Selection of a contrast agent in the cardiac catheterization laboratory

The evolution of contrast material for intravascular use has been directed toward the development of better-tolerated agents. Currently, a variety of such "dyes" are available for coronary angiography and left ventriculography. Considerable animal and human investigation suggests that significant differences exist between the families of contrast agents that relate to patient tolerance. The newer low osmolality agents (especially the nonionic agents) produce less perturbation of the homeostatic state, which is clinically manifested by a lessened incidence of side effects, including those of a hemodynamic and electrophysiologic nature. While controversy continues over the cost/benefit ratio of the low osmolality contrast agents compared to traditional high osmolality agents, the former are rapidly becoming the community standard for diagnostic and especially therapeutic cardiologic procedures. Accepting the advantages of the low osmolality contrast agents, differences between the ionic dimers and the nonionic agents have been examined. Both experimental and clinical data suggest superiority of the nonionic agents. Although controversy still surrounds the issue of thromboembolism with the nonionic agents, accumulating evidence fails to support a clinically significant relation. The choice of contrast material is the responsibility of the invasive cardiologist. While the benefits of low osmolality agents are most obvious in high-risk patients, experience with large-scale intravenous studies suggests that the choice of contrast agent is a better discriminator of adverse reaction than is preprocedural risk stratification.