Renal injury and recovery in pediatric patients after ventricular assist device implantation and cardiac transplant

Nutritional status and cannula infections in pediatric patients on ventricular assist device support

BACKGROUND

Ventricular assist devices (VADs) are used to bridge pediatric patients to heart transplantation. Paracorporeal VADs require the placement of cannulas, which can create an environment for infections. We examined cannula infections in pediatric VAD patients and the role of nutritional status.

METHODS

This retrospective study (2005-2021) included patients <20 years old on VAD support using Berlin Heart EXCOR® cannulas. Cannula infections were defined by a positive culture and need for antibiotic therapy. Malnutrition was defined using the American Society of Parenteral and Enteral Nutrition guidelines as well as the Michigan MTool.

RESULTS

There were 76 patients with a median age at implant of 0.9 years (IQR 0.4, 3.6), 50% male, with 73.7% having non-congenital heart disease. More than one-quarter (26.3%) of patients developed a cannula infection. Higher pre-implant weight (OR = 1.93, p = 0.05), creatinine (OR = 1.02, p = 0.044), and pre-albumin (OR = 15.79, p = 0.025), as well as duration of VAD support (OR = 1.01; p = 0.003) were associated with increased odds of developing a cannula infection. There was no difference in the malnutrition parameters between those with and without an infection.

CONCLUSIONS

Further exploration in a larger cohort is needed to see whether these associations remain and if the incorporation of objective measures of nutritional status at the time of infection are predictive.

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.

Intraoperative and Postoperative Hemodynamic Predictors of Acute Kidney Injury in Pediatric Heart Transplant Recipients

Acute kidney injury (AKI) is common after pediatric heart transplantation (HT) and is associated with inferior patient outcomes. Hemodynamic risk factors for pediatric heart transplant recipients who experience AKI are not well described. We performed a retrospective review of 99 pediatric heart transplant patients at Lucile Packard Children's Hospital Stanford from January 1, 2015, to December 31, 2019, in which clinical and demographic characteristics, intraoperative perfusion data, and hemodynamic measurements in the first 48 postoperative hours were analyzed as risk factors for severe AKI (Kidney Disease: Improving Global Outcomes [KDIGO] stage ≥ 2). Univariate analysis was conducted using Fisher's exact test, Chi-square test, and the Wilcoxon rank-sum test, as appropriate. Multivariable analysis was conducted using logistic regression. Thirty-five patients (35%) experienced severe AKI which was associated with lower intraoperative cardiac index ( p  = 0.001), higher hematocrit ( p  < 0.001), lower body temperature ( p  < 0.001), lower renal near-infrared spectroscopy ( p  = 0.001), lower postoperative mean arterial blood pressure (MAP: p  = 0.001), and higher central venous pressure (CVP; p  < 0.001). In multivariable analysis, postoperative CVP >12 mm Hg (odds ratio [OR] = 4.27; 95% confidence interval [CI]: 1.48-12.3, p  = 0.007) and MAP <65 mm Hg (OR = 4.9; 95% CI: 1.07-22.5, p  = 0.04) were associated with early severe AKI. Children with severe AKI experienced longer ventilator, intensive care, and posttransplant hospital days and inferior survival ( p  = 0.01). Lower MAP and higher CVP are associated with severe AKI in pediatric HT recipients. Patients, who experienced AKI, experienced increased intensive care unit (ICU) morbidity and inferior survival. These data may guide the development of perioperative renal protective management strategies to reduce AKI incidence and improve patient outcomes.

Associated Factors and Impact of Persistent Renal Dysfunction in Pediatric Heart Transplantation

BACKGROUND

We evaluated the impact of significant renal dysfunction (SRD) on listing and pediatric heart transplantation (PHT) outcomes.

METHODS

The United Network of Organ Sharing registry was queried. Our cohort included 11,625 children listed for PHT (2000-2020). At listing, 1494 (13%) had SRD, defined as an estimated glomerular filtration rate of <45 mL/min/1.73 m2 and/or dialysis requirement. Characteristics of children with and without SRD were compared. SRD impact on outcomes was examined. Factors associated with waiting list mortality, persistent SRD at PHT, and post-PHT survival with and without simultaneous heart-kidney transplantation were assessed.

