Mechanisms of development and progression of cyanotic nephropathy

Tetralogy of Fallot in Low- and Middle-Income Countries

Low- and middle-incomes countries (LMICs) have limited resources for the diagnosis and treatment of congenital heart diseases such as tetralogy of Fallot. This is in part due to lack of infrastructures, financial means, and expertise. As a result, patients undergo surgery much later than in high-income countries. This delay in treatment results in right ventricular dysfunction, cardiac arrhythmias, and poor psychomotor development-complications that are all related to chronic hypoxia. There are limited data and a few small studies of patients treated for tetralogy of Fallot in LMICs, and, therefore, the aim of this review is to analyse and summarize the surgical outcomes of this LMIC population.

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.

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.

Special Considerations in Critical Care of the Congenital Heart Disease Patient

Outcomes of congenital heart disease have improved markedly over the past 20 years, with survival to adulthood now close to 90%. The mean age of admission to an intensive care unit (ICU) is 40 years. The incidence of hospital and critical care admissions have increased significantly as a consequence of this improved survival. Intensivists are now confronted with the management not only of complex adult congenital heart disease (ACHD) lesions from a cardiac perspective, but also of extracardiac organ consequences of years of abnormal circulation after surgical or palliative correction. Kidney and liver dysfunction and respiratory and hematologic abnormalities are very common in this population. ACHD patients can present to the ICU for a vast number of reasons, classified in this review as medical noncardiac, medical cardiac, and surgical. Community/hospital-acquired infections, cerebrovascular accidents, and respiratory failure, alongside arrhythmias and heart failure, are responsible for medical admissions. Surgical admissions include postoperative management after correction or palliation, but also medical optimisation and work-up for advanced therapies. ICU management of this large heterogeneous group requires a thorough understanding of the pathophysiology in order to apply conventional adult critical care modalities; left ventricular or right ventricular dysfunction, pulmonary hypertension, intracardiac, extracardiac, and palliative surgical shunts can be present and require additional consideration. This review focuses on the pathophysiology, long-term sequelae, and different treatment modalities to supply a framework for the ICU physician caring for these patients. Successful outcome, especially in complex lesions, depends on early involvement of specialised ACHD centres.

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.

Glomerular Biomechanical Stress and Lipid Mediators during Cellular Changes Leading to Chronic Kidney Disease

Hyperfiltration is an important underlying cause of glomerular dysfunction associated with several systemic and intrinsic glomerular conditions leading to chronic kidney disease (CKD). These include obesity, diabetes, hypertension, focal segmental glomerulosclerosis (FSGS), congenital abnormalities and reduced renal mass (low nephron number). Hyperfiltration-associated biomechanical forces directly impact the cell membrane, generating tensile and fluid flow shear stresses in multiple segments of the nephron. Ongoing research suggests these biomechanical forces as the initial mediators of hyperfiltration-induced deterioration of podocyte structure and function leading to their detachment and irreplaceable loss from the glomerular filtration barrier. Membrane lipid-derived polyunsaturated fatty acids (PUFA) and their metabolites are potent transducers of biomechanical stress from the cell surface to intracellular compartments. Omega-6 and ω-3 long-chain PUFA from membrane phospholipids generate many versatile and autacoid oxylipins that modulate pro-inflammatory as well as anti-inflammatory autocrine and paracrine signaling. We advance the idea that lipid signaling molecules, related enzymes, metabolites and receptors are not just mediators of cellular stress but also potential targets for developing novel interventions. With the growing emphasis on lifestyle changes for wellness, dietary fatty acids are potential adjunct-therapeutics to minimize/treat hyperfiltration-induced progressive glomerular damage and CKD.

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.

Building an Adult Congenital Heart Program: Critical Components and Important Allies

Purpose of the Review

The purpose of this review is to illustrate specific challenges and opportunities in the building of an adult congenital heart disease (ACHD) program and to highlight critical components and important allies.

Recent Findings

With more than 1.4 million adults with congenital heart disease in the USA alone, access to specialized, compassionate, high-quality comprehensive care requires a shift toward more aggressive expansion of ACHD care, especially in the context of sparse ACHD provider representation in the vast majority of adult medical centers.

