Contrast media-induced ventricular fibrillation. A comparison of Hypaque-76, Hexabrix, and Omnipaque

Addition of Sodium to Iohexol

The addition of sodium to nonionic contrast media has reduced the incidence of arrhythmias in animal models. The influence on cardiac function and safety of sodium addition to the nonionic contrast medium iohexol (Omnipaque) was studied in a randomized, double-blind trial in patients undergoing cardioangiography. Fifty-nine patients received iohexol 350 mg I/ml with NaCl 28 mmol/l and 58, iohexol only. ECG changes after contrast injections were evaluated with continuous computerized dynamic vectorcardiography (VCG). QRS-vector difference (QRS-vd), which reflects changes in the QRS-complex, was chosen as the main parameter. Both contrast media caused changes in the QRS-complex, but there was no significant difference between the two. No serious arrhythmias were observed. Both contrast media were well tolerated. No beneficial effects from enriching iohexol with sodium were found. VCG was found to be a valuable tool in the study of contrast medium-induced ECG changes.

Addition of Sodium to the Nonionic Contrast Medium Iohexol during Coronary Angiography in Man

It has recently been claimed that lack of sodium in nonionic contrast media may increase the risk of ventricular arrhythmias during coronary angiography. Thus, the influence of sodium addition to the nonionic contrast medium iohexol was studied in 75 patients with severe coronary heart disease. The study design was randomized, parallel and double-blind, and iohexol was given either with or without addition of NaCl (28 mmol/l). Both formulations induced a transient drop in arterial blood pressure, and prolongation of the QT interval and QRS duration at 10 s only (p < 0.01). The electrical QRS axis was significantly changed by the coronary artery injections after 10 s, but not later. No differences between iohexol with and without NaCl were observed for any of the variables studied. No serious arrhythmias were observed. Thus, the addition of NaCl (28 mmol/l) to iohexol did not influence the electrocardiographic or hemodynamic changes induced by iohexol during coronary angiography.

Effects of Contrast Media on the RR and QT Interval during Coronary Arteriography

During coronary arteriography, transient prolongation of the RR and QT intervals can be observed to occur. Animal experiments have suggested that low-osmolality contrast media have less effect, but there have been few clinical studies of this phenomenon. We analyzed 95 electrocardiographic records from patients who had undergone coronary arteriography and assessed the maximal prolongation of the RR and QT intervals. The contrast media used for arteriography included meglumine sodium diatrizoate, iopamidol, iohexol, and meglumine sodium ioxaglate. Diatrizoate caused the greatest electrocardiographic changes. Among the low osmolality contrast media, ioxaglate caused the smallest bradycardial effect and iohexol the smallest prolongation of the QT interval. It appears necessary to consider some additional factors for osmolality or ionicity, such as the chemotoxicity of the chemical structure of the iodinated contrast medium moiety, when assessing their potential adverse effect on the cardiac conduction system.

Contemporary analysis of predictors and etiology of ventricular fibrillation during diagnostic coronary angiography

OBJECTIVES

To assess the incidence, investigate the predictors and analyze the causes of ventricular fibrillation (VF) during coronary angiography (CA) on the condition of current techniques.

METHODS

From April 2004 to January 2007, a total 22,254 patients (27,798 procedures) received CA procedures in our center; 27 patients developed VF during CA. This report was to retrospectively analyze the clinical basic characteristics, coronary angiographic characteristics and CA procedure records of these patients.

RESULTS

The incidence of VF during CA was 0.097%. The incidence of VF in radial approaches and femoral approaches was 0.076% and 0.147% (p = 0.085). The VF patients had higher coronary artery bypass grafting (CABG) rates (11.1% vs 2.3%, p = 0.024) and were more likely to have a three-vessel disease (59.3% vs 31.2%, p = 0.002) and a total occlusion lesion (25.9% vs 11.1%, p = 0.014) than non-VF patients. On logistic regression analysis, three-vessel disease (OR: 2.582, 95% CI: 1.165-5.720, p = 0.019) and the history of CABG (OR: 3.959, 95% CI: 1.160-13.513, p = 0.028) were the two independent predictors of VF occurrences. Among 27 episodes of VF, 13 were ischemia-related; 11 were manipulation-related; two were contrast-related; one was hypokalemia-related; and the causes remain unclear in five episodes.

