Double-Blind Comparison of the Clinical, Hemodynamic, and Electrocardiographic Effects of Sodium Meglumine Ioxaglate or Iohexol During Diagnostic Cardiac Catheterization

The clinical effects and the maximal hemodynamic and electrocardiographic effects of two low-osmolality radiographic contrast media (ioxaglate and iohex ol) were directly compared during diagnostic cardiac catheterization in a double- blind, randomized study in 80 patients. Because small changes were expected after injection of both of these agents, sensitive ECG and intracardiac-pressure- monitoring methods were used, and maximal changes, as well as mean changes in variables, were analyzed. Symptoms were absent, mild, or moderate in 67-77% of patients after left ventriculography and in 97-100% of patients after coronary arteriography. Af ter left ventriculography, maximum and minimum left ventricular systolic pres sure and end-diastolic pressure, the first derivative of left ventricular pressure (dp/dt), heart rate, were significantly altered over the two-minute observation period but were not different from the preinjection values at two minutes after both agents. Small but significant increases in mean aortic pressure, cardiac out put, and pulmonary arterial wedge pressures were seen at two minutes after both agents. Persistent prolongation of QTc interval over two minutes after ioxaglate injec tion was not associated with ectopy or clinical events. After coronary arteriog raphy maximum and minimum aortic pressures, ST and T wave segment displacements, and QTc intervals were significantly altered after both agents, but all variables had returned to preinjection values by two minutes. Compari son of the mean changes over time showed that only QTc intervals were altered after left ventriculography. Direct comparison of the maximum changes between the two agents showed that both contrast agents caused similar hemodynamic and electrocardiographic changes except for small but significantly greater decreases in heart rate with iohexol after left ventriculography and after right coronary arteriography. These contrast agents have small differences in osmolality and significant differences in sodium content. Clinical events of nausea and heat sensation were noted more often in the ioxaglate group, but the frequency did not reach statistical significance. Analyses of maximal changes using sensitive monitoring devices showed that the two agents have substantially similar hemodynamic and elec trocardiographic effects. Analysis of mean changes over time was less sensitive in identifying small, transient changes and differences between the two agents.