of the cardiovascular adaptations to spaceflight and of the cardiovascular risk factors associated with prolonged weightlessness in order to establish appropriate countermeasures to maintain cardiovascular function and to mitigate if not prevent the onset of overt cardiovascular disease.
Therefore, it is essential to gain a thorough knowledge of the cardiovascular adaptations to spaceflight and of the cardiovascular risk factors associated with prolonged weightlessness in order to establish appropriate countermeasures to maintain cardiovascular function and to mitigate if not prevent the onset of overt cardiovascular disease.
Scientific objectives
The aim is to measure and quantify cardiac and vascular structural and functional changes and to observe biomarkers during 6-months of spaceflight and up to one year of recovery. The specific goals of this study are to collect data on the following :
- Cardiac contractility markers to assess left ventricle (LV) contraction changes. LV wall motion, LV wall structure, LV electro-mechanical coupling at rest and when the heart is appropriately challenged using 1G posture change.
- Blood vessels (arteries and veins) to obtain details on cellular-level structural changes and dimensions at rest and seated (1G). Four characteristics of vascular function will be investigated.
- Arterial walls might be stiffer : Indices of axial and radial wall motion will be collected and analyzed to quantify stiffness.
- Arterial walls might not dilate in response to a high blood flow challenge : Arterial blood flow and dilation will be monitored after a 5 minute circulatory occlusion of the forearm (Flow Mediated Dilation, FMD).
- Blood flow response to exercise might be impaired : Femoral artery blood flow velocity will be monitored after a brief exercise challenge.
- Arteries and veins might not constrict appropriately to defend blood pressure and preserve blood volume distribution : Vascular properties will be monitored in response to 3 hours partial circulatory occlusion at the thigh.
- Circulating biochemical markers to obtain details from plasma and salivary samples that reflect cardiovascular metabolism, growth, inflammation and oxidative stress.
- Telomere length in leukocytes to reflect cellular mechanisms regulating the balance between breakdown and repair.
- 24h ambulatory blood pressure monitoring with estimate of central arterial pressure to gain an estimate of central artery stiffness during daily life including during sleep. The extended recovery measurements up to 12-months after landing of key variables post-flight will provide new insight into possible long-term consequences of spaceflight.