Creatinine-based estimation of glomerular filtration rate in patients with a Fontan circulation

Cardiorenal syndrome: evolving concepts and pediatric knowledge gaps

Cardiorenal syndrome (CRS) refers to concomitant dysfunction of both the heart and kidneys. The pathology in CRS is bidirectional. Many individuals with kidney disease will develop cardiovascular complications. Conversely, rates of acute kidney injury and chronic kidney disease are high in cardiac patients. While our understanding of CRS has greatly increased over the past 15 years, most research has occurred in adult populations. Improving cardiorenal outcomes in children and adolescents requires increased collaboration and research that spans organ systems. The purpose of this review is to discuss key features of CRS and help bring to light future opportunities for pediatric-specific research.

Noninvasive Advanced Cardiovascular Magnetic Resonance-Derived Fontan Hemodynamics Are Associated With Reduced Kidney Function But Not Albuminuria

BACKGROUND

Kidney disease is the most important predictor of death in patients with a Fontan circulation, yet its clinical and hemodynamic correlates have not been well established.

METHODS AND RESULTS

A total of 53 ambulatory patients with a Fontan circulation (median age, 16.2 years, 52.8% male patients) underwent advanced cardiovascular magnetic resonance assessment, including 4-dimensional flow imaging and computational fluid dynamics. Estimated glomerular filtration rate (eGFR) <90 mL/min per 1.73 m2 was observed in 20.8% and albumin-to-creatinine ratio >3 mg/mmol in 39.6%. The average eGFR decline rate was -1.83 mL/min per 1.73 m2 per year (95% CI, -2.67 to -0.99; P<0.001). Lower eGFR was associated with older age, larger body surface area at examination, longer time since Fontan procedure, and lower systemic ventricular ejection fraction. Higher albumin-to-creatinine ratio was associated with absence of fenestration at the Fontan operation, and older age and lower systemic ventricular ejection fraction at the assessment. Lower cross-sectional area of the Fontan conduit indexed to flow (r=0.32, P=0.038), higher inferior vena cava-conduit velocity mismatch factor (r=-0.35, P=0.022), higher kinetic energy indexed to flow in the total cavopulmonary connection (r=-0.59, P=0.005), and higher total cavopulmonary connection resistance (r=-0.42, P=0.005 at rest; r=-0.43, P=0.004 during exercise) were all associated with lower eGFR but not with albuminuria.

CONCLUSIONS

Kidney dysfunction and albuminuria are common among clinically well adolescents and young adults with a Fontan circulation. Advanced cardiovascular magnetic resonance-derived metrics indicative of declining Fontan hemodynamics are associated with eGFR and might serve as targets to improve kidney health. Albuminuria might be driven by other factors that need further investigation.

Association of albuminuria with kidney function and hemodynamic disturbance in pre-school children who undergo congenital heart disease surgery

BACKGROUND

We validated the prevalence of albuminuria and its association with kidney function and hemodynamics in pre-school children who underwent surgery for congenital heart disease (CHD).

METHODS

From 403 patients who had undergone surgery for CHD at least 6 months before pre-school and were admitted to our hospital between 2011 and 2015, 75 who underwent blood and urine tests and cardiac catheterization were included in this study. The urinary albumin-to-creatinine ratio (ACR) was quantified, and the relationship of ACR with physical and laboratory findings and hemodynamics assessed using cardiac catheterization was analyzed.

RESULTS

The study cohort was divided into three groups: Fontan group (n = 25), tetralogy of Fallot (TOF) group (n = 18), and control group (other biventricular CHDs; n = 32). The median age of patients was 5.9 years. ACR was higher in the Fontan group than in the TOF and control groups (median: 15.0 vs. 5.0 and 0.0 mg/g, p < 0.001). Moreover, albuminuria (ACR > 30 mg/g) was observed in 20.0% of Fontan patients, while ACR was associated with potential complicating factors of Fontan circulation: high central venous pressure, high mean pulmonary artery pressure, and worse than moderate atrioventricular regurgitation. ACR showed a moderate correlation with the cystatin C-based estimated glomerular filtration rate (r =  - 0.725, p < 0.001).

