Preventing contrast nephropathy: what is the best strategy? A review of the literature

Effect of Carvedilol Versus Metoprolol on Contrast-Induced Nephropathy in Patients with Acute Coronary Syndrome Undergoing Percutaneous Intervention Therapy

Carvedilol can inhibit inflammation, vasoconstriction, and oxidative stress, which play important roles in the development and progression of contrast-induced nephropathy (CIN). To the best of our knowledge, no studies have investigated the potential effect of carvedilol on the prevalence of CIN after percutaneous coronary intervention (PCI) for acute coronary syndrome (ACS). The present study aimed to determine whether carvedilol use is associated with the development of CIN. A total of 319 patients (mean age, 59.2 ± 12.4 years; 77.7% male) with ACS who underwent urgent PCI at our institution between May 2019 and May 2022 were included prospectively. Overall, 100 and 219 patients were assigned to the carvedilol and metoprolol groups, respectively. The prevalence of CIN was significantly lower in the carvedilol group (6.0%) than in the metoprolol group (18.3%; P = .003). Multivariate analysis revealed that carvedilol use (odds ratio [OR] .250, 95% confidence interval [CI] .092-.677, P = .006), amount of contrast agent (OR 1.004, 95% CI 1.000-1.008, P = .031), and admission estimated glomerular filtration rate (OR .978, 95% CI 0.960-.995, P = .014) were independently associated with the development of CIN. The use of carvedilol may be a promising option for the prevention of CIN in patients with ACS undergoing urgent PCI.

Manual der Arbeitsgruppe Interventionelle Kardiologie (AGIK) der Deutschen Gesellschaft für Kardiologie – Herz- und Kreislaufforschung e. V. (DGK)

Dieses Manual zur diagnostischen Herzkatheteruntersuchung (Teil 1) ist eine Anwendungsempfehlung für interventionell tätige Ärzte, die den gegenwärtigen Kenntnisstand unter Berücksichtigung neuester Studienergebnisse wiedergibt. Hierzu wurde in den einzelnen Kapiteln speziell auf die Alltagstauglichkeit der Empfehlungen geachtet, sodass dieses Manual jedem interventionell tätigen Kardiologen als Entscheidungshilfe im Herzkatheterlabor dienen soll. Trotz der von vielen Experten eingebrachten praktischen Hinweise kann dieses Manual dennoch nicht die ärztliche Evaluation des individuellen Patienten ersetzen und damit eine Anpassung der Diagnostik bzw. Therapie ersetzen.

Kidney Injury Molecule-1 Is Associated with Contrast-Induced Nephropathy in Elderly Patients with Non-STEMI

BACKGROUND

Contrast-induced nephropathy (CIN) is associated with an increased risk of major adverse cardiovascular events (MACE), and the association between CIN and oxidative mechanisms is well documented.

OBJECTIVE

This study aimed to evaluate the relationship between serum levels of kidney injury molecule-1 (KIM-1) and CIN in elderly patients with non-ST-segment elevation myocardial infarction (NSTEMI).

METHODS

This study included a total of 758 patients with NSTEMI, who underwent percutaneous coronary intervention (PCI); 15 developed CIN after PCI, and another 104 were the control group, matched for age > 65 years. Baseline to 48-to-72-hour laboratory values and clinical outcomes were recorded. Patients were followed during one year. P values of < 0.05 were considered significant.

RESULTS

CIN was observed in 12.60% of the patients. Serum KIM-1 was significantly higher in the CIN group than in the non-CIN group (14.02 [9.53 - 19.90] vs. 5.41 [3.41 - 9.03], p < 0.001). The Mehran score was significantly higher in the CIN group than in the non-CIN group (14 [5 - 22] vs. 5 [2 - 7], p = 0.001). MACE were significantly higher in the CIN group than in the non-CIN group (7 [46.70%] vs. 12 [11.50%], p = 0.001). Multivariate logistic regression analysis showed that baseline KIM-1 level (OR = 1.652, 95% CI: 1.20 - 2.27, p = 0.002) and Mehran score (OR = 1.457, 95% CI: 1.01 - 2.08, p = 0.039) were independent predictors of CIN in elderly patients with NSTEMI.

CONCLUSION

Baseline serum KIM-1 concentration and Mehran score are independent predictors of CIN in elderly patients with NSTEMI. Additionally, all-cause mortality, cardiovascular death, myocardial reinfarction, stroke, and MACE were significantly higher in the CIN group at one-year follow-up. (Arq Bras Cardiol. 2021; [online].ahead print, PP.0-0).

