The Pathophysiology and the Management of Radiocontrast-Induced Nephropathy

Reduction in the risk of contrast-induced nephropathy using enhanced external counter-pulsation in patients with chronic kidney disease

OBJECTIVE

To evaluate the efficacy of EECP in the prevention of contrast-induced nephropathy (CIN) in patients with chronic kidney disease (CKD).

METHODS

A prospective trial was undertaken in the participants. A total of 280 patients with an estimated glomerular filtration rate (eGFR) of <60 ml/min/1.73 m2 who underwent percutaneous coronary artery procedures were enrolled and divided into two groups: the control group (n = 100) and the EECP group (n = 180). All patients received extracellular fluid volume expansion therapy with 0.9% normal saline, and patients in the EECP groups were also treated with EECP. The renal function indexes of the two groups were determined 48-72 h after coronary artery procedures.

RESULTS

In the EECP group, the BUN and serum creatinine (Scr) after coronary artery procedures were significantly lower than those before coronary artery procedures (BUN: 8.4 ± 3.5 vs. 6.6 ± 2.7 mmol/L, p < 0.001; Scr: 151.9 ± 44.7 vs. 144.5 ± 48.3 μmol/L, p < 0.001), while the eGFR was significantly increased (43.6 ± 11.4 vs. 47.1 ± 13.9 ml/min/1.73 m2, p < 0.001). The degree of Scr elevation was lower in the EECP group than in the control group (12.4 ± 15.0 vs. 20.9 ± 24.8 μmol/L, p = 0.026). Additionally, the EECP group had a lower incidence of post-procedures Scr elevation than the control group (36.5 vs. 48.0%, p = 0.042), a higher incidence of post-procedures eGFR elevation (62.2 vs. 48.0%, p = 0.021), and a lower risk of CIN (1.1 vs. 6.0%, p = 0.019).

CONCLUSION

EECP therapy has a protective effect on renal function and can reduce the risk of CIN in patients with CKD.

[Biomarkers of oxidative stress and inflammation in contrast-associated acute kidney injury]

BACKGROUND

Iodinated contrast-induced acute kidney injury (CI-AKI) is a common cause of renal failure, especially in patients with risk factors. This study analyses different renal biomarkers in patients undergoing computed tomography scans with iodinated contrast to identify the molecular and cellular mechanisms involved in the pathogenesis of CI-AKI.

METHODOLOGY

Prospective study that included patients with high risk of renal disease who received iodinated contrast (iohexol) for the computed tomography scans. Functional biomarkers (creatinine and cystatin C), inflammatory and oxidative stress markers (neutrophil gelatinase-associated lipocalin [NGAL], interleukin-8 [IL-8], superoxide dismutase [SOD], F2-isoprostanes, and cardiotrophin-1), and cell cycle biomarkers (Nephrocheck®) were analysed before the iodinated contrast and 4, 12, 24, and 48 hours post-contrast, in relation to the incidence of IC-AKI.

RESULTS

IC-AKI was observed in 30.6% of the 62 study participants and in 57.1% of the patients with diabetes and renal dysfunction. Factors associated with IC-AKI were a higher mean age (74.4 vs 64.9 years), pre-existing renal dysfunction (60 vs 16.7%), and higher adjusted mean volume of iohexol (42.9 vs 32.1%). As for non-functional biomarkers. No differences were found between patients with and without CI-AKI. The use of iodinated contrast was associated with a decrease in SOD antioxidant activity at 4 hours and an increase in IL-8 at 12 hours post-administration of the iodinated contrast.

CONCLUSIONS

Administration of iohexol in computed tomography scans in patients with high risk of renal disease results in an elevated percentage of CI-AKI, attributable to ischemia/reperfusion injury and/or direct toxicity of the iodinated contrast.

Is eGFR ≥60 mL/min/1.73 m2 in Patients Undergoing Coronary Angiography Really Safe for Contrast Nephropathy?

