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© Lab. of Experimental Cardiology, Leuven, Belgium - 2003

The Belgian ODISSEA mission: The Belgian ODISSEA mission: changes in cardiovascular variability changes in cardiovascular variability

during and after space flightduring and after space flight

Frank Beckers, Bart Verheyden, André E Aubert Laboratory of Experimental Cardiology

Univ. Hospital Gasthuisberg, Leuven, Belgium

These data were presented at the 24th Annual International Gravitational Physiology Meeting, 2003, Santa Monica, CA, USA

Annual meeting of the Belgian Working Group of Pacing and Electrophysiology 2003, Oostende, Belgiumand Europace 2003, Paris, France


These data were presented at the 24th Annual International Gravitational Physiology Meeting, 2003, Santa Monica, CA, USA

Annual meeting of the Belgian Working Group of Pacing and Electrophysiology 2003, Oostende, Belgiumand Europace 2003, Paris, France

• The data presented in the following slides are part of the preliminary analysis carried out on the data of the Belgian ODISSEA mission

• Further information can be obtained with the authorsFrank.Frank.beckersbeckers@@medmed..kuleuvenkuleuven.ac.be.ac.be

Bart.Bart.verheydenverheyden@@medmed..kuleuvenkuleuven.ac.be.ac.beAndreAndre..aubertaubert@@medmed..kuleuvenkuleuven.ac.be.ac.be

Laboratory of Experimental CardiologyLaboratory of Experimental CardiologyCampus Gasthuisberg O/NCampus Gasthuisberg O/N

Herestraat 49Herestraat 493000 Leuven3000 Leuven

BelgiumBelgium


Effects of microgravity


Problems of spaceflight


Problems of spaceflightFluid shift towards thorax

• Reduction in circulating blood volume (plasma volume ↓ → blood cell mass ↓)

• ↓ stroke volume and cardiac output• ↑ risk of cardiac arrhythmia• ↑ venous compliance (legs), ↓ muscle blood flow• Attenuated baroreflex sensitivity• Altered central integration of cardiovascular

control mechanisms


After return to gravity ± 2/3rd of astronauts suffer from orthostatic intolerance

= inability to stand upright without feeling dizzy or loss of consciousness

• problem in case of emergency evacuation• problem after long term space mission to e.g. Mars

⇒


Related problem on earth

• Patients with unexplained loss of consciousness (syncope)– caused by dysfunction of cardiovascular control

mechanisms


Aims of the study• To study the evolution of autonomic

cardiovascular control in space• To follow the recovery of autonomic

cardiovascular control after return to earth

Ultimate goal

• To develop a model of cardiovascular changes induced by microgravity using indices of cardiovascular variability.


Cardiovascular control

BRAIN STEMsympathetic parasympathetic

VASOMOTOR TONE HEART RATE

BLOOD PRESSURE

COTPR

arterial baroreceptors

n. vagus

SV

-

-+ ++ (-)

+-

BAROREFLEX

α (β) β

Heart Rate VariabilityBlood Pressure Variability

Baroreflex Sensitivity


BP

(mmHg)

TimeVariation in heart rate and blood pressure provide information about cardiovascular modulation by the autonomic nervous system

* sympathetic modulation* vagal modulation


• Time domain: mean RR, SD, pNN50 …

• Frequency domain:

Analysis of HRV

Low Frequency power (LF) [0.04-0.15 Hz] ~ sympathsympathetic modulationetic modulation

baroreflexbaroreflex

High Frequency power (HF) [0.16-0.4 Hz]~ vagal modulationvagal modulation

Total power [0.0078-0.5 Hz] ~ global global autonomautonomicic modulationmodulation

Akselrod et al. Science (1981)


Study set-up

• 3 cosmonauts• Continuous ECG• Continuous BP

– 45 days before launch– flight days 5 and 8– After return: from day 1 -> day 25

• Earth-bound measurements: standing, supine and sitting

15 minutes baseline recordingSampling rate: 100 Hz


Results heart rate standing

3233333332N =

R+25R+19R+15R+9R+4R+2R+185L-45

Mea

n R

R (m

s) 1200

1100

1000

900

800

700

600

500

60 bpm

100 bpm

Mean RR during spaceflight is higher compared to the control measurements before flight.

Beckers et al. J Grav. Physiol, in press 2003


Results HRV standing

3233333332N =

R+25R+19R+15R+9R+4R+2R+185L-45

LF p

ower

(ms^

2/H

z) 4000

3000

2000

1000

03233333332N =

R+25R+19R+15R+9R+4R+2R+185L-45

HF

pow

er (m

s^2/

Hz) 700

600

500

400

300

200

100

0

3233333332N =

R+25R+19R+15R+9R+4R+2R+185L-45

Perc

enta

ge L

F (%

) 80

70

60

50

40

303233333332N =

R+25R+19R+15R+9R+4R+2R+185L-45

Perc

enta

ge H

F (%

) 16

14

12

10

8

6

4

2

Sympathetic modulation Vagal modulationBeckers et al. J Grav. Physiol, in press 2003


Results blood pressure0

0

00

0

0

00

0

0

45 5 8 1 2 4 9 15 19 25 45 5 8 1 2 4 9 15 19 25 45 5 8 1 2 4 9 15 19 25

Supine Sitting Standing

LF power +/- SEM (mmHg^2)

0

50

100


Results blood pressure

HF

pow

er +

- 2 S

EM

30

20

10

0

HF

pow

er +

- 2 S

EM (m

s^2) 30

15

0

0

5

45 5 8 1 2 4 9 15 19 25 45 5 8 1 2 4 9 15 19 25 45 5 8 1 2 4 9 15 19 25

Supine Sitting Standing

HF power +/- SEM (mmHg^2)

0

15

30


Conclusions• Space environment causes heart rate to slow down. • This is caused by a strong vagal predominance of

heart rate modulations. HF power of HRV is increased in space and LF power of HRV is decreased.

• After return to earth the autonomic modulation of heart rate is depressed, as well in LF power as in HF power.


Conclusions• Blood pressure during spaceflight is lower

compared to standing position, but similar to BP in sitting position

• LF power of BPV pre- and post-flight shows no significant differences

• HF power of BPV pre- and post-flight shows no significant differences


Conclusions• Recovery of autonomic heart rate control after

spaceflight is very slow. Even after 25 days, the autonomic modulation of the heart is not yet at the level of 45 days before the flight.

• Long-term clinical monitoring of astronauts after spaceflight could be important

• The behaviour of the baroreflex mechanism and the relation with orthostatic intolerance has yet to be determined


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The Belgian ODISSEA mission: changes in cardiovascular ...eea.spaceflight.esa.int/attachments/spacestations/ID456d531f1d298.pdf · The Belgian ODISSEA mission: changes in cardiovascular