Pathophysiology of radiocontrast nephropathy: a role for medullary hypoxia

Effects of platelet-to-lymphocyte ratio on renal function following acute myocardial infarction: A retrospective observational study

Increased platelet-to-lymphocyte ratio (PLR) and neutrophil-to-lymphocyte ratio (NLR) in acute myocardial infarction (AMI), which indicate accelerated thrombus formation and inflammatory response, potentially have prognostic implications. Given that cardiovascular disease and renal function exacerbate each other, an elevated PLR and NLR at admission for AMI may worsen renal function after AMI. However, only a few clinical studies have addressed this issue. Therefore, this study aimed to examine the effects of PLR and NLR at AMI onset on renal function. This retrospective study analyzed data from 234 patients hospitalized for AMI. First, correlations between various parameters (age; sex; body mass index; hemoglobin level, albumin level, B-type natriuretic peptide level, C-reactive protein level, creatinine (Cr) level, blood urea nitrogen (BUN) level, PLR, and NLR at admission; contrast medium usage; and maximum creatine kinase) and Cr and BUN levels at discharge were examined using single and multiple regression analyses. Then, correlations between these parameters and the change in Cr (ΔCr) and BUN levels (ΔBUN) were investigated using single and multiple regression analysis, followed by structural equation modeling (SEM). Multiple regression analysis revealed significant positive correlations between PLR at admission and Cr level at discharge (β = 0.135, P = .021), PLR at admission and BUN level at discharge (β = 0.218, P = .006), PLR at admission and ΔCr (β = 0.244, P = .019), and PLR at admission and ΔBUN (β = 0.312, P = .003). SEM results revealed significant positive correlations between PLR at admission and ΔCr (β = 0.260, P = .008) and PLR at admission and ΔBUN (β = 0.292, P = .003). Conversely, NLR demonstrated a minimal association with renal function at discharge compared to PLR. This study suggests that increased PLR at admission in AMI significantly affects and exacerbates renal function but does not increase NLR at admission. PLR is one of the predictors of renal dysfunction after AMI.

Serum total bilirubin level is associated with contrast induced nephropathy after primary percutaneous coronary intervention

Contrast Induced Nephropathy (CIN) is a major complication of angiographic procedures. Primary percutaneous coronary intervention (pPCI) is the preferred treatment for ST-segment elevation myocardial infarction (STEMI) but is associated with a risk of CIN. Oxidative stress and free radical damage play a role in the pathogenesis of CIN. Bilirubin has anti-inflammatory and antioxidant activity and has been shown to have a protective effect on endothelial cells. The present study aimed to assess the association between serum bilirubin level and development of CIN after pPCI. Sequential STEMI patients (n = 595) who underwent pPCI between January 2021 and December 2022 were enrolled. Among the participants, 116 (19.5%) developed CIN. Serum total bilirubin level was significantly lower in the CIN group (P = .001). In multivariate logistic regression analysis, serum bilirubin level was found as an independent predictor of CIN. Age, gender, contrast volume, and white blood cell count were other independent predictors of CIN. A higher serum bilirubin level is associated with a lower risk of CIN in the present study. In STEMI patients undergoing pPCI, serum bilirubin level may be helpful to predict the risk of CIN and may help ensure early initiation of preventive treatment and careful follow-up.

Contrast-Associated Acute Kidney Injury: Definitions, Epidemiology, Pathophysiology, and Implications

Acute kidney injury (AKI) is a common occurrence after contrast media administration. Hemodynamic changes, direct tubular injury, and reactive oxygen species are the proposed mechanisms involved in AKI. However, in most scenarios, it is not possible to establish causality despite extensive clinical evaluation, therefore, contrast-associated AKI (CA-AKI) has become a widely accepted term to define AKI postcontrast. CA-AKI is associated with worse clinical outcomes including cardiovascular events and mortality; however, discussions are ongoing whether CA-AKI is a marker of an increased risk of adverse outcomes or a mediator of such outcomes.

Endogenous and Exogenous Antioxidants as Agents Preventing the Negative Effects of Contrast Media (Contrast-Induced Nephropathy)

The use of conventional contrast media for diagnostic purposes (in particular, Gd-containing and iodinated agents) causes a large number of complications, the most common of which is contrast-induced nephropathy. It has been shown that after exposure to contrast agents, oxidative stress often occurs in patients, especially in people suffering from various diseases. Antioxidants in the human body can diminish the pathological consequences of the use of contrast media by suppressing oxidative stress. This review considers the research studies on the role of antioxidants in preventing the negative consequences of the use of contrast agents in diagnostics (mainly contrast-induced nephropathy) and the clinical trials of different antioxidant drugs against contrast-induced nephropathy. Composite antioxidant/contrast systems as theranostic agents are also considered.

The Value of C-reactive Protein/Albumin Ratio in the Prediction of Contrast-Induced Nephropathy in Emergency Department Patients

BACKGROUND

Contrast-induced nephropathy (CIN) is the third most common cause of acute renal failure in hospitalized patients and is an important cause of prolonged hospital stay, morbidity, and mortality. We aimed to investigate the effectiveness and sufficiency of the prognostic capacity of the inflammatory biomarkers C-reactive Protein (CRP) and albumin ratio (CAR) in predicting the development of CIN in patients undergoing contrast-enhanced computed tomography (CT) imaging in the emergency department (ED).

METHODS

This study was performed on patients whose laboratory values ​​could be reached within 48 hours after contrast-enhanced CT imaging in the emergency department of our hospital. The patients were divided into two groups as those with and without CIN according to their increased creatinine levels. Its effectiveness in detecting the development of CIN in the early period was evaluated comparatively.

RESULTS

One hundred and twenty-five patients were included. CIN developed in 10.4% of the patients. The CAR was 0.19 (IQR: 0.17-0.33) in the group with CIN and 0.02 (IQR: 0.01-0.06) in the group without CIN; and the difference between the two groups was significant (p<0.001). In multivariate logistic regression analysis, it was found that the CAR increased as an independent risk factor for CIN (OR: 2.326; 95% CI: 1.39-3.893; p=0.001).

CONCLUSIONS

We think that early identification of patients who may develop CIN through the CAR in EDs and early initiation of treatment for CIN may affect the morbidity-mortality rate and reduce the duration of hospitalization and treatment costs.

SIRM-SIN-AIOM: appropriateness criteria for evaluation and prevention of renal damage in the patient undergoing contrast medium examinations-consensus statements from Italian College of Radiology (SIRM), Italian College of Nephrology (SIN) and Italian Association of Medical Oncology (AIOM)

The increasing number of examinations and interventional radiological procedures that require the administration of contrast medium (CM) in patients at risk for advanced age and/or comorbidities highlights the problem of CM-induced renal toxicity. A multidisciplinary group consisting of specialists of different disciplines—radiologists, nephrologists and oncologists, members of the respective Italian Scientific Societies—agreed to draw up this position paper, to assist clinicians increasingly facing the challenges posed by CM-related renal dysfunction in their daily clinical practice.

The major risk factor for acute renal failure following CM administration (post-CM AKI) is the preexistence of renal failure, particularly when associated with diabetes, heart failure or cancer.

In accordance with the recent guidelines ESUR, the present document reaffirms the importance of renal risk assessment through the evaluation of the renal function (eGFR) measured on serum creatinine and defines the renal risk cutoff when the eGFR is < 30 ml/min/1.73 m2 for procedures with intravenous (i.v.) or intra-arterial (i.a.) administration of CM with renal contact at the second passage (i.e., after CM dilution with the passage into the pulmonary circulation).