CONCLUSIONS

The incidence of VF during CA is low on the condition of current techniques. The severity of coronary artery disease (CAD) is an independent predictor of VF occurrence during CA. Acute ischemia and inappropriate manipulation may be the two main causes in VF development.

Incessant ventricular tachycardia acutely controlled with intracoronary injection of radiographic contrast media

Management of patients with incessant monomorphic ventricular tachycardia is challenging. We report on 2 patients who had incessant ventricular tachycardia despite emergency treatment with antiarrhythmic drugs and repeated electrical cardioversions. In both cases, the arrhythmia was acutely terminated with intracoronary administration of radiographic contrast media, allowing hemodynamic stabilization. No tachycardia recurrences occurred.

The risk of contrast media-induced ventricular fibrillation is low in canine coronary arteriography with ioxilan

Previous studies have proposed that sodium supplement to nonionic contrast media (CM) can decrease the risk of ventricular fibrillation (VF). This study was designed to compare the occurence of VF induced by ioxilan (containing 9 mmol/LNa+) with other nonionic CMs. After wedging a catheter in the right coronary artery, test solutions including ioxilan, ioversol, iomeprol, and iopromide were infused for 30 sec at the rate of 0.4 ml/sec or until VF occurred. Then, incidence of VF, contact time (i.e. the time required to produce VF), and QTc were measured. Also, the CMs other than ioxilan were investigated at sodium levels adjusted to 9 and 20 mmol/L Na+. The incidence of VF with ioxilan (0%) was the lowest of all. In the other CMs, the incidence decreased in accordance with increase of sodium. Iomeprol and iopromide showed significant reduction of VF incidence at the sodium level of 20 mmol/L. The higher sodium supplements also prolonged the contact times. The increase of QTc was the greatest in ioxilan. Ioxilan has the least arrythmogenic property among the current low-osmolality nonionic CMs. This property might be attributable to an optimal sodium concentration of 9 mmol/L in the CM.

Comparison of Iotrolan 320 and Iohexol 350 in cardiac angiography: a randomised double-blind clinical study

OBJECTIVE

A double-blind randomised study was conducted in two British centres, to evaluate the safety, tolerance and efficacy of the new dimeric non-ionic contrast medium Iotrolan 320 in comparison with the monomeric non-ionic compound Iohexol 350 in coronary angiography.

METHODS AND MATERIAL

120 patients were randomised to receive either Iotrolan at a concentration of 320 mgI/ml or Iohexol at a concentration of 350 mgI/ml, during selective coronary angiography and left ventriculography. The variables measured were: maximum increase of the left ventricular end-diastolic pressure up to 6 min after ventriculography, haemodynamic and electrocardiographic variables, arrhythmogenicity, clinical laboratory parameters, tolerance, adverse events and efficacy.

RESULTS

Iotrolan resulted in a smaller change of left ventricular end-diastolic pressure compared to Iohexol, but the difference was not statistically significant. Transient changes in left ventricular systolic pressure, intra-arterial systolic pressure, intra-arterial diastolic pressure, and in electrocardiographic parameters, occurred after the injections, but they were not clinically significant. Changes in the clinical laboratory markers from baseline values were comparable between the two groups and confirmed good renal and hepatic tolerance. During the left ventriculogram, Iotrolan resulted in less symptoms compared to Iohexol (P = 0.002). Adverse events, which were mild or moderate in most cases, were observed with no statistical difference between the two agents. The contrast quality of both agents was good with no statistical difference.

CONCLUSION

This study did not show a significant difference between Iotrolan 320 and Iohexol 350 with regard to cardiovascular safety or patient tolerance, except for a minor difference in the intensity of heat/warmth sensation.

Asystole associated with iohexol myelography in a dog

This is a report of a 10-year-old female neutered Doberman Pinscher with a clinical diagnosis of myelopathy. The dog was anesthetized using oxymorphone, thiopental, and halothane in oxygen for a cerebrospinal tap and a myelogram. Iohexal injection into the subarachnoid space by lumbar puncture was uneventful. Additional iohexal was given into the cerebeliomedullary cistern. Immediately following iohexal administration into the cerebellomedullary cistern, several electrocardiographic changes occurred. Two extended periods of asystole responded to intravenous glycopyrrolate administration. A slow multiform ventricular escape rhythm was established after the second dose of glycopyrrolate. Ultimately, atrial activity with apparent AV dissociation resumed, atrial fibrillation developed, and the rhythm converted to normal sinus rhythm. The dog had a normal cardiac examination the following day. Two days later, the dog was anesthetized using a similar anesthetic regimen with maintenance on isoflurane in oxygen for a hemilaminectomy. The dog recovered uneventfully from surgery and was discharged 2 days later.

