The Hemodynamic Effects of the Injection of Contrast Medium (Isopaque)

Abstract

During studies evaluating the hemodynamic changes following the intravascular injection of new contrast agent, Na and N-methylglucamine metrizoate (Isopaque 440), it was found that within sec. after injection of the contrast medium into the heart and great vessels there was a prompt decrease of hematocrit, due to the loss of red cell water and a reduction of red cell volume. Observations by light microscopy of the effect of contrast medium on red cells indicated that these changes occurred rapidly enough to be completed during the initial transit of the contrast-medium-blood mixture. These agents alter the permeability of the cell membrane to K. Such changes in permeability were not produced by 5% sodium chloride, despite a similar rapid reduction of cell volume. It was suggested that similar changes may occur in endothelial cells. It is possible that the efflux of ions from these cells may have an effect on the downstream receptor cells and be responsible for certain of the hemodynamic changes observed following the injection of contrast medium.