Summary

The effective build of an ACHD program requires measured escalation in management of ACHD complexity matched with cultivation of key resources and clinical services ranging from congenital cardiac surgery and interventional cardiology to acquired heart disease as well as partnerships with non-cardiac specialists. By reframing ACHD care as a shared goal between patients, providers, hospitals, pharmaceutical and device industry, and payers, a potent business model can be built around the developing ACHD program to facilitate acquisition of these key resources.

Assessment of Potential Renal Dysfunction in Patients with Congenital Heart Disease after Biventricular Repair

Background and Objectives

There are few reports on renal dysfunction in the remote period after biventricular repair, and biomarkers for early detection of renal dysfunction are not well understood. We examined whether early fluctuation of biomarkers of renal function occurs in the remote period after biventricular repair in patients with congenital heart disease (CHD).

Methods

Fourteen patients with CHD after biventricular repair were included. The examination values obtained by cardiac catheterization test and renal function indices based on blood and urine sampling were compared.

Results

The median estimated glomerular filtration rate (eGFR) of creatinine was 113 mL/min/1.73 m², and the median eGFR of cystatin C was 117 mL/min/1.73 m². A urine albumin-to-creatinine ratio (UACR) ≥10 mg/gCr was considered a risk factor for cardiovascular disease in 6 (43%) patients. There was a significant difference in right ventricular ejection fraction and deviation in right ventricular end-diastolic volume from the normal value between the 2 groups divided by UACR. Cyanosis before biventricular repair was noted in 2 (25%) patients with UACR <10 mg/gCr and in 4 (67%) patients with UACR ≥10 mg/gCr.

Conclusions

Increased UACR was noted in 43% of patients. In patients with UACR ≥10 mg/gCr, right heart system abnormality was observed, and several patients had cyanosis before radical treatment. Measurement for UACR may be able to detect renal dysfunction early in the postoperative remote period.

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.

Diagnosis and Management of Noncardiac Complications in Adults With Congenital Heart Disease: A Scientific Statement From the American Heart Association

Life expectancy and quality of life for those born with congenital heart disease (CHD) have greatly improved over the past 3 decades. While representing a great advance for these patients, who have been able to move from childhood to successful adult lives in increasing numbers, this development has resulted in an epidemiological shift and a generation of patients who are at risk of developing chronic multisystem disease in adulthood. Noncardiac complications significantly contribute to the morbidity and mortality of adults with CHD. Reduced survival has been documented in patients with CHD with renal dysfunction, restrictive lung disease, anemia, and cirrhosis. Furthermore, as this population ages, atherosclerotic cardiovascular disease and its risk factors are becoming increasingly prevalent. Disorders of psychosocial and cognitive development are key factors affecting the quality of life of these individuals. It is incumbent on physicians who care for patients with CHD to be mindful of the effects that disease of organs other than the heart may have on the well-being of adults with CHD. Further research is needed to understand how these noncardiac complications may affect the long-term outcome in these patients and what modifiable factors can be targeted for preventive intervention.

Medium-term follow-up of renal function in hypoxaemic congenital heart disease patients

Introduction Hypoxaemic congenital heart disease (CHD) patients are at higher risk of complications. The aim of this study was to compare and follow-up blood and 24-hour urine analytical data in hypoxaemic and non-hypoxaemic CHD patients.

METHODS

The inclusion criteria for this study were as follows: patients older than 14 years of age with a structural CHD with or without associated hypoxaemia.

RESULTS

In total, 27 hypoxaemic and 48 non-hypoxaemic CHD patients were included in order to compare blood and 24-hour urine analytical data. Among hypoxaemic patients, 13 (48.1%) were male, two (7.4%) had diabetes mellitus, one of whom was a smoker, one (3.7%) had systemic arterial hypertension, and 11 (40.7%) showed pulmonary arterial hypertension. The mean follow-up time was 3.1±1.9 years. Hypoxaemic CHD patients showed higher proteinuria concentrations (g/24 hours) (0.09 (0.07; 0.46) versus 0.08 (0.07; 0.1), p=0.054) and 24-hour albumin excretion rate (µg/min) (16.5 (11.2; 143.5) versus 4.4 (0.0; 7.6), p<0.001) compared with non-hypoxaemic CHD patients; however, no significant differences were found in the proteinuria levels and in the 24-hour albumin excretion rate in CHD patients with associated hypoxaemia, both at baseline and at follow-up. When divided into groups, hypoxaemic patients with palliative shunts showed significantly higher proteinuria concentrations compared with hypoxaemic patients not operated on or with Fontan procedures (p=0.01). No significant differences were seen in 24-hour proteinuria and 24-hour albumin excretion rate during the follow-up of patients with palliative shunts.

