Sodium addition to nonionic contrast media. Effects on cardiac monophasic action potentials and hemodynamics in a dog model.

In order to study the electrophysiologic and hemodynamic effects of sodium addition to low-osmolality contrast media during coronary arteriography, eight dogs with surgically opened thoraces were studied. Epicardial monophasic action potentials (MAP) were recorded from the contrast perfused area, using suction electrodes. Six milliliters of iohexol, iohexol with addition of 20 to 80 mmol/L Na+ and ioxaglate, were selectively administered into the left coronary artery. Only minor hemodynamic alterations occurred with the iohexol solutions, whereas ioxaglate decreased left ventricular (LV) inotropy and pressures initially. Iohexol and iohexol containing less than 40 mmol/L Na+ did not change MAP duration significantly. The addition of 80 mmol/L Na+ to iohexol lengthened MAP duration at 25%, 50%, and 90% repolarization by 14 +/- 2, 18 +/- 3, and 18 +/- 5 mseconds, respectively. Ioxaglate lengthened MAP duration by 14 +/- 3, 17 +/- 3, and 26 +/- 8 mseconds, respectively. Thus, during coronary arteriography in dogs, iohexol with sodium added, like ioxaglate, induced regional electrophysiologic changes in the contrast-perfused area of the myocardium, while sodium-free iohexol did not.