A study of dromotropic effects of intracoronary arterial injections of various contrast materials in anesthetized dogs.

Abstract

In two groups of open-chest, pentobarbital-anesthetized dogs, cardiac dromotropic effects of contrast materials were studied, using His bundle recordings. Retrograde injections (3 and 6 ml) in the left anterior descending coronary artery were done with iodinated compounds (ioxaglate solution, iopamidol, diatrizoate solution) and iso-osmolar glucose solutions as controls. Administration of 6 ml of contrast material and glucose solution resulted in a significant prolongation of StH interval with no change in HV; on QRS the increase was significant but more slight and more brief. In group 1 (n = 8) the maximum effect (6 ml) on atrioventricular conduction was significantly greater with diatrizoate solution than with iso-osmolar glucose solution and with ioxaglate solution: + 25.1 ± 2.8%, + 15.0 ± 3.6%, + 10.7 ± 1.8%, respectively. On QRS interval, the maximum increase was significant after ioxaglate (+ 8.7 ± 3.1%) and after diatrizoate (+ 13.5 ± 5.0%). There were no significant differences among the effects of these different solutions. In group 2 (n = 8), at 6 ml, ioxaglate, iopamidol, and their iso-osmolar glucose solution exerted similar and significant dromotropic effects: on StH, + 4.6 ± 0.8%, + 4.4 ± 1.2%, + 5.6 ± 1.0%, respectively; on QRS, + 6.7 ± 2.7%, + 5.9 ± 2.1%, + 5.7 ± 2.2%, respectively. The importance of the osmolarity factor on intracardiac conduction is emphasized by comparison of the osmolality of diatrizoate (1700 mOsm/kg), which is higher than those of ioxaglate (580 mOsm/kg) and iopamidol (740 mOsm/kg). Direct toxicity of the molecule possibly also plays a role, since the effects of diatrizoate were significantly greater on atrioventricular conduction than those of isoosmotic glucose solution.