Use of nonionic or low osmolar contrast agents in cardiovascular procedures. American College of Cardiology Cardiovascular Imaging Committee

Nonrenal Complications of Contrast Media

Injection of contrast media is the foundation of invasive and interventional cardiovascular practice. Iodine-based contrast was first used in the 1920s for urologic procedures and examinations. The initially used agents had high ionic and osmolar concentrations, which led to significant side effects, namely nausea, vomiting, and hypotension. Newer contrast agents had lower ionic concentrations and lower osmolarity. Modifications to the ionic structure and iodine content led to the development of ionic low-osmolar, nonionic low-osmolar, and nonionic iso-osmolar contrast media. Contemporary contrast agents are better tolerated and produce fewer major side effects.

Baseline Hemodynamics and Response to Contrast Media During Diagnostic Cardiac Catheterization Predict Adverse Events in Heart Failure Patients

BACKGROUND

Contrast media administered during cardiac catheterization can affect hemodynamic variables. However, little is documented about the effects of contrast on hemodynamics in heart failure patients or the prognostic value of baseline and changes in hemodynamics for predicting subsequent adverse events.

METHODS AND RESULTS

In this prospective study of 150 heart failure patients, we measured hemodynamics at baseline and after administration of iodixanol or iopamidol contrast. One-year Kaplan-Meier estimates of adverse event-free survival (death, heart failure hospitalization, and rehospitalization) were generated, grouping patients by baseline measures of pulmonary capillary wedge pressure (PCWP) and cardiac index (CI), and by changes in those measures after contrast administration. We used Cox proportional hazards modeling to assess sequentially adding baseline PCWP and change in CI to 5 validated risk models (Seattle Heart Failure Score, ESCAPE [Evaluation Study of Congestive Heart Failure and Pulmonary Artery Catheterization Effectiveness], CHARM [Candesartan in Heart Failure: Assessment of Reduction in Mortality and Morbidity], CORONA [Controlled Rosuvastatin Multinational Trial in Heart Failure], and MAGGIC [Meta-Analysis Global Group in Chronic Heart Failure]). Median contrast volume was 109 mL. Both contrast media caused similarly small but statistically significant changes in most hemodynamic variables. There were 39 adverse events (26.0%). Adverse event rates increased using the composite metric of baseline PCWP and change in CI (P<0.01); elevated baseline PCWP and decreased CI after contrast correlated with the poorest prognosis. Adding both baseline PCWP and change in CI to the 5 risk models universally improved their predictive value (P≤0.02).

CONCLUSIONS

In heart failure patients, the administration of contrast causes small but significant changes in hemodynamics. Calculating baseline PCWP with change in CI after contrast predicts adverse events and increases the predictive value of existing models. Patients with elevated baseline PCWP and decreased CI after contrast merit greatest concern.

Nonrenal Complications of Contrast Media

Nonrenal complications of contrast media are caused by chemotoxic or anaphylactoid reactions related to the contrast agent used. Chemotoxicity is mainly attributed to ionic concentration and osmolality. Anaphylactoid reactions are typically caused by direct activation of basophils, mast cells, and complement rather than an observable antigen-antibody interaction, and may be acute or delayed. History of an adverse reaction following prior exposure is the strongest predictor of a subsequent adverse reaction to contrast. Premedication regimens of corticosteroids or antihistamines can lower the risk of repeat adverse reactions. Treatment of anaphylactoid reactions depends on the severity of symptoms.

Understanding Contrast Media

More than 10 million radiologic examinations requiring intravascular injection of iodinated contrast media are performed in the United States each year. Iodinated contrast media are considered to be safe diagnostic drugs, and the incidence of adverse reaction is low. However, as with any drug, the administration of contrast media is not without risk. Nurses involved in patient care should have some understanding of the properties and potential effects of iodinated contrast media.

Prevention of radiocontrast nephropathy with N-acetylcysteine in patients with chronic kidney disease: a meta-analysis of randomized, controlled trials

BACKGROUND

Radiocontrast nephropathy (RCN) is a common cause of hospital-acquired acute renal failure. Results of several studies using N-acetylcysteine (NAC) for the prevention of RCN have yielded conflicting results. We performed a meta-analysis of group data extracted from previously published studies to assess the effect of NAC on the prevention of RCN in patients with pre-existing chronic kidney disease (CKD).