The cutoff of renal risk is considered an eGFR < 45 ml/min/1.73 m2 in patients undergoing i.a. administration with first-pass renal contact (CM injected directly into the renal arteries or in the arterial district upstream of the renal circulation) or in particularly unstable patients such as those admitted to the ICU.

Intravenous hydration using either saline or Na bicarbonate solution before and after CM administration represents the most effective preventive measure in patients at risk of post-CM AKI. In the case of urgency, the infusion of 1.4% sodium bicarbonate pre- and post-CM may be more appropriate than the administration of saline.

In cancer patients undergoing computed tomography, pre- and post-CM hydration should be performed when the eGFR is < 30 ml/min/1.73 m2 and it is also advisable to maintain a 5 to 7 days interval with respect to the administration of cisplatin and to wait 14 days before administering zoledronic acid.

In patients with more severe renal risk (i.e., with eGFR < 20 ml/min/1.73 m2), particularly if undergoing cardiological interventional procedures, the prevention of post-CM AKI should be implemented through an internal protocol shared between the specialists who treat the patient.

In magnetic resonance imaging (MRI) using gadolinium CM, there is a lower risk of AKI than with iodinated CM, particularly if doses < 0.1 mmol/kg body weight are used and in patients with eGFR > 30 ml/min/1.73 m2. Dialysis after MRI is indicated only in patients already undergoing chronic dialysis treatment to reduce the potential risk of systemic nephrogenic fibrosis.

Kidney Microcirculation as a Target for Innovative Therapies in AKI

Acute kidney injury (AKI) is a serious multifactorial conditions accompanied by the loss of function and damage. The renal microcirculation plays a crucial role in maintaining the kidney’s functional and structural integrity for oxygen and nutrient supply and waste product removal. However, alterations in microcirculation and oxygenation due to renal perfusion defects, hypoxia, renal tubular, and endothelial damage can result in AKI and the loss of renal function regardless of systemic hemodynamic changes. The unique structural organization of the renal microvasculature and the presence of autoregulation make it difficult to understand the mechanisms and the occurrence of AKI following disorders such as septic, hemorrhagic, or cardiogenic shock; ischemia/reperfusion; chronic heart failure; cardiorenal syndrome; and hemodilution. In this review, we describe the organization of microcirculation, autoregulation, and pathophysiological alterations leading to AKI. We then suggest innovative therapies focused on the protection of the renal microcirculation and oxygenation to prevent AKI.

Targeting Oxidative Stress in Septic Acute Kidney Injury: From Theory to Practice

Sepsis is the leading cause of acute kidney injury (AKI) and leads to increased morbidity and mortality in intensive care units. Current treatments for septic AKI are largely supportive and are not targeted towards its pathophysiology. Sepsis is commonly characterized by systemic inflammation and increased production of reactive oxygen species (ROS), particularly superoxide. Concomitantly released nitric oxide (NO) then reacts with superoxide, leading to the formation of reactive nitrogen species (RNS), predominantly peroxynitrite. Sepsis-induced ROS and RNS can reduce the bioavailability of NO, mediating renal microcirculatory abnormalities, localized tissue hypoxia and mitochondrial dysfunction, thereby initiating a propagating cycle of cellular injury culminating in AKI. In this review, we discuss the various sources of ROS during sepsis and their pathophysiological interactions with the immune system, microcirculation and mitochondria that can lead to the development of AKI. We also discuss the therapeutic utility of N-acetylcysteine and potential reasons for its efficacy in animal models of sepsis, and its inefficacy in ameliorating oxidative stress-induced organ dysfunction in human sepsis. Finally, we review the pre-clinical studies examining the antioxidant and pleiotropic actions of vitamin C that may be of benefit for mitigating septic AKI, including future implications for clinical sepsis.

Kidney physiology and susceptibility to acute kidney injury: implications for renoprotection

Kidney damage varies according to the primary insult. Different aetiologies of acute kidney injury (AKI), including kidney ischaemia, exposure to nephrotoxins, dehydration or sepsis, are associated with characteristic patterns of damage and changes in gene expression, which can provide insight into the mechanisms that lead to persistent structural and functional damage. Early morphological alterations are driven by a delicate balance between energy demand and oxygen supply, which varies considerably in different regions of the kidney. The functional heterogeneity of the various nephron segments is reflected in their use of different metabolic pathways. AKI is often linked to defects in kidney oxygen supply, and some nephron segments might not be able to shift to anaerobic metabolism under low oxygen conditions or might have remarkably low basal oxygen levels, which enhances their vulnerability to damage. Here, we discuss why specific kidney regions are at particular risk of injury and how this information might help to delineate novel routes for mitigating injury and avoiding permanent damage. We suggest that the physiological heterogeneity of the kidney should be taken into account when exploring novel renoprotective strategies, such as improvement of kidney tissue oxygenation, stimulation of hypoxia signalling pathways and modulation of cellular energy metabolism.

Contrast Media-Different Types of Contrast Media, Their History, Chemical Properties, and Relative Nephrotoxicity

History of contrast dates back to the 1890s, with the invention of the radiograph. Nephrotoxicity has been a main limitation in ideal contrast media (CM). High-osmolar contrast media no longer are in clinical use due to overwhelming evidence supporting greater nephrotoxicity with these CM compared with current CM. Contrast-induced nephropathy (CIN) remains a common cause of in-hospital acute kidney injury. The choice contrast agent is determined mainly by cost and institution practice. This review focuses on the history, chemical properties, and experimental and clinical studies on the various groups of CM and their role in CIN.

Pathophysiology of Contrast-Induced Acute Kidney Injury

Passing contrast media through the renal vascular bed leads to vasoconstriction. The perfusion decrease leads to ischemia of tubular cells. Through ischemia and direct toxicity to renal tubular cells, reactive oxygen species formation is increased, enhancing the effect of vasoconstrictive mediators and decreasing the bioavailability of vasodilative mediators. Reactive oxygen species formation leads to oxidative damage to tubular cells. These interacting pathways lead to tubular necrosis. In the pathophysiology of contrast-induced acute kidney injury, low osmolar and iso-osmolar agents have theoretic advantages and disadvantages; however, clinically the difference in incidence of contrast-induced acute kidney injury has not changed.

Increased fibrotic signaling in a murine model for intra-arterial contrast-induced acute kidney injury

Contrast-induced acute kidney injury (CI-AKI) is a vexing problem, and more than 70 million patients undergo studies using iodinated contrast. The molecular mechanisms responsible for CI-AKI are poorly understood. The goal of the present article was to determine the role of transforming growth factor-β1 (TGF-β1)/mothers against decapentaplegic homolog (SMAD)3 and associated collagen expression in a murine model of intra-arterial CI-AKI. The murine model of CI-AKI after intra-arterial contrast agent administration was created by first performing a partial nephrectomy to induce chronic kidney disease. Twenty-eight days later, 100 μL of contrast agent [iodixanol (320 mg/mL)] or saline were administered via the carotid artery. Two days after contrast administration, compared with saline, average serum creatinine was significantly elevated (P < 0.05). In the cortex, there was a significant increase in phosphorylated SMAD3 and gene expression of TGF-β1, TGF-β receptor type I, and TGF-β receptor type II at day 2 in the contrast group compared with the saline group. Average gene expressions of connective tissue growth factor, matrix metalloproteinase-2 and -9, and collagen type I-α and type IV-α were significantly increased at 2 days after contrast administration (all P < 0.05). Moreover, there was a decrease in Ki-67 staining in the cortex, with an increase in terminal deoxynucleotidyl transferase dUTP nick-end labeling in the cortex and medulla after contrast administration (P < 0.05). In the murine intra-arterial CI-AKI model, there was increased hypoxia and TGF-β1/SMAD3 pathway activation and collagen expression, resulting in renal fibrosis. Together, these results suggest that the TGF-β1/SMAD3 pathway could be a potential target in alleviating tissue fibrosis in CI-AKI.

