Comparative cytotoxicity of ionic and non-ionic radiocontrast agents on MDCK cell monolayers in vitro. (1/41)

BACKGROUND: Intravascular radiocontrast agents may cause acute renal failure, particularly in patients with pre-existing renal insufficiency. Direct cytotoxic effects of radiocontrast agents on renal tubular cells may contribute to the pathogenesis of radiocontrast-induced nephropathy. METHODS: We analysed the cytotoxicity of the ionic radiocontrast agents diatrizoate (monomeric) and ioxaglate (dimeric), as well as of the non-ionic radiocontrast agents iohexol (monomeric) and iodixanol (dimeric) on the renal epithelial Madin Darby Canine Kidney (MDCK) cell line grown on permeable supports. The toxicity assays assessed cell viability, transmonolayer resistance and inulin permeability between the apical and basal cell culture compartment. In addition, the distribution of the tight-junction-associated membrane proteins ZO-1 and occludin was analysed using immunofluorescence microscopy. RESULTS: In all assays the high osmolal ionic compound diatrizoate had significant cytotoxic effects that included the partial redistribution of the tight-junction-associated membrane proteins into a cytoplasmic compartment. To a lesser extent this redistribution also occurred with the dimeric ionic compound ioxaglate, but not with the non-ionic radiocontrast agents. With regards to cell viability, transmonolayer resistance and inulin permeability the radiocontrast agents with reduced osmolality were significantly less toxic than diatrizoate, independent of their ionic strength. CONCLUSIONS: Physicochemical factors contribute to the cytotoxicity of radiocontrast agents in vitro. The redistribution of tight-junction-associated membrane proteins by the ionic radiocontrast agents corresponds with the loss of the barrier function of the epithelial cell monolayer, which is a major pathophysiological mechanism in acute renal failure. The radiocontrast agents with reduced osmolality are less cytotoxic than diatrizoate, independent of their ionicity. Hyperosmolality appears to be a more important determinant of the cytotoxicity of diatrizoate than ionic strength.  (+info)

Influence of a nonionic, iso-osmolar contrast medium (iodixanol) versus an ionic, low-osmolar contrast medium (ioxaglate) on major adverse cardiac events in patients undergoing percutaneous transluminal coronary angioplasty: A multicenter, randomized, double-blind study. Visipaque in Percutaneous Transluminal Coronary Angioplasty [VIP] Trial Investigators. (2/41)

BACKGROUND: The potential merits and disadvantages of the use of ionic or nonionic contrast media in patients undergoing percutaneous transluminal coronary angioplasty (PTCA) have been the subjects of controversy. The present study was designed to evaluate the possible influence of both types of contrast media on major adverse cardiac events (MACE) in patients undergoing PTCA. METHODS AND RESULTS: In a randomized, parallel-group, double-blind study, 1411 patients received either iodixanol (a nonionic, iso-osmolar contrast medium) or ioxaglate (an ionic, low-osmolar contrast medium) during PTCA. A standardized anticoagulation regimen was followed. Patients were monitored in the hospital for 2 days and followed-up at 1 month. The primary end point, a composite of MACE (death, stroke, myocardial infarction, coronary artery bypass grafting, and re-PTCA) after 2 days, occurred in 4.3% of the total population, with no statistically significant difference between groups (iodixanol, 4.7%; ioxaglate, 3.9%; P=0.45). Further, between 2-day and 1-month follow-ups, no significant difference (P=0.27) existed between the groups in the rates of MACE. Hypersensitivity reactions (P=0.007) and adverse drug reactions (P=0.002) were significantly less frequent in the iodixanol group. The only significant predicting factors for the occurrence of MACE were dissection/abrupt closure and country. CONCLUSIONS: No significant differences were observed between the iodixanol and ioxaglate groups with regard to MACE, although hypersensitivity and adverse drug reactions were significantly less frequent in patients who received iodixanol.  (+info)

Randomized trial of contrast media utilization in high-risk PTCA: the COURT trial. (3/41)