METHODS

Ovid's multidatabase search for MEDLINE, Cochrane Central Registry of Controlled Trials, Cochrane Database of Systematic Reviews, and HealthSTAR were used to identify candidate articles. Abstracts from proceedings of scientific meetings also were screened. We selected blinded and unblinded randomized controlled trials (RCTs) performed in humans 18 years and older with pre-existing CKD, defined by a mean baseline serum creatinine level of 1.2 mg/dL or greater (> or =106.1 micromol/L) or creatinine clearance less than 70 mL/min (<1.17 mL/s). The overall risk ratio (RR) for the development of RCN was computed using a random-effects model.

RESULTS

Eight RCTs (n = 885 patients) published in full-text articles were included in the primary analysis. In the control group, the overall rate of RCN was 18.5% (95% confidence interval [CI], 15 to 22). In the primary analysis, overall RR for RCN associated with the use of NAC was 0.41 (95% CI, 0.22 to 0.79; P = 0.007). In a sensitivity analysis that included 4 additional RCTs published in abstract form, RR remained significant at 0.55 (95% CI, 0.34 to 0.91; P = 0.020).

CONCLUSION

NAC reduces the risk for RCN in patients with CKD.

Lower-extremity wounds. 1: Vascular disease assessment

Non-healing arterial and/or diabetic wounds of the lower extremity are the reflection of a systemic process — that is, the presence of atherosclerosis and/or diabetes mellitus. The disease process is accelerated by specific risk factors including smoking, obesity, hypertension, decreased activity, lipid disorders and infection.

Hemodynamic effects of iodixanol and iohexol during ventriculography in patients with compromised left ventricular function

A crossover study was performed to compare the hemodynamic effects of the iso-osmolar contrast agent iodixanol (Visipaque) 320 mg I/ml to those of the low-osmolar iohexol (Omnipaque) 350 mg I/ml. The main hypothesis was that iodixanol and iohexol would affect left ventricular end-diastolic pressure (LVEDP) to different degrees. In 48 patients with reduced cardiac function (mean ejection fraction 33. 4%), one ventricular injection was performed with each contrast medium. Ventricular, aortic and right atrial pressures and heart rate were measured continuously. Cardiac output (using Fick's principle) and systemic vascular resistance were calculated. LVEDP increased with both agents, but significantly less after iodixanol than after iohexol (P < 0.01), also in subgroups of patients in whom baseline LVEDP was severely increased and in whom 3-vessel disease was present. Immediate changes in variables reflecting vasodilatation were similar with both agents. In conclusion, both contrast agents influenced hemodynamics during ventriculography, but iodixanol had significantly less influence on LVEDP than did iohexol.

Effects of dopamine and aminophylline on contrast-induced acute renal failure after coronary angioplasty in patients with preexisting renal insufficiency

In phase 1 of this study, 60 patients undergoing coronary angioplasty were randomized to receive saline, dopamine, or aminophylline; the overall incidence of contrast-induced renal failure was 38%, without difference among the 3 groups. In phase 2 of this study, 72 patients with established contrast-induced renal failure were randomized to receive saline or dopamine; dopamine had a deleterious effect on the severity of renal failure, prolonging the course.

Safety and criteria for selective use of low-osmolality contrast for cardiac angiography

OBJECTIVES

Recommendations to restrict low-osmolality contrast to high-risk patients having cardiac angiography have been challenged because of safety and uncertainty about selection criteria. The authors document frequency and severity of adverse events with diagnostic cardiac angiography under the influence of guidelines for selective use of low-osmolality contrast in high-risk patients and refine high-risk criteria.

METHODS

Subjects of this prospective cohort study were 7,448 unselected patients having diagnostic cardiac angiography in St. John's, Newfoundland or Ottawa, Ontario. Measures included prespecified risk factors, procedure, contrast, and adverse events such as death within 24 hours, myocardial infarction, stroke, arrhythmias, hypotension, and anaphylactoid reactions.

RESULTS

Patients were similar at both sites. Fourteen point two percent received low-osmolality nonionic agents in St. John's. Thirty-four point one percent received low-osmolality (mostly ionic) media in Ottawa. Overall adverse event rates were similar at both sites: death, 0.07%; myocardial infarction or stroke, 0.03%; moderate events, 2%; and mild events, 16.8%. Event rates were low in those given high-osmolality media: death, 0.02%; myocardial infarction or stroke, 0.24%; moderate events, 1.6%; and mild events, 18%. The risk with cardiogenic shock and prior severe reaction to contrast could not be examined, but otherwise only current heart failure and markers of recent ischemia were associated with events after high-osmolality media.