Intravascular Iodinated Contrast Is an Independent Cause of Acute Kidney Injury Following Coronary Angiography

OBJECTIVES

Recent studies have questioned whether intravascular iodinated contrast remains an independent cause of acute kidney injury (AKI). We sought to assess whether iodinated contrast administered during coronary angiography is an independent cause of AKI.

METHODS

We identified all of the patients who underwent coronary angiography between July 1, 2015 and June 30, 2017 with a discharge diagnosis of AKI that developed within 7 days following angiography. Using chart review, we categorized patients as having multifactorial AKI if ≥1 insults other than intravascular contrast potentially contributed to kidney injury or contrast-induced AKI (CI-AKI) if the only insult was contrast administration. We compared the severity of AKI and renal function upon discharge between patients with CI-AKI and multifactorial AKI.

RESULTS

We identified 78 patients who experienced AKI within 7 days following angiography, 10 (13%) of whom had CI-AKI and 68 of whom (87%) experienced multifactorial AKI. Nine (90%) patients with CI-AKI manifested stage 1 disease, 1 (10%) had stage 2 disease, and 9 (90%) experienced full recovery of kidney function. More patients with multifactorial AKI developed stage 2 or 3 disease (42% vs 10%, χ² = 3.73, P = 0.05) and experienced either partial recovery of kidney function or persistent kidney impairment compared with patients with CI-AKI (25% vs 10%, χ² = 1.9, P = 0.17), although the latter comparison was not statistically significant.

CONCLUSIONS

The intravascular administration of iodinated contrast remains an independent cause of AKI. Compared with those with multifactorial AKI, patients with CI-AKI appear to be more likely to experience mild decrements in kidney function that recover completely.

Hypoxia and Hypoxia-Inducible Factors in Kidney Injury and Repair

Acute kidney injury (AKI) is a major kidney disease characterized by an abrupt loss of renal function. Accumulating evidence indicates that incomplete or maladaptive repair after AKI can result in kidney fibrosis and the development and progression of chronic kidney disease (CKD). Hypoxia, a condition of insufficient supply of oxygen to cells and tissues, occurs in both acute and chronic kidney diseases under a variety of clinical and experimental conditions. Hypoxia-inducible factors (HIFs) are the "master" transcription factors responsible for gene expression in hypoxia. Recent researches demonstrate that HIFs play an important role in kidney injury and repair by regulating HIF target genes, including microRNAs. However, there are controversies regarding the pathological roles of HIFs in kidney injury and repair. In this review, we describe the regulation, expression, and functions of HIFs, and their target genes and related functions. We also discuss the involvement of HIFs in AKI and kidney repair, presenting HIFs as effective therapeutic targets.

Epidemiology of acute kidney injury and associated factors among patients with malignancy: Analysis of hospital inpatient database in Shanghai, China

Objective:

This study aimed to understand the incidence of acute kidney injury in cancer patients, to figure out which clinical factors could increase the risks of acute kidney injury, and then to assess the effect of acute kidney injury on in-hospital mortality, length of stay, and hospital cost.

Methods:

This study was designed as a retrospective cohort study based on the hospital inpatient database in Zhongshan Hospital, Shanghai, China. Patients with malignancy and admitted to the hospital between 1 October 2014 and 30 September 2015 were recruited. Data on demographics, comorbidities, and clinical records were exported for analysis. Acute kidney injury was diagnosed using KDIGO (Kidney Disease: Improving Global Outcomes) criteria and stratified into community-acquired and hospital-acquired acute kidney injury. Multivariate model and survival analysis were applied to discover the influencing factors of acute kidney injury among cancer patients.

Results:

Of the 26,914 eligible cancer admissions, 3326 acute kidney injury cases were identified with an incidence of 12.4%. Of them, 2961 patients located in acute kidney injury stage 1 and another 365 cases developed to stage 2–3. The highest rates were localized to renal cancer (27.3%), multiple myeloma (24.1%), and leukemia (23.9%). Patients with older age and hematologic cancer shared a higher acute kidney injury incidence. Pre-existing chronic kidney disease (adjusted odds ratio = 7.14), heart failure (adjusted odds ratio = 4.20), surgery/chemotherapy (adjusted odds ratio = 0.99/2.28), hyponatremia (adjusted odds ratio = 2.84), hypokalemia (adjusted odds ratio = 2.42), and hyperuricemia (adjusted odds ratio = 2.62) were the major factors associated with acute kidney injury. In-hospital mortality for acute kidney injury patients was 5.1% as compared with those without acute kidney injury (0.8%). Survival analysis reveals that the risk of death was higher among patients with hospital-acquired acute kidney injury (adjusted hazard ratio = 4.50) and severe acute kidney injury stage (adjusted hazard ratio = 2.68/3.91). Furthermore, the length of stay (13.5 days) and hospital cost (45,066 CNY) were significantly greater in patients with community-acquired acute kidney injury.

Conclusion:

Acute kidney injury was common in cancer patients and associated with an ominous outcome. Pre-existing comorbidities, electrolyte disturbances, and abnormal biochemical were the predicting factors for acute kidney injury incidence. Better monitoring of electrolytes, identification of high-risk patients, and early acute kidney injury diagnosis should be considered as a priority during anti-cancer treatment.

Baseline atrial fibrillation is associated with contrast-induced nephropathy after cardiac catheterization in coronary artery disease: Systemic review and meta-analysis

BACKGROUND

Atrial fibrillation (AF) is the most common arrhythmia, independently associated with significant mortality and morbidity. Recent studies suggest that AF is potentially associated with contrast-induced nephropathy (CIN) in patients with coronary artery disease (CAD) undergoing catheterization. However, the association was not conclusive. Thus, we assessed the association between AF in patients with CAD and CIN by a systematic review of the literature and a meta-analysis.

HYPOTHESIS

AF is a predictor of CIN in patients with CAD.

METHODS

We comprehensively searched the databases of MEDLINE and EMBASE from inception to April 2018. Included studies were published observational studies that compared the risk of CIN among CAD patients with AF vs those without AF. Data from each study were combined using the random-effects, generic inverse variance method of DerSimonian and Laird to calculate risk ratios and 95% confidence intervals (CIs).

RESULTS

Eight cohort studies from June 2007 to November 2017 were included in this meta-analysis involving 16,691 subjects with CAD (1,030 with AF and 15,661 without its presence). The presence of AF was associated with CIN (pooled risk ratio = 2.17, 95% CI: 1.50-3.14, P < 0.001, I² = 54.1%). In our subgroup analysis by urgency and multivariable adjustment, both groups still showed substantial association between AF and CIN (P < 0.05).

CONCLUSIONS

AF increased the risk of CIN up to two fold among patients with CAD compared to the absence of it. Our study suggests that the presence of AF in CAD is prognostic for the development of CIN.

Cancer and the kidney: dangereoux liasons or price paid for the progress in medicine?