The aim of the present study was to define the risk factors associated with contrast-induced acute kidney injury (CI-AKI) in patients who underwent coronary artery angiography (CAG). In this retrospective cohort study, patients who underwent CAG between March 2014 and January 2022 were evaluated. A total of 2923 eligible patients were included in the study. Univariate and multivariate logistic regression analysis was used to identify the predictive factors. CI-AKI developed in 77 (2.6%) of 2923 patients. In multivariate analysis, diabetes mellitus (DM), chronic kidney disease (CKD), and estimated glomerular filtration rate (eGFR) were found to be independent factors associated with CI-AKI. In the subgroup analysis of patients with eGFR ≥60 mL/min/1.73 m2, eGFR remained a predictor of CI-AKI (Odds ratio (OR): .89, 95% CI: .84-.93; that is, a lower eGFR remains a risk factor for CI-AKI). In the receiving operating characteristic (ROC) analysis of patients with eGFR ≥60 mL/min/1.73 m2, the area under the curve of the eGFR was .826. Using the ROC curve based on Youden's index, the eGFR cut-off was found to be 70 mL/min/1.73 m2 for patients with eGFR ≥60 mL/min/1.73 m2. eGFR is also an important risk factor in patients with eGFR 60-70 mL/min/1.73 m2.

Possibilities of Azilsartan Medoxomil for Preparation for Planned Percutaneous Coronary Intervention in Patients With Type 2 Diabetes Mellitus

AIM

To evaluate the efficacy and safety of azilsartan medoxomil for preoperative preparation and improving the long-term prognosis of elective percutaneous coronary intervention (PCI) in patients with ischemic heart disease (IHD), arterial hypertension (AH), and type 2 diabetes mellitus (DM).

MATERIAL AND METHODS

The study sample included patients with type 2 DM referred for elective PCI who had poor blood pressure (BP) control according to 24-hour BP monitoring (24-BPM) (mean daily systolic BP ≥130 mmHg, mean daily diastolic BP ≥80 mmHg). The data were collected from 2018 through 2020. A total of 75 patients was included and distributed by simple randomization into two groups: group 1 (main, n=37) received azilsartan medoxomil as an antihypertensive drug at a dose of 40 mg/day (previously prescribed angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers (ARB) were discontinued); group 2 (control, n=38) continued on their previous antihypertensive therapy. The follow-up period was 6 months. During each of 5 consecutive follow-up visits, the patient was examined, 24-BPM was recorded, and urinary markers of renal dysfunction (glomerular filtration rate, GFR; neutrophil gelatinase-associated lipocalin, NGAL; urine albumin-creatinine ratio, UACR; kidney injury molecule, KIM-1; and interleukin-18, IL-18) were measured.

RESULTS

During the azilsartan treatment, GFR decreased by 7.4%, while in the control group, it decreased by 18.9% (p<0.001). For 6 months of follow-up, no changes in the NGAL concentration were found in the main group, while the NGAL concentration in the control group increased by 12.9%. With azilsartan, there was a decrease in the urinary concentration of IL-18 (16.9%), while in patients of the control group, IL-18 increased (7.14%). Proteinuria progressed in both groups, which was expectable given the presence of DM; however, in patients receiving azilsartan, the UACR value increased by 37.5%, while in patients of the control group, it increased by 96.15%. These differences were statistically significant. No statistically significant differences were found in the concentrations of cystatin C and KIM-1.

CONCLUSION

This study demonstrated two important facts: the possibility for diagnosing contrast-induced acute kidney injury (CI-AKI) using new, more sensitive markers of kidney damage, which is important for assessing the effectiveness of prevention, and the possibility of using ARBs, in particular azilsartan, for the prevention of CI-AKI in patients with IHD in combination with AH and DM.

High-mobility group box 1 and its related receptors: potential therapeutic targets for contrast-induced acute kidney injury

Percutaneous coronary intervention (PCI) is a crucial diagnostic and therapeutic approach for coronary heart disease. Contrast agents' exposure during PCI is associated with a risk of contrast-induced acute kidney injury (CI-AKI). CI-AKI is characterized by a sudden decline in renal function occurring as a result of exposure to intravascular contrast agents, which is associated with an increased risk of poor prognosis. The pathophysiological mechanisms underlying CI-AKI involve renal medullary hypoxia, direct cytotoxic effects, endoplasmic reticulum stress, inflammation, oxidative stress, and apoptosis. To date, there is no effective therapy for CI-AKI. High-mobility group box 1 (HMGB1), as a damage-associated molecular pattern molecule, is released extracellularly by damaged cells or activated immune cells and binds to related receptors, including toll-like receptors and receptor for advanced glycation end product. In renal injury, HMGB1 is expressed in renal tubular epithelial cells, macrophages, endothelial cells, and glomerular cells, involved in the pathogenesis of various kidney diseases by activating its receptors. Therefore, this review provides a theoretical basis for HMGB1 as a therapeutic intervention target for CI-AKI.

