PRINCIPAL INVESTIGATOR(S) : Stuart A. Bergman, G. Wyckliffe Hoffler, and 



Robert L. Johnson 



EXPERIMENT TITLE/NUMBER : Evaluation of the Electromechanical Properties of 



the Cardiovascular System After Prolonged 

 Weightlessness 



PROGRAM/MISSION : Skylab 2, 3, 4 



CLASSIFICATION : Human 



DISCIPLINE(S) : Cardiovascular 



OBJECTIVES : To evaluate the electromechanical properties of the 

 cardiovascular system. 



PROTOCOL : Cardiovascular electromechanical measurements were collected on all 

 returning Skylab crewmen at rest ana during both lower body negative pressure 

 and exercise stress testing. These data were compared with averaged responses 

 from multiple pref light tests. Systolic time intervals and first heart sound 

 amplitude changes were measured. Clinical cardiovascular examinations 

 included phonocardiograms, apexcardiograms , pneumograms, and carotid pulse 

 analyses . 



EQUIPMENT : Lower body negative pressure device, phonocardiographic system, 

 vectorcardiograph, strain gage, displacement transducer. 



RESULTS : In all crewmen, there were significant postf light changes in 

 ejection time index, pre-ejection period, and in the ratio of the two. All 

 systolic time intervals returned to preflight values within one month. There 

 were decreases in first heart sound amplitude responses to lower body negative 

 pressure. The systolic time interval data were consistent with a reduced 

 stroke volume. There was a marked reduction in all heart sounds, precordial 

 movement, and arterial pulsations. 



CONCLUSIONS : The results suggest that there is a functional impairment to 

 venous return and perhaps a myocardial factor in the overall decreased 

 tolerance to stress in the postf light period. All changes noted returned to 

 normal within 30 days postf light. Therefore, the processes seem transient and 

 self-limited. The cardiovascular system seems to adapt to 0-g, and is capable 

 of readaption to one-g after long duration space flight. Repeated exposures 

 to 0-g also appear to have no detrimental effects on the cardiovascular 

 system. 



PUBLICATIONS : 40, 41, 42 



