Renal function and injury in infants and young children with congenital heart disease

Impact of congenital heart disease on mortality and other associated outcomes in children hospitalised for acute asthma exacerbation

BACKGROUND

Acute asthma exacerbation is one of the most common reasons for paediatric emergency room visits and hospital admissions in the United States of America.

OBJECTIVE

To assess the impact of CHD on outcomes of children hospitalised for acute asthma exacerbation.

METHODS

Children primarily admitted for acute asthma exacerbation were sampled from 2006, 2009, 2012, and 2016 kid inpatient database of the Healthcare Cost and Utilization Project using ICD codes. The disease outcomes were compared between those with and without CHD using multivariate logistic regressions in Stata version 17.

RESULTS

There were a total of 639,280 acute asthma exacerbation admissions, of which 5,907 (0.92%) had CHD. The mortality rate was 0.079% for patients without CHD and 0.72% for those with co-existing CHD. Children with CHD had higher odds of mortality (5.51, CI 3.40-8.93, p < 0.001), acute respiratory failure (2.84, CI 2.53-3.20; p < 0.001), need for invasive mechanical ventilation (4.58, CI 3.80-5.52; p < 0.001), acute kidney injury (adjusted odds ratio 3.03, CI 3.03-7.44; p < 0.001), and in-hospital cardiac arrest (adjusted odds ratio 4.52, CI 2.49-8.19; p < 0.001) when compared with those without CHD. The adjusted mean length of hospital stays (CI 2.91-3.91; p < 0.001) and hospital charges (95% CI $31060-$47747) among children with acute asthma exacerbation and CHD were significantly higher than in those without CHD.

CONCLUSION AND SIGNIFICANCE

CHD is an independent predictor of mortality, more severe disease course, and higher hospital resource utilisation. Strategies that improve CHD care will likely improve the overall health outcomes of children with CHD hospitalised for acute asthma exacerbation.

Model-Informed Vancomycin Dosing Optimization to Address Delayed Renal Maturation in Infants and Young Children with Critical Congenital Heart Disease

Ensuring safe and effective drug therapy in infants and young children often requires accounting for growth and organ development; however, data on organ function maturation are scarce for special populations, such as infants with congenital diseases. Children with critical congenital heart disease (CCHD) often require multiple staged surgeries depending on their age and disease severity. Vancomycin (VCM) is used to treat postoperative infections; however, the standard pediatric dose (60-80 mg/kg/day) frequently results in overexposure in children with CCHD. In this study, we characterized the maturation of VCM clearance in pediatric patients with CCHD and determined the appropriate dosing regimen using population pharmacokinetic (PK) modeling and simulations. We analyzed 1,254 VCM serum concentrations from 152 postoperative patients (3 days-13 years old) for population PK analysis. The PK model was developed using a two-compartment model with allometrically scaled body weight, estimated glomerular filtration rate (eGFR), and postmenstrual age as covariates. The observed clearance in patients aged ≤ 1 year and 1-2 years was 33% and 40% lower compared with that of non-CCHD patients, respectively, indicating delayed renal maturation in patients with CCHD. Simulation analyses suggested VCM doses of 25 mg/kg/day (age ≤ 3 months, eGFR 40 mL/min/1.73 m2 ) and 35 mg/kg/day (3 months < age ≤ 3 years, eGFR 60 mL/min/1.73 m2 ). In conclusion, this study revealed delayed renal maturation in children with CCHD, could be due to cyanosis and low cardiac output. Model-informed simulations identified the lower VCM doses for children with CCHD compared with standard pediatric guidelines.

Validation of the STARZ neonatal acute kidney injury risk stratification score in an independent prospective cohort

OBJECTIVE

A rapid AKI risk assessment score would allow for improving management and outcomes. STARZ (Sethi, Tibrewal, Agrawal, Raina, waZir) score was developed for acute kidney injury (AKI) risk stratification of critically ill neonates. This is the first independent validation for the novel score outside the original enrolled centres.