A long time ago, the links between renal disease and malignancy were observed, however, quite recently, their importance was recognized and 'new' subspecialty in nephrology, namely 'onconephrology' was established. In the XXI century, patients with malignancy make up the most growing number of the subjects seen for nephrology consult and/or critical care nephrology services. A plethora of renal problems may be found in patients with malignancy. They may influence not only their short-term outcomes but also the adequate therapy of the underlying oncological problem. Thus, all these kidney-related issues pose an important challenge for both specialities: oncology and nephrology. In the review a spectrum of acute and chronic renal injury caused by the malignancy is presented as well as the associations between renal disease and cancer. Assessment of kidney function and its importance in patients with malignancy is also discussed as medical oncologists should check the appropriate dose of chemotherapeutic drugs in relation to the actual renal function before prescribing them to the patients. Moreover, effects of kidney function on outcomes in oncology is presented. In addition, nephrology services should better understand both the biology of malignancy with its treatment to become a valuable part treating team to yield the best possible outcome. It is important for nephrology services to be acknowledged and to take an active participation in care of oncology patients.

Effects of tolvaptan in patients with chronic kidney disease and chronic heart failure

BACKGROUND

Tolvaptan, a vasopressin V₂ receptor blocker, has a diuretic effect for patients with heart failure. However, there were a few data concerning the effects of tolvaptan in patients with chronic kidney disease (CKD).

METHODS

We retrospectively analyzed 21 patients with chronic heart failure and CKD. Tolvaptan was co-administered with other diuretics in-use, every day. We compared clinical parameters before and after the treatments with tolvaptan. Furthermore, we examined the correlations between baseline data and the change of body weight.

RESULTS

Tolvaptan decreased the body weight and increased the urine volume (p = 0.001). The urine osmolality significantly decreased throughout the study period. Urinary Na/Cr ratio and FENa changed significantly after 4 h, and more remarkable after 8 h (p = 0.003, both). Serum creatinine increased slightly after 1 week of treatment (p = 0.012). The alteration of body weight within the study period correlated negatively with the baseline urine osmolality (r = -0.479, p = 0.038), the baseline urine volume (r = -0.48, p = 0.028), and the baseline inferior vena cava diameter (IVCD) (r = -0.622, p = 0.017). Hyponatremia was improved to the normal value, and the augmentations of the sodium concentration were negatively associated with the basal sodium levels (p = 0.01, r = -0.546).

CONCLUSIONS

Tolvaptan is effective in increasing diuresis and improved hyponatremia, even in patients with CKD. The baseline urine osmolality, urine volume, and IVCD may be useful predictors for diuretic effects of tolvaptan.

Contrast media use in patients with chronic kidney disease undergoing coronary angiography: A systematic review and meta-analysis of randomized trials

BACKGROUND

Patients with chronic kidney disease (CKD) undergoing coronary angiography (CA), adequate hydration and minimizing volume of contrast media (CM) are class 1b recommendations for preventing contrast induced nephropathy (CIN). Current data are insufficient to justify specific recommendations about isoosmolar vs. low-osmolar contrast media by the ACCF/AHA/SCAI guidelines.

METHODS

Randomized trials comparing IOCM to LOCM in CKD stage 3 and above patients undergoing CA, and reporting incidence of CIN (defined by a rise in creatinine of 25% from baseline) were included in the analysis. The secondary outcome of the study was the incidence of serum creatinine increase by >1mg/dl.

RESULTS

A total of 2839 patients were included in 10 trials, in which 1430 patients received IOCM and 1393 received LOCM. When compared to LOCM, IOCM was not associated with significant benefit in preventing CIN (OR=0.72, [CI: 0.50-1.04], P=0.08, I2=59%). Subgroup analysis revealed non-significant difference in incidence of CIN based on baseline use of N-acetylcystine (NAC), diabetes status, ejection fraction, and whether percutaneous coronary intervention vs coronary angiography alone was performed. The difference between IOCM and LOCM was further attenuated when restricted to studies with larger sample size (>250 patients) (OR=0.93; [CI: 0.66-1.30]) or when compared with non-ionic LOCM (OR=0.79, [CI: 0.52-1.21]).

CONCLUSION

In patients with CKD stage 3 and above undergoing coronary angiography, use of IOCM showed overall non-significant difference in incidence of CIN compared to LOCM. The difference was further attenuated when IOCM was compared with non-ionic LOCM.

Radiocontrast-Induced Acute Renal Failure

The intravascular administration of iodinated radiocontrast media can lead to acute renal dysfunction. Even small changes in renal function have been associated with increased morbidity and mortality, making the prevention of radiocontrast nephropathy of paramount importance. This review summarizes the principal risk factors for radiocontrast nephropathy and evidence-based preventive strategies that should be used to limit its occurrence. Risk factors for radiocontrast nephropathy include preexistent kidney disease, diabetes mellitus, dose of radiocontrast used, advanced congestive heart failure, and intravascular volume depletion. Proven preventive measures include volume expansion with intravenous saline or sodium bicarbonate and the use of low-osmolar or iso-osmolar radiocontrast media. Studies evaluating N-acetylcysteine have been conflicting, with meta-analyses suggesting a small beneficial effect. Studies of other pharmacologic agents have not demonstrated clinical benefit.

Antioxidant and renoprotective effects of sphingosylphosphorylcholine on contrast-induced nephropathy in rats

Contrast induced nephropathy (CIN) is a major cause of morbidity, and increased costs as well as an increased risk of death. This study was evaluated effects of exogenous sphingosylphosphorylcholine (SPC) administration on CIN in rats. Eight animals were included in each of the following eight groups: control, control phosphate-buffered solution (PBS), control SPC 2, control SPC 10, CIN, CIN PBS, CIN SPC 2 and CIN SPC 10. The induced nephropathy was created by injected with 4 g iodine/kg body weight. SPC was administered 3 d at a daily two different doses of 2 μm/mL and 10 μm/mL intraperitoneally. The severity of renal injury score was determined by the histological and immunohistochemical changes in the kidney. Malondialdehyde (MDA), nitric oxide (NO) and superoxide dismutase (SOD) were determined to evaluate the oxidative status in the renal tissue. Treatment with 2 and 10 μM SPC inhibited the increase in renal MDA, NO levels significantly and also attenuated the depletion of SOD in the renal injuryCIN. These data were supported by histopathological findings. The inducible nitric oxide synthase positive cells and apoptotic cells in the renal tissue were observed to be reduced with the 2 and 10 μM SPC treatment. These findings suggested that 2 and 10 μM doses can attenuate renal damage in contrast nephropathy by prevention of oxidative stress and apoptosis. The low and high dose SPC may be a promising new therapeutic agent for CIN.

Delayed kidney injury following coronary angiography

It is occasionally observed that patients without contrast-induced nephropathy (CIN) develop kidney injury within 1-6 months after coronary angiography (CAG), termed delayed CIN or delayed kidney injury (DKI) following CAG. The present study aimed to investigate the associated risk factors of delayed CIN and its possible pathogenesis. Subjects with CAG or coronary stenting from January 2008 to December 2009 were studied. A retrospective survey on DKI after CAG was conducted and the risk factors were analyzed. There were 436 cases receiving CAG with complete medical records enrolled in the present cohort, in which the DKI incidence was 7.1% (31/436). Patients with DKI after CAG exhibited lower hemoglobin (121.2±17.3 vs. 133.8±18.6 g/l), estimated glomerular filtration rate (eGFR; 66.4±30.2 vs. 71.9±28.6 ml/min), higher serum creatinine (110.9±43.2 vs. 91.7±37.6 µmol/l), higher rate of heart failure (22.6 vs. 5.4%) and 300 mg aspirin therapy (29 vs. 5.7%) compared with non-DKI patients (all P<0.05). However, no differences were observed in morbidities of diabetes, hypertension, hyperlipidemia and proteinuria, or in the treatments with angiotensin converting enzyme (ACE) inhibitors/angiotensin II receptor-1 blockers (ARBs), diuretics, statins and other anti-platelets between the two groups (P>0.05). Logistic regression revealed that anemia, heart failure and 300 mg aspirin intake were risk factors of DKI (P<0.05), while the contrast level, isotonic contrast, diabetes, ACE inhibitors/ARBs, eGFR and other factors were not associated with DKI (P>0.05). Heart dysfunction and 300 mg aspirin therapy may contribute to DKI after CAG, and iodinated contrast media administration is not a risk factor.