Navigating nephrotoxic waters: A comprehensive overview of contrast-induced acute kidney injury prevention

Contrast-induced acute kidney injury (CI-AKI) is the third leading cause of acute kidney injury deriving from the intravascular administration of contrast media in diagnostic and therapeutic procedures and leading to longer in-hospital stay and increased short and long-term mortality. Its pathophysiology, although not well-established, revolves around medullary hypoxia paired with the direct toxicity of the substance to the kidney. Critically ill patients, as well as those with pre-existing renal disease and cardiovascular comorbidities, are more susceptible to CI-AKI. Despite the continuous research in the field of CI-AKI prevention, clinical practice is based mostly on periprocedural hydration. In this review, all the investigated methods of prevention are presented, with an emphasis on the latest evidence regarding the potential of RenalGuard and contrast removal systems for CI-AKI prevention in high-risk individuals.

Vitamin E for the Prevention of Contrast-Induced Nephropathy: A Systematic Review and Meta-Analysis

Contrast-induced nephropathy (CIN) is a serious condition that may develop in patients undergoing diagnostic radiologic procedures. Several treatments have been assessed to prevent CIN development. This study aims to assess the efficacy and safety of vitamin E in the prevention of CIN compared to intravenous (IV) saline hydration. The literature search included MEDLINE/PubMed, Cochrane Central Register of Controlled Trials, the Web of Science, ProQuest, and Scopus for articles published until May 11, 2024, without language or time limits. The outcomes included the incidence of CIN, new-onset dialysis, and death (primary), as well as the change in serum creatinine and glomerular filtration rate (GFR) (secondary). Numerical and dichotomous outcomes were presented as standardized mean difference (SMD) and risk ratio (RR), respectively, with 95% confidence intervals (CI). Six clinical trials were included. Vitamin E was administered orally in varying doses, but one study used IV infusion. Vitamin E decreased the risk of developing CIN by 59% (n=5; pooled RR: 0.41; 95% CI: 0.25, 0.65; P<0.001) compared to IV hydration. None of the patients required renal replacement therapy. One patient on vitamin E died due to the occurrence of acute coronary syndrome. Vitamin E is a promising effective prophylaxis against CIN. However, the number of included studies and their sample sizes are small. The studies showed several limitations. There is a need for further high-quality clinical trials to ascertain the effectiveness of vitamin E compared to IV hydration and to compare vitamin E to other therapies, such as N-acetyl cysteine.

Microvascular changes following exposure to iodinated contrast media in vitro. A qualitative comparison to serum creatinine concentrations in post-cardiac catheterization patients

INTRODUCTION

Contrast-associated acute kidney injury (CA-AKI) is characterized as a loss of renal function following radiological contrast media administration. While all contrast media induce variable changes in microvascular endothelial cells in vitro, only few studies report clinical significance of their findings. A comprehensive assessment of the effect of iodinated contrast media on the renal function in vitro and in vivo is essential. The aim of our study was to morphometrically quantify the effect of two different contrast media (Iobitridol and Iodixanol) on vascular endothelial capillaries in vitro and to analyze their effect on the renal function of patients who underwent cardiac catheterization including the intra-arterial administration of contrast media, by measuring serum creatinine concentration (SCr), a byproduct of muscle metabolism, primarily excreted by the kidneys. Our hypothesis suggests that conducting a qualitative comparison of both outcomes will enable identification of differences and similarities between in vitro and in vivo exposure.

MATERIAL AND METHODS

In vitro, co-cultures of human dermal fibroblasts and human dermal microvascular endothelial cells forming capillary beds were exposed to a mixture of phosphate buffered saline and either Iobitridol, Iodixanol, or one of their supplements EDTA or Trometamol for 1.5 or 5 min. Negative control co-cultures were exposed exclusively to phosphate buffered saline. Co-cultures were either directly fixed or underwent a regeneration time of 1, 3 or 7 days. An artificial intelligence software was trained for detection of labeled endothelial capillaries (CD31) on light microscope images and measurements of morphometric parameters. In vivo, we retrospectively analyzed data from patients who underwent intra-arterial administration of contrast media and for whom SCr values were available pre- and post-contrast exposition (1, 3, and 7 days following procedure). Temporal development of SCr and incidence of CA-AKI were assessed. Both exposure types were qualitatively compared.

RESULTS

In vitro, Iobitridol, Iodixanol and EDTA induced a strong decrease of two morphometric parameters after 3 days of regeneration. In vivo, a significant increase of SCr and incidence of CA-AKI was observed 3 days following procedure in the post-contrast media patients. No difference was observed between groups.