Additive hemodynamic and electrophysiologic effects of repeated intracoronary contrast media injections in dogs with heart failure

RATIONALE AND OBJECTIVES

We investigated the cardiac effects of single and repeated contrast media injections in dogs with heart failure and compared the effects of iohexol with iohexol supplemented with electrolytes (30 mmol/l NaCl, 0.15 mmol/l CaCl2, 0.9 mmol/l KCl, and 0.1 mmol/l MgCl2; iohexol + electrolytes [IPE]). Although it has a higher osmolality than iohexol, IPE appears to be safer when injected through a wedged catheter.

METHODS

Acute ischemic heart failure was induced by injections of small plastic microspheres into the left coronary artery of 16 anesthetized dogs. Iohexol, IPE, and Ringer acetate were injected into the left coronary artery either as a 5-ml single injection or repeatedly five times, once every 10th second.

RESULTS

Single injections of iohexol and IPE induced small hemodynamic and electrophysiologic effects. However, repeated injections of iohexol and IPE increased the maximum rate of isovolumetric contraction by 46% and 36%, reduced heart rate by 8% and 7%, and lengthened QTc (the Q-T interval corrected for heart rate) time by 44 and 39 msec, respectively. No statistically significant differences were found in a comparison of IPE and iohexol.

CONCLUSION

During heart failure, repeated injections of iohexol and IPE induced similar additive hemodynamic and electrophysiologic effects without inducing arrhythmias or serious hemodynamic changes.

A review of coronary arteriography- and contrast media-induced ventricular fibrillation

Since the first animal coronary arteriogram in 1933 there have been many innovations in techniques and contrast media. From 1933 through the late 1950s the procedures used involved nonselective aortic injections and the use of acetylcholine to slow the heart. The first selective coronary arteriogram in animals was performed by West, Kobayashi & Guzman in 1958 (45) and in 1959 Guzman & West (7) observed ventricular fibrillation with some media but not others. In 1967 Judkins (14) described the catheter designs for right and left coronary catheterizations that we still use today. In the 1970s and 80s many authors observed the ionic monomeric contrast media reduced plasma calcium causing fibrillation and myocardial depression. Supplementation of ionic media with calcium was shown to moderate these adverse effects. Almen's vision of low osmolality contrast media and the creation of metrizamide (1) stimulated the rapid development of monomeric and dimeric nonionic contrast media. The ionic dimeric medium ioxaglate also provided low osmolality. Digital frame grabbers and computers lead to the development of digital subtraction angiography and new applications of arteriography, frequently using dilute media. Unexpectedly, during prolonged right coronary arteriography in animals, dilute nonionic media were found to produce increased fibrillation as compared to dilute ionic media. The addition of sodium to nonionic media significantly reduced the incidence of fibrillation. Animal studies with the nonionic medium iodixanol supplemented with sodium and calcium (Visipaque) have demonstrated minimal incidences of fibrillation and myocardial depression.

Cardiac effects of iodixanol compared to those of other nonionic and ionic contrast media on the isolated rat heart

This study was designed to compare the cardiac electrophysiology and mechanical effects of iodixanol to those of iotrolan, iopromide, ioxaglate and diatrizoate. Two consecutive injections of contrast media (CM) (0.3 g I/kg and 0.9 g I/kg b.w.) were given to spontaneously beating, Langendorff-perfused rat hearts. CM were given as a single, short-lasting bolus injection (i.e. over 2 and 5 s). Changes in aortic pressure, left ventricular pressures and ECG were continuously recorded during constant volume perfusion. The nonionic CM had less pronounced effects on aortic pressure than had the ionic media. The peak rate of isovolumetric contraction (LV dP/dt(max)) was slightly decreased by iodixanol and iotrolan, slightly more decreased by iopromide and markedly decreased by ioxaglate and diatrizoate. Similarly, the peak rate of pressure decline (LV dP/dt (min)) was only slightly decreased by iodixanol and iotrolan. Also, the 2 nonionic dimers had the smallest effects on the left ventricular end diastolic pressure (LVEDP) and heart rate. Ioxaglate lengthened the PQ-interval, but less so than diatrizoate. THe QT-interval was only slightly lengthened by iodixanol and iotrolan, as compared to the lenghthening caused by iopromide, ioxaglate and diatrizoate. Single ventricular extrasystoles were seen in all groups. Extrasystoles up to 3 coupled beats were registered after ioxaglate and diatrizoate. No episodes of ventricular fibrillation occurred with any CM. In conclusion, the nonionic dimers, and in particular iodixanol, induce only minor changes in cardiac function, whereas the ionic dimer ioxaglate and the ionic monomer diatrizoate induce pronounced effects.

