Acceleration tolerance of asymptomatic aircrew with mitral valve prolapse and significant +Gz-induced ventricular dysrhythmias
Whinnery, J.E.; Hickman, J.R.
Aviation Space and Environmental Medicine 59(8): 711-717
1988
ISSN/ISBN: 0095-6562 PMID: 3178618 Document Number: 317455
The +Gz tolerance of asymptomatic aircrew with mitral valve prolapse (MVP) who had advanced Lown grade ventricular ectopy (multiformed or paired premature ventricular contractions and ventricular tachycardia) during +Gz-stress testing was investigated. The +Gz tolerance to an aeromedical centrifuge stress testing protocol revealed that these individuals had slightly lower +Gz tolerance for each of the different types of +Gz profiles, with the gradual onset of +Gz while using an anti-G straining maneuver (GOR-S) tolerance being significantly lower (p less than 0.05). As a subgroup of a larger group of individuals with MVP, these MVP individuals with advanced ventricular ectopy had an increased incidence of +Gz-induced loss of consciousness and motion sickness. The advanced ventricular ectopy occurred before, during, and after +Gz stress; however, there was a tendency for the ectopy to occur in the post +Gz stress period. The post +Gz stress period is a period of high parasympathetic (vagal) tone, and these findings may indicate that these individuals are in some way sensitive to high vagal tone. Acceleration stress testing is a valuable tool in the aeromedical evaluation of asymptomatic individuals desiring to fly fighter aircraft. Advanced ventricular ectopy not seen in other clinical testing (treadmill and ambulatory monitoring) occurred in these individuals. The current results suggest that these individuals with MVP and advanced ventricular ectopy are not currently prime candidates for flying fighter aircraft, not only because of the ventricular ectopy, but because of decreased +Gz tolerance and susceptibility to +Gz-induced loss of consciousness.