Left ventricular function changes during pharmacological and physiological interventions and routine activities monitored in healthy volunteers by a portable radionuclide probe (VEST).
A miniaturized radionuclide cardiac probe incorporated in a semi-rigid plastic chest garment has made ambulatory left ventricular (LV) function evaluation possible, with gated nuclear data being stored on tape together with electrocardiographic data, for subsequent off-line processing. After red blood cell labelling with 555 MBq (15 mCi) 99mTc and standard gated blood pool imaging in 45 degrees LAO, we performed a continuous monitoring of LV function in 20 healthy male volunteers (age range: 22-25 years), in resting control conditions as well as during activities (standing, walking, climbing stairs) and after interventions (isosorbide dinitrate intake, Trendelenburg position, inflation of cuffs around the thighs). VEST-monitoring proved to be a reliable method that gave reproducible results: changes of ejection (EF) in basal conditions were lower than 5% in 95% of the patients. Changes in LV function caused by daily activities were easily demonstrated. While standing effected no significant EF changes, walking and climbing increased EF by 6.9% (p less than 0.05) and 21.2% (p less than 0.05) respectively. Changes in LV volumes caused by alterations in venous return were also demonstrated. Compared with baseline, Trendelenburg increased end-diastolic volume (EDV) by 2.9% while isosorbide dinitrate and inflation of cuffs decreased it by 5.7% and 2.2% respectively.