Clinical pharmacology of iomeprol

The pharmacodynamic effects of iomeprol on the cardiovascular, central nervous, coagulation, and complement systems and on renal and thyroid functions using a wide range of intravenous and intraarterial radiological procedures were evaluated in Phase I, Phase II and Phase III clinical studies. The pharmacokinetics and metabolism of iomeprol were studied in healthy volunteers. Iomeprol 350 and 400 mgI/ml at doses ranging from 100 to 300 ml did not cause any significant changes of the basal haemodynamic parameters when used in CT of the chest and upper abdomen. No significant alterations of haemodynamic and ECG parameters were seen in patients who underwent cardiac-angiography or coronary angiography with iomeprol 400 mgI/ml. Intensive monitoring of haemodynamic and EEG parameters in patients undergoing conventional cerebral angiography with iomeprol 300 mgI/ml confirmed good toleration by the CNS. Neither renal and thyroid functions nor the coagulation and complement systems were significantly affected by iomeprol. Iomeprol was not metabolised and did not bind to plasma proteins. In healthy volunteers it was excreted almost exclusively by renal glomerular filtration (about 90% of the injected dose after 24 h). The pharmacokinetic behaviour of iomeprol was very similar to the behaviour of other nonionic, monomeric agents.

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

Low osmolar contrast agents produce less adverse electrophysiologic and hemodynamic alterations during cardiac catheterization. The nonionic agents probably reduce the risk of provoking myocardial ischemia during coronary arteriography or ventriculography. Patients also report less subjective sensation of discomfort during administration of low osmolar agents for cardiovascular procedures. However, nonionic agents have not been proved to reduce the incidence of several serious complications of cardiac catheterization, including acute renal failure and anaphylactoid reaction. Although evidence is inconclusive, there may be an increased risk of thromboembolic complications during cardiac catheterization when certain low osmolar nonionic agents are administered. Nonionic contrast agents have not been definitely proved to reduce the risk of death after cardiac catheterization.

Contractile, metabolic and arrhythmogenic effects of ionic and nonionic contrast agents in the isolated rat heart

Intracoronary administration of contrast agents may be associated with contractile dysfunction and arrhythmias. To further establish the mechanisms of these alterations, we studied high-energy phosphate metabolism, developed pressure, the occurrence of arrhythmias, and the effects of verapamil during infusion of ionic and nonionic agents in isovolumic, retrogradely perfused rat hearts using 31P nuclear magnetic resonance imaging (NMR). Diatrizoate meglumine (Renografin) infusion reduced developed pressure (DP) to 17.1 +/- 3.4% (p less than 0.001) of the control level, and immediately following termination of the infusion, sudden ventricular tachycardia (VT) was observed in four of six hearts. In the presence of verapamil, meglumine reduced DP to 13 +/- 1.9% of control values and none of these six hearts developed VT. Iopamidol infusion in the presence of verapamil (n = 6) and alone (n = 6) resulted in a decrease in DP to 87% of control value, and no arrhythmias, significant change in high-energy phosphate levels, or changes in pH were observed. These results suggest that contrast-induced contractile depression is not mediated by changes in high-energy phosphate metabolism or pH. Arrhythmias associated with meglumine administration alone and suppressed by verapamil are probably related to calcium loading.