Hypoxia: The Force that Drives Chronic Kidney Disease

In the United States the prevalence of end-stage renal disease (ESRD) reached epidemic proportions in 2012 with over 600,000 patients being treated. The rates of ESRD among the elderly are disproportionally high. Consequently, as life expectancy increases and the baby-boom generation reaches retirement age, the already heavy burden imposed by ESRD on the US health care system is set to increase dramatically. ESRD represents the terminal stage of chronic kidney disease (CKD). A large body of evidence indicating that CKD is driven by renal tissue hypoxia has led to the development of therapeutic strategies that increase kidney oxygenation and the contention that chronic hypoxia is the final common pathway to end-stage renal failure. Numerous studies have demonstrated that one of the most potent means by which hypoxic conditions within the kidney produce CKD is by inducing a sustained inflammatory attack by infiltrating leukocytes. Indispensable to this attack is the acquisition by leukocytes of an adhesive phenotype. It was thought that this process resulted exclusively from leukocytes responding to cytokines released from ischemic renal endothelium. However, recently it has been demonstrated that leukocytes also become activated independent of the hypoxic response of endothelial cells. It was found that this endothelium-independent mechanism involves leukocytes directly sensing hypoxia and responding by transcriptional induction of the genes that encode the β2-integrin family of adhesion molecules. This induction likely maintains the long-term inflammation by which hypoxia drives the pathogenesis of CKD. Consequently, targeting these transcriptional mechanisms would appear to represent a promising new therapeutic strategy.

Impact of Iodinated Contrast on Renal Function and Hemodynamics in Rats with Chronic Hyperglycemia and Chronic Kidney Disease

Iodinated contrast (IC) is clinically used in diagnostic and interventional procedures, but its use can result in contrast-induced acute kidney injury (CI-AKI). Chronic kidney disease (CKD) and chronic hyperglycemia (CH) are important predisposing factors to CI-AKI. The aim of this study was to investigate the impact of iodinated contrast on the renal function and hemodynamics in rats with chronic hyperglycemia and chronic kidney disease. A total of 30 rats were divided into six groups; Sham: control of chronic renal disease; Citrate: control of chronic hyperglycemia (CH); Nx5/6: rats with 5/6 nephrectomy; Chronic Hyperglycemia: rats receiving Streptozotocin 65 mg/kg; Nx5/6 + IC: rats Nx5/6 received 6 mL/kg of IC; CH + IC: Chronic hyperglycemia rats receiving 6 mL/kg of IC. Renal function (inulin clearance; urinary neutrophil gelatinase-associated lipocalin, NGAL) and hemodynamics (arterial blood pressure; renal blood flow; renal vascular resistance) were evaluated. Iodinated contrast significantly increased urinary NGAL and reduced inulin clearance, while the hemodynamics parameters showed changes in arterial blood pressure, renal blood flow, and renal vascular resistance in both CKD and CH groups. The results suggest that the iodinated contrast in risk factors models has important impact on renal function and hemodynamics. NGAL was confirmed to play a role of highlight in diagnosis of CI-AKI.

A novel approach to contrast-induced nephrotoxicity: the melatonergic agent agomelatine

OBJECTIVE

To study the potential nephroprotective role of agomelatine in rat renal tissue in cases of contrast-induced nephrotoxicity (CIN). The drug's action on the antioxidant system and proinflammatory cytokines, superoxide dismutase (SOD) activity, levels of glutathione (GSH) and malondialdehyde (MDA) and the gene expression of interleukin-6 (IL-6), tumour necrosis factor (TNF)-α and nuclear factor kappa B (NF-κB) was measured. Tubular necrosis and hyaline and haemorrhagic casts were also histopathologically evaluated.

METHODS

The institutional ethics and local animal care committees approved the study. Eight groups of six rats were put on the following drug regimens: Group 1: healthy controls, Group 2: GLY (glycerol), Group 3: CM (contrast media--iohexol 10 ml kg(-1)), Group 4: GLY+CM, Group 5: CM+AGO20 (agomelatine 20 mg kg(-1)), Group 6: GLY+CM+AGO20, Group 7: CM+AGO40 (agomelatine 40 mg kg(-1)) and Group 8: GLY+CM+AGO40. The groups were evaluated by one-way analysis of variance and Duncan's multiple comparison test.

RESULTS

Agomelatine administration significantly improved the serum levels of blood urea nitrogen (BUN) and creatinine, SOD activity, GSH and MDA. The use of agomelatine had substantial downregulatory consequences on TNF-α, NF-κB and IL-6 messenger RNA levels. Mild-to-severe hyaline and haemorrhagic casts and tubular necrosis were observed in all groups, except in the healthy group. The histopathological scores were better in the agomelatine treatment groups.

CONCLUSION

Agomelatine has nephroprotective effects against CIN in rats. This effect can be attributed to its properties of reducing oxidative stress and inhibiting the secretion of proinflammatory cytokines (NF-κB, TNF-α and IL-6).

ADVANCES IN KNOWLEDGE

CIN is one of the most important adverse effects of radiological procedures. Renal failure, diabetes, malignancy, old age and non-steroidal anti-inflammatory drug use pose the risk of CIN in patients. Several clinical studies have investigated ways to avoid CIN. Theophylline/aminophylline, statins, ascorbic acid and iloprost have been suggested for this purpose. Agomelatine is one of the melatonin ligands and is used for affective disorders and has antioxidant features. In this study, we hypothesized that agomelatine could have nephroprotective, antioxidant and anti-inflammatory effects against CIN in rats.

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.

Efficacy of preventive interventions for iodinated contrast-induced acute kidney injury evaluated by intrarenal oxygenation as an early marker

OBJECTIVE

The objective of this study was to evaluate the effects of potential renoprotective interventions such as the administration of N-acetylcysteine (NAC; antioxidant) and furosemide (diuretic) on intrarenal oxygenation as evaluated by blood oxygen level-dependent (BOLD) magnetic resonance imaging (MRI) in combination with urinary neutrophil gelatinase-associated lipocalin (NGAL) measurements.

MATERIALS AND METHODS

Rats received nitric oxide synthase inhibitor L-NAME (10 mg/kg) and cyclooxygenase inhibitor indomethacin (10 mg/kg) to induce the risk for developing iodinated contrast-induced acute kidney injury before receiving one of the interventions: NAC, furosemide, or placebo. One of the 3 iodinated contrast agents (iohexol, ioxaglate, or iodixanol) was then administered (1600-mg organic iodine per kilogram body weight). Fifty-four Sprague-Dawley rats were allocated in a random order into 9 groups on the basis of the intervention and the contrast agent received.Blood-oxygen-level-dependent MRI-weighted images were acquired on a Siemens 3.0-T scanner using a multiple gradient recalled echo sequence at baseline, after L-NAME, indomethacin, interventions or placebo, and iodinated contrast agents. Data acquisition and analysis were performed in a blind fashion. R2* (=1/T2*) maps were generated inline on the scanner. A mixed-effects growth curve model with first-order autoregressive variance-covariance was used to analyze the temporal data. Urinary NGAL, a marker of acute kidney injury, was measured at baseline, 2 and 4 hours after the contrast injection.