Bilirubin Levels are Associated With Contrast-Induced Nephropathy in Peripheral Artery Disease

The relationship between contrast-induced nephropathy (CIN) and oxidative mechanisms is well documented. Our aim was to demonstrate the possible relationship between CIN and serum bilirubin as an antioxidant molecule. This retrospective study included 359 patients with peripheral artery disease (PAD) who underwent peripheral diagnostic angiography; 179 developed CIN after the intervention and another 180 were the control group, matched for age, gender, and cardiovascular risk factors. Baseline, 48- to 72-hour, and 30-day laboratory values, major adverse cardiovascular events, and dialysis requirements were recorded. Patients with CIN had significantly higher levels of uric acid, red cell distribution width, and neutrophil-to-lymphocyte ratio (NLR) but lower total bilirubin compared to the control patients ( P < .05). Multivariate logistic regression analysis showed that diabetes mellitus, left ventricular ejection fraction, uric acid, NLR, and total bilirubin levels were independent predictors of CIN development ( P = .01, P = .001, P = .001, P = .01, and P = .001, respectively). This study demonstrated that decreased total bilirubin was associated with CIN development after the administration of radiocontrast agents in patients with PAD.

Short-Term High-Dose Vitamin E to Prevent Contrast Medium-Induced Acute Kidney Injury in Patients With Chronic Kidney Disease Undergoing Elective Coronary Angiography: A Randomized Placebo-Controlled Trial

Background

Contrast medium–induced acute kidney injury (CIAKI) is a leading cause of acquired renal impairment. The effects of antioxidants have been conflicting regarding the prevention of CIAKI. We performed a study of vitamin E use to decrease CIAKI in patients undergoing elective coronary angiography.

Methods and Results

In a placebo‐controlled randomized trial at 2 centers in Iran, 300 patients with chronic kidney disease—defined as estimated glomerular filtration rate <60 mL/min per 1.73 m²—were randomized 1:1 to receive 0.9% saline infusion 12 hours prior to and after intervention combined with 600 mg vitamin E 12 hours before plus 400 mg vitamin E 2 hours before coronary angiography or to receive placebo. The primary end point was the development of CIAKI, defined as an increase ≥0.5 mg/dL or ≥25% in serum creatinine that peaked within 72 hours. Based on an intention‐to‐treat analysis, CIAKI developed in 10 (6.7%) and 21 (14.1%) patients in the vitamin E and placebo groups, respectively (P=0.037). Change in white blood cell count from baseline to peak value was greater in the vitamin E group compared with the placebo group (−500 [−1500 to 200] versus 100 [−900 to 600]×10³/mL, P=0.001). In multivariate analysis, vitamin E (odds ratio 0.408, 95% CI 0.170–0.982, P=0.045) and baseline Mehran score (odds ratio 1.257, 95% CI 1.007–1.569; P=0.043) predicted CIAKI.

Conclusions

Prophylactic short‐term high‐dose vitamin E combined with 0.9% saline infusion is superior to placebo for prevention of CIAKI in patients undergoing elective coronary angiography.

Clinical Trial Registration

URL: https://www.clinicaltrials.gov/. Unique identifier: NCT02070679.

Nephroprotective potential of carnitine against glycerol and contrast-induced kidney injury in rats through modulation of oxidative stress, proinflammatory cytokines, and apoptosis

OBJECTIVE

Contrast media (CM) are a major cause of nephropathy in high-risk patients. The aim of this study was to examine the effects of carnitine (CAR) in advanced nephrotoxicity due to CM administration in rats with glycerol-induced renal functional disorder.

METHODS

40 rats were divided randomly into five groups (n = 8): (1) healthy group; (2) glycerol only (GLY); (3) glycerol and CM (GLY + CM); (4) glycerol, CM and 200 mg kg(-1) carnitine (CAR200, Carnitene(®); Sigma-tau/Santa Farma, Istanbul, Turkey); and (5) glycerol, CM and 400 mg kg(-1) carnitine (CAR400). Kidney injury was induced with a single-dose, intramuscular injection of 10 ml kg(-1) body weight (b.w.) of GLY. CAR was administered intraperitoneally. CM (8 ml kg(-1) b.w. iohexol, Omnipaque™; Opakim Medical Products, Istanbul, Turkey) was infused via the tail vein to the rats in Groups 3-5.

