Effects of a new nonionic and a conventional ionic contrast agent on coronary sinus ionized calcium and left ventricular hemodynamics in dogs

• Published in: Journal of the American College of Cardiology 1985-10, Vol.6 (4), p.845-853
• Main Authors: Bourdillon, Patrick D., Bettmann, Michael A., McCracken, Sara, Poole-Wilson, Philip A., Grossman, William
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Calcium - analysis; Contrast Media - pharmacology; Contrast media. Radiopharmaceuticals; Coronary Vessels - analysis; Coronary Vessels - drug effects; Diatrizoate Meglumine - pharmacology; Dogs; Heart Ventricles - drug effects; Hemodynamics - drug effects; Iohexol; Medical sciences; Pharmacology. Drug treatments; Triiodobenzoic Acids - pharmacology
• ISSN: 0735-1097; 1558-3597
• DOI: 10.1016/S0735-1097(85)80493-9

Transient myocardial depression associated with intracoronary injections of contrast medium has been attributed to hypertonicity and to calcium binding. To further assess the importance of calcium binding, a new technique for continuous monitoring of coronary sinus ionized calcium with an intravascular calcium-selective electrode was used. With this calcium-selective electrode the effects of intracoronary injection in dogs of a conventional ionic contrast agent, sodium meglumine diatrizoate (Renografin-76), and a new nonionic agent, iohexol, were assessed and compared. Left ventricular pressure was measured with a micromanometer catheter. After bolus injection of 0.2 ml/kg body weight of Renografin-76 (n =10), coronary sinus pCa increased by 0.27 from 2.98 ± 0.02 to 3.25 ± 0.03, indicating a decrease in ionized calcium from 2.0 to 1.1 mEq/liter. With iohexol (n=9), pCa increased by only 0.05 ± 0.01 (p < 0.001), indicating a decrease in ionized calcium from 2.0 to 1.8 mEq/liter. Peak changes occurred approximately 6 seconds after injection. Renografin-76 caused a marked decrease in left ventricular systolic pressure (140 ± 7 to 106 ± 8 mm Hg) and in heart rate (122 ± 7 to 101 ± 5 beats/min) with an increase in enddiastolic pressure (5 ± 1 to 12 ± 1 mm Hg), whereas iohexol did not significantly alter these variables. Using Renografin-76 with calcium added to achieve an ionized calcium level of 2 (n = 4), 4 (n = 4) or 6 (n = 4) mEgAiter, the changes in coronary sinus pCa were abolished and the hemodynamic changes attenuated. These findings indicate that Renografin-76 results in greater myocardial depression than the new nonionic agent iohexol. This is due largely to lowering of the ionized calcium in the coronary circulation resulting mainly from calcium binding by the calcium-chelating additives in Renografin-76, although hypertonicity also plays a role.