CONCLUSIONS

Clinicians, using guidelines, can identify high-risk patients and should be able to safely limit use of low-osmolality media to them.

Complications of cardiac angiography using low- or high-osmolality contrast agents in patients with left main coronary stenosis

Recently published guidelines suggest that, in view of cost concerns, low-osmolal contrast should be selectively used in patients at increased risk of experiencing a contrast-related complication during cardiac angiography. The suggested criteria include the presence of left main coronary disease. However, the presence of left main disease is not usually known prior to angiography. Contrast-related complications of cardiac angiography were therefore analyzed in a group of 111 clinically stable patients found to have left main coronary stenosis, to determine if use of low-osmolality contrast had any beneficial effect when compared to standard contrast. Data were gathered prospectively as part of a randomized controlled trial, and the subgroup of patients with left main disease was analyzed retrospectively. Complications were divided into minor, intermediate, and major categories. In the 58 patients who received high-osmolar contrast, there were 4 contrast-related minor reactions, 8 intermediate events requiring treatment, and 1 major adverse event. Among the 53 patients who received low-osmolar contrast, there were no minor reactions, 7 intermediate events requiring treatment, and no major adverse events. The only difference of borderline significance was in the incidence of minor reactions requiring no treatment (P = 0.05). Although small and therefore not definitive, this study suggests that 1) universal use of low-osmolar contrast agents would not be expected to eliminate the risk of contrast-related reactions to cardiac angiography; 2) the well-documented clinical differences between high- and low-osmolar contrast primarily involve mild reactions; and 3) standard high-osmolar contrast is reasonably safe in clinically stable patients with left main coronary stenosis. The results therefore are consistent with the notion that selective use of low-osmolar contrast only in unstable patients is safe and appropriate.

Acute renal failure after coronary intervention: incidence, risk factors, and relationship to mortality

PURPOSE

This study set out to define the incidence, predictors, and mortality related to acute renal failure (ARF) and acute renal failure requiring dialysis (ARFD) after coronary intervention.

PATIENTS AND METHODS

Derivation-validation set methods were used in 1,826 consecutive patients undergoing coronary intervention with evaluation of baseline creatinine clearance (CrCl), diabetic status, contrast exposure, postprocedure creatinine, ARF, ARFD, in-hospital mortality, and long-term survival (derivation set). Multiple logistic regression was used to derive the prior probability of ARFD in a second set of 1,869 consecutive patients (validation set).

RESULTS

The incidence of ARF and ARFD was 144.6/1,000 and 7.7/1,000 cases respectively. The cutoff dose of contrast below which there was no ARFD was 100 mL. No patient with a CrCl > 47 mL/min developed ARFD. These thresholds were confirmed in the validation set. Multivariate analysis found CrCl [odds ratio (OR) = 0.83, 95% confidence interval (CI) 0.77 to 0.89, P <0.00001], diabetes (OR = 5.47, 95% CI 1.40 to 21.32, P = 0.01), and contrast dose (OR = 1.008, 95% CI 1.002 to 1.013, P = 0.01) to be independent predictors of ARFD. Patients in the validation set who underwent dialysis had a predicted prior probability of ARFD of between 0.07 and 0.73. The in-hospital mortality for those who developed ARFD was 35.7% and the 2-year survival was 18.8%.

CONCLUSION

The occurrence of ARFD after coronary intervention is rare (<1%) but is associated with high in-hospital mortality and poor long-term survival. Individual patient risk can be estimated from calculated CrCl, diabetic status, and expected contrast dose prior to a proposed coronary intervention.

Legal and policy considerations in using clinical practice guidelines

The increased use of clinical practice guidelines has implications for both public policy and for litigation. Physicians are concerned that the introduction of practice guidelines will reduce their clinical decision-making authority and that the failure to follow clinical practice guidelines will lead to medical liability. Although practice guidelines are an increasing part of medical practice, there has been only limited litigation to determine the extent to which guidelines will be used to set the applicable standard of care. This article discusses the potential legal and public policy issues raised by the introduction and use of clinical practice guidelines. From a legal perspective, the primary issue is whether guidelines will be used to set the "standard of care" or will be one piece of evidence that a jury would use to determine the outcome of medical liability litigation. Based on an assessment of the applicable legal and policy considerations, the article concludes that courts should admit guidelines into evidence, but that they should not be used as the sole determinant of the standard of care. Instead, guidelines should be treated as one piece of evidence to be weighed by the jury. This approach will facilitate physician acceptance of guidelines by not imposing liability for the failure to follow guidelines without additional evidence to determine the standard of care.

