Effects of Low Osmolality Contrast Materials on Coronary Hemodynamics, Myocardial Function, and Coronary Sinus Osmolality in Normal and Ischemic States

The effects of intracoronary administration of contrast materials on regional and global left ventricular (LV) function and coronary sinus osmolality were assessed in six anesthetized dogs with segmental myocardial ischemia produced by critical stenosis of the circumflex coronary artery. Effects caused by Renografin (sodium meglumine diatrizoate), two new low osmolality contrast agents (Hexabrix and Hexabrix with added calcium ions), and metrizamide were evaluated. In a nonischemic state, Renografin produced an early (0–10 seconds) decrease in LV contractility followed by a late (10–20 seconds) rebound augmentation in contractility. In the presence of regional ischemia, there was prolongation of the depression of the myocardial contractile state. The monoacid dimer, Hexabrix, demonstrated a similar biphasic response, although the initial depression of myocardial contractility was significantly less than that observed with Renografin. Hexabrix with added calcium ions and metrizamide produced only augmentation in global and regional parameters of LV contractile function. This lack of depressant effects was also observed in the ischemic state. Renografin caused a significantly greater increase in coronary sinus osmolality (Tp) as compared with Hexabrix, Hexabrix-Ca, and metrizamide. The increases in osmolality in response to the latter three contrast agents were statistically indistinguishable.