Long-term kidney outcomes in pediatric continuous-flow ventricular assist device patients.

BACKGROUND: Continuous-flow ventricular assist devices (CF-VADs) are used increasingly in pediatric end-stage heart failure (ESHF) patients. Alongside common risk factors like oxidant injury from hemolysis, non-pulsatile flow constitutes a unique circulatory stress on kidneys. Post-implantation recovery after acute kidney injury (AKI) is commonly reported, but long-term kidney outcomes or factors implicated in the evolution of chronic kidney disease (CKD) with prolonged CF-VAD support are unknown. METHODS: We studied ESHF patients supported > 90 days on CF-VAD from 2008 to 2018. The primary outcome was CKD (per Kidney Disease Improving Global Outcomes (KDIGO) criteria). Secondary outcomes included AKI incidence post-implantation and CKD evolution in the 6-12 months of CF-VAD support. RESULTS: We enrolled 134 patients; 84/134 (63%) were male, median age was 13 [IQR 9.9, 15.9] years, 72/134 (54%) had preexisting CKD at implantation, and 85/134 (63%) had AKI. At 3 months, of the 91/134 (68%) still on a CF-VAD, 34/91 (37%) never had CKD, 13/91 (14%) developed de novo CKD, while CKD persisted or worsened in 49% (44/91). Etiology of heart failure, extracorporeal membrane oxygenation use, duration of CF-VAD, AKI history, and kidney replacement therapy were not associated with different CKD outcomes. Mortality was higher in those with AKI or preexisting CKD. CONCLUSIONS: In the first multicenter study to focus on kidney outcomes for pediatric long-term CF-VAD patients, preimplantation CKD and peri-implantation AKI were common. Both de novo CKD and worsening CKD can happen on prolonged CF-VAD support. Proactive kidney function monitoring and targeted follow-up are important to optimize outcomes.

Preserved Cerebral Oxygenation with Worsening Global Myocardial Strain during Pediatric Chronic Hemodialysis.

BACKGROUND: Cerebral and myocardial hypoperfusion occur during hemodialysis in adults. Pediatric patients receiving chronic hemodialysis have fewer cardiovascular risk factors, yet cardiovascular morbidity remains prominent. METHODS: We conducted a prospective observational study of pediatric patients receiving chronic hemodialysis to investigate whether intermittent hemodialysis is associated with adverse end organ effects in the heart or with cerebral oxygenation (regional tissue oxyhemoglobin saturation [rSO2]). We assessed intradialytic cardiovascular function and rSO2 using noninvasive echocardiography to determine myocardial strain and continuous noninvasive near-infrared spectroscopy for rSO2. We measured changes in blood volume and measured central venous oxygen saturation (mCVO2) pre-, mid-, and post-hemodialysis. RESULTS: The study included 15 patients (median age, 12 years; median hemodialysis vintage, 13.2 [9-24] months). Patients were asymptomatic. The rSO2 did not change during hemodialysis, whereas mCVO2 decreased significantly, from 73% to 64.8%. Global longitudinal strain of the myocardium worsened significantly by mid-hemodialysis and persisted post-hemodialysis. The ejection fraction remained normal. Lower systolic BP and faster blood volume change were associated with worsening myocardial strain; only blood volume change was significant in multivariate analysis (ß-coefficient, -0.3; 95% confidence interval [CI], -0.38 to -0.21; P<0.001). Blood volume change was also associated with a significant decrease in mCVO2 (ß-coefficient, 0.42; 95% CI, 0.07 to 0.76; P=0.001). Access, age, hemodialysis vintage, and ultrafiltration volume were not associated with worsening strain. CONCLUSIONS: Unchanged rSO2 suggested that cerebral oxygenation was maintained during hemodialysis. However, despite maintained ejection fraction, intradialytic myocardial strain worsened in pediatric hemodialysis and was associated with blood volume change. The effect of hemodialysis on individual organ perfusion in pediatric versus adult patients receiving hemodialysis might differ.

Left ventricular strain and left atrial strain are impaired during hemodialysis in children.