STUDY DESIGN

750 neonates were included in the study. The STARZ score was calculated after 12 hours of admission. Neonates admitted in NICU and receiving IV fluids for at least 48 hours were included.

RESULTS

A total of 8.8% neonates had AKI in the first 7 days post admission. The duration of hospital stay was significantly higher among neonates with AKI [10.5 (7-19) vs. 7 (5-10) days; p < 0.001]. Mortality risk was 6.4 times higher among those with AKI [8 (12.1%) vs. 13 (1.9%); p < 0.001; RR (95% CI): 6.38 (2.74-14.83)]. In this study, the STARZ neonatal scoring model showed a sensitivity of 89.4% in detecting AKI with a 90.9% specificity and a high negative predictive value of 98.9%. The area under ROC was 0.958 (0.934-0981) - a high discriminative power.

CONCLUSIONS

The STARZ score allows for AKI risk stratification, providing opportunity for therapeutic interventions which may improve outcomes in critically ill neonates.

Acute Kidney Injury Predictors and Outcomes after Cardiac Surgery in Children with Congenital Heart Disease: An Observational Cohort Study

Acute Kidney Injury (AKI) commonly complicates cardiac surgery in children with congenital heart disease (CHD). In this study we assessed incidence, risk factors, and outcomes of postoperative AKI, while testing the hypothesis that, depending on the underlying diagnosis, there would be significant differences in AKI incidence among different diagnostic groups. We conducted an observational cohort study of children with CHD undergoing cardiac surgery in a single tertiary center between January 2019 and August 2021 (n = 362). Kidney Disease Improving Global Outcome (KDIGO) criteria were used to determine the incidence of postoperative AKI. Diagnosis was incorporated into multivariate models using an anatomic-based CHD classification system. Overall survival was estimated using Kaplan−Meier curves. Log-rank test and adjusted Cox proportional hazard modelling were used to test for differences in survival distributions and determine AKI effect on survival function, respectively. AKI occurred in 70 (19.3%), with 21.4% in-hospital mortality for AKI group. Younger age, lower weight, longer cardiopulmonary bypass time, preoperative mechanical ventilation and diagnostic category were associated with postoperative AKI. Resolution rate was 92.7% prior to hospital discharge for survivors. AKI was associated with longer duration of mechanical ventilation, ICU and hospital length of stay. AKI patients had significantly higher probability of all-cause mortality postoperatively when compared to the non-AKI group (log-rank test, p < 0.001). Adjusted hazard ratio for AKI versus non-AKI group was 11.08 (95% CI 2.45−50.01; p = 0.002). Diagnostic category was associated with cardiac surgery-related AKI in children with CHD, a finding supporting the development of lesion specific models for risk stratification. Postoperative AKI had detrimental impact on clinical outcomes and was associated with decreased survival to hospital discharge.

Perioperative albuminuria and clinical model to predict acute kidney injury in paediatric cardiac surgery

BACKGROUND

AKI is an important complication post cardiac surgery in children. An early diagnosis can help in mitigating complications and allow for prognostication. Urinary albumin:creatinine ratio (ACR) as a biomarker can provide a cheaper and more accessible AKI risk assessment and prediction. There is a paucity of paediatric literature regarding its utility.

METHODS

This was a prospective observational study, enrolling all children aged 1 month to 18 years, who underwent cardiac surgery, with use of cardiopulmonary bypass. Cohort was divided into groups < 2 years and ≥ 2 years for analyses to account for differences in physiological albumin excretion with age.

RESULTS

Of 143 children enrolled in the study, 36 developed AKI. In both age groups, the post-operative ACR was higher than pre-operative ACR among patients with and without AKI. In the group aged ≥ 2 years, the highest first post-operative ACR tertile (> 75.8 mg/g) predicted post-operative AKI after adjusting for clinical variables (adjusted RR, 11.71; 1.85-16.59). In the group aged < 2 years, the highest first post-operative ACR tertile (> 141.3 mg/g) predicted post-operative AKI in unadjusted analysis but not after adjusting for clinical variables (RR, 2.78; 0.70-6.65). For AKI risk prediction, AUC (95% CI) was highest after combining clinical model and pre-operative ACR for groups aged < 2 years [0.805 (0.713-0.896)] and ≥ 2 years [0.872 (0.772-0.973)].