CONCLUSIONS

Measurement of albuminuria in Fontan patients before they join elementary school is useful because it reflects kidney function and hemodynamic factors that can worsen their condition. Identification and management of patients with albuminuria may facilitate early therapeutic intervention for worsening Fontan factors, eventually delaying the deterioration of kidney function. A higher resolution version of the Graphical abstract is available as Supplementary information.

A Multimodal Score Accurately Classifies Fontan Failure and Late Mortality in Adult Fontan Patients

Objectives

Despite the outstanding success of the Fontan operation, it is a palliative procedure and a substantial number of patients experience late failure of the Fontan circulation. Clinical presentation and hemodynamic phenotypes of Fontan failure are considerably variable. While various parameters have been identified as risk factors for late Fontan failure, a feasible score to classify Fontan failure and possibly allow timely risk stratification is lacking. Here, we explored the possibility of developing a score based on hemodynamic, clinical and laboratory parameters to classify Fontan failure and mortality.

Methods

We performed a retrospective study in our cohort of adult Fontan patients from two institutions [n = 198, median follow-up after Fontan 20.3 (IQR 15.6–24.3) years], identifying those patients with clinical Fontan failure (n = 52, 26.3%). Various hemodynamic, echocardiographic, laboratory and clinical data were recorded and differences between patients with and without Fontan failure were analyzed. We composed a Fontan Failure Score containing 15 parameters associated with Fontan failure and/or mortality and assessed its accuracy to discriminate between patients with and without late Fontan failure as well as late mortality and survival.

Results

Late failure occurred at a median of 18.2 (IQR 9.1–21.1) years after Fontan completion. Mortality associated with Fontan failure was substantial (25/52, 48.1%) with freedom of death/transplantation/take-down of 64% at 5 years and 36% at 10 years after onset of Fontan failure, respectively. Patients with Fontan failure had a significantly higher median Fontan Failure Score compared to non-failing Fontan patients [8 points (IQR 5–10) vs. 2 points (IQR 1-5), p < 0.001]. The score accurately classifies Fontan failure as well as mortality as assessed with receiver operating characteristic analysis. Area under the curve of the Fontan Failure Score was 0.963 (95% CI 0.921; 0.985, p < 0.001) to discriminate failure and 0.916 (95% CI 0.873; 0.959, p < 0.001) to classify mortality.

Conclusion

We have developed an uncomplex yet remarkably accurate score to classify Fontan failure and late mortality in adult Fontan patients. Prospective validation and most likely refinement and calibration of the score in larger and preferably multi-institutional cohorts is required to assess its potential to predict the risk of Fontan failure and late mortality.

Surveillance of End-Organ Damage in Fontan Patients Prior to Transition to Adult Care: Are We There Yet?

BACKGROUND

Recently published guidelines and consensus statements have outlined recommended screening practices for monitoring of end-organ dysfunction in Fontan patients. We reviewed the current approach to end-organ screening in a local population of Fontan patients at the time of transition to adult care.

METHODS

Patient data from the Australia and New Zealand Fontan Registry and patient medical records were used to review investigations performed in Fontan patients transitioned from The Royal Children's Hospital Melbourne to an adult centre between 1 July 2015 and 30 June 2020.

RESULTS

A total of 32 patients were referred for transition to an adult centre between 1 July 2015 and 30 June 2020 at a mean age of 18.5±0.7 years (12.7±2.5 years post-Fontan). Liver function tests were performed in 22 patients (69%) within 5 years prior to transition and were abnormal in 15 patients (68%). Liver ultrasound was performed in 13 patients (41%) within 5 years prior to the date of transition, of whom 10 (77%) had abnormal findings (features suggestive of hepatic fibrosis in seven [54%], cirrhosis in two [15%], and portal hypertension in three [23%]). Fourteen (14) patients (44%) had no record of a liver ultrasound being performed between the date of the Fontan procedure and the time of transition to adult care. Hepatocellular carcinoma was diagnosed in one patient at 18 months following transition. A total of 24 patients (75%) had a serum creatinine measured within the 5 years prior to transition, and two (8%) had an estimated glomerular filtration rate (eGFR) less than 90 ml/min/1.73 m². No patient had a urine protein-creatinine ratio measured between the date of the Fontan procedure and the time of transition to adult care.

