Reduction of the risk of ventricular fibrillation in the isolated rabbit heart by small additions of electrolytes to non-ionic monomeric contrast media.

Perfusion of the isolated rabbit heart with solutions (350 mg I/ml) of the non-ionic contrast media iohexol and iopentol, both containing NaCl (20 mmol/l), caused a significantly lower frequency of ventricular fibrillation (VF) than solutions without NaCl. Iohexol or iopentol with NaCl (10 mmol/l) caused an intermediate frequency of VF. Iohexol with 10 or 20 mmol NaCl/l caused about the same frequency of VF as iohexol solutions with about the same total electrolyte concentration but with electrolyte composition as that of Krebs' solution. At 320 mg I/ml, solutions of iohexol (20 mmol NaCl/l), iodixanol (20 mmol NaCl/l) and ioxaglate (155 mmol Na/l) all produced a significantly lower frequency of VF than iohexol without NaCl. Ioxaglate caused the largest and iodixanol the smallest decrease in contractile force of the media. The investigation suggests that the small risk of VF from non-ionic monomeric media can be further reduced by adding a small amount of sodium chloride or of the electrolytes of Krebs' solution.