Prevention of anaphylactoid reactions in high-risk patients receiving radiographic contrast media

Risks and complications of coronary angiography: a comprehensive review

Coronary angiography and heart catheterization are invaluable tests for the detection and quantification of coronary artery disease, identification of valvular and other structural abnormalities, and measurement of hemodynamic parameters. The risks and complications associated with these procedures relate to the patient’s concomitant conditions and to the skill and judgment of the operator. In this review, we examine in detail the major complications associated with invasive cardiac procedures and provide the reader with a comprehensive bibliography for advanced reading.

Emergency pretreatment for contrast allergy before direct percutaneous coronary intervention for ST-elevation myocardial infarction

Patients with previous adverse contrast reactions occasionally present with ST-segment elevation myocardial infarction. Whether they can undergo catheterization safely using current contrast and medications is unknown. We reviewed catheterization laboratory records of all 501 patients (January 2005 to December 2006) presenting with ST-segment elevation myocardial infarction who underwent emergency coronary angiography. Six patients (1.2%) reported a previous contrast reaction including rash, acute bronchospasm, or anaphylaxis. All received a combination of intravenous steroids and H1 and H2 blockers in the emergency department or catheterization laboratory before catheterization. None of these had complications or evidence of allergy in any patient. In conclusion, some patients with previous contrast reaction may undergo emergency catheterization without adverse consequences, although the safety of this approach has not been proved.

[Optimal timing of contrast enhancement in coronary CT angiography using the Bolus-tracking method]

Negative product value for coronary artery disease is 98% to 99%. Therefore, the number of unnecessary cardiac catheterization procedures is reduced as the usefulness of CT systems for examination of the coronary arteries improves. In the bolus-tracking method, in which an ROI is placed in the ascending aorta to trigger scanning, scanning may not be performed at the optimal time of contrast enhancement depending on the patient. In addition to identifying the causes of this problem, we have developed a new method in which ROIs are placed in the right ventricle and left atrium to trigger scanning when the concentrations of contrast medium in the right ventricle and left atrium become equal. The two methods were then compared and evaluated. In the scan method, in which an ROI is placed in the ascending aorta, the reason for non-optimal scan timing is considered to be that the time required for contrast medium injected via an antecubital vein to reach the heart varies depending on the individual patient(approximately 3 times the variation of our method)followed by a delay of approximately 5 seconds between the scan trigger time and the actual scan start time. In the scan method in which scanning is triggered when the concentrations of contrast medium in the right ventricle and left atrium become equal, scanning can be performed at the time of peak enhancement regardless of differences in the time required for the injected contrast medium to reach the target region or differences in the injection rate, demonstrating the usefulness of this method.

Amiodarone Use in Patients with Documented Allergy to Iodine-Containing Compounds

The popularity of amiodarone has grown due to its effectiveness in converting arrhythmia and its formulation availability. Formulations of the drug also contain iodine; the iodine content is 75 mg in a 200-mg tablet of amiodarone and 18.7 mg/ml in the intravenous solution. Approximately 10% of the iodine content of oral amiodarone is released into the circulatory system and may increase the risks of hypersensitivity reactions in iodine-sensitive patients. Documented allergies to contrast media or shellfish should not imply that a patient is allergic to iodine. Reactions to contrast media are likely due to the high osmolar or ionic content of the dye. The primary allergen in shellfish that stimulates allergic reactions is tropomyosin. Although amiodarone can cause thyroid disorders due to the high iodine load delivered to the body with each dose, no known association exists between amiodarone and reactions to contrast media or shellfish. Three patients whose medical charts listed an allergy to iodine were administered amiodarone for chemical cardioversion of arrhythmia to normal sinus rhythm. No anaphylactic or anaphylactoid reactions were observed in any of the patients during oral or intravenous amiodarone administration. In patients with true iodine hypersensitivity, however, the potential for such reactions exists.

Comparison of cellular mechanisms underlying histamine release from rat mast cells induced by ionic and nonionic radiographic contrast media

PURPOSE

To determine the cellular mechanisms underlying mast cell histamine release induced by ionic and nonionic radiographic contrast media.

MATERIALS AND METHODS

Histamine release from rat pulmonary mast cells was measured after incubation with various radiographic contrast media. The cellular cAMP content was determined by an enzymatic immunoassay.

RESULTS

Both ionic and nonionic contrast media stimulated the histamine release, although the former was more potent than the latter. Dibutyryl cAMP suppressed histamine release evoked by ionic but not nonionic contrast media in a manner dependent on A kinase. The cellular cAMP content was lowered only by ionic contrast media. However, a secretory phospholipase A2 inhibitor p-bromophenacyl bromide inhibited both ionic and nonionic contrast media-evoked histamine releases.