RESULTS

Compared with children with an estimated glomerular filtration rate >45 mL/min/1.73 m2, those with SRD had higher waiting list death (37% vs 14%, P < .01) and lower transplantation rate (51% vs 71%, P < .01). On multivariable analysis, SRD was associated with waiting list death (hazard ratio, 3.016; P < .0001). Among 767 children with SRD who received PHT, 361 (47%) had persistent SRD at the time of PHT. On multivariable analysis, factors associated with persistent SRD were older age (odds ratio [OR], 1.147 per year; 95% CI, 1.046-1.258 per year; P = .0035), bilirubin (OR, 1.127 per 1-mg/dL; 95% CI, 1.061-1.197 per 1-mg/dL; P < .0001), dialysis (OR, 1.839; 95% CI, 1.017-3.326; P = .0115), mechanical ventilation (OR, 1.972; 95% CI, 1.336-2.911; P = .0006), extracorporeal membrane oxygenation (OR, 1.747; 95% CI, 1.074-2.842; P = .0247), and not using a ventricular assist device (VAD) (OR, 0.498 [VAD use]; 95% CI, 0.277-0.895 VAD use; P = .0198). Post-PHT survival was 72%, 70%, and 56% (P < .01) at 8 years for PHT alone with improved renal function, simultaneous heart-kidney transplantation (n = 69), and PHT alone with persistent SRD, respectively.

CONCLUSIONS

SRD is associated with high waiting list death and decreased transplantation rate. Timely proper pre-PHT support with VAD could enhance kidney recovery. Simultaneous heart-kidney transplantation neutralized persistent SRD effect on survival and might be considered in high-risk patients such as those on dialysis, mechanical ventilation, or extracorporeal membrane oxygenation support.

A novel acute kidney injury scoring system for renal and clinical outcomes in pediatric heart transplant patients

BACKGROUND

The development of acute kidney injury (AKI) has been associated with worse outcomes in children after heart transplantation. Our study compares the application of a cumulative six-point Kidney Diseases Improving Global Outcomes (KDIGO) AKI scoring system, utilizing both creatinine and urine output criteria that we term as the AKI-6 criteria, to traditional AKI staging as a predictor for clinical and renal outcomes in the pediatric heart transplant recipients.

METHODS

We conducted a retrospective single-center chart review on 155 pediatric patients who underwent heart transplantation from May 2014 to December 2021. The primary independent variable was the presence of severe AKI. Severe AKI by KDIGO was defined as Stage ≥2, whereas severe AKI by AKI-6 was defined as cumulative scores ≥4 or Stage 3 AKI based on either KDIGO criterion alone. Primary outcomes included actuarial survival and renal dysfunction by 1-year post-transplant, defined as an estimated glomerular filtration rate <60 mL/min/1.73 m2 .

RESULTS

In total, 140 (90%) patients developed AKI; 98 (63%) patients developed severe AKI by KDIGO, and 60 (39%) by AKI-6. Severe AKI by AKI-6 was associated with worse actuarial survival following heart transplantation compared with KDIGO (p = 0.01). Of the 143 patients with 1-year creatinine data, 6 (11%) patients out of 54 with severe AKI by AKI-6 had evidence of renal dysfunction (p = 0.01), compared with 6 (7%) patients out of 88 by KDIGO (p = 0.3).

CONCLUSIONS

AKI-6 scoring provides greater prognostic utility for actuarial survival and renal dysfunction by 1-year post-heart transplantation in pediatric patients than traditional KDIGO staging.

Heart-kidney listing is better than isolated heart listing for pediatric heart transplant candidates with significant renal insufficiency

OBJECTIVES

Significant renal insufficiency is identified as a risk factor for post-transplantation mortality in pediatric heart transplant recipients. This study evaluates simultaneous heart-kidney transplantation listing outcomes compared with heart transplant for pediatric candidates with significant renal insufficiency.

METHODS

The United Network for Organ Sharing registry was searched for patients (January 1987 to March 2020) who were simultaneously listed for a heart-kidney transplantation or for heart transplant with significant renal insufficiency at the time of listing. Significant renal insufficiency was defined as needing dialysis or having a low estimated glomerular filtration rate (<40 mL/min). Survival was calculated using Kaplan-Meier analysis.