CONCLUSIONS

This study provides evidence for use of albuminuria as a feasible biomarker in AKI prediction in children post cardiac surgery, especially when added to a clinical model. A higher resolution version of the Graphical abstract is available as Supplementary information.

The use of diagnostic tools for pediatric AKI: applying the current evidence to the bedside

Given the known deleterious consequences of acute kidney injury (AKI), exciting recent research efforts have focused on developing strategies for the earlier recognition of AKI in the pediatric population. Recognizing the limitations of serum creatinine, investigators have focused on the study of novel biomarkers and practical bedside tools for identifying patients at risk for AKI prior to a rise in serum creatinine. In PubMed, there are presently over 30 original research papers exploring the use of pediatric AKI risk prediction tools in just the last 2 years. The following review highlights the most recent advances in the literature regarding opportunities to refine our ability to detect AKI early. Importantly, this review discusses how prediction tools including novel urine and serum biomarkers, practical risk stratification tests, renal functional reserve, and electronic medical record alerts may ultimately be applied to routine clinical practice.

Population pharmacokinetics of meropenem in critically ill infant patients

BACKGROUND

Population pharmacokinetic analysis in critically ill infants remains a challenge for lack of information.

OBJECTIVES

To determine the population pharmacokinetic parameters of meropenem and evaluate the covariates affecting population pharmacokinetic parameters.

METHODS

A prospective study was conducted on 35 patients. A total of 160 blood samples were collected and determined free of drug concentrations of meropenem. Population pharmacokinetic data were analyzed using NONMEM software. Internal validation methods, including bootstrapping and prediction-corrected visual predictive checks, were applied to evaluate the robustness and predictive power of the final model.

RESULTS

A one-compartment model with first-order elimination showed the best fit to the data. The typical clearance (CL) values and volume of distribution (V_d) were 1.33 L/h and 2.27 L, respectively. Weight and creatinine clearance were influential covariates for CL, while weight was a significant covariate for V_d of meropenem. The model evaluation results suggested robustness and good predictability of the final model. The standard dosage regimens of meropenem achieved 40% f T_>MIC but not enough if a more aggressive target of 80% f T_>MIC at MIC value of ≥ 16 µg/mL is desired.

CONCLUSIONS

This population pharmacokinetic model could be used for suggesting individualized meropenem dosage regimens in critically ill infants.

Mild Hypoxia Enhances the Expression of HIF and VEGF and Triggers the Response to Injury in Rat Kidneys

Background

Hypoxia contributes to a cascade of inflammatory response mechanisms in kidneys that result in the development of renal interstitial fibrosis and subsequent chronic renal failure. Nonetheless, the kidney possesses a self-protection mechanism under a certain degree of hypoxia and this mechanism its adaptation to hypoxia. As the hypoxia-inducible factor (HIF)–vascular endothelial growth factor (VEGF) axis is a key pathway for neovascularization, the activation of this axis is a target for renal hypoxia therapies.

Methods

Sprague–Dawley rats were exposed to normobaric hypoxia and subdivided into three groups, namely group A (21% O₂), group B (10% O₂), and group C (7% O₂). Renal tissue samples were processed and analyzed to determine pathological morphological changes, the expression of HIF, VEGF, inflammation factor and vascular density.

Results

We found that as the duration of hypoxia increased, destructive changes in the kidney tissues became more severe in group C (7% O₂). In contrast, the increased duration of hypoxia did not exacerbate kidney damage in group B (10% O₂). As the hypoxia was prolonged and the degree of hypoxia increased, the expression of HIF-1α increased gradually. As hypoxia time increased, the expression of VEGF increased gradually, but VEGF expression in group B (10% O₂) was the highest. Group C (7% O₂) had higher levels of IL-6, IL-10, and TNF-alpha. Additionally, the highest vascular density was observed in group B.