CONCLUSION

We demonstrated for the first time the difference and similarity in the cellular mechanisms underlying histamine release induced by ionic and nonionic contrast media, in which the reduction in cAMP was specific for ionic materials and the activation of secretory phospholipase A2 may be common to both agents.

Safe administration of contrast media: what do physicians know?

BACKGROUND

Radiographic contrast media (RCM) are among the most commonly used materials in medicine. Nevertheless, there seems to be a little agreement between current practice and accepted guidelines regarding their adverse reactions, the indications for premedication, and use of low-osmolar contrast agents (LOCAs). Misconceptions exist regarding the relationship between hypersensitivity to RCM and foods and medications that contain iodine.

OBJECTIVE

To evaluate physicians' knowledge, misconceptions, and attitudes regarding the use of RCM and the prevention of their adverse reactions.

METHODS

Physicians from university-affiliated general hospitals were asked to complete an anonymous questionnaire on RCM.

RESULTS

A total of 157 physicians (45%), including radiologists, internists, pediatricians, surgeons, and primary family physicians, agreed to participate. All physicians demonstrated limited knowledge regarding adverse effects of RCM and the patients who might be at increased risk of developing them. Most physicians were not familiar with accepted guidelines for using premedication and LOCAs. Misconceptions regarding the association between the use of drugs or foods that contain iodine and adverse effects to RCM were common among all physicians.

CONCLUSIONS

The level of knowledge about the adverse reactions of RCM among physicians is unsatisfactory, which may result in unwarranted use of expensive LOCAs or premedication in healthy patients. Alternatively, physicians' failure to use these measures when indicated may endanger patients. Despite the lack of association between adverse effects to RCM and safe consumption of iodine-containing substances, physicians continue to harbor these misconceptions. Educational programs that may improve physicians' knowledge are urgently needed.

Coronary artery bypass grafting and aortic valve replacement with cold cardioplegia in a patient with cold-induced urticaria

BACKGROUND

Cold-induced urticaria is an uncommon but well described phenomenon in which a spectrum of responses may result from exposure to a cold stimulus. Patients with cold-induced urticaria who require cold cardiopulmonary bypass are at risk for hypotensive episodes.

OBJECTIVE

To describe the case of a 69-year-old man with documented cold-induced urticaria who required aortic valve replacement and coronary artery bypass surgery.

METHODS

After receiving a prophylactic anti-inflammatory regimen, the patient underwent cold cardiopulmonary bypass. After systemic cooling to 32 degrees C, cold blood cardioplegia was administered at 4 degrees C to obtain initial cardiac standstill. Thirty minutes before anticipated rewarming, anti-inflammatory medications were again administered. After rewarming to 37 degrees C for more than 33 minutes, he was successfully weaned from cardiopulmonary bypass without inotropic or pressor support and with normal pulmonary compliance. The prophylactic regimen was continued postoperatively.

RESULTS

The patient was extubated 11 hours after surgery, and with the exception of a brief, self-limited episode of atrial fibrillation, his course was uneventful. He experienced no urticaria, angioedema, or hypotension and was discharged home on the fourth postoperative day.

CONCLUSIONS

Although it is likely that the need for cold cardiopulmonary bypass surgery in patients with cold-induced urticaria is uncommon, it is encouraging that such a regimen may allow for the successful completion of the surgery.

Roles of intracellular Ca2+ and cyclic AMP in mast cell histamine release induced by radiographic contrast media

Mast cell histamine release is considered to be associated with the etiology of anaphylactoid reactions to iodinated radiographic contrast media (RCM). In the present study, the effects of various ionic and non-ionic RCM on histamine release from mast cells were compared, and the possible mechanisms of the histamine release were subsequently determined. Both ionic (ioxaglate and amidotrizoate) and non-ionic (iohexol, ioversol, iomeprol, iopamidol and iotrolan) RCM increased histamine release from the dissociated rat pulmonary cells, whereby ionic materials were more potent than non-ionic agents. There was no significant correlation between the extent of histamine release and the osmolarity of each RCM solution. In addition, hyperosmotic mannitol solution (1000 mOsm/kg) caused no marked histamine release. Thus, it is unlikely that the hyperosmolarity of RCM solutions contributes to the histamine release. RCM also stimulated, but to a lesser extent, the histamine release from rat peritoneal cells. The RCM-induced histamine release from both types of cells was inhibited by dibutyl cyclic AMP or combined treatment with forskolin and 3-isobutyl-1-methylxanthine. Corresponding to these results, RCM markedly reduced the cellular cyclic AMP content. On the other hand, the removal of intracellular but not the extracellular Ca2+ attenuated the RCM-induced mast cell histamine release. From these findings, it is suggested that the decrease in cellular cyclic AMP content and an increase in intracellular Ca2+ contribute at least in part to the RCM-induced mast cell histamine release.