RESULTS

l-carnitine administration significantly decreased serum creatinine and blood urea nitrogen levels. Superoxide dismutase and glutathione activity increased significantly in the treatment groups compared with the nephrotoxic groups. CAR400 significantly reduced malondialdehyde levels to healthy levels. In the treatment groups, tumour necrosis factor (TNF)-α, transforming growth factor 1β, interleukin 1β and caspase-3 gene expression decreased compared with the nephrotoxic groups. TNF-α and nuclear factor kappa-beta (NF-κB) protein expression increased after CM and CAR administration reduced both TNF-α and NF-κB expressions. Histopathologically, hyaline and haemorrhagic casts and necrosis in proximal tubules increased in the nephrotoxicity groups and decreased in the CAR groups.

CONCLUSION

The results reveal that l-carnitine protects the oxidant/antioxidant balance and decreases proinflammatory cytokines and apoptosis in CM-induced nephrotoxicity in rats with underlying pathology.

ADVANCES IN KNOWLEDGE

Depending on the underlying kidney pathologies, the incidence of CM-induced nephropathy (CIN) increases. Therefore, this is the best model to represent clinically observed CIN.

Comparison of Carvedilol and Metoprolol for Preventing Contrast-Induced Nephropathy after Coronary Angiography

AIMS

Contrast-induced nephropathy (CIN) is one of the most common causes of hospital-acquired acute renal failure. Oxidative stress and vasoconstriction might play key roles in its pathogenesis. In a few experimental models, antioxidant properties of carvedilol have been documented. The aim of this study was to analyze and compare the effects of carvedilol and metoprolol on the development of CIN in patients undergoing coronary angiography.

METHODS

One hundred patients currently taking metoprolol and 100 patients currently taking carvedilol were enrolled into the study. Venous blood samples were obtained before and 48 h after contrast administration. Cystatin C and malondialdehyde values were examined and compared. CIN was defined as a creatinine increase of at least 25% or 0.5 mg/dl from the baseline value.

RESULTS

Seven patients in the carvedilol group (7%) and 22 patients in the metoprolol group (22%) developed CIN (p = 0.003). In the metoprolol group, the median cystatin C concentration increased significantly from 978 to 1,086 ng/ml (p = 0.001) 48 h after radiocontrast administration. In the carvedilol group, the median cystatin C concentration did not change significantly (1,143 vs. 1,068 ng/ml; p = 0.94). In the metoprolol group, the mean malondialdehyde concentration increased significantly from 7.09 ± 1.48 to 8.38 ± 2.6 nmol/l (p < 0.001). In the carvedilol group, the mean serum malondialdehyde concentration did not change significantly (7.44 ± 1.21 vs. 7.56 ± 1.11 nmol/l; p = 0.59).

CONCLUSION

When compared to metoprolol, carvedilol might decrease oxidative stress and subsequent development of CIN.

Can previous diagnostic examinations prevent preoperative angiographic assessment of the internal mammary perforators for (micro)surgical use?

BACKGROUND AND AIM

Preoperative assessment of the internal mammary artery perforating (IMAP) branches enhances IMAP-based reconstructive procedures. Conventionally, color-flow Doppler, selective catheter arteriography, or CT angiography is used for such assessment. We studied how often these examinations may be rendered superfluous by assessment of previously performed diagnostic examinations.

METHODS

A radiologist and a plastic surgeon jointly assessed whether information on the dominant IMAP could sufficiently be obtained from the thoracic CT scans of 12 head and neck cancer patients and 12 breast cancer patients, and from the mammary MRI of 12 breast cancer patients. Secondly, we retrospectively assessed in how many of the 10 patients who underwent an IMAP-flap head and neck reconstruction, and in how many of the 10 women who consecutively underwent a deep inferior epigastric perforator (DIEP) flap mammary reconstruction such previous diagnostic examinations were available and informative regarding the level of the dominant perforator.

RESULTS

All 24 CT scans and 11 of the 12 MRI scans sufficiently allowed assessment of the level of the dominant IMAP. Previous information had already been available in all 10 DIEP flap patients and 6 of the 10 IMAP-flap patients. The distribution of IMAP dominance over the intercostal levels on the scans differed from that found by cadaveric or intraoperative assessment.

CONCLUSIONS

Previously performed diagnostic CT scans and MRI scans that included the parasternal region usually allow sufficient preoperative assessment of the internal mammary perforators for reconstructive procedures. We advocate re-assessment of such previous examinations before ordering additional angiography. Additionally, we suggest to include the parasternal region in diagnostic scans.

