OpNom: Integrated CardiovascularExperiment Overview
Cardiac Atrophy and Diastolic Dysfunction During and After Long Duration Spaceflight: Functional Consequences for Orthostatic Intolerance, Exercise Capability and Risk for Cardiac Arrhythmias (Integrated Cardiovascular) aims to quantify the extent, time course and clinical significance of cardiac atrophy (decrease in the size of the heart muscle) associated with long-duration space flight and identify the mechanisms of this atrophy and the functional consequences for crewmembers who spend extended periods of time in space.Principal Investigator(s)
Johnson Space Center, Human Research Program, Houston, TX, United States
National Aeronautics and Space Administration (NASA)Sponsoring Organization
Human Exploration and Operations Mission Directorate (HEOMD)Research Benefits
Information PendingISS Expedition Duration:
March 2009 - September 2013Expeditions Assigned
19/20,21/22,23/24,25/26,27/28,29/30,31/32,33/34,35/36Previous ISS Missions
Integrated Cardiovascular began operations during ISS Expedition 19/20. The investigators also have extensive previous experience with cardiovascular investigations performed on Space Shuttle and Mir.
Cardiac atrophy (a decrease in the size of the heart muscle) appears to develop during space flight or its ground-based analogues leading to diastolic dysfunction (abnormal left ventricular function in the heart) and orthostatic hypotension (drop in blood pressure upon standing). Such atrophy may have been a potential mechanism for the cardiac arrhythmias (irregular heart rhythms) identified in some crewmembers after long-duration exposure to microgravity aboard the Mir Space Station. Recent studies suggest that cardiac atrophy may be progressive, without a clear plateau over at least 12 weeks of bedrest, and thus may be a significant limiting factor for extended duration space exploration missions. This experiment aims to quantify the extent, time course and clinical significance of cardiac atrophy and identify its mechanisms. The functional consequences of this atrophy are also determined for cardiac filling dynamics, orthostatic tolerance under both normal gravity (Earth) and fractional gravity (Mars and moon) conditions, exercise tolerance, and arrhythmia susceptibility both in space on board the International Space Station (ISS) and following return to Earth.
The Integrated Cardiovascular experiment investigates the magnitude of left and right ventricular atrophy associated with long-duration space flight (using magnetic resonance imaging or MRI), relates this type of atrophy to measures of physical activity and cardiac work inflight, and determines the time course and pattern of the progression of cardiac atrophy inflight using cardiac ultrasound. This investigation also determines the functional importance of cardiac atrophy for cardiac diastolic function and the regulation of stroke volume (volume of blood pumped by the heart in one contraction) during gravitational transitions, as well as identifies changes in ventricular conduction, depolarization and repolarization during and after long-duration space flight, and relates these factors to changes in heart mass and morphology (shape and form).
Once the magnitude, time course, and inciting factors for cardiac atrophy are determined, effective countermeasures currently being developed by the investigators in parallel ground-based experiments may be applied, focused on normalizing cardiac work and volume during long-duration space flight. Upon completion of these experiments, a number of important risks for long-duration space flight, such as cardiac function and arrhythmia risk, may either be deemed manageable by current preventive measures, or clearly defined for future countermeasure research.Earth Applications
The information obtained from these space flight experiments has relevance for patients after prolonged confinement to bedrest, or chronic reduction in physical activity, as well as for patients with disease processes that alter cardiac stiffness such as congestive heart failure, ischemic heart disease, and normal ageing.
A total of twelve subjects are required for this investigation. Inflight scanning sessions are planned on flight day 14 (FD14) ± 4 days, FD30 ±5 days, FD75 ±5 days, FD135 ±5 days, and Return minus (R-) 15 -4/+15 days. Ambulatory blood pressure, Holter and activity monitoring is required within one week (preferably three days) of each session. The total number of sessions required depends on the length of the mission. Both an operator and a subject are required for the ultrasound scans along with real-time video downlink to enable remote guidance by ground experts.Operational Protocols
Inflight, resting echocardiograms using the HRF Ultrasound are performed on FD14, FD30, FD135, and return minus 15 days (R-15) using real-time remote guidance. On FD75, an exercise echocardiogram session is performed with measurements taken before and after exercise. Both the resting and exercise sessions are preceded or followed by 24 hours of ambulatory blood pressure and 48 hours of Holter and activity monitoring. For these sessions, subjects apply electrodes and then don the HRF Holter Monitor 2, ESA Cardiopres, and two Actiwatch Spectrums (one at the waist and one at the ankle). After removal, the data from the experiment hardware is downloaded to the HRF PC and downlinked to the ground. Inflight exercise and medication logs are obtained through data sharing.
