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EXPERIMENT INFORMATION

Cardiovascular Adaptation to Weightlessness (Rhythm)
Principal Investigator
Research Area:
Cardiovascular physiology
Pulmonary physiology
Species Studied
Scientific Name: Homo sapiens Species: Human

Description
OBJECTIVES:
Even after short-duration space flights the incidence of postflight orthostatic intolerance, being one of the aspects of cardiovascular deconditioning, is about 20 percent and long-duration space flight even markedly increases the incidence of orthostatic intolerance. Despite many studies, the origin or physiopathogenesis of the cardiovascular deconditioning syndrome still remains unclear. A better knowledge would be of tremendous importance, as orthostatic intolerance could result in dramatic situations upon return to earth in case of emergency evacuation.

Heart rate fluctuates constantly. These fluctuations are called heart rate variability and they are modulated by the autonomic nervous system. In a similar way blood pressure also varies on a beat-to-beat basis and its fluctuations are defined as blood pressure variability. It has become clear over the years that analysis of these fluctuations provides a window on the action of the autonomic nervous system of the cardiovascular system. Continuous feedback is established through pressure sensors in the baroreflex system. The objectives of this study were:

  1. To evaluate changes in cardiovascular function induced by long-term periods in space.
  2. To compare altered functions to pre- and post-flight data.
  3. To compare continuous weightless effects on the cardiovascular system to short period (induced during parabolic flights) and to simulations (HOI: head out of water).

The hypothesis underlying this study is that cardiovascular control and adaptation mechanisms undergo significant but reversible changes due to long-term space flights. These changes will also influence post-flight cardiovascular function. These hypotheses will be confirmed or rejected by comparing ECG, blood pressure variability and flow data pre-, in flight and postflight. These mechanisms are also related to the ageing process to pathologies on earth (i.e. syncope) and to fluid shift resulting from heart disease.

The objectives of this study were - after obtaining continuous, short recordings (+ or - 15 minutes) of ECG and blood pressure (non-invasive) during normal gravity (control baseline measurements before and after the space flight in 1g) in supine, sitting and standing positions:
1. To obtain short time recordings in space during a Soyuz mission starting from the 3rd day at the station (awake) using Cardioscience equipment (ECG and blood pressure).
2. Compute heart rate variability (HRV) and blood pressure variability (BPV) parameters from the ECG and blood pressure signals on an almost beat-to-beat resolution with time- and frequency domain methods and non-linear analysis.
3. From HRV and BPV deduct information about cardiovascular function and adaptation and also baroreflex response during long-term space flight.
4. Compare the evolution of autonomic function during pre-, in flight and postflight periods, to monitor a possible restoration of autonomic function.


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Publications
Beckers F, Verheyden B, and Aubert AE. Evolution of heart rate variability before, during and after spaceflight. Journal of Gravitational Physiology. 2003; 10: 107-108.

Vandeput S, Widjaja D, Aubert AE, and van Huffel S. Adaptation of autonomic heart rate regulation in astronauts after spaceflight. Medical Science Monitor. 2013. January 04; 19: 9-17. [pubmed.gov]

Keywords
Heart rate
Blood pressure
Orthostatic intolerance
Tilt-table test
Electrocardiography

Data Information
Data Availability
Archive is complete. No data sets are available for this experiment. Please Contact LSDA if you know of available data for this investigation.

Parameters
Blood pressure
Blood pressure variability
Heart rate
Heart rate variability
Orthostatic intolerance

Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
Expedition 7 04/25/2003 10/27/2003 185 days
Expedition 8 10/18/2003 04/29/2004 195 days

Additional Information
Managing NASA Center
Johnson Space Center (JSC)
Responsible NASA Representative
Johnson Space Center LSDA Office
Project Manager: Pamela A. Bieri
Institutional Support
European Space Agency (ESA)
Proposal Date
04/25/2002