Conclusion

These findings suggest that activating the HIF–VEGF signaling pathway to regulate angiogenesis after infliction of hypoxic kidney injury may provide clues for the development of novel CKD treatments.

A randomized controlled trial comparing controlled reoxygenation and standard cardiopulmonary bypass in paediatric cardiac surgery

OBJECTIVES

Controlled reoxygenation on starting cardiopulmonary bypass (CPB) rather than hyperoxic CPB may confer clinical advantages during surgery for congenital cyanotic heart disease.

METHODS

A single-centre, randomized controlled trial was carried out to compare the effectiveness of controlled reoxygenation (normoxia) versus hyperoxic CPB in children with congenital cyanotic heart disease undergoing open-heart surgery (Oxic-2). The co-primary clinical outcomes were duration of inotropic support, intubation time and postoperative intensive care unit (ICU) and hospital stay. Analysis of the primary outcomes included data from a previous trial (Oxic-1) conducted to the same protocol.

RESULTS

Ninety participants were recruited to Oxic-2 and 79 were recruited to the previous Oxic-1 trial. There were no significant differences between the groups for any of the co-primary outcomes: inotrope duration geometric mean ratio (normoxia/hyperoxic) 0.97, 95% confidence interval (CI) (0.69-1.37), P-value = 0.87; intubation time hazard ratio (HR) 1.03, 95% CI (0.74-1.42), P-value = 0.87; postoperative ICU stay HR 1.14 95% CI (0.77-1.67), P-value = 0.52, hospital stay HR 0.90, 95% CI (0.65-1.25), P-value = 0.53. Lower oxygen levels were successfully achieved during the operative period in the normoxic group. Serum creatinine levels were lower in the normoxic group at day 2, but not on days 1, 3-5. Childhood developmental outcomes were similar. In the year following surgery, 85 serious adverse events were reported (51 normoxic group and 34 hyperoxic group).

CONCLUSIONS

Controlled reoxygenation (normoxic) CPB is safe but with no evidence of a clinical advantage over hyperoxic CPB.

CLINICAL TRIAL REGISTRATION NUMBER

Current Controlled Trials-ISRCTN81773762.

Evaluation of renal injury in children with uncorrected CHDs with significant shunt using urinary neutrophil gelatinase-associated lipocalin

BACKGROUND

CHDs can be complicated by renal injury which worsens morbidity and mortality. Urinary neutrophil gelatinase-associated lipocalin, a sensitive and specific biomarker of renal tubular injury, has not been studied in children with uncorrected CHDs. This study evaluated renal injury in children with uncorrected CHDs using this biomarker.

METHODS

The patients were children with uncorrected CHDs with significant shunt confirmed on echocardiogram with normal renal ultrasound scan, in the paediatric cardiology clinic of a tertiary hospital. The controls were age-matched healthy children recruited from general practice clinics. Information on bio-data and socio-demographics were collected and urine was obtained for measurement of urinary neutrophil gelatinase-associated lipocalin levels.

RESULTS

A total of 65 children with uncorrected CHDs aged 2 to 204 months were recruited. Thirty-one (47.7%) were males while 36 (55.4%) had acyanotic CHDs. The median urinary neutrophil gelatinase-associated lipocalin level of patients of 26.10 ng/ml was significantly higher than controls of 16.90 ng/ml (U = 1624.50, p = 0.023). The median urinary neutrophil gelatinase-associated lipocalin level of patients with cyanotic and acyanotic CHDs were 30.2 ng/ml and 22.60 ng/ml respectively; (Mann-Whitney U = 368.50, p = 0.116). The prevalence of renal injury using 95th percentile cut-off value of urinary neutrophil gelatinase-associated lipocalin was 16.9%. Median age of patients with renalinjury was 16 (4-44) months.

CONCLUSIONS

Children with uncorrected CHDs have renal injury detected as early as infancy. The use of urinary neutrophil gelatinase-associated lipocalin in early detection of renal injury in these children may enhance early intervention and resultant prevention of morbidity and reduction in mortality.