BACKGROUND: Previous in vitro and in vivo studies have suggested an association between thrombus-related events and type of contrast media. Low osmolar contrast agents appear to improve the safety of diagnostic and coronary artery interventional procedures. However, no data are available on PTCA outcomes with an isosmolar contrast agent. METHODS AND RESULTS: A multicenter prospective randomized double-blind trial was performed in 856 high-risk patients undergoing coronary artery intervention. The objective was to compare the isosmolar nonionic dimer iodixanol (n=405) with the low osmolar ionic agent ioxaglate (n=410). A composite variable of in-hospital major adverse clinical events (MACE) was the primary end point. A secondary objective was to evaluate major angiographic and procedural events during and after PTCA. The composite in-hospital primary end point was less frequent in those receiving iodixanol compared with those receiving ioxaglate (5.4% versus 9.5%, respectively; P=0.027). Core laboratory defined angiographic success was more frequent in patients receiving iodixanol (92.2% versus 85. 9% for ioxaglate, P=0.004). There was a trend toward lower total clinical events at 30 days in patients randomized to iodixanol (9.1% versus 13.2% for ioxaglate, P=0.07). Multivariate predictors of in-hospital MACE were use of ioxaglate (P=0.01) and treatment of a de novo lesion (P=0.03). CONCLUSIONS: In this contemporary prospective multicenter trial of PTCA in the setting of acute coronary syndromes, there was a low incidence of in-hospital clinical events for both treatment groups. The cohort receiving the nonionic dimer iodixanol experienced a 45% reduction in in-hospital MACE when compared with the cohort receiving ioxaglate.  (+info)

Acute and subacute stent occlusion; risk-reduction by ionic contrast media. (4/41)

AIMS: Current data concerning the influence of X-ray contrast media on the incidence of thrombotic complications in interventional cardiology are controversial. The effect of ionic contrast media on acute (< or =72 h) and subacute (< or =30 days) stent thrombosis has not been investigated. METHODS: Three thousand, nine hundred and ninety consecutive patients underwent coronary stent placement. Group I (n=1808) received non-ionic contrast media while group II (n=2182) was given the ionic Ioxaglate. All patients were treated with a standard regimen of aspirin and ticlopidine for 4 weeks post intervention. RESULTS: Both acute and subacute stent occlusion occurred more frequently in patients receiving non-ionic contrast media compared to ionic contrast media (acute stent occlusion: 1.3% in group I vs 0.3% in group II, P=0.001; subacute stent occlusion: 2.4% in group I vs 0.7% in group II, P=0.001). The incidence of the combined clinical end-point of coronary artery bypass grafting, target lesion revascularization, and overall mortality within 12 months was significantly reduced by the use of Ioxaglate (22.9% vs 16.3%, P=0.001). CONCLUSIONS: Based upon these data, we recommend the use of Ioxaglate in coronary interventions when stent placement is anticipated.  (+info)

Index matching to improve optical coherence tomography imaging through blood. (5/41)

BACKGROUND: Most myocardial infarctions are caused by the rupture of small rather than large plaques in the arteries of the heart that are beyond the detection limit of current technologies. METHODS AND RESULTS: Recently, optical coherence tomography (OCT) has demonstrated considerable potential as a method for high-resolution assessment of vulnerable plaque. However, intravascular OCT imaging is complicated by the need to remove blood from the imaging field because blood results in substantial signal attenuation. This work examines index matching as a method for increasing penetration. Index matching is based on the hypothesis that the predominant source of scattering in blood is the difference in refractive index between the cytoplasm of erythrocytes and serum. By increasing the refractive index of serum to a value near that of the cytoplasm, or index matching, scattering can be substantially reduced. The concept was tested with a system that pumped blood in vitro through transparent tubing. The test compounds, dextran and intravenous contrast agent, both led to significant improvements in penetration (69+/-12% and 45+/-4%). No significant effect was seen with the saline control. For dextran, the effect could not be attributed to reductions of red cell number or volume because changes in these parameters were not different from the control. In the case of intravenous contrast, a small but significant relative reduction in red cell volume was seen. CONCLUSIONS: This study demonstrates the feasibility of index matching for improving OCT imaging through blood. Future studies are required to identify compounds for effective index matching in vivo.  (+info)

Glaucoma as a complication of superselective ophthalmic angiography. (6/41)