CONCLUSIONS

Hypoxaemic CHD patients have significant higher 24-hour proteinuria concentration and 24-hour albumin excretion rate compared with non-hypoxaemic CHD patients. Among hypoxaemic CHD patients, those with palliative shunts showed the highest 24-hour proteinuria concentrations.

Proteinuria and clinical outcome in CHD patients

INTRODUCTION

CHD patients, especially those with associated hypoxaemia, usually have some level of renal function impairment, even though they are relatively young. The aim of the study was to evaluate those clinical and analytical factors that may contribute to microalbuminuria and determine the association of 24-hour proteinuria with thrombotic events and mortality.

METHODS

A total of 251 CHD patients were studied and demographic characteristics, blood test, and 24-hour urinalysis were analysed.

RESULTS

Of the patients, 221 were non-hypoxaemic, and 30 were hypoxaemic (oxygen saturation of 84.3±5.9%). Of the non-hypoxaemic patients, 30 (13.6%), and of the hypoxaemic patients 9 (30%), showed proteinuria (>0.15 g/24 hours) (p=0.028). Hypoxaemic CHD patients also showed higher haematocrit (%) (50.7 (34.6; 72.1) versus 42.8 (34.6; 48.9), p<0.001), serum creatinine (mg/dl) (1.07±0.2 versus 0.96±1.9, p=0.004), microalbuminuria (mg/dl/24 hours) (1.2 (0.0; 261.5) versus 0.5 (0.0; 4.37), p<0.001), proteinuria (gr/24 hours) (1.0 (0.4; 3.1) versus 0.08 (0.04; 0.52), p=0.043), and N-terminal pro-B-type natriuretic peptide (pg/ml) (417.8 (35.7; 8534.0) versus 44.9 (0.0; 670.5), p<0.001) concentrations than non-hypoxaemic CHD patients. During a median follow-up of 26.0 (16.9; 57.7) months, five patients died - one patient had 24-hour proteinuria and four patients did not (p=0.581) - and three patients had some type of thrombosis - two patients had 24-hour proteinuria and one patient did not (p=0.014). Kaplan-Meier survival analysis showed no significant difference between CHD patients with and without 24-hour proteinuria (p=0.631).

CONCLUSION

CHD patients with proteinuria have significantly more thrombosis and more hypoxaemia than those patients without proteinuria.

Critical care management of the adult patient with congenital heart disease: focus on postoperative management and outcomes

OPINION STATEMENT

Advances in surgical techniques and in the medical management of children with congenital heart disease has increased survival into adulthood, resulting in a population of adults with congenital heart disease now surpassing the pediatric population in numbers. Furthermore, many of the patients will require repeat surgical, catheter-based, procedures and/or obstetrical care in their adult lives, and understanding the specific cardiopulmonary physiology and the involvement of other organ systems is critical to successful intervention. A team approach, with consultants from medical specialties in the setting of an established adult congenital heart center, is the optimal setting for superior outcomes. In this review, we discuss critical care management of the adult congenital heart disease patient in the perioperative period.

Nephrotic Syndrome in a Child Suffering from Tetralogy of Fallot: A Rare Association

Nephrotic syndrome is an uncommon complication of tetralogy of Fallot and has been rarely reported in pediatric population. We describe a 4-year-old female Congolese child who was referred for investigation for persistent dyspnea, edema, and cyanosis and nephrotic range proteinuria. Our patient presented with a tetralogy of Fallot and nephrotic syndrome. Conclusion. This case reminds us that children with tetralogy of Fallot may develop nephrotic proteinuria.

Urine β 2-Microglobolin in the Patients with Congenital Heart Disease

BACKGROUND

This study aimed to evaluate the renal tubular function in the patients with congenital heart disease using β2-microglobulin.