Influence of radiographic contrast agents on quantitative coronary angiography

PURPOSE

Quantitative angiographic studies on the vasomotility of epicardial coronary arteries are gaining increasing relevance. We investigated whether radiographic contrast agents might influence coronary vasomotor tone and thereby the results of such studies.

METHODS

Coronary angiograms were taken in 12 patients with coronary artery disease at intervals of 5, 3, 2, and 1 min with the low-osmolar, nonionic contrast agent iopamidol 300, and were repeated at identical intervals with the high-osmolar, ionic agent diatrizoate 76%.

RESULTS

Quantitative cine film analysis demonstrated no significant diameter changes in angiographically normal and stenotic coronary arteries with iopamidol. With diatrizoate, however, normal segments were dilated 2% +/- 2% (p < 0.01) after 2 min and 10% +/- 3% after the 1 min interval (p < 0.001). Stenoses showed no uniform responses to diatrizoate.

CONCLUSION

Low-osmolar, nonionic contrast agents should be preferred for quantitative angiographic studies on epicardial coronary vasomotility. When using ionic contrast agents, injection intervals of at least 3 min are required.

High dose dipyridamole as a pharmacological stress test during cardiac catheterisation in patients with coronary artery disease

AIM

To validate dipyridamole as a pharmacological stress test during cardiac catheterisation, allowing both functional and morphological estimation of stenosis severity.

METHODS

The study encompassed 74 patients: 62 patients with significant coronary artery disease (age 61 (SD 8) years; seven women, 55 men) and 12 controls. Regional wall motion, left ventricular ejection fraction and end diastolic pressure were analysed in the resting state and after high dose intravenous dipyridamole. Patients were subdivided into four groups: group I (n = 32, 43%) had stopped all anti-ischaemic treatment for > 24 h, group II (n = 14, 19%) was under treatment, group III (n = 16, 22%) had significant coronary artery disease only in regions with regional wall motion abnormalities at rest, and group IV consisted of 12 control patients (16%) with no significant coronary artery disease (age 62 (8) years, three women, nine men).

RESULTS

The sensitivity of dipyridamole testing in patients with coronary artery disease was poor. The best sensitivity was obtained with regional wall motion analysis (26/62 = 42%) and with global left ventricular ejection fraction (25/62 = 40%). Specificity was 100% for regional wall motion and 100% for ejection fraction. Calculated positive and negative predictive values for regional wall motion were 100% and 63%, respectively.

CONCLUSIONS

Although safe, handy, and inexpensive, dipyridamole is not an adequate pharmacological stress test during cardiac catheterisation because of its low sensitivity.

The use of low-osmolar contrast agents: technological change and defensive medicine

The escalating cost of medical care in the United States, especially in the past decade, has resulted in efforts to identify the factors contributing to rising costs. One factor often assumed to cause higher medical costs is the physician's fear of liability for not using the latest available technology. In this article, we report the results of a case study we conducted to better understand the relationship between the introduction and use of one particular technology, low-osmolar contrast agents, and liability concerns. Our study suggests that both clinicians and administrators are primarily guided by the medical benefits of low-osmolar contrast agents, and that liability concerns, although widespread, are of secondary importance. The inability to control this and similar technologies is likely to put a far greater strain on the nation's health care resources than is the practice of defensive medicine. These findings may be helpful to health policy makers, physicians, administrators, and legislators considering choices for health care reform in general and for medical liability reform in particular.

In-hospital cost of percutaneous coronary revascularization. Critical determinants and implications

BACKGROUND

Hospital charges associated with percutaneous transluminal coronary revascularization (PTCR) in the United States exceeded $6 billion in 1994 and are likely to be constrained in some manner in the near future. Despite this high cost to the public, little is known about the major determinants and sources of variability of PTCR.