Chronic Kidney Disease in Adolescents after Surgery for Congenital Heart Disease

BACKGROUND

The onset of chronic kidney disease (CKD) is an important prognostic factor in young adults with congenital heart disease (CHD). Although it is likely that CKD is manifest early in CHD patients, the prevalence among adolescents is still unknown. The National Kidney Foundation's Kidney Disease Improving Global Outcomes guidelines 2012 recommend new equations for the estimated glomerular filtration rate (eGFR) and highlight the importance of albuminuria for CKD screening. The objective of the present study was to estimate the prevalence of CKD in CHD adolescents.

METHODS

This observational cross-sectional study included 115 patients aged 10-18 years attending the cardiologic outpatient clinic at our institution as a follow-up after cardiac surgery in infancy related to various CHDs. CKD assessment used the CKD criteria 2012, including eGFR equations based on serum creatinine and cystatin C, and measurement of albuminuria.

RESULTS

No patient had an eGFR <60 mL min-1 1.73 m-2. However, 28.7% of all patients (95% CI 20.7-37.9) had eGFRbetween 60 and 89 mL min-1 1.73 m-2 when estimated by the bedside Schwartz creatinine-based equation,and 17.4% (95% CI 11.2-24.1) had eGFRbetween 60 and 89 mL min-1 1.73 m-2 when estimated by the Zappitelli equation, combining creatinine and cystatin C. Of all patients, 20.0% (95% CI 12.1-26.7) had orthostatic proteinuria, and none had persistent albuminuria.

CONCLUSIONS

There was no evidence of CKD in the present population aged 10-18 years. The significance of an eGFR between 60 and 90 mL min-1 1.73 m-2 is not concordant for this age range and requires further investigations.

Baseline tubular biomarkers in young adults with congenital heart disease as compared to healthy young adults: Detecting subclinical kidney injury

BACKGROUND

There are significant implications for kidney disease in young adults with congenital heart disease. Prior investigations have not focused on the use of urinary tubular biomarkers for the early identification of kidney disease in this growing patient group.

OBJECTIVE

Determine if young adults with congenital heart disease have differences in the baseline concentration of urinary tubular biomarkers when compared to healthy young adults.

DESIGN/METHODS

In a pilot case control study, 30 patients from 18 to 35 years of age with congenital heart disease and a normal serum creatinine were recruited during a routine follow-up visit. In the same age group, 30 control subjects without history of heart or kidney disease were recruited. Urine samples were obtained to measure beta 2-microglobin, alpha 1-microglobin, N-acetyl-B-D-glucosaminidase, liver fatty acid binding protein, kidney injury molecule-1, insulin-like growth factor binding protein 7, and tissue inhibitor of metalloproteinases-2. Comparisons were done using Wilcoxon rank-sum or Fisher's exact test.

RESULTS

No study participants had proteinuria on urine dipstick. Median concentrations of kidney injury molecule-1 were higher (P = .01) and concentrations of insulin-like growth factor binding protein 7 (P = .001) and tissue inhibitor of metalloproteinases-2 (P = .009) were lower in the subjects with congenital heart disease when compared to the control subjects. There were no significant differences between the groups with respect to the other biomarkers.

CONCLUSION

Our data suggest that young adults with congenital heart disease may have subclinical kidney dysfunction. Lower levels of insulin-like growth factor binding protein 7 and tissue inhibitor of metalloproteinases-2 may indicate an impaired ability to respond to injury, while higher levels of kidney injury molecule-1 may reflect early tubular injury.

Kidney injury biomarkers after cardiac angiography in children with congenital heart disease

OBJECTIVE

This study aims to investigate the changes in renal function and levels of urinary biomarkers before and after cardiac angiography in children with congenital heart disease (CHD).

SETTING

Children with CHD are at a risk for kidney injury during contrast exposure in cardiac angiography.

OUTCOME MEASURES

We measured urinary protein, albumin, N-acetyl-β-D-glucosaminidase (NAG), β2-microglobulin (BMG), and liver-type fatty acid-binding protein (L-FABP) levels, as well as serum creatinine and cystatin C levels, before and after cardiac angiography in 33 children with CHD.

