Pulmonary plethysmography using radionuclide chest scintigraphy

The cardiac stroke volume which is ejected during systole into the pulmonary vasculature increases its blood volume. The ratio between the pulmonary systolic blood volume increase and stroke volume depends on the compliance of the pulmonary blood vessels. The relative pulmonary systolic blood volume increase was measured by using ECG-gated chest scintigrams, from the total radiation counts in regions of interest, which included the left ventricle and the two lungs. On the average, the systolic increase of the total pulmonary radiation was found to be 56% of the systolic decrease of the left ventricle radiation.