RESULTS

A total of 427 cases were identified; 109 were listed for heart-kidney transplantation, and 318 were listed for heart transplant alone. Median time on the waitlist was 101 days (interquartile range, 28-238) for heart-kidney transplantation listings compared with 39 days (14-86) and 23.5 days (6-51) for heart transplant recipients with a low estimated glomerular filtration rate (P = .002) or on dialysis (P < .001), respectively. Of all heart-kidney transplantation listings, 66% (n = 71) received a transplant compared with 54% (n = 173) of heart transplantation with significant renal insufficiency (P = .005) with a mean survival of 14.6 years (12.7-16.4 years) for heart transplant without significant renal insufficiency at transplantation and 7.6 years (5.4-9.9 years) for heart transplant with significant renal insufficiency at transplantation. At 1 year after listing, 69% of heart-kidney transplantation listed recipients were alive, compared with 51% of heart transplant listed recipients (P = .029). Heart-kidney transplantation recipients had better 1-year post-transplantation survival (86%) than heart transplantation with significant renal insufficiency at transplant (66%) (P = .001). There was no significant difference in the 1- and 5-year survivals of those undergoing heart transplantation listed with significant renal insufficiency but no significant renal insufficiency at the time of transplant (89% and 78%) and heart-kidney transplantation recipients (86% and 81%; P = .436).

CONCLUSIONS

Pediatric candidates with significant renal insufficiency listed for heart-kidney transplantation have superior waitlist and post-transplantation outcomes compared with those listed for heart transplant alone. Patients with significant renal insufficiency should be listed for heart-kidney transplantation, however; if their renal function improves significantly, heart transplant alone appears judicious.

Acute kidney injury and kidney recovery after cardiopulmonary bypass in children

BACKGROUND

Acute kidney injury (AKI) that improves in the pediatric intensive care unit (PICU) is associated with better outcomes compared to AKI that persists, but no study has investigated whether this also occurs in children undergoing cardiopulmonary bypass (CPB).

METHODS

A retrospective study of children ≤18 years who underwent CPB in three children's hospitals was conducted. Patients were classified into groups by kidney recovery after AKI according to Acute Disease Quality Initiative (ADQI) guidelines. Adjusted regression models evaluated associations between kidney recovery group and hospital outcomes.

RESULTS

Among 3620 children, AKI developed in 701 (19.4%): 610 transient AKI, 47 persistent AKI, and 44 acute kidney disease (AKD). Mortality increased with severity of kidney recovery group: 4.5% in the never developed AKI group, 8.9% in the transient AKI group, 25.5% in the persistent AKI group, and 31.8% in the AKD group (p <0.0001). In adjusted analysis, transient AKI (HR 1.4, CI 1.02, 2), persistent AKI (HR 22.4, CI 10.2, 49.2), and AKD (HR 3.7, CI 1.7, 7.9) had a greater hazard of mortality when compared to the never developed AKI group. Patients with transient AKI had a longer length of PICU stay than those with never developed AKI (HR 5.1, CI 2.9, 7.3).

CONCLUSIONS

Patterns of kidney recovery after AKI were associated with worse PICU outcomes in children after CPB compared to those who did not develop AKI, even after rapid AKI recovery. Identification of factors that increase risk for these AKI patterns is necessary for prevention of AKI during CPB in children. A higher resolution version of the Graphical abstract is available as Supplementary information.

Failures of the Fontan System in Univentricular Hearts and Mortality Risk in Heart Transplantation: A Systematic Review and Meta-Analysis

The Fontan procedure (FP) is the standard surgical treatment for Univentricular heart diseases. Over time, the Fontan system fails, leading to pathologies such as protein-losing enteropathy (PLE), plastic bronchitis (PB), and heart failure (HF). FP should be considered as a transitional step to the final treatment: heart transplantation (HT). This systematic review and meta-analysis aims to establish the risk of death following HT according to the presence of FP complications. There was a total of 691 transplanted patients in the 18 articles, immediate survival 88% (n = 448), survival from 1 to 5 years of 78% (n = 427) and survival from 5.1 to 10 years of 69% (n = 208), >10 years 61% (n = 109). The relative risk (RR) was 1.12 for PLE (95% confidence interval [CI] = 0.89-1.40, p = 0.34), 1.03 for HF (0.7-1.51, p = 0.88), 0.70 for Arrhythmias (0.39-1.24, p = 0.22), 0.46 for PB (0.08-2.72, p = 0.39), and 5.81 for CKD (1.70-19.88, p = 0.005). In patients with two or more failures, the RR was 1.94 (0.99-3.81, p = 0.05). After FP, the risk of death after HT is associated with CKD and with the presence of two or more failures.