METHODS

In this case-control study, based on oxymetry, the patients with congenital heart disease were divided into two groups of cyanotic (n=20) and acyanotic (n=20). Congenital heart disease was diagnosed by echocardiography. Healthy individuals within the same age and sex groups were used as controls. Na(+), β2-micro globulin, creatinine (Cr), and β2-microglobulin/Cr ratio were measured in random urine samples and the results were compared to the same parameters in the control group using Tukey, One-Way ANOVA, and X(2) tests.

RESULTS

Based on the study results, urine sodium in the patients with cyanotic heart disease was significantly different from that of the controls (P=0.023). The results also revealed a significant difference between the two groups with congenital heart disease regarding urine β2-microglobulin (P=0.045). In addition, the patients with cyanotic heart disease were significantly different from those with acyanotic heart disease and the controls regarding urine β2-micro globulin/Cr ratio (P=0.012 and P=0.026, respectively).

CONCLUSIONS

The results of this study demonstrated that renal tubular dysfunction began in the patients with congenital heart disease, especially in those with cyanotic congenital heart disease. Besides, early diagnosis before cardiac surgery leads to better control of renal tubular disease.

Hypertrophic osteoarthropathy: what a rheumatologist should know about this uncommon condition

This article presents an updated overview of hypertrophic osteoarthropathy and digital clubbing for the practicing rheumatologist. Discussion includes a brief historical perspective, its definition, incidence and prevalence, classification, pathology and pathophysiology, clinical manifestations, demographics, findings on physical examination, imaging techniques for its detection, differential diagnosis, and treatment modalities.

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

BACKGROUND

The aim of this study was to investigate renal function and injury in infants and young children with congenital heart disease (CHD).

METHODS

We prospectively enrolled 58 CHD children aged ≤3 years and 20 age-matched controls and divided these into four groups: Group I, acyanotic CHD (n = 24); Group II, cyanotic CHD with arterial oxygen saturation of >75 % (n = 20); Group III, cyanotic CHD with arterial oxygen saturation of ≤75 % (n = 14); Group IV, normal controls (n = 20). Urinary levels of microalbumin (MA), N-acetyl-ß-D-glucosaminidase (NAG), and α1-microglobulin (α1-MG) corrected by creatinine (UCr) were compared.

RESULTS

Children with CHD had elevated urinary α1-MG/UCr levels, with Group III children having the highest level. Groups I and III children had higher urinary NAG/UCr levels than those of Groups II and IV. Urinary MA/UCr levels in the three patient groups were comparable and significantly higher than that in the control group. A α1-MG × 100/ (α1-MG + MA) of <15 %, indicative of glomerular damage, was present in two patients in Group I and one in Group III, but none in Group II.

CONCLUSIONS

Tubular injury can occur in CHD patients during infancy and early childhood. Among our patient cohort, it was most prominent in children with severe cyanosis. Glomerular injury was detected in some individuals with advanced heart failure or severe cyanosis.

Glomerular hyperfiltration: definitions, mechanisms and clinical implications

Glomerular hyperfiltration is a phenomenon that can occur in various clinical conditions including kidney disease. No single definition of glomerular hyperfiltration has been agreed upon, and the pathophysiological mechanisms, which are likely to vary with the underlying disease, are not well explored. Glomerular hyperfiltration can be caused by afferent arteriolar vasodilation as seen in patients with diabetes or after a high-protein meal, and/or by efferent arteriolar vasoconstriction owing to activation of the renin-angiotensin-aldosterone system, thus leading to glomerular hypertension. Glomerular hypertrophy and increased glomerular pressure might be both a cause and a consequence of renal injury; understanding the renal adaptations to injury is therefore important to prevent further damage. In this Review, we discuss the current concepts of glomerular hyperfiltration and the renal hemodynamic changes associated with this condition. A physiological state of glomerular hyperfiltration occurs during pregnancy and after consumption of high-protein meals. The various diseases that have been associated with glomerular hyperfiltration, either per nephron or per total kidney, include diabetes mellitus, polycystic kidney disease, secondary focal segmental glomerulosclerosis caused by a reduction in renal mass, sickle cell anemia, high altitude renal syndrome and obesity. A better understanding of the mechanisms involved in glomerular hyperfiltration could enable the development of new strategies to prevent progression of kidney disease.

