Risk of thromboembolism during diagnostic and interventional cardiac procedures with nonionic contrast media

Article Abstract:

Contrast media are chemicals used in patients undergoing diagnostic or interventional procedures to help visual the area being examined or treated. They are frequently used during cardiac procedures, and are injected directly into the coronary system. Traditionally, ionic contrast media have been used, although they are associated with a number of side effects. Nonionic contrast media have been recently introduced as an alternative to ionic contrast media. Although they do not cause the side effects of ionic media, recent reports have suggested they may encourage blood clot development. This study compared nonionic contrast media with ionic contrast media in the effect each had on blood clot formation. It also examined if using heparin along with the contrast media could prevent clot formation. In the first part of the study, blood clot formation was evaluated in a catheter-syringe system and a catheter-steerable wire system, using various contrast agents and blood either treated or not treated with heparin. In the catheter-syringe system, blood clot formation occurred with the nonionic media, but not with the ionic media when blood without heparin was used. No clots formed when blood treated with heparin was used. In the catheter-wire system, blood clot formation occurred with all types of media when blood without heparin was used. Blood clot weights were greater for all contrast media in the catheter-wire system than in the catheter-syringe system. When heparin-treated blood was used in the catheter-wire system, no clotting occurred. In the second part of the study, 12 dogs were subjected to coronary procedures using contrast media, with 6 of the dogs also receiving heparin. Blood clot formation occurred in heparin-treated dogs receiving nonionic contrast media, but not in those receiving ionic contrast media. These results indicate that nonionic contrast media may increase the risk for blood clot formation during cardiac procedures, but the risk can be eliminated by also using heparin. (Consumer Summary produced by Reliance Medical Information, Inc.)

Management, Risk factors, Thromboembolism, Heparin, Blood clotting, Blood coagulation

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Nephrotoxicity from contrast material in renal insufficiency: ionic versus nonionic agents

Article Abstract:

Contrast materials are chemicals that increase the ability of a diagnostic technique to detect and define the problem being evaluated. These materials can cause side effects, including damage to the kidneys. Recently, many studies have examined the side effects of a new set of contrast materials, low-osmolality nonionic agents, as compared with the traditionally used ionic contrast agents. The newer agents have been shown to cause fewer side effects of certain types. However, no study has compared the two types of agents in causing contrast material-induced nephrotoxicity (CN), a major cause of kidney failure. CN is more likely to occur in patients with renal insufficiency, kidneys that are already not functioning properly. An indication of this disorder is elevated blood creatinine levels. This study compared the two types of contrast materials in causing CN in patients with high creatinine levels. The study randomly placed 122 patients who were undergoing contrast-enhanced evaluations and who had high serum creatinine levels into two groups, one receiving an ionic contrast agent and the other receiving a nonionic contrast agent. Final data were obtained from 101 patients. Results showed that 7 of 50 patients receiving the ionic agents (14 percent) had a large increase in creatinine levels following the procedure, while 1 of 51 (2 percent) receiving the nonionic agent had such increases. Three of nine diabetic patients in the ionic group had such increases, while none of the 16 diabetic patients in the nonionic group had increases. No cases of severe CN occurred. These results indicate that ionic contrast agents are more likely to contribute to renal insufficiency than are nonionic agents. It is not certain that this effect is strong enough to warrant recommending that only nonionic agents be used. (Consumer Summary produced by Reliance Medical Information, Inc.)

Causes of, Kidneys, Kidney, Chronic kidney failure

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Thrombin generation in nonclottable mixtures of blood and nonionic contrast agents

Article Abstract:

Contrast agents are chemicals given to patients undergoing diagnostic or other medical procedures to enhance visualization of the tissue examined or treated. Ionic contrast agents have been commonly used, but because of adverse side effects, nonionic contrast agents have been developed and introduced. Although the nonionic agents do avoid some of the problems associated with ionic agents, there is concern that they may cause other adverse affects such as blood clot formation. This study measured the generation of thrombin, a protein involved in blood clotting, in different mixtures of blood and contrast agents. Four different agents, iopamidol, iohexol, ioversol (all nonionic agents) and ioxaglate (an ionic agent) were tested at three concentrations. The concentrations of the agents were high enough to prevent blood clotting. Thrombin levels were measured with a chromogenic assay. No thrombin was detected for any concentration of ioxaglate, but thrombin was detected when each of the three nonionic agents were mixed with blood in a 1:1 ratio. The amount of thrombin present increased with time after mixing. These results indicate that nonionic contrast agents may cause thrombin formation, and thus, increase the risk for blood clots. Heparin, an anticoagulant, might be added to nonionic agents to prevent this effect. (Consumer Summary produced by Reliance Medical Information, Inc.)

Measurement, Thrombin

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