Dopamine-1 Receptor Agonist: Renal Effects and Its Potential Role in the Management of Radiocontrast-Induced Nephropathy

Radiocontrast-induced nephropathy remains the third leading cause of hospital-acquired acute renal failure. Once established, this syndrome is associated with increased morbidity and mortality as well as increased health care costs. Recently, studies have been initiated to evaluate the potential of a selective dopamine-1 receptor agonist (fenoldopam) in ameliorating radiocontrast-induced renal failure. Selective dopamine-1 receptor agonists exhibit many desirable renal effects that support their use for the prophylaxis of radiocontrast-induced nephropathy, including decreases in renal vascular resistance and increases in renal blood flow, glomerular filtration, and sodium and water excretion. Several reports have documented a beneficial effect of fenoldopam administration in attenuating radiocontrast-induced nephropathy. In contrast, a recent multicenter, randomized study did not demonstrate a renoprotective effect of fenoldopam against radiocontrast-induced nephropathy. The presence of multiple confounders, however, precludes a definitive conclusion regarding the ability of fenoldopam to protect against radiocontrast-induced nephropathy. Additional studies are needed to properly evaluate the role of fenoldopam in radiocontrast-induced nephropathy prophylaxis.

Association of serum bilirubin with contrast-induced nephropathy and future cardiovascular events in patients undergoing coronary intervention

Objectives

Enhanced reactive oxygen species formation within the kidney following the administration of contrast media may play a key role in the development of contrast-induced nephropathy (CIN). Bilirubin has emerged as an important endogenous antioxidant molecule. This study was undertaken to determine whether bilirubin is associated with CIN and future cardiovascular events in patients undergoing coronary intervention.

Methods

Totally, 544 consecutive patients received coronary intervention were enrolled. All patients were followed up for at least 3 years or until the occurrence of a major event. The primary endpoint was CIN, defined as a rise in serum creatinine (SCr) of 0.5 mg/dl or a 25% increase from the baseline value within 48 hours after the procedure. The secondary endpoint was the combined occurrence of major adverse cardiovascular events (MACE), including death, nonfatal myocardial infarction, and ischemic stroke.

Results

Overall, CIN occurred in 85 (15.6%) patients. All patients were stratified into 3 groups (low/normal/high) according to the serum bilirubin levels. In a multivariate logistic analysis, the odds ratio for CIN with low-bilirubin levels relative to high-bilirubin levels was 11.82 (95% CI, 3.25–43.03). By Cox regression analysis, serum bilirubin levels was an independent predictor of MACE in patients undergoing coronary intervention (low vs. high hazard ratio 2.26; 95% CI, 1.05–4.90).

Conclusions

CIN is a serious complication of coronary intervention. Higher serum bilirubin concentrations were associated with lower risk of CIN and fewer cardiovascular events. The development of interventions that promote bilirubin levels may be a potential target to reduce CIN and future MACE in patients undergoing coronary intervention.

Efficacy of allopurinol pretreatment for prevention of contrast-induced nephropathy: a randomized controlled trial

BACKGROUND

Contrast-induced nephropathy (CIN) remains a common complication of radiographic procedures. Radiocontrast agents can cause a reduction in renal function that may be due to reactive oxygen species. Conflicting evidence suggests that administration of antioxidants prevents CIN.

METHODS

We assessed the efficacy of allopurinol in preventing CIN. We prospectively randomized 159 patients with a serum creatinine concentration >1.1mg/dL undergoing cardiac catheterization/interventions to receive allopurinol (300 mg, p.o.) 24h before administration of radiocontrast agent and hydration (1mg/kg/hN/saline for 12h pre- and post-contrast, n=79), or hydration alone (1mg/kg/hN/saline for 12h pre- and post-contrast, n=80).

RESULTS

CIN occurred in 6 of 80 patients (7.5%) in the control group and no subjects in the allopurinol group (p=0.013). In the allopurinol group, median serum creatinine concentration decreased significantly from 1.43 mg/dL [1.1-4.15 mg/dL] to 1.35 mg/dL [0.7-4.15 mg/dl] at 48 h and to 1.27 mg/dL [0.66-4.37 mg/dL] at 4 days after radiocontrast administration (p<0.0001 and p<0.0001 compared with baseline, respectively). In the control group, median serum creatinine concentration decreased non-significantly from 1.48 mg/dL [1.1-2.96 mg/dL] to 1.43 mg/dL [0.73-3.02 mg/dL] and to 1.45 mg/dL [0.86-3.71 mg/dL] (p=0.045 and p=0.57, respectively) 48 h and 4 days after radiocontrast administration.

CONCLUSIONS

Prophylactic oral administration of allopurinol, along with hydration, may protect against CIN in high-risk patients undergoing coronary procedures.