DISCUSSION

Two of the morphometric parameters were inversely proportional to the SCr of the patients. If the endothelial damages observed in vitro occur in vivo, it may result in renal hypoxia, inducing a loss of kidney function clinically translated into an increase of SCr. Further development of our in vitro model could allow closer replication of the internal structure of a kidney and bridge the gap between in vitro studies and their clinical findings.

Evaluating the Differential Risk of Contrast-Induced Nephropathy Among Diabetic and Non-diabetic Patients Following Percutaneous Coronary Intervention

Background Contrast-induced nephropathy (CIN) significantly complicates percutaneous coronary intervention (PCI), with a higher prevalence in diabetic patients. This study compares the incidence of CIN in diabetic and non-diabetic patients undergoing PCI. Material and methods Conducted at Lady Reading Hospital, Peshawar, PAK, from January to December 2023, this observational study involved 450 adult patients with coronary artery disease (CAD) undergoing PCI. The cohort was categorized based on diabetes status, excluding patients with chronic kidney disease and those on renal replacement therapy. Baseline characteristics documented included age, gender, blood pressure, creatinine levels, and the presence of acute coronary syndrome (ACS). CIN was defined as a ≥25% increase in serum creatinine from baseline within 48-72 hours post-PCI. Data analysis was performed using the Statistical Package for the Social Sciences (IBM SPSS Statistics for Windows, IBM Corp., Version 25.0, Armonk, NY), incorporating descriptive statistics, Chi-square tests, and independent t-tests, with a significance level of p<0.05. Results The median age of the study population was 55 years. The cohort comprised 52% male (n=234) and 48% female (n=216). Notably, 33% (n=149) had ACS. Diabetic patients exhibited a significantly higher incidence of CIN post-PCI compared to non-diabetics. The highest incidence of CIN (17%, n=77) occurred in the 70+ age group. The findings highlight the criticality of renal function monitoring and procedural adjustments for diabetic patients. Conclusion Diabetic patients demonstrate an increased risk of CIN following PCI. This necessitates the development of tailored prevention strategies for this high-risk subgroup.

Differential renal proteomics analysis in a novel rat model of iodinated contrast-induced acute kidney injury

Contrast-induced acute kidney injury (CI-AKI), which occurs after the use of iodinated contrast media, has become the third leading cause of hospital-acquired acute kidney injury (AKI). It is associated with prolonged hospitalization and increased risks of end-stage renal disease and mortality. The pathogenesis of CI-AKI is unclear and effective treatments are lacking. By comparing different post-nephrectomy times and dehydration times, we constructed a new, short-course CI-AKI model using dehydration for 24 h two weeks after unilateral nephrectomy. We found that the low-osmolality contrast media iohexol caused more severe renal function decline, renal morphological damage, and mitochondrial ultrastructural alterations compared to the iso-osmolality contrast media iodixanol. The shotgun proteomics based on Tandem Mass Tag (TMT) was used to conduct proteomics research on renal tissue in the new CI-AKI model, and 604 distinct proteins were identified, mainly involving complement and coagulation cascade, COVID-19, PPAR signalling pathway, mineral absorption, cholesterol metabolism, ferroptosis, staphylococcus aureus infection, systemic lupus erythematosus, folate biosynthesis, and proximal tubule bicarbonate reclamation. Then, using parallel reaction monitoring (PRM), we validate 16 candidate proteins, of which five were novel candidates (Serpina1, Apoa1, F2, Plg, Hrg) previously unrelated to AKI and associated with an acute response as well as fibrinolysis. The pathway analysis and 16 candidate proteins may help to discover new mechanisms in the pathogenesis of CI-AKI, allowing for early diagnosis and outcome prediction.

Acute Kidney Injury Management Strategies Peri-Cardiovascular Interventions

In many countries, the aging population and the higher incidence of comorbid conditions have resulted in an ever-growing need for cardiac interventions. Acute kidney injury (AKI) is a common complication of these interventions, associated with higher mortalities, chronic or end-stage kidney disease, readmission rates, and hospital and post-discharge costs. The AKI pathophysiology includes contrast-associated AKI, hemodynamic changes, cardiorenal syndrome, and atheroembolism. Preventive measures include limiting contrast media dose, optimizing hemodynamic conditions, and limiting exposure to other nephrotoxins. This review article outlines the current state-of-art knowledge regarding AKI pathophysiology, risk factors, preventive measures, and management strategies in the peri-interventional period.