METHODS AND RESULTS

From a consecutive series of 1258 procedures with attempted PTCR at a single tertiary referral center, we analyzed 65 clinical, angiographic, physician, and outcome variables as potential correlates of total (hospital and physician) cost. Direct and indirect costs, both hospital and physician, were determined on the basis of resource utilization using "top-down" methodology and were available for 1237 procedures (1086 patients) (98.3%). Mean (+/- SD) patient age was 62 +/- 11 years, 76% were male, 3% had acute myocardial infarction, 71% had unstable angina, 58% had multivessel disease, left ventricular ejection fraction was 54 +/- 12%, 26% had use of at least one nonballoon revascularization device, and median length of stay was 4.4 days. Procedural success was obtained in 89%, and major complications (death, bypass surgery, or Q-wave myocardial infarction) occurred in 3.8%. The median cost was $9176, but it was asymmetrically distributed, and the interquartile and total ranges were wide ($7333 to $13,845 and $3422 to $193,474, respectively). Analyses of independent correlates of cost and loge(cost) were performed using multivariate linear regression in training and test populations. Modeling found 15 independent preprocedural correlates of loge(cost) (R2 = .37) and 23 overall correlates (R2 = .65), excluding length of stay per se. Additional of length of stay to the model increased the explanatory power of the model to R2 = .82. Preprocedural variables most predictive of loge(cost) included presentation with acute myocardial infarction, decision delay (> 48 hours between admission and diagnostic angiography and/or > 24 hours between angiography and intervention), weekend delay, use of intra-aortic balloon counterpulsation, intention to stent, creatinine > or = 2.0 mg%, and lesion complexity (modified American College of Cardiology/American Heart Association score) (all P < .001). In the model that included postprocedural variables as well, length of stay, noncardiac death, urgent bypass surgery, use of the Rotablator, Q-wave myocardial infarction, rise in creatinine > or = 1.0%, and blood product transfusion were all strong independent correlates of loge(cost) (P < .001).

CONCLUSIONS

The range of total hospital costs associated with percutaneous intervention is extraordinarily wide. Baseline patient characteristics account for nearly half of the explained variance, but procedural complications and system delays account for much of the remainder. Quantification of the determinants of cost may promote more economically efficient care in the future.

SC-54684A: an orally active inhibitor of platelet aggregation

BACKGROUND

Intravenous therapy has been shown to be beneficial in the prevention of acute platelet-associated thrombotic events. However, orally active agents would be advantageous for chronic therapy. Fibrinogen receptor antagonists block the fibrinogen/platelet interaction and thus inhibit a step required for thrombus formation. To date, no orally active fibrinogen binding inhibitors have been characterized. SC-54684A, now in clinical trial, is the orally active prodrug of a potent and specific fibrinogen binding antagonist.

METHODS AND RESULTS

We measured inhibition of 125I-fibrinogen binding to activated platelets and inhibition of aggregation in platelet-rich plasma to selected agonists and showed IC50s of 1.0 x 10(-8) and 3 to 7 x 10(-8) mol/L, respectively. Specificity of the active moiety was determined by studying its effect on the binding of (1) neutrophils to interleukin (IL)-1 beta-stimulated endothelial cells, (2) endothelial cells to fibronectin, and (3) vitronectin to isolated vitronectin and fibrinogen receptors. No effect was observed on the binding neutrophils to IL-stimulated endothelial cells or endothelial cell binding to fibronectin. There was a fivefold separation between binding to isolated receptors of vitronectin and fibrinogen. Collagen-induced aggregation was inhibited by 80%, and bleeding time was increased approximately 2.5-fold when the active moiety was infused to steady state at 0.2 micrograms/kg per minute in dogs. When the ester prodrug was given orally and the active moiety was given intravenously, the oral systemic activity was approximately 20%. Pharmacokinetic analysis after intravenous infusion of the prodrug or active moiety showed that the prodrug was rapidly converted to the active moiety; the active moiety had a t1/2 of 6.5 hours. When the prodrug was administered both orally and intravenously, the systemic availability of the active moiety was 62%.

CONCLUSIONS

SC-54684A, an orally active antiplatelet drug now in clinical trial, is shown to be a potent, specific fibrinogen binding inhibitor that blocks platelet aggregation to a wide variety of known stimuli and has good bioavailability in animals.

Transient loss of sensing and capture during coronary angiography in two patients with permanent pacemakers

Two cases of transient pacemaker failure to sense and capture during angiography are reported. This phenomenon is due to a transient increase in sensing and pacing thresholds beyond the pacemakers programmed settings. The underlying mechanism may be related to blood displacement, the electrochemical properties of the injectate, the high concentration of the contrast media, or a combination of these properties. Even though the chambers in which sensing and pacing loss occurred differed (ventricle in the first and atria in the second), the episode occurred repeatedly after injection of contrast media into the artery supplying the respective electrode-tissue interface. In pacemaker dependent patients, provisions for external pacing should be implemented prior to injection of contrast into the coronary arteries.

