Radionuclide techniques in studies of cardiac performance and circulatory changes during anti-hypertensive treatment

A non-invasive radionuclide technique to determine variables in the systematic and pulmonary circulation useful in outpatient studies is described. Indium 113m chloride was chosen as the tracer, and iodine 125 iothalamate may be used for simultaneous determination of the glomerular filtration rate. The counting geometry is discussed at some length. The errors of the method and reproducability seem to be acceptable. The method was tested two groups of healthy subjects, one of which was composed of well- trained athletes, and two groups of patients, one with chronic cardiac insufficiency, the other with primary hypertension. Tables are presented giving hemodynamic data for these groups. It is concluded that the technique gives some useful data, but that further refinement and supplementation is necessary to obtain a guidance in drug therapy. (JIW)