Quantification of tricuspid regurgitation by radionuclide method

Tricuspid regurgitation was quantified with radioisotope. After rapid infusion of sup(99m)Tc-MAA into the cubitus vein, time-activity curves of the superior vena cava, and the right atrium and ventricle, were obtained using a gamma camera and a computer. These curves were analysed by an analog computer according to a circulation model; in which it is assumed that the superior vena cava, and the right atrium and the right ventriculus are independent mixer rooms, and that the tricuspid regurgitation is caused by partial regurgitation of RI ejected from the right ventricle into the right atrium with one-pulse delay. Thus estimated regurgitation rate showed some correlation with clinical findings and results of contrast echography, supporting validation of this method. (Ueda, J.)