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

Framework for Kidney Health Follow-Up Among Neonates With Critical Cardiac Disease: A Report From the Neonatal Kidney Health Consensus Workshop

Acute kidney injury is common among neonates with critical cardiac disease. Risk factors and associations with kidney-related outcomes are heterogeneous and distinct from other neonates. As survival of children with critical cardiac disease increases to adulthood, the burden of chronic kidney disease is increasing. Thirty percent to 50% of adults with congenital heart disease have impaired kidney function, even in the absence of prior kidney injury episodes. This may be related to the current standardized acute kidney injury criteria, which may not fully capture clinically meaningful kidney injury and long-term kidney health risks. An improved understanding of which neonates with critical cardiac disease should undergo kidney health follow-up is imperative. During the National Institutes of Health-supported Neonatal Kidney Health Consensus Workshop to Address Kidney Health meeting conducted in February 2024, a panel of 51 neonatal nephrology experts focused on at-risk groups: (1) preterm infants, (2) critically ill infants with acute kidney injury, and (3) infants with critical cardiac disease. The critical cardiac disease subgroup, comprising multidisciplinary experts, used a modified Delphi process to achieve consensus on recommendations for kidney health follow-up. In this report, we review available data on kidney health follow-up in critical cardiac disease and summarize the 2 consensus-based recommendations. We introduce novel diagnostic and risk-stratification tools for acute kidney injury diagnosis in neonates with cardiac disease to guide follow-up recommendations. Finally, we identify important knowledge gaps, representing areas of focus for future research. These should be prioritized to understand and improve long-term kidney health in critical cardiac disease.

Overexpression of plasmalemmal vesicle-associated protein-1 in patient with cyanotic nephropathy: a case report

BACKGROUND

Cyanotic nephropathy (CN) is a known complication of cyanotic congenital heart disease (CCHD). However, many aspects of its pathophysiology remain unclear.

CASE PRESENTATION

We report the case of a 29-year-old male with a history of tetralogy of Fallot. Renal biopsy revealed glomerular hypertrophy and focal segmental glomerulosclerosis. Electron microscopy revealed extensive endothelial cell damage. To investigate the etiology of endothelial cell damage, PAL-E staining was conducted, revealing staining along the glomerular capillary wall.

CONCLUSION

This is the first report of PAL-E staining in CN, suggesting potential overexpression of PV-1. The association of PV-1 expression with endothelial cell damage indicates its role in the pathogenesis of CN.

Independent prognostic value of lipocalin-2 in congenital heart disease-associated pulmonary artery hypertension

BACKGROUND

Timely and accurate evaluation of the patient's pulmonary arterial pressure (PAP) is of great significance for the treatment of congenital heart disease. Currently, there is no non-invasive gold standard method for evaluating PAP.

AIM

To assess the prognostic value of lipocalin-2 (LCN2) in relation to PAP in patients with congenital heart disease associated with pulmonary artery hypertension.

METHODS

We conducted a retrospective analysis of 69 pediatric patients diagnosed with ventricular septal defects. The patients' clinical and laboratory data were collected. The serum LCN2 concentrations were compared between the pulmonary arterial hypertension (PAH) group and the nonPAH group. The correlation of LCN2 concentration with PAH classification was evaluated using binary logistic regression analysis. The receiver operating characteristic (ROC) curve was used to evaluate the diagnostic potential of LCN2 for PAH.

RESULTS

Serum LCN2 concentration significantly correlated with patients' mean PAP (r = 0.544, P < 0.001), but not correlated with creatinine (P = 0.446) or blood urea nitrogen (P = 0.747). LCN2 levels were significantly correlated with PAH in both univariate [odds ratio (OR) 1.107, 95%CI: 1.033-1.185, P = 0.004)] and multivariate regression analysis (OR 1.150, 95%CI: 1.027-1.288, P = 0.015). ROC curve analysis revealed an area under the curve of 0.783 for LCN2. At the cutoff value of 19.42 ng/mL, the sensitivity and specificity of LCN2 for diagnosing PAH is 90.19% and 55.56%, respectively. LCN2 concentration also significantly correlated with the post-repair mean PAP in patients with congenital heart disease (r = 0.532, P = 0.009).

CONCLUSION

LCN2 is emerging as a candidate biomarker for assessing PAP in patients with congenital heart disease. Its high sensitivity in diagnosing PAH makes it a valuable tool in patient management.

