The Effects of Iopamidol on Myocardial Metabolism A Comparison with Renografin-76

Abstract

The purpose of this study was to determine the effects of a new nonionic contrast agent (iopamidol) on myocardial metabolism and to compare these effects with those of Renografin-76. Eighteen patients with symptoms of ischemic heart disease undergoing elective left ventriculography and coronary angiography were included in a randomized, double-blind study of iopamidol (n= 8) and Renografin-76. (n= 10). Coronary sinus and arterial blood samples were obtained for free fatty acids, lactate, and oxygen content before and for the 20-minute period following the left ventriculogram. Coronary blood flow was determined by the thermodilution technique. In both groups there was a significant fall in the arterial level of free fatty acids following the left ventriculogram (P < 0.005). In the Renografin-76 group there was a significant fall in myocardial lactate uptake (P < 0.025) at 5 minutes following ventriculography, which persisted and was still significant at the end of the sampling period (P < 0.025). In the iopamidol group there was significant increase in myocardial lactate uptake at 5 minutes after the contrast ventriculogram (P < 0.01) Although the increase in lactate uptake persisted at the 20-minute sampling period, it was no longer statistically significant after 5 minutes. The physiologic response to a fall in arterial free fatty acids is an increase in myocardial lactate extraction. The increase in lactate uptake following the injection of iopamidol follows this physiologic response. Following Renografin-76 ventriculography, there was a decrease in lactate uptake associated with the fall in arterial free fatty acids; this fall in lactate extraction may be related to myocardial ischemia. These metabolic parameters indicate that iopamidol is a less toxic contrast medium for the myocardium than Renografin-76.