EFFECTS OF ALTERATIONS IN SYSTOLIC PRESSURE ON RADIONUCLIDE MEASUREMENTS OF LEFT-VENTRICULAR FILLING DYNAMICS

To determine the effects of steady-state left ventricular systolic pre ssure alterations on radionuclide measures of left ventricular filling dynamics, we studied 15 normal patients and 17 patients with nonische mic heart disease. Micromanometer left ventricular pressures and compu ter assisted forward gated radionuclide angiograms were acquired simul taneously. Right atrial pacing maintained heart rates constant during the baseline condition and methoxamine and nitroprusside infusions. Di astolic filling dynamics, peak filling rate and time to peak filling r ate were calculated using a three harmonic Fourier analysis of the lef t ventricular time-activity curves. Left ventricular systolic pressure increased to 165 +/-25 mmHg with methoxamine (p < 0.001) and decrease d to 106 +/- 18 mmHg with nitroprusside (p < 0.001) from a baseline va lue of 133 +/- 16 mmHg. Radionuclide left ventricular filling dynamics did not change significantly. Thus, we conclude that radionuclide mea surements of left ventricular filling dynamics are not affected by mod est, steady-state alterations in left ventricular systolic pressure an d can therefore be useful for the assessment of left ventricular diast olic function during interventions which may also affect left ventricu lar systolic pressure.