RESULTS

Compared with the placebo-treated rats, those treated with furosemide showed a significantly lower rate of increase in R2* (P < 0.05) in the renal inner stripe of the outer medulla. The rats treated with NAC showed a lower rate of increase in R2* compared with the controls, but the difference did not reach statistical significance. Urinary NGAL showed little to no increase in R2* after administration of iodixanol in the rats pretreated with furosemide but demonstrated significant increase in the rats pretreated with NAC or placebo (P < 0.05).

CONCLUSIONS

This is the first study to evaluate the effects of interventions to mitigate the deleterious effects of contrast media using BOLD MRI. The rate of increase in R2* after administration of iodinated contrast is associated with acute renal injury as evaluated by NGAL. Further studies are warranted to determine the optimum dose of furosemide and NAC for mitigating the ill effects of contrast media. Because NGAL has been shown to be useful in humans to document iodinated contrast-induced acute kidney injury, the method presented in this study using BOLD MRI and NGAL measurements can be translated to humans.

Utility of the Logistic Clinical Syntax Score in the Prediction of Contrast-Induced Nephropathy After Primary Percutaneous Coronary Intervention

BACKGROUND

The Logistic Clinical Syntax Score (log CSS) is a combined risk scoring system that includes clinical and anatomic parameters; it has been found to be effective for the prediction of mortality in patients with ST-elevation myocardial infarction (STEMI). The aim of the present study was to assess whether the log CSS was associated with the development of contrast-induced nephropathy (CIN) in patients who underwent primary percutaneous coronary intervention (pPCI).

METHODS

A total of 930 patients with STEMI undergoing pPCI between January 2012 and August 2013 were included prospectively. The patients were grouped according to the development of CIN. Either an absolute serum creatinine level ≥ 0.5 mg/dL or a 25% increase in the serum creatinine level compared with the baseline level within 48 hours after the administration of contrast medium was defined as CIN.

RESULTS

The Synergy Between Percutaneous Coronary Interventions With Taxus and Cardiac Surgery score (SYNTAX [SS]) and log CSS were higher in patients with CIN than in those without. In the multivariate analysis, log CSS (odds ratio, 1.405, 95% confidence interval, 1.318-1.497; P < 0.001), hemoglobin, and contrast volume were found to be independent predictors of CIN. In the receiver operating characteristic analysis, a log CSS > 9.5 had a 74.5% sensitivity and a 90.5% specificity for predicting CIN, with an area under the curve (AUC) of 0.892, whereas an SS > 18.5 had a 64% sensitivity, a 58.1% specificity, and an AUC of 0.625 (0.892 vs 0.625; P < 0.001). A log CSS > 9.5 was associated with in-hospital and long-term mortality, reinfarction, revascularization, and in-hospital hemodialysis (P < 0.001 for each).

CONCLUSIONS

The log CSS may improve the accuracy of risk stratification for the development of CIN in patients undergoing pPCI.

Charting the course of renal cryoinjury

We sought to characterize a minor renal cryoinjury that allows investigation into renal damage processes and subsequent endogenous repair mechanisms. To achieve this, we induced a small cryoinjury to mice, in which the transient superficial application of a liquid nitrogen-cooled cryoprobe to the exposed kidney induces a localized lesion that did not impair renal function. The resulting cryoinjury was examined by immunohistochemistry and Laser-Doppler flowmetry. Within hours of cryoinjury induction, tubular and vascular necrotic damage was observed, while blood flow in the directly injured area was reduced by 65%. The injured area demonstrated a peak in tubular and perivascular cell proliferation at 4 days postinjury, while apoptosis and fibrosis peaked at day 7. Infiltration of macrophages into the injury was first observed at day 4, and peaked at day 7. Vascular density in the direct injured area was lowest at day 7. As compared to the direct injured area, the (peripheral) penumbral region surrounding the directly injured area demonstrated enhanced cellular proliferation (2.5-6-fold greater), vascular density (1.6-2.9 fold greater) and blood perfusion (twofold greater). After 4 weeks, the area of damage was reduced by 73%, fibrosis decreased by 50% and blood flow in the direct injured area was reestablished by 63% with almost complete perfusion restoration in the injury's penumbral region. In conclusion, kidney cryoinjury provides a flexible facile model for the study of renal damage and associated endogenous repair processes.

Association between Platelet-to-Lymphocyte Ratio and Contrast-Induced Nephropathy in Patients Undergoing Percutaneous Coronary Intervention for Acute Coronary Syndrome

OBJECTIVE

Contrast-induced nephropathy (CIN) is associated with significantly increased morbidity and mortality after percutaneous coronary intervention (PCI). Patients with acute coronary syndrome (ACS) are at higher risk of CIN. The platelet-to-lymphocyte ratio (PLR) is closely linked to inflammatory conditions. We hypothesized that PLR levels on admission can predict the development of CIN after PCI for ACS.

SUBJECTS AND METHODS

A total of 426 patients (mean age 63.17 ± 13.01 years, 61.2% males) with ACS undergoing PCI were enrolled in this study. Admission PLR levels were measured before PCI. Serum creatinine values were measured before and within 72 h after the administration of contrast agents. Patients were divided into 2 groups: the CIN group and the no-CIN group. CIN was defined as an increase in serum creatinine level of ≥0.5 mg/dl or 25% above baseline within 72 h after contrast administration.

RESULTS

CIN developed in 53 patients (15.9%). Baseline PLR was significantly higher in patients who developed CIN compared to those who did not (160.8 ± 29.7 and 135.1 ± 26.1, respectively; p < 0.001). Multivariate analyses found that PLR [odds ratio (OR) 3.453, 95% confidence interval (CI) 1.453-8.543; p = 0.004] and admission creatinine (OR 6.511, 95% CI 1.759-11.095; p = 0.002) were independent predictors of CIN.

CONCLUSIONS

The admission PLR level is an independent predictor of the development of CIN after PCI in ACS.

Evaluation of intrarenal oxygenation in iodinated contrast-induced acute kidney injury-susceptible rats by blood oxygen level-dependent magnetic resonance imaging

OBJECTIVES

The objectives of this study were to evaluate differences in intrarenal oxygenation as assessed by blood oxygen level-dependent (BOLD) magnetic resonance imaging in contrast-induced acute kidney injury (CIAKI)-susceptible rats when using 4 contrast media with different physicochemical properties and to demonstrate the feasibility of acquiring urinary neutrophil gelatinase-associated lipocalin (NGAL) levels as a marker of CIAKI in this model.

MATERIALS AND METHODS

Our institutional animal care and use committee approved the study. Sixty-six Sprague-Dawley rats were divided into CIAKI-susceptible groups (received nitric oxide synthase inhibitor N-nitro-L-arginine methyl ester [10 mg/kg] and cycloxygenase inhibitor indomethacin [10mg/kg]) and control groups (received saline instead). One of the 4 iodinated contrast agents (iothalamate, iohexol, ioxaglate, or iodixanol) was then administered (1600-mg organic iodine per kilogram of body weight). Multiple blood oxygen level-dependent magnetic resonance images were acquired on a Siemens 3.0-T scanner using a multiple gradient recalled echo sequence at baseline, after N-nitro-L-arginine methyl ester (or saline), indomethacin (or saline), and iodinated contrast agent (or placebo). R2* (R2*=1/T2*) maps were generated inline on the scanner. A mixed-effects growth curve model with first-order autoregressive variance-covariance was used to analyze the temporal data. Urinary NGAL, a marker of kidney injury (unlike serum creatinine), was measured 4 hours after contrast injection in the 2 subgroups.

