Histamine release following the administration of iodinated contrast media during cardiac catheterization.

This study was motivated by the discrepancy in the results of published studies on the amount of histamine released following the intravascular administration of iodinated contrast media (ICM) in humans. From a group of patients due to undergo cardiac catheterization, we selected 45 subjects with no history of atopy. A central blood sample (left ventricle) was taken from each subject before and at various times following the administration of the ICM. We determined total and basal histamine levels in every sample. We did not find any significant difference in the total histamine concentration between the samples taken before and after the administration of the ICM; but the basal histamine concentration rose from 5.32 ng/ml to 11.26 ng/ml (p less than 10(-9)). This increase was inversely proportional to the time that had elapsed between the administration of the ICM and the taking of the sample (p less than 0.01). We believe that the inconclusiveness of the results from studies on histamine release following the administration of ICM may be explained by the dilution and inactivation of histamine in the systemic circulation.