RESULTS

No significant decrease was noted in either the creatinine-based or cystatin C-based estimated glomerular filtration rate at 24 hours after angiography compared with that before angiography. Urinary protein, NAG, BMG, and L-FABP levels were significantly increased at 24 hours after angiography, all of which returned to baseline levels at more than 7 days after angiography. An increase in urinary level of protein, albumin, NAG, or BMG was mostly associated with increased urinary L-FABP level. An increase in both urinary BMG and L-FABP, but not that in urinary L-FABP alone, was associated with increased levels of urinary protein and NAG, as well as the greater dose of contrast media.

CONCLUSIONS

Transient increases of kidney injury biomarkers following cardiac angiography are not necessarily associated with the impairment of renal function in a short time period; however, the increase in urinary protein, albumin, NAG, or BMG level may indicate greater stresses to the kidneys than the increase in urinary L-FABP alone in children with CHD.

Altered in utero kidney development in newborns with congenital heart disease

BACKGROUND

It is known that the heart is not the only organ affected in congenital heart disease (CHD); there is growth restriction of both the brain and the whole body. The protective mechanism of "the brain-sparing phenomenon" re-directs blood flow toward the growing brain in fetuses with CHD. We hypothesized that these changes would result in impaired fetal kidney growth.

METHODS

The preoperative ultrasound measurements of kidney length were obtained retrospectively from 452 neonates requiring surgery for CHD. Percentiles were generated based on regression analysis of normative kidney length from three datasets according to both corrected gestational age and to birthweight.

RESULTS

As a cohort, neonates with CHD have significantly enlarged kidneys, with a mean percentile ranging from 54.1-72.7 (p < 0.001), depending on the three normal population datasets used for comparison. The kidneys of neonates with left heart obstruction were consistently demonstrated to be greater than normal, unlike those with cyanotic heart disease which were shown to have either normal or enlarged kidneys, depending on the reference population used.

CONCLUSIONS

The kidneys of newborns with CHD are not reduced in size, and on average are larger than normal. The nature of this size discrepancy and its subsequent clinical significance is unknown.

Prevalence and associated factors of renal dysfunction and proteinuria in cyanotic congenital heart disease

BACKGROUND

Cyanotic nephropathy (CN), seen in 30-50% of patients with congenital cyanotic heart disease (CCHD), affects both tubular and glomerular function, resulting in proteinuria and azotemia. Microalbuminuria is an early marker for glomerular damage and an independent predictor of progressive renal disease.

METHODS

A cross-sectional study was conducted. A total of 116 patients aged 1 month to 15 years with CCHD at Chiang Mai University Hospital between 2015 and 2016 were assessed and 94 patients were enrolled. To determine the prevalence and associated factors of significant albuminuria in CCHD patients, baseline characteristics, oxygen saturation, surgery, hemoglobin (Hb), hematocrit (Hct), spot urine albumin, urine protein, and creatinine were obtained. Binary logistic-regression modeling was used to identify associated factors.

RESULTS

Prevalence of CN in children with CCHD was 58.51% and 92.55% according to albuminuria and proteinuria staging respectively. Prevalence of significant proteinuria, significant albuminuria, and decreased GFR was 88.30%, 41.49% and 31.91% respectively. Participants with significant albuminuria had fewer previous surgeries (p = 0.05), a longer waiting time for surgery (p = 0.02), enalapril usage (p = 0.04), pulmonary hypertension (p = 0.03), higher Hct z-score (p = 0.03) and lower platelet count (p = 0.001) compared with those without significant albuminuria. Using multivariate logistic regression analysis, waiting duration for surgery (p = 0.04), Hct >40% (p = 0.02), and platelet count <290,000/mm³ (p = 0.04) were predictive of microalbuminuria.

CONCLUSIONS

Cyanotic nephropathy can be detected in the first decade of life with the presentation of microalbuminuria. High Hct level and low platelet count were identified as a predictor of microalbuminuria, whereas early cardiac surgery decreased the risk of developing significant albuminuria.

