Echocardiographic findings in NATO pilots: do acceleration (+Gz) stresses damage the heart? AGARD, Neuilly-sur-Seine, France.
BACKGROUND: Based on physiologic considerations, observations in animal experiments and the results of a preliminary French study, there has been an aeromedical concern that repeated exposure to high sustained G-forces might have a deleterious effect on the heart. The AGARD Aerospace Medical Panel initiated a multi-national study to address the question. HYPOTHESIS: The study addressed the null hypothesis that "there is no difference in cardiac chamber dimensions, wall thickness or echocardiographic functional parameters between pilots who fly high sustained G (HSG) aircraft and pilots who fly primarily rotary wing or transport aircraft." METHODS: The study was a cross-sectional design comparing echocardiographic parameters in NATO active duty male pilots of HSG aircraft with a control group of transport and rotary wing pilots (CNTL). Some 13 NATO nations participated using a detailed protocol which included specific echocardiographic technical instructions, and procedures for collecting quantitative data on demographic variables including exercise, smoking and flying hours. Data was forwarded on a specially-designed software program to a central data registry. Careful quality control was carried out. RESULTS: Comparing data from 289 HSG pilots with 254 CNTL pilots, when corrected for the covariates, there were no differences for any of 16 echocardiographic parameters including right and left ventricular dimensions and wall thickness, aortic and left atrial dimensions, and tricuspid and mitral inflow velocities. CONCLUSIONS: The results support the null hypothesis. The conclusions are limited to the resolution of the technology employed and to the flight envelopes and +Gz exposure in the current generation of fighter aircraft.