Influence of radiographic contrast media on myocardial tissue oxygen tension: NaCl-controlled, randomised, comparative study of iohexol versus iopromide in an animal model.

It was tested whether a bolus injection of 10 ml radiographic contrast medium (iopromide vs. iohexol), compared to a 10 ml NaCl bolus and administered into the left anterior descending artery (LAD) of farm pigs, influenced the tissue pO2 in the territory of this artery. The radiographic contrast media and the NaCl bolus were given in randomised order. The mean pO2 LAD fell from initially 40.3+/-10.9 mmHg to a minimal value of 22.5+/-8.9 mmHg 241+/-44 sec after injecting the iopromide bolus, with this result representing a mean decrease of 44.2% (p=0.0003). The initial pO2 (baseline) was reached again after approximately 10 minutes. The mean pO2 LAD fell from the initial value of 34.5+/-14.6 mmHg to a minimal value of 29.4+/-13.9 mmHg 171.7+/-11.9 sec after injection of the iohexol bolus, with this result representing a mean decrease of 14.8% (p=0.0003). The baseline pO2 was reached again after approx. 5 minutes. The drop in the pO2 after iopromide administration was significantly larger than that after iohexol (p=0.0001), and also the time after which the baseline pO2 is reached again was considerably shorter for iohexol (p=0.001). The two radiographic contrast media did not influence the tissue pO2 in either the territory of the right coronary artery or in skeletal muscle. Injection of a NaCl bolus into the LAD influenced neither the tissue pO2 of the territory of the LAD nor that of the RCA or of the skeletal muscle. The tissue temperature, heart rate and the systolic and diastolic blood pressure were not affected during the three injections. Injection of radiographic contrast media into a coronary artery can lead to a distinct, local microcirculatory impairment in the myocardial territory supplied by this artery. In this case, the extent of the microcirculation impairment seems to depend not only on the viscosity of the contrast media but rather also on its chemotoxicity.