Noninvasive quantitation of valvular regurgitation by gated equilibrium radionuclide angiography

R-wave synchronous equilibrium radionuclide angiography (RNA) is a noninvasive method that provides time-activity curve count information proportional to ventricular volumes and is used for relative volume comparisons within the left or right ventricle to derive the ejection fraction. Comparison of the ventricular count output between both ventricles may permit quantitation of the relative amount of valvular regurgitation, i.e., the regurgitant fraction. We performed resting gated RNA in 30 consecutive patients undergoing cardiac catheterization and quantitative contrast ventriculography for aortic or mitral valvular regurgitation. RNA regurgitant fraction correlated well with cardiac catheterization regurgitant fraction (r = 0.85). In 11 patients imaged before and 1-4 months after successful valve replacement, the regurgitant fraction declined from 0.68 ± 0.11 to -0.09 ± 0.13 (p < 0.001). In 20 control patients without valvular regurgitation, the calculated regurgitant fraction did not exceed 0.20. We conclude that valvular regurgitation may be accurately detected, quantitated and followed serially after therapeutic intervention using gated RNA.