PRINCIPAL INVESTIGATOR (S): G. Wycliffe Hoffler, Robert L. Johnson, Arnauld E. 



Nicogossian, Stuart A. Bergman, and Margaret M. 

 Jackson 



EXPERIMENT TITLE/NUMBER : Vectorcardiographic Results from M092 



PROGRAM/MISSION : Skylab 



CLASSIFICATION : Human 



DISCIPLINE(S) : Cardiovascular 



OBJECTIVES : To determine the degree and the time course of cardiovascular 

 adaptation under zero-gravity conditions. 



PROTOCOL : Vectorcardiograms were recorded via a modified Frank lead system on 

 all crewmen of the three Skylab missions in conjunction with the Lower Body 

 Negative Pressure experiment. Data were analyzed by a specially developed 

 computer program (VECTAN). Design of the test sequences allowed direct 

 comparisons of supine resting, Earth based (reference) vectorcardiograms with 

 those taken during lower body negative pressure stress and those obtained at 

 rest in orbit, as well as combinations of these conditions. 



EQUIPMENT : Lower Body Negative Pressure Device, vectorcardiograph. 



RESULTS : No adverse vectorcardiographic changes occurred during flight. 

 Analysis of inflight measurements showed significantly increased PR interval, 

 QT interval, QRS maximum vector magnitude, QRS-Eigenloop vector magnitude , and 

 QRS-T angle. Recovery measurements (R+0) showed significantly elevated vector 

 magnitudes for QRS maximum, QRS-Eigenloop and T. Other parameters measured 

 (QRS duration, QT interval, P maximum vector magnitude, ST maximum vector 

 magnitude, ST slope) were not significantly changed inflight or postflight. 



CONCLUSIONS : Vectorcardiograms have shown several consistent changes 

 apparently related to space flight. There were changes in temporal intervals, 

 vector magnitudes and their orientations, and certain derived parameters, 

 presumably as a consequence of altered autonomic neural inputs upon the 

 myocardial conduction system and/or of major fluid shifts known to have 

 occurred inflight. All observed measurements were well within accepted normal 

 limits and are considered to represent adaptive phenomena rather than 

 pathological conditions. 



PUBLICATIONS : 211, 27^, 275 



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