Case report: Challenging kidney transplantation in an adolescent patient with tetralogy of Fallot

Tetralogy of Fallot is the most common cyanotic congenital heart disease. This severe disorder of cardiac physiology can impair renal function and lead to the development of cardiorenal syndrome and eventually to end-stage renal disease. Kidney transplantation may be the best option for renal replacement treatment in patients with tetralogy of Fallot, but only after correcting cardiac abnormalities and optimizing cardiac functions, all of which require a multidisciplinary approach. We report the first case of kidney transplantation in an adolescent patient with tetralogy of Fallot. Our findings confirms that kidney transplantation is a valuable treatment option in selected congenital heart disease cases.

Cyanotic Nephropathy in an Adult Patient with Eisenmenger Syndrome: A Case Report and Literature Review

INTRODUCTION

Cyanotic nephropathy, a rare disease characterized by proteinuria, decreased estimated glomerular filtration rate, thrombocytopenia, polycythemia, and hyperuricemia, may occasionally be secondary to cyanotic congenital heart disease (CHD). There are currently no detailed diagnostic criteria or treatments for cyanotic nephropathy, owing to its extremely low incidence. Eisenmenger syndrome (ES) was initially defined by Paul Wood in pathophysiologic terms as "pulmonary hypertension (PH) at the systemic level, caused by a high pulmonary vascular resistance, with a reversed or bidirectional shunt at the aorto-pulmonary, ventricular, or atrial level." It typically develops in the presence of large, unrepaired atrial or ventricular septal defects, arterial shunts, or complex forms of CHD and is the most severe hemodynamic phenotype of pulmonary arterial hypertension associated with CHD. This study aimed to outline the case of an ES patient who developed cyanotic nephropathy and successfully achieved clinical remission through primary disease treatment and symptomatic management. Overall, this case expands our understanding of cyanotic nephropathy and lays a theoretical reference for the treatment of ES.

CASE PRESENTATION

A 33-year-old Chinese female attended the outpatient department with abnormal urine test results over the past two and a half years. Following a comprehensive medical history collection, she underwent the necessary tests. Cardiac color ultrasound displayed a significant widening of the pulmonary artery and PH (severe), as well as mild tricuspid regurgitation and patent ductus arteriosus. The results of the kidney biopsy, combined with clinical findings, suggested a high risk of polycythemia-related kidney disease. She was eventually diagnosed with cyanotic nephropathy and ES. Her symptoms were relieved following symptomatic treatment, such as the administration of ambrisentan, febuxostat, and home oxygen therapy. Her follow-up visit at 6 months demonstrated improvements in hyperuricemia and a significant increase in physical strength.

CONCLUSION

Cyanotic nephropathy is a rare condition in adults. Kidney biopsy remains the gold standard of diagnosis for various nephropathies. Active treatment of CHD and alleviating hypoxia may be pivotal for the treatment of cyanotic nephropathy.

Activation of renal epithelial Na+ channels (ENaC) in infants with congenital heart disease

Introduction

This study was designed to measure the concentration and activity of urinary proteases that activate renal epithelial sodium channel (ENaC) mediated Na+ transport in infants with congenital heart disease, a potential mechanism for fluid retention.

Methods

Urine samples from infants undergoing cardiac surgery were collected at three time points: T1) pre-operatively, T2) 6-8 h after surgery, and T3) 24 h after diuretics. Urine was collected from five heathy infant controls. The urine was tested for four proteases and whole-cell patch-clamp testing was conducted in renal collecting duct M-1 cells to test whether patient urine increased Na+ currents consistent with ENaC activation.

Results

Heavy chain of plasminogen, furin, and prostasin were significantly higher in cardiac patients prior to surgery compared to controls. There was no difference in most proteases before and after surgery. Urine from cardiac patients produced a significantly greater increase in Na+ inward currents compared to healthy controls.

Conclusion

Urine from infants with congenital heart disease is richer in proteases and has the potential to increase activation of ENaC in the nephron to enhance Na+ reabsorption, which may lead to fluid retention in this population.

