Cardiovascular and Cerebrovascular Control on Return from ISS (CCISS) - 01.16.19

Overview | Description | Applications | Operations | Results | Publications | Imagery

ISS Science for Everyone

Science Objectives for Everyone
Cardiovascular and Cerebrovascular Control on Return from ISS (CCISS) will study the effects of long-duration space flight on crewmembers' heart functions and their blood vessels that supply the brain. Learning more about the cardiovascular and cerebrovascular systems could lead to specific countermeasures that might better protect future space travelers. This experiment is collaborative effort with the Canadian Space Agency.
Science Results for Everyone
Can space break your heart, or hurt your head? Cardiovascular and Cerebrovascular Control on Return from ISS (CCISS) aims to find out, testing long-duration space flight’s effects on the heart and blood vessels supplying the brain. Changes observed are less than expected, suggesting that current exercise equipment and training regimens have astronauts well-prepared for return to Earth. However, scientists did see problems in blood vessels supplying the brain, increased reactivity to carbon dioxide, and evidence showing thickened cerebral arteries. Additional research is needed to determine whether these changes predict health complications from long-duration space flight.

The following content was provided by Richard Lee Hughson, Ph.D., and is maintained in a database by the ISS Program Science Office.
Experiment Details


Principal Investigator(s)
Richard Lee Hughson, Ph.D., Schlegel-University of Waterloo, Waterloo, Ontario, Canada

Philippe Arbeille, M.D., Universite Francois-Rabelais, Tours, France
Andrew Philip Blaber, Ph.D., Simon Fraser University, Burnaby, British Columbia, Canada
Danielle Kathleen Greaves, M.Sc., University of Waterloo, Waterloo, Ontario, Canada
Joel Kevin Shoemaker, Ph.D., University of Western Ontario, London, Ontario, Canada

NASA Johnson Space Center, Human Research Program, Houston, TX, United States

Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)

Sponsoring Organization
Human Exploration and Operations Mission Directorate (HEOMD)

Research Benefits
Information Pending

ISS Expedition Duration
April 2007 - April 2008; October 2008 - March 2010

Expeditions Assigned

Previous Missions
CCISS is a continuing investigation which began observation of the first subject during ISS Expedition 15.

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Experiment Description

Research Overview

  • For crewmembers' health, the need to be able to maintain blood pressure immediately after returning to Earth is essential.

  • To obtain information on the baroreflex stability (blood pressure regulation) of ISS crewmembers an electrocardiogram and blood pressure data will be gathered prior to flight, inflight and postflight.

  • In addition to the electrocardiogram and blood pressure data, a lower body negative pressure (LBNP) session will be conducted preflight and postflight. The level of lower body suction will be gentle and short duration. The resulting stress on the body will be less than simply standing up in 1G. Other data collected during the LBNP session will be brain, brachial artery, and aortic blood flows. These flows are all done non-invasively with ultrasound. Arm vein pressure, blood pressure, electrocardiogram, breathing rate and the amount of carbon dioxide expired will also be measured. The data gathered during this investigation will lead to countermeasures to help crewmembers maintain sufficient blood pressure after long duration missions.

  • This study will provide a basis for studies of individuals who are susceptible to fainting in the upright posture.

The ability to maintain arterial blood pressure and brain blood flow immediately on return to Earth after prolonged space flight is one of the most critical factors for crew health and safety. Although the heart rate component of the arterial baroreflex is impaired on return from space, this is not in itself a critical issue as crewmembers who are about to faint normally have markedly elevated heart rate. Rather, their inability to maintain blood pressure appears to be related to inadequate increases in peripheral vascular resistance. This study will incorporate a new methodology that determines the simultaneous gains of the arterial and cardiopulmonary baroreflexes in the control of peripheral vascular resistance.

