Pii: S0002-9149(96)00179-8

S ignificant acute hemodynamic changes occur in pilots upon transient exposure to high gravity forces (+G,).’ It is not well established, however, whether frequent repeated exposure to high values (up to 9) of acceleration stress may induce structural cardiovascular changes. A French study’ performed among 32 pilots flying high +G, revealed a statistically significant increase in left atria1 dimension and ventricular septal thickness as assessed by echocardiography. A similar echocardiographic study3 was unable to reproduce these results. The present study examines the significance of repeated exposure to high +G, on cardiac dimensions and compares the measurements with those of air crew not exposed to high +G, (non +G,). . . . The study consisted of 2 parts: a cross-sectional study and a longitudinal follow-up study. The first part was a retrospective cross-sectional study in which the echocardiographic studies of 109 graduate air crew members (54 in the +G, group and 55 non +G, group) were reevaluated. These studies were recent consecutive studies performed as part of the routine follow-up program of the echocardiographic laboratory of the Israeli Air Force Aero-Medical Center. This part of the study compared various echocardiographic variables between the high +G, and the non +G, groups. Since not all high +G, members were actively flying, a subanalysis of echocardiographic variables from active aviators (n = 36) was performed for comparison with non +G, personnel. The second part of the study was a retrospective longitudinal follow-up study in which echocardiographic parameters from 2 echocardiographic studies performed several years apart in the same air crew personnel were compared ( 16 high +G, members and 15 non +G, personnel). Exclusion criteria were known cardiovascular or pulmonary disease, use of cardiovascular drugs, and unacceptable echocardiographic quality. All echocardiographic studies were performed by the same cardiac sonographer, and the same procedures and techniques were used in all studies. Twodimensional M-mode guided measurements were performed according to the recommendations of the American Society of Echocardiography. Left ventricular (LV) mass was determined by the cube for-