Long-Term Renal Involvement in Association with Fontan Circulation

Multiorgan dysfunction is a concern of Fontan patients. To clarify the pathophysiology of Fontan nephropathy, we characterize renal disease in the long-term observational study. Medical records of 128 consecutive Fontan patients [median age: 22 (range 15-37) years old] treated between 2009 and 2018 were reviewed to investigate the incidence of nephropathy and its association with other clinical variables. Thirty-seven patients (29%) showed proteinuria (n = 34) or < 90 mL/min/1.73 m2 of estimated glomerular filtration rate (eGFR) (n = 7), including 4 overlapping cases. Ninety-six patients (75%) had liver dysfunction (Forns index > 4.21). Patients with proteinuria received the Fontan procedure at an older age [78 (26-194) vs. 56 (8-292) months old, p = 0.02] and had a higher cardiac index [3.11 (1.49-6.35) vs. 2.71 (1.40-4.95) L/min/m2, p = 0.02], central venous pressure [12 (7-19) vs. 9 (5-19) mmHg, p < 0.001], and proportion with > 4.21 of Forns index (88% vs. 70%, p = 0.04) than those without proteinuria. The mean renal perfusion pressure was lower in patients with a reduced eGFR than those without it [55 (44-65) vs. 65 (45-102) mmHg, p = 0.03], but no other variables differed significantly. A multivariable analysis revealed that proteinuria was associated with an increased cardiac index (unit odds ratio 2.02, 95% confidence interval 1.12-3.65, p = 0.02). Seven patients with severe proteinuria had a lower oxygen saturation than those with no or mild proteinuria (p = 0.01, 0.03). Proteinuria or a decreased eGFR differentially occurred in approximately 30% of Fontan patients. Suboptimal Fontan circulation may contribute to the development of proteinuria and reduced eGFR.

Using Serum Cystatin C to Predict Acute Kidney Injury Following Infant Cardiac Surgery

Acute kidney injury (AKI) following cardiopulmonary bypass (CPB) is associated with increased morbidity and mortality. Serum Cystatin C (CysC) is a novel biomarker synthesized by all nucleated cells that may act as an early indicator of AKI following infant CPB. Prospective observational study of infants (< 1 year) requiring CPB during cardiac surgery. CysC was measured at baseline and 12, 24, 48, and 72 h following CPB initiation. Each post-op percent difference in CysC (e.g. %CysC12h) from baseline was calculated. Clinical variables along with urine output (UOP) and serum creatinine (SCr) were followed. Subjects were divided into two groups: AKI and non-AKI based upon the Kidney Disease Improving Global Outcomes (KDIGO) classification. AKI occurred in 41.9% (18) of the 43 infants enrolled. Patient demographics and baseline CysC levels were similar between groups. CysC levels were 0.97 ± 0.28 mg/L over the study period, and directly correlated with SCr (R = 0.71, p < 0.0001). Although absolute CysC levels were not significant between groups, the %CysC12h was significantly greater in the AKI group (AKI: - 16% ± 22% vs. Non-AKI - 28% ± 9% mg/L; p = 0.003). However, multivariate analysis demonstrated that a lower UOP (Odds Ratio:0.298; 95% CI 0.073, 0.850; p = 0.02) but not %CysC12h was independently associated with AKI. Despite a significant difference in the %CysC12h, only UOP was independently associated with AKI. Larger studies of a more homogenous population are needed to understand these results and to explore the variability in this biomarker seen across institutions.

Acute Hospital Outcomes for Renal Transplantation in Patients With Moderate or Severe Congenital Heart Disease

Children and adults with congenital heart disease (CHD) are increasingly recognized to be at risk for acute and chronic renal injury. Some of these may progress to the need for renal transplantation. We hypothesized that patients with underlying moderate or severe CHD who undergo renal transplantation will have worse acute hospital outcomes. Using a national administrative database, we queried for admissions aged 0 to 50 years with moderate or severe CHD and renal transplantation and compared these to admissions without CHD. There were 56 admissions for renal transplantation in the CHD group (0.04%) and 26,285 admissions in the group without CHD (0.21%, p<0.001). The CHD group were younger, had a higher proportion of Whites, longer length of stay, higher complication rates, higher in-hospital mortality, and higher costs. In conclusion, although renal transplantation is still relatively uncommon in the CHD population, there is an increasing recognition of severe chronic renal disease in the setting of CHD, making it important to understand the potential implications of these findings.

Early post-operative PV-ACO2/CA-VO2 predicts subsequent acute kidney injury after complete repair of tetralogy of Fallot

BACKGROUND

Acute kidney injury is a severe complication following complete repair of tetralogy of Fallot. Anaerobic metabolism is believed to contribute to the development of acute kidney injury. The ratio of central venous to arterial carbon dioxide tension to arterio-venous oxygen content (PV-ACO2/CA-VO2) has been proposed as a surrogate for respiratory quotient and an indicator of tissue oxygenation. We hypothesised that a small increase of PV-ACO2/CA-VO2 might have superior discrimination ability in subsequent acute kidney injury prediction.