We aimed to investigate intradialytic changes in ventricular and atrial function using speckle tracking echocardiography (STE) in pediatric hemodialysis (HD). Children with HD vintage > 3 months were enrolled, and echocardiography was performed prior to, during, and after HD. STE was analyzed using GE EchoPAC. Left ventricular (LV) global longitudinal strain (GLS), strain rate (Sr), and mechanical dispersion index (MDI) were calculated as the average from 3 apical views; diastolic strain (Ds) and Sr from 4-chamber tracing; left atrial strain (LAS) and Sr from the 4- and 2-chamber views. A total of 15 patients were enrolled at a median age of 12 years (IQR 8, 16) and median HD vintage of 13 months (IQR 9, 25). GLS worsened during HD (- 15.8 ± 2.2% vs - 19.9 ± 1.9%, p < 0.001). Post-HD GLS was associated with BP decrease (coefficient = 0.62, p = 0.01). LV MDI and systolic Sr did not change. LV Ds progressively worsened (- 8.4% (- 9.2, - 8.0) vs - 11.9% (- 13.4, - 10.3), p < 0.001). LAS changes at mid-HD returned to baseline post-HD. Ds, DSr, LAS, LASr were not associated with BV removal or BP decrease (p > 0.1). In conclusions, intradialytic LV strain and LAS changes consistent with subclinical systolic and diastolic dysfunction were observed during HD in children. Changes in Ds, DSr, LAS, and LASr were not associated with BP change or BV removal and may be related to the disease progression. Longitudinal study using these novel indices may unfold the effect of these subclinical changes on long-term cardiovascular health in children requiring chronic HD.

Kidney replacement therapy in pediatric patients on mechanical circulatory support: challenges for the pediatric nephrologist.

The use of mechanical circulatory support (MCS) therapies in children with medically refractory cardiac failure has increased over the past two decades. With the growing experience and expertise, MCS is currently offered as a bridge to recovery or heart transplantation and in some cases even as destination therapy. Acute kidney injury (AKI) is common in patients with end-stage heart failure (ESHF). When severe AKI develops requiring kidney replacement therapy (KRT), these patients present unique challenges for the pediatric nephrology team. The use of KRT has not been adequately described in children with ESHF on the newer MCS. We also present original case series data from our center experience. The purpose of this review is to familiarize the reader with the current MCS technologies, approach to their selection, how they interact when combined with current KRT circuits, and distinguish similarities and differences. We will attempt to highlight the distinctive features of each technology, specifically focusing on growing trends in use of continuous-flow ventricular assist devices (CF-VAD) as it poses additional challenges to the pediatric nephrologist.

Correlation of Venous Oxygen Saturations from Noninvasive Hematocrit Monitoring Using Blood Gas Measured Oximetry in Chronic Pediatric Hemodialysis Patients.

INTRODUCTION: Noninvasive hematocrit monitoring (NIVHM) during pediatric hemodialysis (pedHD) provides data in real time regarding changes in hematocrit and blood volume and also provides venous oxygen saturations. The latter has been proposed to indicate changes in tissue oxygen consumption. It is not known how well NIVHM oxygen saturations (O2sat) approximate blood gas measured oximetry saturation (mO2sat) in the course of pedHD. We aimed to assess the validity and reliability of NIVHM O2sat compared to mO2sat. METHODS: This is a prospective study in 15 patients <21 years old with >90 days on hemodialysis (HD) without congenital heart disease. HD access was fistula (AVF) in 4 patients and tunneled catheters in the remainder. Pulse oximetry (spO2) was continuously monitored; mO2sat was measured via oximetry in a blood gas analyzer and NIVHM O2sat values collected at the start, middle, and end of HD treatment. RESULTS: A total of 45 dyad measurements were obtained. NIVHM O2sat correlated well with mO2sat (R = 0.89, p < 0.0001); the same was seen at pre, mid, and post HD time points (R = 0.86-0.95, p < 0.001). NIVHM O2sat was lower than mO2sat; with catheter as access, the difference was 9.3 ± 8.6 (CI: 12.3-6.22, p < 0.0001) and with AVF was 2.1 ± 0.78 (CI: 2.6-1.7, p < 0.0001). Bland-Altman analysis demonstrated the difference but did not show any systematic bias. Continuous monitor of spO2 showed no hypoxia. DISCUSSION/CONCLUSION: Intradialytic NIVHM O2sat correlates well with mO2sat but yield lower values. Future studies can include NIVHM O2sat changes as a surrogate for central venous O2 saturation changes and potentially yield useful information regarding tissue oxygen consumption in pedHD patients.