Hemodynamic and electrophysiologic effects of low osmolar contrast agents during coronary angiography in the dog and the rabbit.

The electrophysiological tolerability of ioxaglate (160 mgI/ml) and iohexol (140 mgI/ml) was assessed in rabbits (n = 12 per group). There was a significant induction of ventricular fibrillation in the group given iohexol. An explanation for this phenomenon could be the lack of sodium in this preparation. Ioxaglate, iopamidol and iohexol (all at 320 mgI/ml) were also compared during coronary angiography in the dog (n = 10) after bolus administration, using the carotid approach (5 and 8 ml-0.5 ml/sec). Each dog received all the compounds in the left coronary artery and selectively in the left anterior descending artery, at random. Four dogs had lethal ventricular fibrillations after iohexol. Iopamidol and iohexol induced significant bradycardia in comparison with saline. A biphasic effect on myocardial contractility was observed with all contrast media: a short-lasting, typical decrease in dP/dt was seen with ioxaglate by the end of injection, while iohexol and iopamidol caused a similar negative inotropic effect in some cases (25%) after increasing dP/dt. The positive inotropic effect was greater with iopamidol and iohexol than with ioxaglate (p less than 0.05). The possible clinical consequences of the lack of sodium in contrast media preparations and of the changes in myocardial function are discussed in the light of the present results.