Sodium-calcium balance in coronary angiography and experimental experience with iodixanol

The present short review describes the physiological effects of rapid transient changes in cardiac extracellular ions (electrolytes) caused by the bolus of x-ray contrast medium (CM) during coronary angiography. The underlying hypothesis is that as the molecular and osmolal toxicities of modern CM is low, cardiac side-effects result mainly from secondary and biphasic ionic changes which occur during the initial washout phase and during the later reintroduction of blood. In particular, the washout pattern for sodium (Na) and calcium (Ca) has great influence on cardiac function. Thus the Na-Ca exchange system of the cardiac cell membrane plays a pivotal role in controlling intracellular Ca and contractility during very brief coronary bolus injections of both nonionic and ionic CM. The nonionic dimeriodixanol is hyposmolal without an additive. Animal experiments demonstrate the value of taking myocardial Na-Ca relationships into careful consideration when adding ions to iodixanol and formulating an isotonic CM like Visipaque.