Comparison of echocardiographic changes after short- and long-duration spaceflight.
BACKGROUND
Previous echocardiographic studies of astronauts before and after short-duration (4-17 d) missions have demonstrated a decrease in resting left ventricular stroke volume, but maintained ejection fraction (EF) and cardiac output. Similar studies before and after long-duration (129-144 d) spaceflight have been rare and their overall results equivocal.


METHODS
Echocardiographic measurements (M-mode, 2-D, and Doppler) were obtained from short-duration (n = 13) and long-duration (n = 4) crewmembers to evaluate cardiac chamber sizes and function.


RESULTS
Compared with short-duration astronauts, long-duration crewmembers had decreases in EF (+6+/-0.02 vs. -10.5+/-0.03%, p = 0.005) and percent fractional shortening (+7+/-0.03 vs. -11+/-0.07%, p = 0.015), and an increase in left ventricular end systolic volume (-12+/-0.06 vs. +39+/-0.24%, p = 0.011).


CONCLUSIONS
These data suggest a reduction in cardiac function that relates to mission duration. As the changes in BP and circulating blood volume are reported to be similar after short- and long-duration flights, the smaller EF after longer spaceflights may be due to a decrease in cardiac function rather than altered blood volume.
Martin
David S
DS
Wyle Laboratories, Houston, Texas, USA.
South
Donna A
DA
Wood
Margie L
ML
Bungo
Michael W
MW
Meck
Janice V
JV
D000328:Adult; D002302:Cardiac Output; D018493:Cardiovascular Deconditioning; D004452:Echocardiography; D015150:Echocardiography, Doppler; D006801:Humans; D008297:Male; D008875:Middle Aged; D013026:Space Flight; D013318:Stroke Volume; D013997:Time Factors; D014893:Weightlessness