Comparative trial of Omnipaque 350 (iohexol) and Telebrix 350 (sodium-meglumine-ioxithalamate) in left ventriculography and coronary arteriography

In a double-blind randomized trial, the hemodynamic and electrophysiologic effects of the low-osmolar nonionic contrast medium iohexol (Omnipaque) and the standard high-osmolar ionic monomer sodium-meglumine-ioxithalamate (Telebrix) at left ventricular angiography and selective coronary arteriography were evaluated. Sixty patients were divided into two groups of 30 patients; one group received Omnipaque in a dosage of 350 mgI/ml and the other group received Telebrix in a dosage of 350 mgI/ml. The Omnipaque showed significantly less effects on heart rate and myocardial contractility, and induced less electrophysiological changes than did Telebrix. However, there was a significant increase of 10% in the diameter of the left coronary artery following selective coronary injection with Telebrix, while Omnipaque induced practically no change in vessel diameter. All hemodynamic and electrophysiologic effects proved to be short-lasting. We conclude that ionic and nonionic agents are similarly efficacious in providing adequate images with minimal risk to the patient. However, the nonionic agents exert slightly more alterations in cardiac hemodynamics and in electrocardiographic intervals. The vasodilatory effect on coronary artery diameter by Telebrix may entail a more rapid clearance of contrast medium from the coronary circulation, which might be of some advantage over nonionic contrast media.

Adverse reactions of low osmolality contrast media during cardiac angiography: a prospective randomized multicenter study

A multicenter study was performed to determine the incidence of adverse reactions to two contrast media with similar low osmolality during cardiac angiography. The study was of a randomized double-blind design comparing ioxaglate (an ionic dimer) and iopamidol (a nonionic compound) and included 500 patients; 250 patients received ioxaglate and 250 iopamidol. There were 58 adverse reactions attributed to the contrast media in the ioxaglate group and 29 in the iopamidol group (p less than 0.001). Chest pain occurred in 11 patients in the ioxaglate group compared with 5 in the iopamidol group (p = 0.123). Nausea or vomiting was present in 20 and 2 patients, respectively (p less than 0.0003). Allergic adverse reactions, such as bronchospasm, urticaria and itching, occurred in 15 of the ioxaglate group and only 1 of the patients receiving iopamidol (p less than 0.0007). Fifty-two patients in the ioxaglate group had a known allergic history (not to contrast medium) or asthma, whereas 77 receiving iopamidol had a similar history. Seven of the 52 ioxaglate-treated patients developed an allergic adverse reaction compared with none of the 77 in the iopamidol group (p = 0.001). Of 41 patients receiving ioxaglate who were premedicated with diphenhydramine, 4 had an allergic adverse event. In the iopamidol group 45 patients received similar premedication and none had an allergic adverse reaction (p less than 0.03). Thus, this multicenter study shows that adverse reactions occur more often with ioxaglate than with iopamidol and that patients with an allergic history have a greater risk with ioxaglate therapy compared with iopamidol.

Effects of intracoronary administration of contrast media on coronary hemodynamics in a canine post ischemic reperfusion model

Hemodynamic changes due to intracoronary injections of nonionic contrast medium Omnipaque-350 (OM), ionic dimer Hexabrix (HB), and ionic contrast medium Renografin-76 (R76) were compared at baseline and during reperfusion after a 30-minute left anterior descending coronary artery (LAD) occlusion. In 11 open chest, anesthetized, and atrially paced dogs, 4 ml of either OM, HB, R76, or 0.9% NaCl were injected into the carotid-LAD bypass system. Coronary blood flow (CBF) and coronary vascular resistance (CVR) were measured before, during and after the intracoronary injection. The maximal hyperemic change (in percentage) from the preinjection value of CBF and CVR were calculated. The results at baseline and during reperfusion for CBF were: 104 +/- 14% vs. 85 +/- 10% for OM (NS); 76 +/- 11% vs. 39 +/- 9% for R76 (p less than 0.05); 57 +/- 8% vs. 33 +/- 5% for HB (P less than 0.05); and 30 +/- 7% vs. 9 +/- 4% for 0.9% NaCl (p less than 0.05). Consequently, the hyperemic changes of CVR at baseline and during reperfusion were: -49 +/- 3 vs. -42 +/- 4% for OM (NS); -44 +/- 3% vs. -24 +/- 6% for R76 (p less than 0.01); -36 +/- 3% vs. -24 +/- 4% for HB (p less than 0.05); and -18 +/- 4% vs. -7 +/- 3% for 0.9% NaCl (p less than 0.05). Thus, ischemia and reperfusion significantly dampened the coronary hemodynamic and vascular response to R76, HB, and 0.9% NaCl but not to OM. The preserved coronary vascular reserve with high flow in this canine post-ischemic reperfusion model may explain the advantage of nonionic over ionic contrast media used in emergency coronary angiography following thrombolysis.

