The effect of head-up tilt with and without anti-G suit inflation on continuous left ventricular function using miniaturized radionuclide ventriculography

grantor: University of TorontoAicrew flying high performance aircraft must contend with high rates and magnitudes of headward acceleration (+Gz). Exposure to such forces may result in visual disturbances as well as G-induced loss of consciousness (G-LOC) due to impaired cerebral blood perfusion. The initial 15 seconds of rapid onset rate (ROR) +Gz exposure are critical for flight safety since they correspond to the lag period of the baroreceptor-mediated response mounted by the cardiovascular system to offset the effects of +Gz exposure. Anti-G suit inflation during +Gz exposure is frequently used to attenuate the effects of high rates of headward acceleration. Head-up tilt (HUT) using a tilt table also generates a baroreceptor-mediated response similar to that seen during +Gz exposure. The purpose of this experiment was threefold. Left ventricular performance in response to HUT with and without anti-G suit inflation was determined using miniaturized nuclear probe. Secondly, the experiment measured the shift of the left ventricle in response to HUT. Thirdly, the experiment provided a basis for validating the Cardioscint$\sp{\rm TM}$ (Oakfield, UK) nuclear probe system against the VEST system (Capintec, NJ). (Abstract shortened by UMI.)M.Sc