A series of six objectives have been identified that will allow a more complete understanding of any alteration in cardiovascular or cerebrovascular responses following long duration space flight. The first two will be addressed with very brief inflight experiments that monitor the heart rate component of the arterial baroreflex and the relationship between heart rate variability and physical activity as indicators of autonomic nervous system control. The remaining objectives will be evaluated during a 32-minute test protocol conducted pre- and immediately postflight. During this test period, the central vein compliance will be monitored. In addition, the arterial and cardiopulmonary baroreflexes will be monitored during experiments that use an optimized schedule of lower body negative pressure (LBNP) to manipulate arterial and central venous blood pressures. Within these same experimental sessions assessments of cerebrovascular responsiveness to changes in arterial blood pressure and arterial partial pressure of carbon dioxide (CO2). It is anticipated that the ability to regulate blood pressure through baroreflex control of blood vessel constriction will be impaired after space flight. Similarly, it is expected that brain blood flow will be more sensitive to changes in arterial blood CO2 and, thus, will not be as tightly regulated after space flight.

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Space Applications
The information derived from this study will help to better understand the effects of spaceflight on cardiovascular and cerebrovascular functions. By gaining increased knowledge of the specific components of the cardiovascular and cerebrovascular systems that deviate from the normal Earth-baseline responses, it will be possible to recommend specific countermeasures that might better protect future space travelers from complications that could put them at risk on return to the effects of gravity as will occur on re-entry to Earth or landing on the moon or Mars.

Earth Applications
The risk of fainting and falling is increased in older adults. Falls are very serious because they often cause fracture of the hip which is a major cause of prolonged disability, loss of independence and unfortunately for a high percentage of individuals the complications from the fracture will lead to death. Gaining improved knowledge of the mechanisms of loss of blood pressure and the warning signs that might predict risk will reduce the incidence of fainting and falls in the elderly.

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Operational Requirements and Protocols
A total of 6 long-duration crewmembers are needed as subjects for the experiment. Baseline data for each subject will be collected at L-30 (Launch minus 30 days) for the Baro Study, 24-hr Heart Rate Study, and LBNP protocol. Baseline data will also be collected at R+1 (Return plus 1 day) for the Baro and 24-hr Heart Rate Studies and R+0 (U.S.) or R+1 (Russia) for the LBNP protocol.
Crewmembers will perform CCISS operations on FD+14 (+7) (Flight Day 14) and R-14 (-7). During Day 1 operations the crewmember will don and activate the Actiwatches, CBPD, and Holter Monitor and conduct a 10-minute Baro Study. During the Baro Study, the crewmember will breathe normally for 5 minutes and then breathe at a set pace for 5 minutes. The crewmember will doff the CBPD after the conclusion of the Baro Study. The Actiwatch and Holter Monitor are worn to collect data during the 24-hr Heart Rate Study. Day 2 operations consist of the crewmember downloading data from the 24-hr Heart Rate Study and doffing the hardware.

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Decadal Survey Recommendations

Information Pending

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Results/More Information

Early evidence from the Cardiovascular and Cerebrovascular Control on Return from ISS (CCISS) and the Cardiovascular Health Consequences of Long-Duration Space Flight (Vascular) investigations highlighted some of the individual variability of astronaut’s responses related to regulation of arterial blood pressure and brain blood flow, as well as factors related to arterial stiffness and overall cardio-metabolic health.

Recent studies examined the spontaneous oscillations in blood pressure and heart rate to quantify the effectiveness of the arterial baroreflex response. The CCISS study revealed, in contrast to short-duration spaceflight, that the heart rate responses to changes in arterial blood pressure were well maintained during long-duration spaceflights on ISS. However, on return to Earth, the baroreflex response was significantly impaired with considerable variability between astronauts, potentially placing some of them at greater risk for dizziness and possibly for fainting. The study also found that the heart rate responses during periods of normal daily activities while in space were similar to pre-flight but importantly the astronauts had greatly reduced overall activity levels when measured with ankle-mounted sensors over 24-hours. The countermeasures employed by these astronauts on ISS were sufficient to maintain cardiovascular stability under resting conditions in space; however, the marked reduction in overall physical activity while in space did alter the heart rate control and could influence key aspects of cardiovascular health with potential long-term consequences.