The protective effect of erdosteine on radiocontrast induced nephrotoxicity in rats

Acute renal failure resulting from radiocontrast-induced nephrotoxicity (RIN) is suggested to occur via medullary ischemia coupled with the generation of free radicals and oxidative injury to tubular cells. The aim of the present study was to assess the effects of erdosteine on prevention of RIN. Thirty-three Wistar-albino rats were divided into five groups: control (group 1, n = 6), radiocontrast media (group 2, n = 6), erdosteine (group 3, n = 7), erdosteine four doses before radiocontrast application (group 4, n = 7) and erdosteine one dose at the same day with radiocontrast application (group 5, n = 7). RIN was induced by administration of intravenous high osmolar contrast media amidotrizoate (6 mL/kg). Total RNA was extracted from the kidney, and the expression levels of Lipocalin 2 (Lcn2) and secreted phosphoprotein 1 (Spp1) genes were evaluated by real time reverse transcription polymerase chain reaction (real-time RT-PCR). Total antioxidant status (TAS) and total oxidant status (TOS) were measured in kidney homogenates and serum samples. Serum creatinine, BUN (Blood Urea Nitrogen) and cystatin-C levels were measured from serum samples. The kidneys were evaluated histopathologically. The expression levels of Spp1 and Lcn2 genes in group 2 were significantly higher than groups 1, 3, 4, and 5. The expression levels of Spp1 and Lcn2 genes in group 4 were four and two times lower than group 5, respectively. Kidney TOS levels in group 2 were significantly higher than groups 1, 3, 4, and 5. Kidney TAS levels in group 3 were higher than group 2. Kidney oxidative stress index (OSI) levels in group 2 were significantly higher than groups 4 and 5. All rats in contrast media group developed tubular necrosis, proteinaceous casts, medullary congestion although these changes were significantly reduced in groups 4 and 5. This study demonstrated that multiple doses of erdosteine before application may have higher protective effects against RIN.

Methylxanthines and the kidney

This chapter describes the effects of the natural methylxanthines caffeine and theophylline on kidney function. Theophylline in particular was used traditionally to increase urine out put until more potent diuretics became available in the middle of the last century. The mildly diuretic actions of both methylxanthines are mainly the result of inhibition of tubular fluid reabsorption along the renal proximal tubule. Based upon the use of specific adenosine receptor antagonists and the observation of a complete loss of diuresis in mice with targeted deletion of the A1AR gene, transport inhibition by methylxanthines is mediated mainly by antagonism of adenosine A1 receptors (A1AR) in the proximal tubule. Methylxanthines are weak renal vasodilators, and they act as competitive antagonists against adenosine-induced preglomerular vasoconstriction. Caffeine and theophylline stimulate the secretion of renin by inhibition of adenosine receptors and removal of the general inhibitory brake function of endogenous adenosine. Since enhanced intrarenal adenosine levels lead to reduced glomerular filtration rate in several pathological conditions theophylline has been tested for its therapeutic potential in the renal impairment following administration of nephrotoxic substances such as radiocontrast media, cisplatin, calcineurin inhibitors or following ischemia-reperfusion injury. In experimental animals functional improvements have been observed in all of these conditions, but available clinical data in humans are insufficient to affirm a definite therapeutic efficacy of methylxanthines in the prevention of nephrotoxic or postischemic renal injury.

The role of dialysis in contrast-induced nephropathy: doubts and certainties

Over past years, there has been a progressive increase in percutaneous endovascular procedures in patients with chronic renal disease, owing to the high incidence of vascular disease, particularly coronary artery disease, in this population. The use of contrast media may further worsen renal function in such patients, in some cases even accelerating the progression towards end-stage renal failure, and may increase patient morbidity and mortality. In this review, we discuss the role of dialysis in preventing contrast-induced nephropathy as well as present indications to its use in patients already on dialysis treatment undergoing diagnostic or therapeutic procedures with contrast medium injection.

Iodixanol

OBJECTIVE

To assess the risk of contrast-induced nephropathy in cancer patients with underlying renal insufficiency receiving the iso-osmolar intravenous contrast agent iodixanol for diagnostic computed tomography (CT) examinations.

METHODS

Institutional review board approval was obtained with waiver of informed consent. Our study was a retrospective evaluation comparing the incidence of contrast-induced nephropathy in consecutive patients with underlying renal insufficiency undergoing diagnostic CT examinations receiving iodixanol from November 2003 to June 2005 with a comparison group of patients with normal baseline renal function over the same period. Renal insufficiency was considered a serum creatinine level more than 1.2 mg/dL in females and more than 1.5 mg/dL in males. Contrast nephropathy was considered an absolute elevation of 0.5 mg/dL or 25% elevation in serum creatinine level.