CONCLUSIONS

In this study we have identified that the majority of patients transitioned from a tertiary paediatric centre to an adult centre within the last 5 years did not undergo routine surveillance for end-organ dysfunction. Routine screening for end-organ complications of the Fontan circulation should be incorporated into clinical practice and is an important part of Fontan patient care both pre- and post-transition to adult services.

End-Organ Function and Exercise Performance in Patients With Fontan Circulation: What Characterizes the High Performers?

Background The physiologic hallmarks of the Fontan circulation-chronically elevated central venous pressures and low cardiac output-have significant effects not only on cardiovascular status but also impact other organ systems. Exercise capacity is limited in many and declines with age, accelerating in adolescence, but with wide variability. We explore the relationship between exercise performance and end-organ function in outpatient subjects with a Fontan circulation. Methods and Results This is a cross-sectional analysis of subject end-organ characterization from our outpatient Fontan circulation clinic with peak oxygen consumption (peak Vo₂) at cardiopulmonary exercise testing as the primary outcome. We perform linear regression to assess associations between clinical characteristics and peak Vo₂ as well as the magnitude of the association of clinical characteristics with peak Vo₂. Of 265 subjects age 12.8 (9.5-16.4) years, there is a negative correlation between age and peak Vo₂ (-0.49, P<0.001). Of those undergoing ramp cycle exercise testing, 34% perform above 80% predicted peak Vo₂. Variables positively associated with peak Vo₂ and their effect size include vitamin D sufficiency (+3.00, P=0.020) and absolute lymphocyte count (+0.23, P=0.005). Status as overweight/obese (-3.91, P=0.003) and hemoglobin (-0.77, P=0.003) are negatively associated. Neither ventricular morphology, timing of Fontan palliation, nor Fontan circulation type affect peak Vo₂. Conclusions Higher peak Vo₂ in those with a Fontan circulation is associated with younger age, vitamin D sufficiency, absence of overweight/obese, lower hemoglobin, and a healthier hepatic profile. Whether exercise training or other initiatives can modify organ characteristics in those with a Fontan circulation is worthy of exploration.

Clinical significance of serum cystatin C in early evaluation of renal impairment caused by chemotherapy in elderly patients

Background

This study aims to discuss the application value of serum cystatin C (Cys C) in detecting early renal function injury in elderly patients with malignant tumors after chemotherapy.

Methods

The data at different chemotherapy time points (before chemotherapy, after two cycles of chemotherapy, and after four cycles of chemotherapy) were analyzed.

Results

Serum Cys C was significantly higher after chemotherapy than before chemotherapy in elderly patients with malignant tumors, and the endogenous creatinine clearance rate (CCr) significantly decreased. These were significantly correlated. However, there was no significant change in serum creatinine (SCr) and blood urea nitrogen (BUN). Cys C continued to increase with the prolonged time of chemotherapy. In addition, Cys C was sensitive for detecting renal impairment caused by platinum-based chemotherapy drugs.

Conclusions

The diagnostic effect of Cys C on early renal function injury after chemotherapy in elderly patients with malignant tumors is better, when compared to traditional renal function test items, such as SCr, BUN and CCr.

What have we learnt 50 years after the first Fontan procedure?

The Fontan procedure is often the only definitive palliative surgical option for patients with a variety of complex CHD sharing in common, a single, dominant ventricle. In recent decades, imaging and therapeutic improvement have played a crucial role in those patients in whom many complications can hamper their life. After 50 years from the first procedure, heart transplantation remains the only definitive treatment for those with a failing Fontan circulation.