Quantitative assessment of aortic valvular insufficiency by radionuclide angiography.

Gated blood pool cardiac scintigraphy was used to assess quantitatively the degree of aortic insufficiency in 25 patients. The difference between the number of counts, corrected by time and background, at end-diastole and end-systole (stroke counts) in the left ventricle and right ventricle were used as indices of total (forward plus regurgitant) stroke volume and forward stroke volume respectively. From these, two radionuclide parameters were measured: 1) regurgitant fraction = 100 x (left ventricular stroke counts--right ventricular stroke counts)/left ventricular stroke counts; and 2) left ventricular/right ventricular stroke volume ratio = left ventricular stroke counts/right ventricular stroke counts. A good correlation was found between the regurgitant fraction calculated by contrast and Doppler studies and the two radionuclide parameters: regurgitant fraction (r = 0.81) and stroke volume ratio (r = 0.80). In 20 patients without valvular heart disease studied by the radionuclide method, the results of regurgitant fraction (11 +/- 10 percent, mean +/- SD) and stroke volume ratio (1.13 +/- 0.12) closely approached the theoretical normal values of 0 and 1.00, respectively. These results validate previous observations and demonstrate the value of blood pool cardiac scintigraphy in the noninvasive quantitation of aortic insufficiency in the clinical setting.