Key Considerations regarding the Renal Risks of Iodinated Contrast Media: The Nephrologist's Role

BACKGROUND

The administration of iodinated contrast medium during diagnostic and therapeutic procedures has always been associated with the fear of causing acute kidney injury (AKI) or an exacerbation of chronic kidney disease. This has led, on the one hand, to the deterrence, when possible, of the use of contrast medium (preferring other imaging methods with the risk of loss of diagnostic power), and on the other hand, to the trialling of multiple prophylaxis protocols in an attempt to reduce the risk of kidney injury.

SUMMARY

A literature review on contrast-induced (CI)-AKI risk mitigation strategies was performed, focussing on the recognition of individual risk factors and on the most recent evidence regarding prophylaxis.

KEY MESSAGES

Nephrologists can contribute significantly in the CI-AKI context, from the early stages of the decision-making process to stratifying patients by risk, individualising prophylaxis measures based on the risk profile, and ensuring appropriate evaluation of kidney function and damage post-procedure to improve care.

Use of Prophylactic High-Dose Statin Therapy to Reduce Contrast-Induced Acute Kidney Injury in Adults Undergoing Acute Coronary Angiography: Evaluation of a Practice Change

BACKGROUND

Development of contrast-induced acute kidney injury (CI-AKI) is associated with increased morbidity, mortality, hospital length of stay, and overall health care costs.

OBJECTIVES

The purpose of this project was to evaluate a clinical practice change-the addition of high-dose statin therapy to standard renal protection measures-in adults undergoing acute cardiac catheterization procedures and assessing its effect on CI-AKI.

METHOD

The evaluation was a pretest/posttest descriptive design. Adult patients undergoing acute cardiac catheterization procedures were evaluated for the rate of CI-AKI before (10 months preimplementation, N = 283) and after (10 months postimplementation, N = 286) a recent practice change that added high-dose statin therapy (within 24 hours of dye exposure) to a standard renal protection bundle (intravenous fluids, maximum dye calculations, and avoidance of nephrotoxic medications). Outcomes included the rate of CI-AKI, stage of acute kidney injury, need for new hemodialysis, discharge disposition (alive or died in the hospital), and hospital length of stay.

RESULTS

Patients in the postintervention group that received renal protection bundle with high-dose statin had significantly lower incidence of CI-AKI (10.1% pre vs 3.2% post; P < .001). There were no significant differences in hospital length of stay, need for new hemodialysis, or mortality. Administration of high-dose statin within 24 hours of the cardiac catheterization procedure improved significantly (19.4% pre vs 74.1% post; P < .001). Adherence to all 5 components of the renal bundle improved post intervention (17% pre vs 73.4% post; P < .001).

DISCUSSION

The addition of a high-dose statin in addition to existing renal protective measures in patients with acute cardiac procedures is associated with a decreased incidence of CI-AKI.

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 Potential Biotherapeutic Targets of Contrast-Induced Acute Kidney Injury

Contrast-induced acute kidney injury (CI-AKI) is manifested by an abrupt decline in kidney function as a consequence of intravascular exposure to contrast media. With the increased applicability of medical imaging and interventional procedures that utilize contrast media for clinical diagnosis, CI-AKI is becoming the leading cause of renal dysfunction. The pathophysiological mechanism associated with CI-AKI involves renal medullary hypoxia, the direct toxicity of contrast agents, oxidative stress, apoptosis, inflammation, and epigenetic regulation. To date, there is no effective therapy for CI-AKI, except for the development of strategies that could reduce the toxicity profiles of contrast media. While most of these strategies have failed, evidence has shown that the proper use of personalized hydration, contrast medium, and high-dose statins may reduce the occurrence of CI-AKI. However, adequate risk predication and attempts to develop preventive strategies can be considered as the key determinants that can help eliminate CI-AKI. Additionally, a deeper understanding of the pathophysiological mechanism of CI-AKI is crucial to uncover molecular targets for the prevention of CI-AKI. This review has taken a step further to solidify the current known molecular mechanisms of CI-AKI and elaborate the biomarkers that are used to detect early-stage CI-AKI. On this foundation, this review will analyze the molecular targets relating to apoptosis, inflammation, oxidative stress, and epigenetics, and, thus, provide a strong rationale for therapeutic intervention in the prevention of CI-AKI.

