Quantitation of left ventricular regurgitant fraction by first pass radionuclide angiocardiography

A new technique for quantitating left ventricular regurgitant fraction from first pass radionuclide angiocardiographic studies is described. The technique involves measurement of the total number of counts ejected from the right and left ventricles (CR and CL, respectively). In the absence of any valve insufficiency and equal counting efficiency from each ventricle, CR/CL = 1. In the presence of mitral or aortic insufficiency, or both, the regurgitant fraction can be calculated as (CL -- CR)/CL, if no right ventricular regurgitation is present. In this report the theoretical derivation of the method and practical aspects of measuring CL and CR are presented. The technique was tried in a small group of 5 normal volunteers, 7 patients studied with cardiac catheterization without regurgitation and 22 patients with mitral or aortic insufficiency, or both. Excellent correlation was found with cardiac catheterization data in the latter group (r = 0.86, n = 22). This method appears to be a simple and accurate technique for measuring left ventricular regurgitant fraction due to mitral or aortic valve disease, or both.