METHODS

This study is retrospective and single-centre design study. The study population consisted of 61 children with tetralogy of Fallot that underwent a complete surgical repair between July 2017 and January 2021. Baseline characteristics and intra-operative parameters were collected through a retrospective chart review. PV-ACO2/CA-VO2 was collected within 12 hours of surgical completion. Acute kidney injury was defined according to the criteria established by the Kidney Disease: Improving Global Outcomes group. Univariate and logistic regression analyses were performed to determine risk factors for acute kidney injury.

RESULTS

Of the 61 patients, 20 (32.8%) developed acute kidney injury. Multivariate logistic analyses showed that age, height, haematocrit, and Pv-aCO2/Ca-vO2 were independently associated with the development of acute kidney injury. The addition of Pv-aCO2/Ca-vO2 to the model significantly increased model discrimination [AUROC 0.939 (95% CI 0.894-0.984) and AUROC 0.922 (95% CI 0.869-0.975), respectively].

CONCLUSIONS

The increase of PV-ACO2/CA-VO2 could improve the predictive ability for subsequent development of acute kidney injury in children with tetralogy of Fallot.

Persistent Markers of Kidney Injury in Children Who Developed Acute Kidney Injury After Pediatric Cardiac Surgery: A Prospective Cohort Study

Background

Acute kidney injury (AKI) after pediatric cardiac surgery is common. Longer‐term outcomes and the incidence of chronic kidney disease after AKI are not well‐known.

Methods and Results

All eligible children (aged <16 years) who had developed AKI following cardiac surgery at our tertiary referral hospital were prospectively invited for a formal kidney assessment ≈5 years after AKI, including measurements of estimated glomerular filtration rate, proteinuria, α₁‐microglobulin, blood pressure, and kidney ultrasound. Longer‐term follow‐up data on kidney function were collected at the latest available visit. Among 571 patients who underwent surgery, AKI occurred in 113 (19.7%) over a 4‐year period. Fifteen of these (13.3%) died at a median of 31 days (interquartile range [IQR], 9–57) after surgery. A total of 66 patients participated in the kidney assessment at a median of 4.8 years (IQR, 3.9–5.7) after the index AKI episode. Thirty‐nine patients (59.1%) had at least 1 marker of kidney injury, including estimated glomerular filtration rate <90 mL/min per 1.73 m² in 9 (13.6%), proteinuria in 27 (40.9%), α₁‐microglobinuria in 5 (7.6%), hypertension in 13 (19.7%), and abnormalities on kidney ultrasound in 9 (13.6%). Stages 1 to 5 chronic kidney disease were present in 18 (27.3%) patients. Patients with CKD were more likely to have an associated syndrome (55.6% versus 20.8%, P=0.015). At 13.1 years (IQR, 11.2–14.0) follow‐up, estimated glomerular filtration rate <90 mL/min per 1.73 m² was present in 18 of 49 patients (36.7%), suggesting an average estimated glomerular filtration rate decline rate of −1.81 mL/min per 1.73 m² per year.

Conclusions

Children who developed AKI after pediatric cardiac surgery showed persistent markers of kidney injury. As chronic kidney disease is a risk factor for cardiovascular comorbidity, long‐term kidney follow‐up in this population is warranted.

Evaluation of neonatal acute kidney injury after critical congenital heart disease surgery

BACKGROUND

Acute kidney injury (AKI) is a common complication of congenital heart diseases (CHDs) after cardiac surgery. This study aimed to define the frequency and critical course, risk factors and short-term outcomes of AKI in postoperative CHD neonates.

METHODS

Postoperatively followed term CHD newborn infants were enrolled in the study. Infants with congenital anomalies of the urinary tract and other major congenital anomalies were excluded. Neonatal modified KDIGO criteria were used to assess AKI.

RESULTS

A total of 199 postoperatively followed newborn infants were included in the study. Acute kidney injury was detected in 71 (35.6%) patients. Of these patients, 24 (33.8%) were in stage 1, 14 (19.7%) in stage 2, and 33 (46.5%) in stage 3. Acute kidney injury occurred within the first week (median 1 day [IQR 1-2 days]) of cardiac surgery in 93% of the patients. The duration of invasive respiratory support and extracorporeal membrane oxygenation (ECMO) and mortality were significantly higher in stage 3 patients. Higher vasoactive-inotropic score (OR, 1.02; 95% CI, 1.0-1.04; p = 0.008) and receiving ECMO (OR, 7.9; 95% CI, 2.6-24.4; p = 0.001) were associated with risk for the development of AKI. The mortality rate was 52.1% in the AKI (+) patients, and having AKI (OR 7.1; 95% CI, 3.5-14.18) was significantly associated with mortality.

