Carbon Dioxide for Angiographic Imaging

Iodinated contrast is well established as an effective agent in angiographic imaging. It provides excellent imaging in most angiographic procedures. It can be utilized in a wide range of diagnostic and interventional procedures. Diagnosticians and interventionalists routinely utilize iodinated contrast and have developed a comfort level with these agents with decades of experience. Iodinated contrast agents have continued to evolve over the years with newer agents providing more patient comfort and safety. Despite these improvements, all iodinated contrast agents remain nephrotoxic, carry risk of allergic reactions including anaphylaxis, and can be expensive. The nephrotoxic effects often necessitate longer hospitalizations. Patients who experience contrast-induced nephropathy have much worse short- and long-term outcomes (including increased mortality), and medical costs are profoundly increased.

In the October issue of Vascular Disease Management, James G. Caridi, MD, FSIR, discusses the increasing utilization of CO₂ as a contrast agent. He explains the science behind CO₂ angiography. He teaches practical methods of utilizing this form of contrast with a series of example cases. Dr. Caridi’s article is comprehensive, scientific, and practical. I believe this is a “must read” article.

Carbon dioxide is inexpensive, has no nephrotoxicity, and carries no risk of severe allergic response. The diminished viscosity as compared to iodinated contrast facilitates diagnostic angiography via smaller catheters and can allow imaging that is actually superior to iodinated contrast in some cases. The potential exists to easily perform diagnostic peripheral angiography via very long, small catheters because of the decreased viscosity compared to iodinated agents. This could decrease the risk of arterial bleeding and the risk of catheters obstructing diseased access vessels. It could also facilitate shorter observation periods with outpatient diagnostic procedures. Carbon dioxide has shortcomings as well as benefits. It typically requires slightly higher radiation doses. The patient must not move during image acquisition. Overlying bowel gas may complicate imaging of the abdominal vessels.

Prior attempts at utilizing CO₂ were cumbersome, required heavy equipment with poor safety mechanisms, and had less than ideal sterility. New dedicated CO₂ angiographic devices are small, easy to use, sterile, and low cost, and they have built-in safety mechanisms to avoid inadvertent injection of large amounts of pressurized CO₂ into a patient. Venous and peripheral arterial imaging utilizing CO₂ has become safe and easy to use, and they should have widespread availability. I believe this must be available for patients with renal insufficiency and will be available routinely in angiographic suites in the future.