Comparison of hemodynamic and Doppler echocardiographic effects of a new low osmolar nonionic and a standard ionic contrast agent after left ventriculography

The hemodynamic effects of a new nonionic low osmolar contrast agent (iomeprol) during left ventriculography (LC) was compared with a standard ionic contrast agent (meglumine diatrizoate) in a randomized double blind study in 30 patients with suspected coronary artery disease and normal systolic ventricular function. LV diastolic function was assessed by Doppler echocardiographic recording of the transmittal filling curve and by intraventricular tip-manometry before and within 30 sec of the LC. In the group receiving the ionic contrast agent the systolic pressure fell from 126 +/- 23 to 111 +/- 18 mmHg (P < 0.05), and heart rate increased from 64 +/- 9 to 71 +/- 11 min-1 (P < 0.05), while no such effects were observed with the nonionic contrast agent, indicating differences in the vasodilator properties. The latter caused an increase of the peak early Doppler velocity (52 +/- 11 to 62 +/- 14 cm/sec; P < 0.05). After the ionic contrast agent, the effect on the peak early Doppler velocity was less pronounced, probably due to an interaction with the known depressant effect of the increase in heart rate on the early Doppler velocity. In both groups the left ventricular end diastolic pressure was increased from 7 +/- 3 to 10 +/- 4 mmHg. No significant effects on peak-dp/dt and dp/dt were observed in either group. The nonionic contrast agent iomeprol had no significant effect on systolic arterial pressure and heart rate in contrast to the ionic contrast agent, probably due to a less pronounced vasodilator effect. Despite these differences of the global hemodynamic response, there were similar effects of both contrast agents on LV diastolic filling.

Iomeprol and iopamidol in cardiac angiography: a randomised, double-blind, parallel-group comparison

During cardiac angiography, hemodynamic alterations and surface electrocardiographic changes are common, predictable and dose-related adverse reactions to radiocontrast media. High osmolality, inadequate sodium content and local transient hypocalcemia are thought to be the main mechanisms responsible for these untoward cardiovascular effects. The purpose of this double-blind, parallel-group trial was to compare the hemodynamic and electrocardiographic responses to cardiac and selective coronary artery injection of iomeprol 400 (400 mgI/ml) and iopamidol 370 (370 mgI/ml). One-hundred consenting adult inpatients were randomised to receive iomeprol 400 (41 males, nine females; mean age, 56.6 years) or iopamidol 370 (46 males, four females; mean age, 57.6 years). Both agents produced minor and transient hemodynamic and electrophysiological effects. Following left ventriculography, iopamidol 370 produced a significantly greater increase in LVEDP than iomeprol 400 (mean increases after first and second left ventriculogram: 2.5 and 4.6 mmHg with iomeprol 400, 3.3 and 9.9 mmHg with iopamidol 370, P = 0.027). The QT-interval was more affected by iopamidol 370 than by iomeprol 400. However, post-contrast prolongation of the QT-interval was not significant with either agent, nor were there any significant T-wave, ST-segment or RR-interval changes associated with the injection of the test compounds. No serious adverse events occurred throughout the study. Mild pain was complained by only one patient, while most patients reported mild to moderate sensation of heat. Image quality of the vast majority of the procedures was rated as good or excellent in both patient groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of a low osmolarity nonionic radiographic contrast agent with a standard medium on renal function in cyanotic and normal dogs

Renal dysfunction may follow administration of iodinated radiographic contrast agents. This complication may be less common when low osmolarity nonionic agents are used. Although potential benefits from the use of low osmolarity nonionic contrast may be minimal in individuals with normal physiology, a greater benefit has been postulated in the presence of chronic cyanosis. To test this hypothesis, six adult mongrel dogs underwent anastomosis of the inferior vena cava to the left atrium. This produced chronic cyanosis with a mean pO2 of 48 +/- 4 mm Hg and polycythemia with a mean hematocrit of 56 +/- 2 gm%. Three to 5 months after preparation, these cyanotic dogs and five control dogs each received diatrizoate (a high osmolarity ionic agent) or ioversol (a low osmolarity nonionic agent), 465 mg iodine/kg body weight, by intravenous bolus injection. One month later, each animal received the other agent. The order of administration was randomized. Renal function studies, including serum creatinine and creatinine clearance, were performed precontrast, after 60 min, and 24 hr postcontrast. Neither agent adversely affected renal function in either the cyanotic or the normal group. We conclude that at the doses that are commonly used in clinical practice, high osmolarity ionic contrast agents do not create a greater risk of renal injury than do low osmolarity nonionic agents in this model of cyanosis.