A method for the estimation of right ventricular volume by equilibrium radionuclide angiography

To develop a method for estimating right ventricular volume and to assess right ventricular volume at rest, we studied 45 persons with equilibrium radionuclide angiography. The study group comprised 15 normal control subjects (5 with atypical chest pain and normal coronary angiograms) and 30 patients with coronary heart disease (CHD). Each coronary patient and 5/15 control subjects had both right and left heart catheterization studies with intracardiac pressure measurements within 24 hours of the radionuclide study. Using a previously described method for generating right ventricular volume curves, we used the counts at end-diastole, corrected for frame time, the total number of processed heart beats, and blood radioactivity to derive right ventricular end-diastolic volume units. All normal controls (group 1) had a right ventricular ejection fraction greater than or equal to 0.40, with a right ventricular volume index less than or equal to 5.8. The CHD patients consisted of two subgroups: group 2 (N = 20) and group 3 (N = 10), with right ventricular end-diastolic pressures less than 10 mm Hg and greater than or equal to 10 mm Hg, respectively. In group 2, 19/20 had a normal right ventricular ejection fraction, and 18 had a normal end-diastolic volume. In group 3, 4/10 patients had a depressed ejection fraction (less than .40) and 9/10 an increased end-diastolic volume. We conclude that right ventricular volume can be estimated with radionuclide angiography, and that dilation may precede depression of the right ventricular ejection fraction in some patients with CHD.