Alterations in heart rate and rhythm at urography with sodium diatrizoate.

One hundred and thirty-five consecutive patients referred for urography were monitored electrocardiographically before, during and after injection of 60 ml Hypaque 45% (sodium diatrizoate 45% w/v) over 60 seconds. The injection produced a significant increase in heart rate, while venepuncture alone had no such effect. Twenty-nine (21%) patients developed minor arrhythmias and 6 (4.4%) major arrhythmias following the injection. Major arrhythmias occurred in the older age groups and were more frequent in males. An abnormal baseline rhythm strip had significant predictive value in determining the development of further arrhythmias.