Reducing the risk of ventricular fibrillation by adding sodium to ionic and non-ionic contrast media with low iodine concentration. Coronary perfusion of the isolated rabbit heart with meglumine diatrizoate or iopentol at 140 mg I/ml and 0-154 mmol Na+/l.

To compare the fibrillatory propensity of low concentrations of contrast media (140 mg I/ml) the ionic, ratio 1.5, contrast medium meglumine diatrizoate, the non-ionic, ratio 3, medium iopentol and equimolar glucose (0.37 mol/l) were perfused into 35 isolated rabbit hearts. The three substances were compared at three levels of sodium concentration (0.77 and 154 mmol Na+/l). Meglumine diatrizoate without sodium caused the highest frequency of ventricular fibrillation (91%). Iopentol without sodium caused a significantly lower frequency of ventricular fibrillation (17%). Glucose without sodium caused no fibrillation. The addition of 77 or 154 mmol Na+/l significantly decreased the frequency of ventricular fibrillation of both meglumine diatrizoate (3% and 6%) and iopentol (0%). Meglumine diatrizoate with sodium added caused a lower frequency of ventricular fibrillation than iopentol without sodium. At equal sodium concentrations (0.77 and 154 mmol Na+/l) glucose caused smaller reduction in contractile force and heart rate than iopentol, and iopentol caused smaller reduction in contractile force and heart rate than diatrizoate. It is concluded that addition of sodium to ionic or non-ionic contrast media without sodium decreases the risk of ventricular fibrillation.