The Effect of SGLT2 Inhibitors on the Development of Contrast-Induced Nephropathy in Diabetic Patients with Non-ST Segment Elevation Myocardial Infarction

Background and Objectives: Percutaneous procedures using contrast agents are modern diagnosis and treatment methods for cardiovascular diseases. Contrast use may cause nephropathy, especially in diabetic patients. SGLT2 inhibitors have strong cardioprotective and renal protective effects. In our study, we investigated the effectiveness of this drug group in preventing the development of Contrast-Induced Nephropathy (CIN). Materials and Methods: The results of 312 diabetic patients who underwent CAG were analyzed. The study group included 104 DM patients using SGLT2 and the control group did not use SGLT2. These groups were compared with each other in terms of clinical, demographic, and laboratory parameters. Results: The groups were similar characteristics. However, post-CAG creatinine values compared with before the procedure, the development of CIN was observed to be significantly less in the group using SGLT2 inhibitor (p = 0.03). When the results of the multivariate analysis were examined, it was seen that the use of SGLT2 inhibitors significantly reduced the risk of CIN (odds ratio (OR): 0.41, 95% confidence interval (CI): 0,142-0.966, p = 0.004). Conclusions: Our study showed that SGLT2 inhibitors may be protective against the development of CIN, especially in patients with comorbid conditions such as diabetes.

Brain natriuretic peptide as a biomarker for predicting contrast-induced nephropathy in patients undergoing coronary angiography/intervention: A systematic review and meta-analysis

BACKGROUND

Contrast-induced nephropathy (CIN) is associated with adverse events. As there are no effective treatments, the early identification of high-risk patients is required. Individual studies have suggested the utility of brain natriuretic peptide in predicting CIN. Therefore, this meta-analysis aimed to systematically investigate the value of brain natriuretic peptide in predicting CIN in patients undergoing coronary angiography (CAG) or percutaneous coronary intervention (PCI).

METHODS

We searched PubMed, Embase, Cochrane Central Register of Controlled Trials Library, and Web of Science from inception date to March 9, 2022. Studies that evaluated the predictive value of brain natriuretic peptide for CIN outcomes in patients after CAG or PCI were included. The quality of the included studies was assessed using the QUADAS-2 tool. Diagnostic accuracy estimates were calculated using a random-effects model. Subgroup and meta-regression analyses were performed to identify the potential sources of heterogeneity.

RESULTS

Twelve studies with 7789 patients were included in the meta-analysis. The pooled sensitivity and specificity of brain natriuretic peptide for the prediction of CIN were 0.73 (95% CI: 0.67-0.78) and 0.77 (95% CI: 0.71-0.82), respectively. The area under the summary receiver operating characteristic curve was 0.80 (95% CI: 0.77-0.84). Meta-regression analysis indicated that the sources of sensitivity heterogeneity may be the country, mean age, and study population. Additionally, country, study population, study design, and index text contributed to the specificity heterogeneity.

CONCLUSION

This study demonstrated that brain natriuretic peptide could function as a novel potential marker for the early detection of CIN in patients undergoing CAG or PCI.

Three-Dimensional Kidney-on-a-Chip Assessment of Contrast-Induced Kidney Injury: Osmolality and Viscosity

Increased viscosity of concentrated contrast media (CM) in the renal tubules can perturb renal hemodynamics and have a detrimental effect on tubular epithelial cells. However, the effects of viscosity on contrast-induced nephropathy (CIN) remain poorly understood. Conventional in vitro culture studies do not reflect the rheological properties of CM. Therefore, we investigated the effects of CM viscosity on renal tubules using a kidney-on-a-chip and two different types of CM. Renal proximal tubule epithelial cells (RPTEC) were cultured in a three-dimensional microfluidic culture platform under bidirectional fluid shear stress. We treated the RPTEC with two types of CM: low- (LOCM, iopromide) and iso-osmolar contrast media (IOCM, iodixanol). Renal tubular cell injury induced by LOCM and IOCM was examined under different iodine concentrations (50–250 mgI/mL) and shear-stress conditions. LOCM showed a significant dose-dependent cytotoxic effect, which was significantly higher than that of IOCM under static and low-to-moderate shear stress conditions. However, high shear-stress resulted in reduced cell viability in IOCM; no difference between IOCM and LOCM was found under high shear-stress conditions. The cytotoxic effects were pronounced at a mean shear stress of 1 dyn/cm2 or higher. The high viscosity of IOCM slowed the fluid flow rate and augmented fluid shear-stress. We suggest an alternative in vitro model of CIN using the three-dimensional kidney-on-a-chip. Our results indicate a vital role of viscosity-induced nephrotoxicity under high shear-stress conditions, contrary to the findings of conventional in vitro studies.