CARDIOVASCULAR-RESPONSES AFTER IONIC AND NONIONIC MAGNETIC-RESONANCE CONTRAST-MEDIA IN RATS WITH ACUTE MYOCARDIAL-INFARCTION

RATIONALE AND OBJECTIVES. Contrast media may have quantitatively or even qualitatively different effects in the presence of underlying pathologic states compared with normal states. This study was designed to examine and compare the hemodynamic effects of bolus administration of ionic (gadopentetate dimeglumine) and nonionic (gadodiamide) magnetic resonance (MR) contrast media in rats subjected to acute myocardial infarction. METHODS. Acute myocardial infarction was induced in two groups of rats (n=20) by ligating the left coronary artery. Each animal received four bolus injections, iso-osmolar glucose followed by three incremental doses of either an ionic or a nonionic MR contrast agent (0.1, 0.3, and 0.5 mmol/kg). The effects of iso-osmolar glucose and each dose of MR contrast agent on the cardiovascular system were monitored for 15 minutes. RESULTS. Iso-osmolar glucose injection did not cause hemodynamic parameters to significantly differ from baseline values. Nonionic gadodiamide produced no significant hemodynamic effects at all injected doses compared with iso-osmolar glucose. However, ionic gadopentetate dimeglumine caused significant deleterious hemodynamic effects in a dose-dependent fashion. Gadopentetate dimeglumine caused depression in left ventricular (LV) systolic pressure and systemic arterial pressure. at the lowest dose (0.1 mmol/kg). At the maximum dose (0.5 mmol/kg), gadopentetate dimeglumine decreased systolic arterial pressure by 48%, rate-pressure product by 55%, LV end systolic pressure by 48%, rate of rise of LV pressure (dP/dt) by 55%, and heart rate by 10%. LV end diastolic pressure increased by 46%. Arrhythmias were observed in 20% (2/10) of the animals after injection of gadopentetate dimeglumine, but not after gadodiamide. CONCLUSIONS. Compared with ionic gadopentetate dimeglumine, nonionic gadodiamide is a hemodynamically safe MR contrast agent in this experimental model when it is injected as a rapid bolus at high doses and in the presence of acute myocardial infarction.