RESULTS

Differences in blood oxygen level-dependent magnetic resonance imaging results between the contrast media were observed in all 4 renal regions. However, the inner stripe of the outer medulla (ISOM) showed the most pronounced changes in the CIAKI-susceptible group and R2* increased significantly (P<0.01) over time with all 4 contrast media. In the control groups, only iodixanol showed an increase in R2* (P<0.05) over time. There was an agreement between increases in NGAL and R2* values in ISOM.

CONCLUSIONS

In rats susceptible to CIAKI, those receiving contrast media had significant increases in R2* in renal ISOM compared with those receiving placebo. The agreement between NGAL and R2* values in the ISOM suggests that the observed immediate increase in R2* after contrast injection may be the earliest biomarker of renal injury. Further studies are necessary to establish threshold values of R2* associated with acute kidney injury and address the specificity of R2* to renal oxygenation status.

A network meta-analysis on randomized trials focusing on the preventive effect of statins on contrast-induced nephropathy

Contrast-induced nephropathy is a common complication of iodinated contrast administration. Statins may reduce the risk of contrast-induced nephropathy, but data remain inconclusive. We summarized the evidence based on statins for the prevention of contrast-induced nephropathy with a network meta-analysis. Randomized trials focusing on statins were searched and pooled with random-effect odds ratios. A total of 14 trials (6,160 patients) were included, focusing on atorvastatin (high/low dose), rosuvastatin (high dose), simvastatin (high/low dose), and placebo or no statin therapy before contrast administration. The risk of contrast-induced nephropathy was reduced by atorvastatin high dose and rosuvastatin high dose, with no difference between these two agents. Results for atorvastatin low dose and simvastatin (high/low dose) in comparison to placebo were inconclusive. Atorvastatin and rosuvastatin administered at high doses and before iodinated contrast administration have a consistent and beneficial preventive effect on contrast-induced nephropathy and may actually halve its incidence.

Contrast Volume-to-Creatinine Clearance Ratio Predicts the Risk of Contrast-Induced Nephropathy After Percutaneous Coronary Intervention in Patients With Reduced Ejection Fraction

We determined a relatively safe contrast media volume-to-creatinine clearance (V/CrCl) cutoff value to avoid contrast-induced nephropathy (CIN) after percutaneous coronary intervention (PCI) in patients (n = 111) with reduced ejection fraction (<40%). Improved prediction of CIN in these patients would be useful. Multivariate regression models were used to evaluate whether V/CrCl is an independent risk factor for CIN. Nine (8.1%) patients developed CIN. The V/CrCl was significantly (P = .023) higher in patients with CIN than in those without. The incidence of CIN in patients with the highest tertile of V/CrCl was significantly higher than the middle and lowest tertiles (18.4% vs. 2.7% and 2.8%; P = .013). After adjusting for other potential risk factors, a V/CrCl ≥3.87 remained significantly associated with risk of CIN. A V/CrCl <3.87 might be valuable in predicting the risk of CIN in patients with reduced ejection fraction undergoing PCI.

Pathophysiology of Contrast-Induced Acute Kidney Injury

Contrast-induced acute kidney injury (CI-AKI) refers to acute kidney injury (AKI) after intravenous or intra-arterial administration of contrast media (CM). The 2 key mechanisms related to AKI are acute tubular necrosis and prerenal azotemia. Although the pathophysiology of AKI is complex, modern frameworks show that AKI has 3 major pathways: hemodynamic injury, systemic inflammation, and toxic injury. In the pathophysiology of CI-AKI, 3 major distinct, but potentially interacting pathways are recognized: hemodynamic effects, increase in oxygen free radicals, and direct CM molecule tubular cell toxicity. This article reviews the pathophysiology of CI-AKI by describing and explaining these pathways.

Contrast-induced Nephropathy

Contrast-induced nephropathy (CIN) is a serious complication of angiographic procedures resulting from the administration of contrast media (CM). It is the third most common cause of hospital acquired acute renal injury and represents about 12% of the cases. CIN is defined as an elevation of serum creatinine (Scr) of more than 25% or ≥0.5 mg/dl (44 μmol/l) from baseline within 48 h. More sensitive markers of renal injury are desired, therefore, several biomarkers of tubular injury are under evaluation. Multiple risk factors may contribute to the development of CIN; these factors are divided into patient- and procedure-related factors. Treatment of CIN is mainly supportive, consisting mainly of careful fluid and electrolyte management, although dialysis may be required in some cases. The available treatment option makes prevention the corner stone of management. This article will review the recent evidence concerning CIN incidence, diagnosis, and prevention strategies as well as its treatment and prognostic implications.

Association between N-terminal pro-brain natriuretic peptide levels and contrast-induced nephropathy in patients undergoing percutaneous coronary intervention for acute coronary syndrome

BACKGROUND

Contrast-induced nephropathy (CIN) is associated with significantly increased morbidity and mortality after percutaneous coronary intervention (PCI). Patients with acute coronary syndrome (ACS) are at higher risk for CIN. N-terminal pro-brain natriuretic peptide (NT-proBNP) is closely linked to the prognosis as a strong predictor of both short- and long-term mortality in patients with ACS.

HYPOTHESIS

We hypothesized that NT-proBNP levels on admission can predict the development of CIN after PCI for ACS.

METHODS

A total of 436 patients (age 62.27 ± 13.01 years; 64.2% male) with ACS undergoing PCI enrolled in this study. Admission NT-proBNP levels were measured before PCI. Serum creatinine values were measured before and within 72 hours after the administration of contrast agents. Patients were divided into 2 groups: CIN group and no-CIN group. CIN was defined as an increase in serum creatinine level of ≥0.5 mg/dL or ≥25% above baseline within 72 hours after contrast administration.

RESULTS

CIN developed in 63 patients (14.4%). Baseline NT-proBNP levels were significantly higher in patients who developed CIN compared to those who did not develop CIN (median 774 pg/mL, interquartile range 177.4-2184 vs median 5159 pg/mL, interquartile range 2282-9677, respectively; P < 0.001). Multivariate analysis found that NT-proBNP (odds ratio [OR]: 3.448, 95% confidence interval [CI]: 1.394-8.474, P = 0.007) and baseline creatinine (OR: 6.052, 95% CI: 1.860-19.686, P = 0.003) were independent predictors of CIN.

CONCLUSIONS

Admission NT-proBNP level is an independent predictor of the development of CIN after PCI in ACS.

The protective effect of single dose tadalafil in contrast-induced nephropathy: an experimental study

Objective:

Contrast-induced nephropathy (CIN) is one of the most common causes of acute renal failure in hospitalized patients. The direct toxic effect of contrast media; ischemic damage caused by reactive oxygen species; increased perivascular hydrostatic pressure; high viscosity and changes in the activity of vasoactive substances play important roles in the pathogenesis. Tadalafil inhibits the phosphodiesterase enzyme which destroys nitric oxide. Nitric oxide causes renal vasodilatation, increases renal medullar blood flow and mediates the removal of free oxygen radicals. Drugs that increase levels of nitric oxide are expected to reduce the development of contrast nephropathy due to contrast media. We aimed to test the hypothesis that tadalafil reduces the development of contrast nephropathy due to contrast toxicity.

Methods:

A total of 24 female Wistar albino rats, three groups of eight, were included in the study. After 48 hours of dehydration, contrast media (meglumine diatrozoate, 6 mL/kg) was administered to the first group, and contrast media with tadalafil (10 mg/kg) was administered to the second group. The third group served as the control group. Blood and tissue samples were taken 48 hours after this procedure.

Results:

Serum cystatin C, serum creatinine and blood urea nitrogen (BUN) values were significantly lower in the contrast with tadalafil group compared to the group given only contrast. Serum and tissue malondialdehyde (MDA) levels were significantly lower in the contrast with tadalafil group than in the contrast only group.

