Automated computer program for radionuclide cardiac output determination.

Radionuclides have provided a safe, reliable, and minimally invasive method for repeated determinations of cardiac output. A completely automated computer program for data analysis is described. Cardiac output values obtained by this technique correlated closely with values obtained by manual determination of the region of interest (r = 0.90 for right-ventricular and 0.98 for left-ventricular outputs, p less than 0.001 for both). Further, cardiac output determined by computer selection of either left-ventricular area of interest or of the "whole heart region" correlated significantly with that simultaneously determined by dye-dilution technique (indocyanine green; r = 0.86, p less than 0.001 for both). The automated approach allows greater objectivity in the selection of the regions of interest, faster turnaround of calculated results, and use of a smaller dose of radionuclide.