On the ground, resting echocardiograms are obtained between launch minus 21 days (L-21) and L-7, and again at return plus 7 days (R+7). An exercise echocardiogram is performed between L-75 and L-60 and again at R+4 and R+14. Preflight, ambulatory blood pressure (for 24 hours), Holter and activity monitoring (for 48-hours) are conducted between L-75 and L-60, and again between L-21 and L-7. The session is repeated upon crew return to Earth (R+0).
Cardiac MRI (with Magnetic Resonance Spectroscopy and gadolinium delayed enhancement) is obtained between L-75 and L-60. Postflight MRIs occur in the R+3 to R+6 timeframe, and between R+22 and R+30. Graded tilt tests with echocardiograms are performed between L-75 and L-60, and again on R+0. Exercise and medication logs are obtained both before and after flight, preferably via data sharing.
Through ISS Increment 29, six subjects have completed pre-, in-, and postflight data collection for the Integrated Cardiovascular experiment. Preflight data collection is complete for three additional subjectsand inflight data collection is in progress. Data analysis is on-going; two “poster” presentations of preliminary results were presented at the IAA Symposium in Houston, Texas in April of 2011 and are referenced in the conference proceedings.
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Fu Q, Cooke WH, Pawelczyk JA, Zuckerman JH, Blomqvist CG, Levine BD, Ertl AC, Cox JF, Diedrich A, Zhang R, Ray CA, Baisch FJ, Smith ML, Iwase S, Mano T, Saito M, Sugiyama Y, Eckberg DL, Iwasaki K, Lane LD, Buckey, Jr. JC, Robertson RM, Robertson D, Biaggioni I. Cardiovascular and sympathetic neural responses to handgrip and cold pressor stimuli in humans before, during and after spaceflight. Journal of Physiology. 2002 08/30/2002; 544.2(2): 653-664. DOI: 10.1113/jphysiol.2002.025098.
Perhonen MA, Zuckerman JH, Levine BD. Deterioration of left ventricular chamber performance after bed rest: "Cardiovascular deconditioning" or hypovolemia?. Circulation. 2001; 103: 1851-1857. DOI: 10.1161/01.CIR.103.14.1851.
Bleeker MW, Pawelczyk JA, De Groot P, Hopman M, Levine BD. Effects of 18 days of bed rest on leg and arm venous properties. Journal of Applied Physiology. 2004; 96(3): 840-847. DOI: 10.1152/japplphysiol.00835.2003.
Fu Q, Witkowski S, Okazaki K, Levine BD. Effects of Gender and Hypovolemia on Sympathetic Neural Responses to Orthostatic Stress. American Journal of Physiology: Regulatory, Integrative and Comparative Physiology. 2005; 289(1): R109-R116. DOI: 10.1152/ajpregu.00013.2005.
Pawelczyk JA, Cooke WH, Zuckerman JH, Ertl AC, Blomqvist CG, Levine BD, Cox JF, Diedrich A, Zhang R, Biaggioni I, Ray CA, Baisch FJ, Smith ML, Iwase S, Mano T, Saito M, Sugiyama Y, Eckberg DL, Iwasaki K, Lane LD, Buckey, Jr. JC, Robertson D. Human muscle sympathetic neural and haemodynamic responses to tilt following spaceflight. Journal of Physiology. 2002 January; 538(1): 331-340. DOI: 10.1113/jphysiol.2001.012575.
NASA Image: ISS028E036079 - Astronaut Mike Fossum uses the Ultrasound 2 to scan the heart of crewmate Satoshi Furukawa for the Integrated Cardiovascular experiment.
NASA Image: ISS030E155942 - NASA astronaut Dan Burbank, Expedition 30 commander, prepares to use the Integrated Cardiovascular (ICV) Resting Echo Scan on a crew member (out of frame) at the Human Research Facility (HRF) rack in the Columbus laboratory of the International Space Station.