Echocardiographic evaluation of USAF pilots with Aortic Insufficiency(AI): Is the flying of High Performance Aircraft(HPA) detrimental to pilots with AI?

ABSTRACT

BACKGROUND AND METHOD: For decades, the presence of aortic insufficiency (AI) has been considered a potential hazard in military aviation and has generally excluded aircrew from high performance flight. The cardiovascular effect of repeated exposure of high +Gz forces associated with AI is largely unknown. To evaluate whether the flying of High Performance Aircraft (HPA) was detrimental to subjects with AI, we performed a retrospective review. we studied 32 asymptomatic patients in whom 16 of them had flying time with AI in HPA(Group I), others(GroupII, Control Gr.) in Low-G Aircraft(LGA). Among them, the data of 24 patients were available, 12 in group I., and 12 in group II. The two groups were matched for age, severity of AI, and flying time. RESULTS: Interval echocardiographic, and cineangiographic studies were obtained over a mean period of 4.6+/-2.6 years in group I and 5.9+/-4.2 years in group II (range, 0.9 to 12.7 years) and mean flying time with AI of 528.1+/-435.0 hours in group I and 865.0+/-816.1 hours in group II (range, 50 to 2290 hours). By paired-t test, there were no significant differences between both groups in left ventricular end-diastolic dimension (LVEDD), end-systolic dimension (LVESD), aortic dimension (Ao.D) and fractional shortening (FS) by echocardiography (p>0.05) and by multiple linear regression, there were no significant interval changes of above values in Gr. I according to increasing of flying time with AI (p>0.05). Visual grade by doppler echocardiography or aortic cineangiography increased 1 patient in Gr.I and 2 patients in Gr.II within no more than one grade. CONCLUSION: Thus, this study demonstrated that 1) Quantitative echocardiographic measurements such as LEVDD, LVESD, Ao.D and FS didn't show significant interval change in Gr.I.2) A single subject with a minor increase in AI severity together with no difference between the HPA and LPA groups argue for a relatively chronic effect of high G exposure in aircrew with mild AI.