We report a case of glaucoma that resulted as a complication of superselective ophthalmic angiography in a 67-year-old man with a recurrent olfactory groove meningioma. Superselective angiography in the right ophthalmic artery was performed to confirm the orifice of the feeding arteries during preoperative embolization. Immediately after the fourth injection of contrast medium, the patient suffered from acute angle-closure glaucoma with elevation of intraocular pressure. Early treatment, including laser iridotomy, relieved the symptoms completely.  (+info)

Radiocontrast agents induce endothelin release in vivo and in vitro. (7/41)

The intravascular administration of the ionic radiocontrast agent sodium iothalamate (2.9 g of iodine/kg body wt) to rats induced an increase in plasma concentration of immunoreactive endothelin from 21.3 +/- 1.2 to 36 +/- 3 fmol/mL, preceded by a transient rise in the plasma level of atrial natriuretic peptide and associated with a fall in RBF. Equi-iodine amounts of the nonionic agents ioxaglate and iohexol elicited similar or more marked changes in plasma endothelin, but hypertonic solutions of NaCl, mannitol, or glucose did not. Comparable levels of endothelin produced by infusions of endothelin-1 induced a reduction of up to 29% in RBF. Iothalamate and iohexol stimulated endothelin release from cultured bovine endothelial cells, suggesting a direct effect of ionic and nonionic agents on vascular endothelium. The data invite speculation that under some circumstances endothelin release might play a role in the circulatory changes caused by these compounds and in the pathogenesis of radiocontrast nephropathy.  (+info)

Effects of time and previous acute rejection episodes on coronary vascular reserve in human heart transplant recipients. (8/41)

OBJECTIVES: This study examined whether previous rejection episodes may have deleterious effects on coronary vascular reserve of heart transplant recipients months after transplantation. BACKGROUND: Coronary reserve has been demonstrated to be within the normal range in long-term transplant patients without previous episodes of rejection. Conversely, acute rejection is associated with a dramatic reduction of coronary reserve, which is rapidly restored after therapy. METHODS: Coronary flow velocity was measured by intracoronary Doppler catheter before and after a maximally vasodilating dose of intracoronary papaverine in 16 control subjects and in 59 transplant patients classified into three groups with respect to time after transplantation: 1 to 6 months (group 1, n = 17), 7 to 18 months (group 2, n = 22) and > 18 months (group 3, n = 20). Coronary vascular reserve was evaluated through peak/rest coronary flow velocity ratio and minimal coronary vascular resistance index. All patients had normal findings on left ventricular angiography and coronary arteriography and a normal left ventricular mass. RESULTS: Arterial pressure was normal in all groups. Heart rate in the three groups of transplant patients, mean aortic pressure in groups 1 and 2, left ventricular systolic pressure in group 2 and rate-pressure product in groups 1 and 2 were higher than in control subjects. Average number of rejection episodes per patient was similar in the three groups of patients (group 1, 2.4 +/- 1.4; group 2, 2.5 +/- 1.9, and group 3, 2.1 +/- 1.3). Results showed no difference between each group of transplant patients and control subjects for peak/rest coronary flow velocity ratio (control subjects, 5.2 +/- 0.8; group 1, 5.3 +/- 1.5; group 2, 4.9 +/- 1.2, and group 3, 4.4 +/- 1.6) and for minimal coronary vascular resistance index (control subjects, 0.18 +/- 0.03; group 1, 0.18 +/- 0.04; group 2, 0.20 +/- 0.06, group 3, 0.23 +/- 0.11). In addition, patients with zero or one rejection episode had similar values of peak/rest coronary flow velocity ratio and minimal coronary vascular resistance index (4.3 +/- 1.3 and 0.23 +/- 0.10, respectively, n = 22) as did those with one or two rejection episodes (5.1 +/- 1.5 and 0.19 +/- 0.07, respectively, n = 24), and those with four or more episodes (5.2 +/- 1.4 and 0.19 +/- 0.05, respectively, n = 13). CONCLUSIONS: This study showed that coronary vascular reserve remains within normal range and is independent from the number of previous episodes of rejection until late after transplantation in human heart transplant patients with angiographically normal coronary arteries.  (+info)