Female exposure to high G: echocardiographic evaluation for chronic changes in cardiac function
Albery WG, Ten Eyck RP, Wolfe MAviat Space Environ Med 1998; 69:857-61
Abstract
Background: Significant changes in cardiac pre-load and post-load are generated by a number of factors present during the operation of high performance aircraft. These include high levels of +Gz, positive pressure breathing and anti-G straining maneuvers. Centrifuge subjects are exposed to these same factors in doses that are comparable to their operational counterparts. The question of whether such exposures produce long-term adverse effects on the heart has not been definitively answered. Methods: In an effort to further address this issue, a longitudinal study was conducted on 18 newly recruited centrifuge panel members (7 males and 11 females) who did not have a previous history of significant high +Gz exposure. In order to document the cumulative long-term effects of high +Gz exposure and G protection measures, baseline echocardiographic studies were conducted prior to any +Gz exposure on the Dynamic Environment Simulator (DES) centrifuge. The echocardiograms were repeated after each panel member completed eight sessions of indoctrination. These follow-up echos were performed after all 18 subjects had been exposed to over 45 min (cumulative) of sustained acceleration to 2 G. Each subject served as his/her own control. All studies were evaluated independently by a cardiologist who was blinded to the order in which the studies were performed. Although complete echocardiographic studies were performed, only the parameters identified as significant in prior studies were evaluated. Results: No significant differences were found between the initial and follow-up echo parameters. No significant differences were found between male and female responses. Conclusions: We found no significant differences in cardiac function after 45 min (cumulative) of exposure to 2G in men or women. These subjects will be monitored during a longitudinal study throughout their centrifuge subject career.
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Table of Contents for Volume 69, Number 9 of the ASEM journal.