ECG changes and arrhythmias induced by ionic and non-ionic contrast media during coronary arteriography in dogs.

Metrizamide (non-ionic, Nyegaard Co., Oslo, Norway), diatrizoate (ionic) and metrizoate (ionic) were selectively injected into the right or the left canine coronary artery. ECG was recorded and external defibrillation was performed whenever ventricular fibrillation occurred. During left coronary injections metrizamide prolonged the PQ and QT intervals less than did the diatrizoate. During right coronary injections metrizamide affected the QT interval less than either diatrizoate and metrizoate. During right coronary infusions metrizamide caused significantly fewer incidences of ventricular fibrillation than diatrizoate. In clinical coronary arteriography it is assumed that metrizamide would generate fewer AV blocks than diatrizoate and fewer incidences of ventricular fibrillation after right coronary injections than diatrizoate. Changes in the PQ and QT intervals during coronary arteriography can be used as tests to predict the safety of new contrast media.