Influence of low osmolality contrast media on electrophysiology and hemodynamics in coronary angiography: differences between an ionic (ioxaglate) and a nonionic (iohexol) agent

It has recently been suggested that the addition of sodium to low osmolality contrast media may reduce the incidence of ventricular fibrillation and conduction disturbances during coronary angiography. In a randomized, double blind study of 30 patients undergoing coronary angiography we therefore examined the electrophysiological and hemodynamic effects of the two low osmolality contrast media-ioxaglate (with sodium) and iohexol (without sodium). Standard ECG, aortic blood pressure, and His bundle electrocardiogram were recorded. The contrast media were well tolerated and no serious arrhythmias were observed. Both induced a transient decrement in systolic blood pressure and reduction in heart rate 10 s following contrast injection (all P less than 0.01). Ioxaglate prolonged the QT interval at 10 s (P less than 0.01) and also when analysed for the whole observation period (120 s) (P less than 0.05), whereas iohexol did not cause any significant changes in the QT-interval. The AH-interval was prolonged by ioxaglate at 10 s (P less than 0.01), but not altered by iohexol. Thus, other factors than osmolality and sodium content might contribute to QT prolongation, since only the contrast agents with sodium (ioxaglate) induced QT prolongation in this study.

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.

Electromechanical effects of two low osmolality contrast media, ioxaglate and iohexol, on isolated rat atria

This study aimed at investigating the direct effects of two low osmolality radiographic contrast media, iohexol (non-ionic) and ioxaglate (ionic), on transmembrane action potentials, contractile force and refractoriness of isolated rat atrial preparations. Superfused with 10% solution, ioxaglate induced a biphasic mechanical response, initially decreasing and thereafter increasing contractile force. The same concentration of iohexol only increased contractile force. The two contrast media increased the resting membrane potential, action potential amplitude and rate of depolarization to the same extent. Iohexol prolonged repolarization. Both contrast media decreased the effective refractory period. The direct effects of contrast media on myocardial contractility in this study can explain the different haemodynamic effects of iohexol and ioxaglate in vivo. The observed effects on the action potentials in vitro can explain commonly observed ECG changes during coronary arteriography. The changes in depolarization, repolarization and refractoriness are probably related to the arrhythmogenic properties of these contrast media.

Comparison of low osmolality ionic (ioxaglate) versus nonionic (iopamidol) contrast media in cardiac angiography

A double-blind randomized study was performed in 60 patients to compare the electrocardiographic and hemodynamic changes induced during cardiac angiography by 2 contrast media with relatively low osmolality. Ioxaglate meglumine sodium, an ionic dimer contrast medium, was compared with iopamidol, a nonionic compound. Of the 30 patients who received ioxaglate, 13 (43%) experienced a mild to moderate adverse reaction to the contrast media, while only 2 of the 30 patients (7%) in the iopamidol group had similar side effects (p less than 0.005). Significant prolongations of the QT intervals occurred with the ioxaglate injections. The QT intervals increased from 402 +/- 46 to 442 +/- 59 ms (p less than 0.001) with the right coronary artery injection and similar changes were observed after the left coronary artery injection and left ventriculography. Significant ST-segment and T-wave amplitude changes also occurred in the ioxaglate group. With iopamidol injections, there were no significant changes in any of these parameters. After the left ventriculogram, there were similar decreases in the systolic arterial pressures in both groups (-14 +/- 10 mm Hg with ioxaglate and -21 +/- 9 mm Hg with iopamidol). The left ventricular end-diastolic pressures increased after the ventriculogram in both groups (5 +/- 5 vs 2 +/- 3 mm Hg with ioxaglate and iopamidol, respectively, 60 seconds after the injection). This report demonstrates that mild to moderate adverse reactions, QT-interval prolongations, ST and T-wave changes were significantly greater during coronary angiography with ioxaglate when compared with iopamidol.(ABSTRACT TRUNCATED AT 250 WORDS)