Ascites in Adult Patients With Cyanotic Congenital Heart Disease

Hematologic, neurologic, renal, and rheumatic complications in patients with cyanotic congenital heart disease are well known. However, the effects of this condition on the liver are poorly described. Between April 2005 and April 2010, 25 adults with cyanotic congenital heart disease were studied to determine clinical history, liver ultrasonographic data, and liver histological presentation. Twenty-five patients, with a median age of 28.7 ± 8.3 years and a basal tissue hemoglobin oxygen saturation of 83.3% ± 6.8%, were studied. Liver ultrasonographic examination showed abnormalities in 10 of 20 patients (50%): 6 patients (30%) had hepatomegaly, 2 patients (10%) heterogeneous parenchyma echo pattern, and 2 patients (10%) increased portal echogenicity. Ascites was found in 7 patients (28%): 4 patients had refractory ascites and 3 patients anasarca. Patients with anasarca responded well to oral and intravenous furosemide, but those with isolated ascites did not. No data to indicate severe ventricular dysfunction or severe valve regurgitation were seen. In patients with refractory ascites who had therapeutic paracentesis, serum–ascites albumin gradient in ascites was greater than 1.1 g/dL. No significant association was found between patients with or without ascites when laboratory data and New York Heart Association functional class were compared. Liver biopsy was performed in 6 patients (24%). The most remarkable liver histological finding, in those with refractory ascites, was the existence of periportal fibrosis associated with sinusoidal dilatation. Periportal liver fibrosis associated with congestive heart failure, sepsis, or a long-term Fontan procedure can trigger refractory ascites formation.

Heart-kidney interaction: epidemiology of cardiorenal syndromes

Cardiac and kidney diseases are common, increasingly encountered, and often coexist. Recently, the Acute Dialysis Quality Initiative (ADQI) Working Group convened a consensus conference to develop a classification scheme for the CRS and for five discrete subtypes. These CRS subtypes likely share pathophysiologic mechanisms, however, also have distinguishing clinical features, in terms of precipitating events, risk identification, natural history, and outcomes. Knowledge of the epidemiology of heart-kidney interaction stratified by the proposed CRS subtypes is increasingly important for understanding the overall burden of disease for each CRS subtype, along with associated morbidity, mortality, and health resource utilization. Likewise, an understanding of the epidemiology of CRS is necessary for characterizing whether there exists important knowledge gaps and to aid in the design of clinical studies. This paper will provide a summary of the epidemiology of the cardiorenal syndrome and its subtypes.

Prevalence and risk factors of chronic kidney disease: a population study in the Tibetan population

BACKGROUND

The prevalence of chronic kidney disease (CKD) at high altitude is not known. We conducted a population-based survey in Tibet to identify the prevalence and associated risk factors of CKD in subjects living at altitudes of > 3500 m.

METHODS

One thousand two hundred and eighty-nine Tibetans (≥ 18 years) from four districts of Lhasa city (altitude 3658 m) and eight villages of Dangxiong County (altitude 4200 m) were interviewed and tested for haematuria, albuminuria and estimated glomerular filtration rate (eGFR).

RESULTS

The adjusted prevalence of hypertension, albuminuria, haematuria and reduced eGFR were 38.8% (95% CI: 36.2-41.5%), 16.2% (95% CI: 14.1-18.2%), 3.9% (95% CI: 2.8-4.9%) and 2.1% (95% CI: 1.3-2.9%), respectively. Both the presence of hypertension and the presence of albuminuria were strongly and independently associated with hyperuricaemia and elevated haematocrit.

CONCLUSIONS

This is the first population-based epidemiological study of CKD in the Tibetan population. We found a higher prevalence of CKD and associated high prevalence of albuminuria, hypertension, hyperuricaemia and high haematocrit in the Tibetan population. The present study indicates the urgent need to develop comprehensive strategies targeted at reducing the CKD burden in this area and may lead to a better understanding of CKD in high-altitude populations.