CASZ1 loss-of-function mutation associated with congenital heart disease

As the most common form of birth defect in humans, congenital heart disease (CHD) is associated with substantial morbidity and mortality in both children and adults. Increasing evidence demonstrates that genetic defects play a pivotal role in the pathogenesis of CHD. However, CHD is of great heterogeneity, and in an overwhelming majority of cases, the genetic determinants underpinning CHD remain elusive. In the present investigation, the coding exons and flanking introns of the CASZ1 gene, which codes for a zinc finger transcription factor essential for the cardiovascular morphogenesis, were sequenced in 172 unrelated patients with CHD. As a result, a novel heterozygous CASZ1 mutation, p.L38P, was identified in an index patient with congenital ventricular septal defect (VSD). Genetic scanning of the mutation carrier's available family members revealed that the mutation was present in all affected patients but absent in unaffected individuals. Analysis of the proband's pedigree showed that the mutation co-segregated with VSD, which was transmitted as an autosomal dominant trait with complete penetrance. The missense mutation, which altered the amino acid that was highly conserved evolutionarily, was absent in 200 unrelated, ethnically-matched healthy subjects used as controls. Functional deciphers by using a dual-luciferase reporter assay system unveiled that the mutant CASZ1 had significantly reduced transcriptional activity as compared with its wild-type counterpart. To the best of our knowledge, the current study firstly identifies CASZ1 as a new gene predisposing to CHD in humans, which provides novel insight into the molecular mechanisms underlying CHD and a potential therapeutic target for CASZ1-associated CHD, suggesting potential implications for personalized prophylaxis and therapy of CHD.

PROGRESSION OF CHRONIC KIDNEY DISEASE AFTER ACUTE KIDNEY INJURY

The incidence of chronic kidney disease (CKD) in children and adults is increasing. Cardiologists have become indispensable members of the care provider team for children with CKD. This is partly due to the high incidence of CKD in children and adults with congenital heart disease, with current estimates of 30-50%. In addition, the high incidence of acute kidney injury (AKI) due to cardiac dysfunction or following pediatric cardiac surgery that may progress to CKD is also well documented. It is now apparent that AKI and CKD are uniquely intertwined as interconnected syndromes. Furthermore, the well-known long-term cardiovascular morbidity and mortality associated with CKD require the joint attention of both nephrologists and cardiologists. Children with both congenital heart disease and CKD are increasingly surviving to adulthood, with synergistically negative medical, financial, and quality of life impact. An improved understanding of the epidemiology, mechanisms, early diagnosis, and preventive measures is of importance to cardiologists, nephrologists, scientists, economists, and policy makers alike. Herein, we report the current definitions, epidemiology, and complications of CKD in children, with an emphasis on children with congenital heart disease. We then focus on the clinical and experimental evidence for the progression of CKD after episodes of AKI commonly encountered in children with heart disease, and explore the role of novel biomarkers for the prediction of CKD progression.

Effects of acute kidney injury and chronic hypoxemia on fibroblast growth factor 23 levels in pediatric cardiac surgery patients

BACKGROUND

Fibroblast growth factor-23 (FGF23) levels are elevated in cardiopulmonary bypass (CPB)-associated acute kidney injury (AKI); however, it is unknown how much of the circulating FGF23 is intact and bioactive. Hypoxia may induce FGF23 production, yet its impact in humans is unknown. Pediatric cardiac surgery patients have both a high incidence of CPB-associated AKI and a high prevalence of chronic hypoxemia.

METHODS

We assessed the effects of hypoxemia and CPB-associated AKI on C-terminal FGF23 (cFGF23) and intact FGF23 (iFGF23) levels in 32 pediatric cardiac surgery patients with normal estimated glomerular filtration rate (eGFR). Plasma cFGF23 and iFGF23 were measured preoperatively and serially postoperatively.