CONCLUSION

Acute kidney injury, a common early complication after critical neonatal CHD cardiac surgery, is associated with increased morbidity and mortality. Stage 3 AKI is associated with significantly higher mortality rates.

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.

Development of nephropathy in an adult patient after Fontan palliation for cyanotic congenital heart disease

Cyanotic congenital heart disease is occasionally associated with kidney dysfunction, which is known as cyanotic nephropathy or cyanotic glomerulopathy. The clinical presentation of cyanotic nephropathy includes proteinuria, decreased estimated glomerular filtration rate, hyperuricemia, thrombocytopenia, or polycythemia. Although advances in surgical procedures have improved the prognosis of cyanotic congenital heart diseases, adult cases of cyanotic nephropathy are still rare, and there are few reports of kidney biopsy in adults with cyanotic nephropathy. Here, we present the case of a 41-year-old patient with Fontan palliation who developed nephrotic range proteinuria and had a kidney biopsy, which showed glomerular hypertrophy with segmental glomerulosclerosis around vascular poles, suggesting adaptive focal segmental glomerulosclerosis. This case provides further understanding of kidney dysfunction due to cyanotic congenital heart disease and shows the need for attention in the management for prevention of progression to end-stage renal disease and in the selection of renal replacement therapy.

Incidence and risk factors for chronic kidney disease in patients with congenital heart disease

BACKGROUNDS

Chronic kidney disease (CKD) is underdiagnosed in children with congenital heart disease (CHD). Our aim was to study the incidence of CKD in CHD children and identify risk factors for CKD.

METHODS

CHD patients were enrolled from the Kaohsiung Veterans General Hospital database between 2010 and 2019. Patient age at enrollment was age at first visit to the hospital. The end of follow-up was marked by the last measurement of serum creatinine, urine protein-to-creatinine ratio (UPCR), or urine microalbumin-to-creatinine ratio (UACR) after enrollment, and only patients who underwent the aforementioned tests in 2 different years were included. Patients with an estimated glomerular filtration rate (eGFR) < 90 mL/min/1.73m² were diagnosed as having CKD and were further classified into clinically recognized CKD (CR-CKD, defined as eGFR <60 mL/min/1.73m², UPCR >0.5, or UACR >30 mg/g) and non-clinically recognized CKD (NCR-CKD). Their demographic data, CHD category, heart surgery types, medications, and contrast-related examinations during follow-up were collected.

RESULTS

The study included 359 CHD patients, of whom 167 (46.5%) developed CKD (18 patients with CR-CKD and 341 with NCR-CKD). Patients with CR-CKD were significantly older at enrollment than patients with NCR-CKD. Corrective heart surgery may be a protective factor for CKD. Furthermore, cyanotic heart disease, two or more image-related contrast exposures, and diuretic use may be associated with CKD.

CONCLUSION

CHD patients have a high incidence of CKD. The early detection of CKD and prompt corrective heart surgery for CHD may be beneficial for kidney function.

Retinal microvasculature impairment in patients with congenital heart disease investigated by optical coherence tomography angiography

Importance

A high prevalence of retinal abnormalities have been reported in congenital heart disease (CHD), but quantitative analysis of retinal vasculature is scarce. Optical coherence tomography angiography (OCTA) is a noninvasive method to quantitatively assess the retinal microvasculature.

Background

To investigate the retinal microvasculature changes in CHD patients by using OCTA.

Design

Cross‐sectional study.

Participants

A total of 158 participants including 57 cyanotic CHD (CCHD) patients, 60 acyanotic CHD (ACHD) patients and 41 control subjects were included.

Methods

All participants underwent a comprehensive ophthalmologic examination, including refraction measurement, intraocular pressure measurement and OCTA.

Main Outcome Measures

Vessel density (VD) was measured within the radial peripapillary capillary (RPC), superficial capillary plexus (SCP) and deep capillary plexus (DCP) of the macula.

Results

CCHD patients had significantly lower VD in the RPC, SCP and DCP (all P < .01) compared to control subjects, and significantly lower VD in the RPC and DCP (both P < .05) compared to ACHD patients. Besides, among the CHD group, VD in the RPC was positively correlated with oxygen saturation (whole image, ρ = 0.45; peripapillary, ρ = 0.48) and negatively correlated with haematocrit (whole image, ρ = 0.55; peripapillary, ρ = 0.55) (all P < .001).

Conclusions and Relevance

Retinal VD might be a surrogate to reflect the effect of chronic systemic hypoxemia in CHD patients. OCTA could be a convenient and noninvasive tool to evaluate the retinal structure and function in CHD patients.