[Effects of 7 d head-down bed rest on human vectorcardiogram (VCG)].
OBJECTIVE
To study the effects of short-term simulated weightlessness on human vectorcardiogram (VCG).


METHODS
Seven d -6 degrees head-down bed rest (HDBR) was used to simulate weightlessness. Eight healthy males, aged 19-21, served as the subjects. VCG was recorded before and on day 1, 3, 7 of HDBR.


RESULTS
QRS loop in the horizontal plane rotated counterclockwise, while QRS loop in the right sagittal plane rotated clockwise during HDBR (P<0.05 or P<0.01). QRS-T angle in the horizontal and right sagittal plane increased significantly during HDBR.


CONCLUSIONS
Seven d HDBR leads to changes of VCG parameters, which were all in normal ranges and in accordance with the volume changes of atrium and ventricle, but obviously different from those resulted from pathological ventricular thickening and myocardial ischemia.
Tang
Zhi-zhong
ZZ
Institute of Space Medico-Engineering, Beijing, China.
Li
Yong-zhi
YZ
Bai
Gui-e
GE
D000328:Adult; D001510:Bed Rest; D018475:Head-Down Tilt; D006801:Humans; D008297:Male; D014672:Vectorcardiography; D018474:Weightlessness Simulation