RESULTS

In the group of patients receiving iodixanol with underlying renal insufficiency (189 patients), 9.0% developed contrast nephropathy (P = 0.015) with 4.8% of patients developing irreversible renal damage (P = 0.03). This compared with 4.9% of patients receiving iodixanol (185 patients) and 3.1% of patients receiving iohexol (194 patients) with normal baseline renal function developing contrast nephropathy (P = 0.38) with 3.2% of the iodixanol patients and 1.0% of the iohexol patients developing irreversible renal damage (P = 0.13).

CONCLUSIONS

The risk of contrast-induced nephropathy is significantly higher in patients with underlying renal insufficiency receiving iodixanol than that for patients with normal baseline renal function, but this should not serve as an absolute contraindication for these patients to receive intravenous iodinated contrast for diagnostic CT examinations particularly in patients with life-threatening clinical questions in which contrasted CT may provide valuable information.

European Society of Urogenital Radiology (ESUR) guidelines on the safe use of iodinated contrast media

Since 1996 the Contrast Media Safety Committee of the European Society of Urogenital Radiology (ESUR) has released 19 guidelines regarding safety in relation to the use of radiographic, ultrasonographic as well as magnetic resonance contrast media. The committee has covered both renal and non-renal adverse events as well as other aspects of contrast media. The present paper is an overview of the work accomplished over the last 10 years regarding radiographic iodinated contrast media.

Selective renal arterial infusion of fenoldopam for the prevention of contrast-induced nephropathy

Contrast-induced nephropathy (CIN) remains an important complication of angiographic procedures, particularly among patients with significant renal impairment. To date, vasodilator therapies such as fenoldopam have failed to prevent CIN, possibly because significant hypotension as a result of systemic infusion has limited the ability to deliver adequate drug levels to the renal vasculature. We present a case of averted CIN after multivessel coronary intervention in a diabetic patient with severe renal insufficiency, potentially due to bilateral renal arterial infusion of fenoldopam. Our subsequent experience with intrarenal fenoldopam in nine additional procedures in eight other high risk patients resulted in one case of asymptomatic transient CIN. Further studies are warranted to evaluate the efficacy of intrarenal administration of vasodilator therapies such as fenoldopam for the prevention of CIN.

Contrast-medium-induced nephropathy: is there a new consensus? A review of published guidelines

The interest in contrast-medium-induced nephropathy has increased considerably during the last few years. Various guidelines regarding identifying patients at risk and measures to reduce the incidence of this complication have been proposed. The aim of this review was to analyse whether there is some consistency amongst these guidelines. A Medline search for the keyword "contrast medium induced nephropathy" during the period from the beginning of 2003 through the end of September 2005 was carried out. Only papers in English were reviewed. Thirteen guidelines were identified. Inconsistency was observed regarding advise on the prophylactic use of drugs and the isoosmolar dimer to reduce the incidence of contrast-medium-induced nephropathy. Consistency was found in relation to the importance of hydration, cessation of intake of nephrotoxic drugs and administration of the lowest possible dose of contrast medium. No new consensus has been observed in comparison to the European Society for Urogenital Radiology (ESUR) guidelines, which were published in 1999.

Involvement of de novo ceramide synthesis in radiocontrast-induced renal tubular cell injury

We reported previously that various radiocontrast media cause apoptosis in porcine proximal tubular (LLC-PK(1)) cells, in which reduction in B-cell lymphoma (Bcl)-2 expression and caspase-3 activation are implicated. In the present study, we investigated a role for ceramide in radiocontrast media-induced apoptosis in renal tubular cells. LLC-PK(1) cells were exposed to radiocontrast media for 30 min, followed by incubation for 24 h in normal medium. Cell viability was assessed by 2-(2-methoxy-4-nitrophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium monosodium salt assay, while apoptosis was determined by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling stain. Immunofluorescent stains were performed using antibodies against phosphorylated Akt (pAkt) and cAMP response element binding protein (CREB) (pCREB), and ceramide. The mRNA expression and protein content of Bcl-2 were determined by reverse transcriptase-polymerase chain reaction and enzyme immunoassay, respectively. In vivo model of contrast-induced renal injury was induced in mice with unilateral renal occlusion. The cell injury induced by the nonionic radiocontrast medium ioversol was reversed by inhibiting de novo ceramide synthesis with fumonisin B(1) (FB(1)) and L-cycloserine, but not by suppressing sphingomyelin breakdown with D609. FB(1) reversed ioversol-induced decrease in the immunoreactivities of pAkt and pCREB, reduction in Bcl-2 expression and caspase-3 activation. Like ioversol, C2 ceramide and the Akt inhibitor Src homology-6 induced apoptosis by reducing pAkt and pCREB-like immunoreactivities, lowering Bcl-2 expression and enhancing caspase-3 activity. Indeed, various radiocontrast media, excluding iodixanol which showed the least nephrotoxicity, enhanced ceramide-like immunoreactivity. The role for de novo ceramide synthesis was also shown in the in vivo model of radiocontrast nephropathy. We demonstrated here for the first time that the enhancement of de novo ceramide synthesis contributes to radiocontrast nephropathy.