RESULTS

Despite normal renal and ventricular function, preoperative cFGF23 levels were high and elevated out of proportion to iFGF23 levels. Preoperative oxygen saturation measurements correlated inversely with FGF23 levels. Preoperative cFGF23 and oxygen saturation both predicted postoperative AKI. Postoperatively, cFGF23 and iFGF23 increased by 2 h postreperfusion; iFGF23 then returned to baseline, but cFGF23 remained elevated through 24 h postreperfusion. Group status (AKI vs. non-AKI) modified the effect of time on changes in iFGF23 levels but not cFGF23 levels.

CONCLUSIONS

Preoperative cFGF23 may predict CPB-associated kidney dysfunction. Changes over time in cFGF23 and iFGF23 levels post-CPB differ. Chronic hypoxemia may affect FGF23 production in humans.

Chronic kidney disease in congenital heart disease patients: a narrative review of evidence

Purpose of review

Patients with congenital heart disease have a number of risk factors for the development of chronic kidney disease (CKD). It is well known that CKD has a large negative impact on health outcomes. It is important therefore to consider that patients with congenital heart disease represent a population in whom long-term primary and secondary prevention strategies to reduce CKD occurrence and progression could be instituted and significantly change outcomes. There are currently no clear guidelines for clinicians in terms of renal assessment in the long-term follow up of patients with congenital heart disease. Consolidation of knowledge is critical for generating such guidelines, and hence is the purpose of this view. This review will summarize current knowledge related to CKD in patients with congenital heart disease, to highlight important work that has been done to date and set the stage for further investigation, development of prevention strategies, and re-evaluation of appropriate renal follow-up in patients with congenital heart disease.

Sources of information

The literature search was conducted using PubMed and Google Scholar.

Findings

Current epidemiological evidence suggests that CKD occurs in patients with congenital heart disease at a higher frequency than the general population and is detectable early in follow-up (i.e. during childhood). Best evidence suggests that approximately 30 to 50 % of adult patients with congenital heart disease have significantly impaired renal function. The risk of CKD is higher with cyanotic congenital heart disease but it is also present with non-cyanotic congenital heart disease. Although significant knowledge gaps exist, the sum of the data suggests that patients with congenital heart disease should be followed from an early age for the development of CKD.

Implications

There is an opportunity to mitigate CKD progression and negative renal outcomes by instituting interventions such as stringent blood pressure control and reduction of proteinuria. There is a need to invest time, thought and money to fill existing knowledge gaps to improve health outcomes in this population. This review should serve as an impetus for generation of follow-up guidelines of kidney health evaluation in patients with congenital heart disease.

Prevalence and predictors of decreased glomerular filtration rate in tibetan children with congenital heart disease

OBJECTIVES

To assess the prevalence of decreased glomerular filtration rate (GFR) in Tibetan children with congenital heart disease (CHD) and its associated risk factors.

METHODS

A total of 207 Tibetan children attending authors' center for treatment of CHD from May 2012 through November 2012, were included in the study. GFR was estimated with the Schwartz formula (eGFR).

RESULTS

The mean eGFR was 104.3±16.6 mL/min/1.73 m2, and decreased in 21 children (10.1%). In the cyanotic category, eGFR was decreased only in severely cyanotic individuals. In the acyanotic category with left ventricular overload, children with decreased eGFR were younger, more commonly lived in areas above 4,700 m, and had higher left ventricular internal dimensions indexed by body surface areas (LVID/BSA) (53.8±6.9 vs. 40.1±6.8 mm/m2, P<0.001) compared with those with normal eGFR. Multivariate analysis identified LVID/BSA as the only independent predictor for decreased eGFR (OR: 1.329, 95% CI: 1.177~1.501, P<0.001). Receiver operating characteristic analysis showed the area under curve for LVID/BSA was 0.921 (95% CI: 0.863 ~ 0.980, P<0.001), with the optimal cutoff value of 49.8 mm/m2 (sensitivity: 75.0%, specificity: 93.9%). In the remaining category, decreased eGFR was only observed in those living above 4,700 m.

CONCLUSIONS

One tenth of Tibetan children with CHD had decreased eGFR. The risk factors included severe cyanosis, younger age, living above 4,700 m and higher LVID/BSA.