Regulatory mechanisms are essential for continuous supply of oxygenated blood to the brain. The results of the CCISS study indicated impairment of dynamic cerebrovascular autoregulation and CO2 reactivity in astronauts on return to Earth. The chronic elevations in blood pressure in the brain while in space, compared to the normal upright posture on Earth, reductions in daily physical activity and the constant exposure to slightly elevated levels of CO2 during long-duration spaceflight might have impaired the ability of the blood vessels of the brain to respond to changes in arterial blood pressure and CO2. It is unclear, at the moment, whether these changes occur in astronauts and whether they might have harmful effects linked to the complications in vision in the Microgravity Ocular Syndrome.

Although cardiovascular stability appears to be well maintained while on ISS by current countermeasures, the chronic changes in arterial blood pressure throughout the body, the reduction in overall physical activity and the restricted access to aerobic-type exercises might have long-term cardiovascular health consequences. Recent results of the Vascular study confirmed an increase in carotid artery stiffness indicators in male and female astronauts on return from 6-months on ISS. The magnitude of increased stiffness was similar to changes expected with 10-20 years of normal aging. Mechanisms underlying the changes in artery structure and function might relate to the higher blood pressure in the head and neck without daily exposure to gravity in an upright posture, as well as to the overall reduction in physical activity. An indication that long periods of sedentary-like behavior in astronauts has potential health impacts was observed in these male and female astronauts with the development of insulin resistance during space flight. Future studies are required to assess the magnitude of insulin resistance and explore appropriate countermeasures to maintain cardio-metabolic health.

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Results Publications

    Hughson RL, Shoemaker JK, Arbeille P.  CCISS, Vascular and BP Reg: Canadian space life science research on ISS. Acta Astronautica. 2014 November; 104(1): 444-448. DOI: 10.1016/j.actaastro.2014.02.008.

    Zuj KA, Arbeille P, Shoemaker JK, Blaber AP, Greaves DK, Xu D, Hughson RL.  Impaired cerebrovascular autoregulation and reduced CO2 reactivity after long duration spaceflight. American Journal of Physiology: Heart and Circulatory Physiology. 2012 June 15; 302(12): H2592-H2598. DOI: 10.1152/ajpheart.00029.2012. PMID: 22492717.

    Hughson RL, Shoemaker JK, Blaber AP, Arbeille P, Greaves DK, Pereira, Jr. PP, Xu D.  Cardiovascular regulation during long-duration spaceflights to the International Space Station. Journal of Applied Physiology. 2012 March; 112(5): 719-727. DOI: 10.1152/japplphysiol.01196.2011. PMID: 22134699.

    Hughson RL, Robertson AD, Arbeille P, Shoemaker JK, Rush JW, Fraser KS, Greaves DK.  Increased post-flight carotid artery stiffness and inflight insulin resistance resulting from six-months spaceflight in male and female astronauts. American Journal of Physiology: Heart and Circulatory Physiology. 2016 January 8; epub: ajpheart.00802.2015. DOI: 10.1152/ajpheart.00802.2015. PMID: 26747504.

    Xu D, Shoemaker JK, Blaber AP, Arbeille P, Fraser KS, Hughson RL.  Reduced heart rate variability during sleep in long-duration spaceflight. American Journal of Physiology: Regulatory, Integrative and Comparative Physiology. 2013 July 15; 305(2): R164-R170. DOI: 10.1152/ajpregu.00423.2012. PMID: 23637139.

    Hughson RL, Helm A, Durante M.  Heart in space: effect of the extraterrestrial environment on the cardiovascular system. Nature Reviews Cardiology. 2018 March; 15: 167 - 180. DOI: 10.1038/nrcardio.2017.157. PMID: 29053152.

    Fraser KS, Greaves DK, Shoemaker JK, Blaber AP, Hughson RL.  Heart Rate and Daily Physical Activity with Long-Duration Habitation of the International Space Station. Aviation, Space, and Environmental Medicine. 2012 Jun; 83(6): 577-584. PMID: 22764612.

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Ground Based Results Publications

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ISS Patents

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Related Publications

    Hughson RL, Shoemaker JK.  Vascular health in space. Journal of Gravitational Physiology. 2004 Jul; 11(2): P71-P74. PMID: 16235421.