Contrast material-induced renal failure: an overview

The administration of iodinated contrast media (CM) is integral to many cardiovascular procedures. While it is clear that CM provide significant diagnostic benefit, there is some risk of contrast medium-related adverse events in a small percentage of patients. Potentially the most serious complication associated with the use of iodinated contrast agents is contrast-induced nephropathy (CIN). Most patients undergoing contrast-enhanced radiographic procedures are not at risk for CIN, however subjects with pre-existing renal insufficiency, diabetes mellitus, or cardiovascular disease receiving intra-arterial administrations of contrast material are at increased risk. Typically, patients with CIN will experience changes in serum creatinine 1-5 days following contrast exposure. While decrements in renal function are generally small and transient, some patients experience a more prolonged decrease and, in rare cases, require dialysis. More importantly, there is substantial literature documenting that patients with CIN after cardiac intervention experience greater morbidity (including prolonged hospitalization) and acute and 1-year mortality. The present article aims to briefly review the pathogenesis of CIN and reviews current opinion on how best to prevent CIN and manage at-risk patients.

The Clinical Epidemiology of Contrast-Induced Nephropathy

Recent improvements in contrast agents and radiologic imaging tools have resulted in an increasing number of patients undergoing contrast media (CM)-enhanced examinations. Although the majority of patients undergoing these diagnostic and therapeutic procedures experience only mild adverse events, some patient subpopulations are at risk for developing contrast-induced nephropathy (CIN), an adverse event that is associated with high morbidity and mortality. Contrast-induced nephropathy is usually defined as an increase of > or =25% in the serum creatinine level relative to baseline. Pathophysiologic mechanisms underlying this disorder are not fully understood, but it is currently believed that disturbances in renal hemodynamics and a direct effect of CM on renal tubules are involved. In the general population, the incidence of CIN is estimated to be 1% to 6%. However, the risk may be as high as 50% in some patient subgroups. Patients with diabetes and pre-existing renal impairment are at high risk, and CIN incidence increases in patients with multiple comorbidities. The volume and osmolality of CM used also play a role in the development of CIN. Patients who develop CIN are more likely to die in-hospital and, for those who are discharged, 1-year mortality rates are high. Whether this is due to CM, comorbidity, or concurrent comorbid events is unclear. Randomized controlled trials that measure non-renal clinical outcomes are necessary to determine whether interventions that prevent CIN can also prevent non-renal adverse events. A review of the incidence, pathogenesis, and clinical consequences of CIN is provided.

Nephropathy induced by contrast media: pathogenesis, risk factors and preventive strategies

With the increasing use of contrast media in diagnostic and interventional procedures, nephropathy induced by contrast media has become the third leading cause of hospital-acquired acute renal failure. It is also associated with a significant risk of morbidity and death. The current understanding of the pathogenesis indicates that contrast-medium nephropathy is caused by a combination of renal ischemia and direct toxic effects on renal tubular cells. Patients with pre-existing renal insufficiency, diabetes mellitus and congestive heart failure are at highest risk. Risk factors also include the type and amount of contrast medium administered. Therapeutic prevention strategies are being extensively investigated, but there is still no definitive answer. In this article, we review the current evidence on the causes, pathogenesis and clinical course of contrast-medium nephropathy as well as therapeutic approaches to its prevention evaluated in clinical trials.

Contrast Dose-to-Creatinine Clearance Ratio as a Potential Indicator of Risk for Radiocontrast-Induced Nephropathy

OBJECTIVES

Identification of risk factors is important for preventing radiocontrast-induced nephropathy (RCIN). Contrast dose and renal function have been shown in most but not all studies to be risk factors for RCIN. We are investigating the ratio of contrast dose to creatinine clearance (D/CrCL) as a risk indicator. Theory shows that the D/CrCL ratio equals the area under the concentration-time curve (AUC), an accepted measure of systemic exposure. This study investigated the correlation between calculated D/CrCL and experimentally measured AUC for the contrast agent iodixanol.