Conclusion:

These results demonstrate the protective effect of tadalafil in the prevention of CIN in rats.

Contrast-induced nephropathy: pharmacology, pathophysiology and prevention

Modern iodinated contrast media (CM) consist of one or two tri-iodobenzene rings. They differ from each other in the composition of the side chains, creating different molecules and thus different brand substances. After intravascular administration, all CM are distributed rapidly into intravascular and extracellular fluids. They are eliminated solely by glomerular filtration. In patients with normal renal function, CMs are eliminated within 24 h. The pathophysiology of contrast-induced nephropathy (CIN) is based on three distinct but interacting mechanisms: medullary ischaemia, formation of reactive oxygen species and direct tubular cell toxicity. The contribution of each of these mechanisms to the development of CIN in the individual patient remains unclear. CIN prevention is extensively described in guidelines, such as the recently updated guideline from the Contrast Media Safety Committee (CMSC) of the European Society of Urogenital Radiology (ESUR). The recent update is briefly discussed. Furthermore, it remains unclear if volume expansion with either NaCl 0.9 % or NaHCO₃ 1.4 % is superior.

Teaching points

• After intravascular injection, CM are distributed over intravascular and extracellular fluids.

• CM are eliminated by glomerular filtration in patients with normal kidney function.

• CIN pathophysiology is based on medullary ischaemia, formation of reactive oxygen species (ROS) and tubular cell toxicity.

• It remains unclear if volume expansion with either NaCl 0.9 % or NaHCO₃1.4 % is superior.

Incidence of contrast-induced nephropathy in hospitalised patients with cancer

OBJECTIVES

To determine the frequency of and possible factors related to contrast-induced nephropathy (CIN) in hospitalised patients with cancer.

METHODS

Ninety adult patients were enrolled. Patients with risk factors for acute renal failure were excluded. Blood samples were examined the day before contrast-enhanced computed tomography (CT) and serially for 3 days thereafter. CIN was defined as an increase in serum creatinine (Cr) of 0.5 mg/dl or more, or elevation of Cr to 25 % over baseline. Relationships between CIN and possible risk factors were investigated.

RESULTS

CIN was detected in 18/90 (20 %) patients. CIN developed in 25.5 % patients who underwent chemotherapy and in 11 % patients who did not (P = 0.1). CIN more frequently developed in patients who had undergone CT within 45 days after the last chemotherapy (P = 0.005); it was also an independent risk factor (P = 0.017). CIN was significantly more after treatment with bevacizumab/irinotecan (P = 0.021) and in patients with hypertension (P = 0.044).

CONCLUSIONS

The incidence of CIN after CT in hospitalised oncological patients was 20 %. CIN developed 4.5-times more frequently in patients with cancer who had undergone recent chemotherapy. Hypertension and the combination of bevacizumab/irinotecan may be additional risk factors for CIN development.

KEY POINTS

• Contrast-induced nephropathy (CIN) is a concern for oncological patients undergoing CT. • CIN occurs more often when CT is performed <45 days after chemotherapy. • Hypertension and treatment with bevacizumab appear to be additional risk factors.

Effect of a recombinant manganese superoxide dismutase on prevention of contrast-induced acute kidney injury

BACKGROUND

Contrast media (CM)-induced nephropathy (CIN) is an acute deterioration of renal function following administration of CM mediated to a large extent by the increased production of ROS within the kidney. Aim of this study was to evaluate whether a novel isoform of a recombinant Manganese SOD (rMnSOD) could provide an effective protection against CIN; this molecule shares the same ability of physiological SODs in scavenging reactive oxygen species (ROS) but, due to its peculiar properties, enters inside the cells after its administration.

METHODS

We studied the effects rMnSOD on oxidative damage in a rat model of CIN in uninephrectomized rats, that were randomly assigned to 3 experimental Groups: Group CON, control rats treated with the vehicle of CM, Group HCM, rats treated with CM and Group SOD, rats treated with CM and rMnSOD.

RESULTS

In normal rats, pretreatment with rMnSOD, reduced renal superoxide anion production, induced by the activation of NAPDH oxidase, by 84 % (p < 0.001). In rats of Group HCM, ROS production was almost doubled compared to rat of Group CON (p < 0.01) but returned to normal values in rats of Group SOD, where a significant increase of SOD activity was detected (+16 % vs HCM, p < 0.05). Administration of CM determined a striking fall of GFR in rats of Group HCM (-70 %, p < 0.001 vs CON), greatly blunted in Group SOD (-28 % vs CON, p < 0.01); this was associated with a lower presence of both tubular necrosis and intratubular casts in SOD-treated rats (both p < 0.01 vs Group HCM).

CONCLUSIONS

Our data indicate that rMnSOD is able to reduce renal oxidative stress, thus preventing the reduction of GFR and the renal histologic damage that follows CM administration.

Relation of the severity of contrast induced nephropathy to SYNTAX score and long term prognosis in patients treated with primary percutaneous coronary intervention

BACKGROUND

SYNTAX score (SXscore) has been developed to assess the severity and complexity of coronary artery disease. The aim of this study was to evaluate whether baseline SXscore was associated with contrast induced nephropathy (CIN) after primary percutaneous coronary intervention (p-PCI) in patients with ST-elevation myocardial infarction (STEMI). Secondarily we aimed to investigate the relation of the severity of CIN to long term prognosis.

METHODS

We retrospectively enrolled 1893 patients with STEMI treated by p-PCI. We prospectively followed up the patients for a mean duration of 45 months. The patients were grouped according to the development of no nephropathy (grade 0, n: 1634), mild nephropathy (grade 1, n: 153) or severe nephropathy (grade 2, n: 106).

RESULTS

SXscore was significantly higher (19.4±5.9 vs 15.6±4.8, p<0.001) in patients with CIN (grades 1 and 2) compared to those without CIN. SXscore was higher in patients with grade 2 CIN compared to those with grade 1 CIN (18.5±5.7 vs 20.7±5.9, p<0.001). In the multivariate analysis, SXscore was identified as an independent predictor of CIN (for one unit increment, OR: 1.06, 95% CI: 1.01-1.14, p=0.006). At long-term follow-up, death (p<0.001), stroke (p=0.006), reinfarction (p=0.024) and permanent HD requirement (p<0.001) were most frequent in grade 2 nephropathy group. HD was associated with very high in-hospital (60%) and long-term (83.3%) mortality rates.

CONCLUSIONS

SXscore is an independent predictor of development and severity of CIN after p-PCI. CIN is associated with poor prognosis during both early and late postinfarction period.

Contrast-induced acute kidney injury following PCI

BACKGROUND

Coronary revascularization using percutaneous coronary intervention (PCI) is one of the major treatments for patients with stable coronary artery disease, with approximately 1.5 million patients undergoing PCI in the United States and Europe every year. An important neglected complication of PCI is contrast-induced acute kidney injury (CI-AKI).

DESIGN

In this article, we review the definition, pathogenesis and management of CI-AKI and highlight potential therapeutic options for preventing CI-AKI in post-PCI patients.

RESULTS

CI-AKI is an important but underdiagnosed complication of PCI that is associated with increased in-hospital morbidity and mortality. Patients with pre-existing renal impairment and diabetes are particularly susceptible to this complication post-PCI. Optimization of the patients' circulating volume remains the mainstay for preventing CI-AKI, although the best strategy for achieving this is still controversial.

CONCLUSION

Following PCI, CI-AKI is an overlooked complication which is associated with significant morbidity and mortality. In this article, we review the pathophysiology of CI-AKI in patients undergoing PCI and discuss the potential therapeutic options for preventing it.

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.