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Contrast agents in angiocardiography.

1984; BMJ; Volume: 52; Issue: 4 Linguagem: Inglês

10.1136/hrt.52.4.361

1468-201X

R Hayward, Peter Dawson,

Cardiac Arrest and Resuscitation

Uncertainty still surrounds the mechanisms of severe idiosyncratic reactions to the intravascular radiological contrast agents.Hyperosmolality itself causes changes due to fluid shift from extravascular to intravascular compartments.' 2 Contrast agents also exert direct actions on mechanical and electro- physiological cardiac function, which may be regarded as cardiotoxic.These may be detectable even during intravenous injection,34 some 5% of normal individuals developing identifiable electrocardiographic changes during intravenous urography.They are clearly most important m cardiac mvestigations m which contrast is injected directly into cardiac cham- bers or coronary arteries, particularly since most patients undergoing such investigations have cardiac disease and may be particularly vulnerable to changes in cardiac rhythm and pump function.Recently, new low osmolality contrast agents have become available.5By definition, these produce smal- ler osmolality mediated fluid shifts and fewer haemodynamic effects.Available data suggest that they may also possess lower intrinsic cardiotoxicity.We review what is known of the adverse cardiovascu- lar effects of radiological contrast agents and consider the evidence that the new agents may be safer. Chemistry and pharmacologyConventional intravascular radiological contrast agents are salts of triiodinated benzoic acid derivatives (Fig. la).The cation is either methylglucamine (meg- lumine) or sodium, or a mixture of both.Conventional materials in use differ only in respect of the balance of these cations and in the detailed structure of the substituted side chains RI and R2.In terms of general systemic toxicity, the various commercial compounds are clearly similar, although the precise cationic composition is important in cardiotoxicity (see below).The need to obtain high contrast density in conve