MATERIALS AND METHODS

Experimental data on AUC from a phase 1 study of iodixanol were plotted against the D/CrCL ratio and the degree of correlation was determined.

RESULTS

Experimentally determined AUC data correlate highly with the D/CrCL ratio.

CONCLUSIONS

The D/CrCL ratio is a rapid and accurate way to estimate AUC for an iodinated x-ray contrast agent without the need for multiple blood samples.

N-acetylcysteine prophylaxis significantly reduces the risk of radiocontrast-induced nephropathy: comprehensive meta-analysis

The objectives of this study was to assess the overall effect of N-acetylcysteine (NAC) in preventing radiocontrast-induced nephropathy (RCIN) using all available data in the literature. RCIN is associated with increased morbidity and mortality. Existing randomized trials of NAC are small and show inconsistent results. Prior meta-analyses do not include data from the most current studies. We used standard search protocols to identify all published articles and abstracts of prospective trials using NAC with fluid hydration compared to hydration alone in patients with chronic renal insufficiency undergoing contrast procedures. A rise in serum creatinine by 0.5 mg/dl or 25% above baseline at 48-72 hr after contrast exposure was used as the primary outcome. We identified 14 trials of NAC with 1,584 patients published as full-text articles. Using a random-effects model, the use of oral NAC resulted in a significant reduction in the risk for developing RCIN (RR = 0.57; 95% CI = 0.37-0.84; P = 0.01). This finding did not significantly change in a fixed-effect model (RR = 0.55; 95% CI = 0.42-0.73) or when the data were reanalyzed using only randomized trials in all forms (i.e., articles and abstracts; RR = 0.67; 95% CI = 0.47-0.95). We identified only one important difference between the positive and the negative studies: the cumulative exposure to contrast media (174 vs. 152 ml). Metaregression did not show a significant relationship between contrast volume and the RR of developing RCIN (P > 0.10). In the trials showing benefit for NAC, the treated patients' postprocedure creatinine unexpectedly decreased by 0.21 mg/dl (95% CI = 0.33-0.08). Prophylaxis with NAC significantly reduces the risk for RCIN. The reasons for improvement in serum creatinine in patients treated with NAC are unclear, but may include improved renal blood flow due to NAC and/or vigorous hydration.

Recent advances in the prevention of radiocontrast-induced nephropathy

PURPOSE OF REVIEW

Radiocontrast nephropathy is a serious clinical problem associated with increased morbidity and mortality, particularly in patients with chronic renal failure. The optimal strategy to prevent radiocontrast nephropathy has not been established. This article reviews recent clinical researches concerning new developments in the prevention of radiocontrast nephropathy and analyzes unresolved issues.

RECENT FINDINGS

Among all prophylactic measures that have been proposed, periprocedural hydration with isotonic saline has demonstrated effectiveness in the prevention of radiocontrast nephropathy. Thus, it remains the most frequently applied measure in clinical practice. Recently, additional benefit has been shown to derive from the infusion of isotonic alkalizing (sodium bicarbonate), instead of isotonic (sodium chloride) solutions. The use of nonionic low-osmolar and, more recently, nonionic iso-osmolar contrast agents has been demonstrated to significantly reduce the risk of radiocontrast nephropathy in patients with renal impairment, in comparison with hyperosmolar contrast media. Recently, periprocedural hemofiltration has emerged as a safe and very effective strategy to prevent radiocontrast nephropathy and to reduce its associated poor outcome in patients with severe chronic renal failure. In the past few years, several trials with acetylcysteine have shown conflicting results. Nevertheless, most of them indicated that acetylcysteine, particularly when associated with adequate hydration, might be useful in preventing radiocontrast nephropathy in patients with renal impairment. A possible dose-dependent protective effect has been suggested by more recent trials that included patients undergoing coronary interventional procedures requiring large contrast volume.

SUMMARY

Adequate prophylaxis is needed to reduce the high morbidity and mortality associated with radiocontrast nephropathy in high-risk patients. By reviewing the available evidence from clinical trials, this article provides an overview of current strategies and unresolved issues concerning the prevention of radiocontrast nephropathy.

Excretory urography

Excretory urography is a type of contrast study used to verify and localize upper urinary tract disease. In some instances, information regarding renal function and disease pathophysiology can also be obtained. With the recent advances in small animal ultrasonagraphy, excretory urography has become an underutilized procedure. This article will help explain why excretory urography remains, and will remain, a ubiquitous test that gives excellent detail of the entire urinary tract, and remains an essential tool for the assessment of the renal pelves and especially the ureters. Specifically, this article will focus on technique and interpretation of a properly performed excretory urogram.