title: Effects of a new nonionic and a conventional ionic contrast agent on coronary sinus ionized calcium and left ventricular hemodynamics in dogs.
abstract: 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 less than 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 end-diastolic 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) mEq/liter, 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.(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000818:Animals; D002118:Calcium / Q000032:analysis; D003287:Contrast Media / Q000494:pharmacology*; D003331:Coronary Vessels / Q000032:analysis / Q000187:drug effects*; D003974:Diatrizoate Meglumine / Q000494:pharmacology; D004285:Dogs; D006352:Heart Ventricles / Q000187:drug effects*; D006439:Hemodynamics / Q000187:drug effects*; D007472:Iohexol; D014283:Triiodobenzoic Acids / Q000494:pharmacology
chemical_list: D003287:Contrast Media; D014283:Triiodobenzoic Acids; D003974:Diatrizoate Meglumine; D007472:Iohexol; D002118:Calcium