MR Lumbar Discography with Intradiscal Gadolinium in Patients with Severe Anaphylactoid Reaction to Iodinated Contrast Material

OBJECTIVE

Describe our experience using discography with intradiscal gadolinium and MR lumbar discography in patients with a history of severe anaphylactoid reaction to iodinated radiocontrast agents.

DESIGN

Observational study of 14 patients.

METHODS

From 1997 to 1999, 14 patients were referred for lumbar discography with intradiscal gadolinium followed by MRI. Patients with a history of a severe anaphylactoid reaction to iodinated radiocontrast media or those who refused the use of iodinated contrast material were included in the study.

RESULTS

In fourteen patients, 58 discs were studied. The post discography MRIs identified seven annular tears and seven annular fissures. None of the fourteen patients reported symptoms suggestive of allergic reaction either during or after discography.

CONCLUSIONS

Discography using intradiscal administration of gadolinium followed by MRI provides a method of obtaining a clinically pertinent study in a subset of patients who likely would not be offered the procedure, secondary to severe anaphylactoid reactions to iodinated contrast materials.

[Anaphylactoid reactions and late skin reactions to iodinated contrast media: present state of the question--idea development]

PURPOSE

Adverse reactions to iodinated contrast media (ICM) share various mechanisms. Anaphylactoid reactions are among the most serious reactions when they are characterized by the elevation of seric tryptase. Pretreatment with corticosteroids and anti-H1 or the use of non-ionic contrast media do not prevent anaphylaxis. Late skin reactions could be mostly related to delayed hypersensitivity. Previous reactions to contrast media, cardiovascular disorders, beta-blockers, asthma, and atopy are risk factors. Female gender and age increase the severity.

CURRENT KNOWLEDGE AND KEY POINTS

Anaphylaxis can be demonstrated by intradermal tests and the identification of specific IgEs. Delayed hypersensitivity is shown by the results of epicutaneous tests and the immunohistology of the skin.

FUTURE PROSPECTS AND PROJECTS

Allergologic tests are advised in the case of previous reactions. In case of emergency, gadopentetate dimeglumine can be alternatively used. The other risk factors lead to the combination of pretreatment and use of non-ionic monomeric contrast media. Immediate hypersensitivity to iodinated media might increase in the near future with the use of divalent molecules.

Management of anaphylactoid reactions to intravenous N-acetylcysteine

STUDY OBJECTIVE

To develop management guidelines for the treatment of anaphylactoid reactions to intravenous N-acetylcysteine (NAC) and to assess the safety of restarting the infusion after a reaction.

METHODS

In phased 1, we used a 6-year retrospective case series of hospitalized patients and a review of the literature to develop the management guidelines for anaphylactoid reactions to intravenous NAC. In phase 2, these guidelines were evaluated prospectively in our poison-control center.

RESULTS

In phase 1, the charts of 11 patients with anaphylactoid reactions (9 cutaneous and 2 systemic) were reviewed. In most cases, no treatment or treatment with diphenhydramine alone or with salbutamol was sufficient to continue or restart NAC infusion safely. On the basis of our findings in those patients and on published experience, we concluded that anaphylactoid reactions to intravenous NAC are dose-related and the antihistamines are useful in controlling and in preventing recurrence of anaphylactoid symptoms. We developed the following guidelines: flushing requires no treatment, urticaria should be treated with diphenhydramine, and NAC infusion should be continued in both cases. Angioedema and respiratory symptoms each require the administration of diphenhydramine and symptomatic therapy. In these cases, NAC infusion should be stopped but, when necessary, can be started 1 hour after the administration of diphenhydramine in the absence of symptoms. In phase 2, 50 patients (31 cutaneous and 19 systemic reactions) were treated prospectively with the use of these guidelines. Recurrence of symptoms occurred in only one case involving a deviation from the guidelines. The NAC infusion was restarted immediately after the administration of diphenhydramine in a patient who sustained a systemic reaction.

CONCLUSION

Non-life-threatening anaphylactoid reactions to intravenous NAC are treated easily and the infusion may be continued or restarted safely after the administration of diphenhydramine.

Refractory anaphylactoid shock potentiated by beta-blockers

Allergic reactions, including anaphylactoid shock due to contrast material, are not uncommon. However, persistent anaphylactoid shock refractory to conventional therapy is rare. We present a case of refractory anaphylactoid shock during coronary angiography unresponsive to aggressive standard therapy in a patient on beta-blockers. Significant clinical improvement was noted upon administration of glucagon. Since beta-blockers are commonly used in patients with coronary artery disease, this potentially life-threatening complication has to be kept in mind with any procedure involving contrast media in patients on beta-blockers. Immediate access to glucagon by keeping it in the procedure room may be lifesaving in these situations.