    Hughson RL, O-Leary DD, Shoemaker JK, Lin DC, Topor ZL, Edwards MR, Tulppo MP.  Searching for the vascular component of the arterial baroreflex. Cardiovascular Engineering. 2004; 4: 155-162.

    Sigaudo-Roussel D, Custaud M, Maillet A, Guell A, Kaspranski R, Hughson RL, Gharib C, Fortrat JO.  Heart rate variability after prolonged spaceflights. European Journal of Applied Physiology. 2002; 86: 258-265.

    Blaber AP, Goswami N, Bondar RL, Kassam MS.  Impairment of Cerebral Blood Flow Regulation in Astronauts With Orthostatic Intolerance After Flight. Stroke. 2011 July; 42(7): 1844-1850. DOI: 10.1161/STROKEAHA.110.610576. PMID: 21617145.

    O-Leary DD, Shoemaker JK, Edwards MR, Hughson RL.  Spontaneous beat-by-beat fluctuations of total peripheral and cerebrovascular resistance in response to tilt. American Journal of Physiology: Heart and Circulatory Physiology. 2004; 287: R670-R679.

    Hughson RL, Shoemaker JK, Topor ZL, Edwards MR, O-Leary DD, Lin DC, Gelb AW.  Optimizing an LBNP protocol to test cardiopulmonary and arterial baroreflex control of vascular resistance. Journal of Gravitational Physiology. 2002; 9: P73-P74.

    Hughson RL, Shoemaker JK, Arbeille P, O-Leary DD, Pizzolitto KS, Hughes MD.  Splanchnic and peripheral vascular resistance during lower body negative pressure (LBNP) and tilt. Journal of Gravitational Physiology. 2004; 11: P95-P96.

    Hughson RL, Shoemaker JK.  Autonomic responses to exercise: Deconditioning/inactivity. Autonomic Neuroscience: Basic and Clinical. 2015 March; 188: 32-35. DOI: 10.1016/j.autneu.2014.10.012. PMID: 25458429.

    Shoemaker JK, Hughson RL, Sinoway LI.  Gender affects sympathetic neurovascular control during postural stress. Journal of Gravitational Physiology. 2002; 9: P83-P84.

    Edwards MR, Topor ZL, Hughson RL.  A new two-breath technique for extracting the cerebrovascular response to arterial carbon dioxide. American Journal of Physiology: Heart and Circulatory Physiology. 2003; 284: R853-R859.

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Related Websites
CCISS-Canadian Space Agency

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image Continuous Blood Pressure Device (CBPD) is a non-invasive device that uses plethysmography to measure blood pressure at the finger. Image courtesy of NASA.
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image Del Mar DigiCorder Model 483 Holter Monitor, continuously records ECG of ambulatory subject. Image courtesy of NASA.
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image MiniMitter Actiwatch is a small wrist or ankle-worn device that simultaneously detects body movement. Image courtesy of NASA.
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image The LBNP Chamber is a simple box design that facilitates entry by the astronaut - a neoprene skirt is secured around the waist and to the front opening of the Chamber. A standard vacuum cleaner controlled by variable voltage output rheostat regulates suction. Image courtesy of NASA.
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image NASA Image: ISS015E14753 - Expedition 15 Flight Engineer Clay Anderson is seen here working with an Actiwatch reader and computer during hardware setup for the Cardiovascular and Cerebrovascular Control on Return from the International Space Station (CCISS) experiment in the U.S. Laboratory, Destiny. The Continuous Blood Pressure Device (CBPD) is also visible in the background.
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image NASA Image: ISS018E009929 - Astronaut Sandra Magnus, Expedition 18 flight engineer, poses for a photo in the Columbus laboratory of the International Space Station.
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image NASA Image: ISS015E14753 - ESA astronaut Clayton Anderson working with a Continuous Blood Pressure Device (CBPD) and computer during hardware set-up for the Cardiovascular and Cerebrovascular Control on Return from the International Space Station (CCISS) experiment.
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