Successful initiation and maintenance of hemodialysis in an adult patient with complete transposition of the great arteries

Cyanotic congenital heart disease (CCHD) is a life-threatening cardiac defect that requires palliative or corrective surgery in early life. Major advances in medical and surgical management have resulted in the survival of CCHD patients to adulthood with or without corrective surgery, though some are at risk of development of end-stage renal disease (ESRD) due to cyanotic nephropathy (CN). There is little or no information on the initiation and maintenance of hemodialysis (HD) in such patients. We present here a case of a 44-year-old man with complete transposition of the great arteries and CN-related ESRD. He had only received a bi-directional Glenn's operation and still suffered persistent severe hypoxemia and impaired cardiac function. ESRD was successfully treated with HD over more than 4 years. The case emphasizes the need for special attention in the selection and initiation of renal replacement therapy.

Repeated phlebotomies improve and stabilise renal function in cyanotic nephropathy

Patients over 10 years of age with cyanotic congenital heart disease (CCHD) risk developing significant glomerular proteinuria, a condition called cyanotic nephropathy. Even though the pathogenesis of glomerulopathy associated with CCHD is still unclear, a potential mechanism is hyperviscosity-induced decrease in peritubular capillary blood flow leading to an increase in glomerular capillary pressure, in turn resulting in proteinuria. Although angiotensin-converting enzyme (ACE) inhibitors have been traditionally used in the treatment of these patients with cyanotic nephropathy, they may, however, not be well tolerated. Here we present a case of an adult patient with CCHD who could not tolerate an ACE inhibitor but showed improvement and stabilisation of her renal function following treatment with repeated phlebotomies.

Aprotinin and renal dysfunction after pediatric cardiac surgery

BACKGROUND

Aprotinin is a potent antifibrinolytic drug, which reduces postoperative bleeding and transfusion requirements. Recently, two observational studies reported increased incidence of renal dysfunction after aprotinin use in adults. Therefore, the aim of the study was to investigate the safety of aprotinin use in pediatric cardiac surgery patients.

METHODS

Data were prospectively and consecutively collected from 657 pediatric patients undergoing cardiac surgery with cardiopulmonary bypass (CPB). The database was assessed with regard to a possible relationship between aprotinin administration and dialysis and between aprotinin and postoperative renal dysfunction [defined as 25% decrease in the creatinine clearance (Ccr) compared with the preoperative value] by propensity-score adjustment and multivariable methods.

RESULTS

The incidence of dialysis (9.6% vs 4.1%; P = 0.005) and renal dysfunction (26.3% vs 16.1%; P = 0.019) was higher in patients who received aprotinin; however, propensity adjusted risk ratios were not significant [odds ratio (OR) of dialysis: 1.22; 95% confidence interval (CI) 0.46-3.22; OR of renal dysfunction 1.26; 95% CI: 0.66-1.92]. Aprotinin significantly reduced blood loss in the first postoperative 24 h. The main contributors of renal dysfunction were CPB duration, cumulative inotropic support, age, preoperative Ccr, amount of transfusion and pulmonary hypertension.

CONCLUSIONS

Despite the higher incidences of renal dysfunction and failure in the aprotinin group, an independent role of the drug in the development of renal dysfunction or dialysis could not be demonstrated in pediatric cardiac patients undergoing CPB.

The pediatric cardiac patient presenting for noncardiac surgery

PURPOSE OF REVIEW

To summarize results of recent papers and discuss current trends concerning anesthesia in children with congenital heart disease presenting for noncardiac surgery.

RECENT FINDINGS

Children with congenital heart disease have a significant incremental risk when presenting for minor or major surgery. It is a current trend that noncardiac surgery should be performed in pediatric centers, which have anesthesiologists and pediatricians familiar with the multiple specialties of children with congenital heart disease. A careful preoperative evaluation using a multidisciplinary approach is of great importance. In recent studies and case reports, the safe use of newer anesthetic agents, such as sevoflurane or desflurane, was reported in combination with opioids or regional blocks. In addition to standard monitors, invasive monitoring should be considered liberally perioperatively in patients with limited hemodynamic reserve and with major surgery. Several case reports reported that laparoscopic surgery was successfully performed even in high-risk patients with congenital heart disease.

SUMMARY

Careful preoperative evaluation, experienced anesthesiologists, suitable anesthetic agents and techniques, and the liberal use of invasive monitoring are integral parts of safe and effective anesthetic care in children with congenital heart disease. Future studies have to show whether laparoscopic surgery may be beneficial in this special subgroup of patients.