Recovery after acute kidney injury requiring kidney replacement therapy in patients with left ventricular assist device: A meta-analysis

BACKGROUND

Acute kidney injury (AKI) is a common and severe complication after left ventricular assist device (LVAD) implantation with an incidence of 37%; 13% of which require kidney replacement therapy (KRT). Severe AKI requiring KRT (AKI-KRT) in LVAD patients is associated with high short and long-term mortality compared with AKI without KRT. While kidney function recovery is associated with better outcomes, its incidence is unclear among LVAD patients with severe AKI requiring KRT.

AIM

To identify studies evaluating the recovery rates from severe AKI-KRT after LVAD placement, which is defined by regained kidney function resulting in the discontinuation of KRT. Random-effects and generic inverse variance method of DerSimonian-Laird were used to combine the effect estimates obtained from individual studies.

METHODS

A total of 268 patients from 14 cohort studies that reported severe AKI-KRT after LVAD were included. Follow-up time ranged anywhere from two weeks of LVAD implantation to 12 mo. Kidney recovery occurred in 78% of enrollees at the time of hospital discharge or within 30 d. Overall, the pooled estimated AKI recovery rate among patients with severe AKI-KRT was 50.5% (95%CI: 34.0%-67.0%) at 12 mo follow up. Majority (85%) of patients used continuous-flow LVAD. While the data on pulsatile-flow LVAD was limited, subgroup analysis of continuous-flow LVAD demonstrated that pooled estimated AKI recovery rate among patients with severe AKI-KRT was 52.1% (95%CI: 36.8%-67.0%). Meta-regression analysis did not show a significant association between study year and AKI recovery rate (P = 0.08). There was no publication bias as assessed by the funnel plot and Egger's regression asymmetry test in all analyses.

RESULTS

A total of 268 patients from 14 cohort studies that reported severe AKI-KRT after LVAD were included. Follow-up time ranged anywhere from two weeks of LVAD implantation to 12 mo. Kidney recovery occurred in 78% of enrollees at the time of hospital discharge or within 30 d. Overall, the pooled estimated AKI recovery rate among patients with severe AKI-KRT was 50.5% (95%CI: 34.0%-67.0%) at 12 mo follow up. Majority (85%) of patients used continuous-flow LVAD. While the data on pulsatile-flow LVAD was limited, subgroup analysis of continuous-flow LVAD demonstrated that pooled estimated AKI recovery rate among patients with severe AKI-KRT was 52.1% (95%CI: 36.8%-67.0%). Meta-regression analysis did not show a significant association between study year and AKI recovery rate (P = 0.08). There was no publication bias as assessed by the funnel plot and Egger's regression asymmetry test in all analyses.

CONCLUSION

Recovery from severe AKI-KRT after LVAD occurs approximately 50.5%, and it has not significantly changed over the years despite advances in medicine.

A Review on the Application and Limitations of Administrative Health Care Data for the Study of Acute Kidney Injury Epidemiology and Outcomes in Children

Administrative health care databases contain valuable patient information generated by health care encounters. These "big data" repositories have been increasingly used in epidemiological health research internationally in recent years as they are easily accessible and cost-efficient and cover large populations for long periods. Despite these beneficial characteristics, it is also important to consider the limitations that administrative health research presents, such as issues related to data incompleteness and the limited sensitivity of the variables. These barriers potentially lead to unwanted biases and pose threats to the validity of the research being conducted. In this review, we discuss the effectiveness of health administrative data in understanding the epidemiology of and outcomes after acute kidney injury (AKI) among adults and children. In addition, we describe various validation studies of AKI diagnostic or procedural codes among adults and children. These studies reveal challenges of AKI research using administrative data and the lack of this type of research in children and other subpopulations. Additional pediatric-specific validation studies of administrative health data are needed to promote higher volume and increased validity of this type of research in pediatric AKI, to elucidate the large-scale epidemiology and patient and health systems impacts of AKI in children, and to devise and monitor programs to improve clinical outcomes and process of care.

Acute kidney injury and chronic kidney disease after combined heart-liver transplant in patients with congenital heart disease: A retrospective case series

Although it is known that children undergoing heart transplantation are at increased risk for both AKI and CKD, renal function following CHLT remains understudied. All pediatric CHLT patients from 2006 to 2019 were included. The prevalence of AKI in the first 7 post-operative days, renal recovery at 30 post-operative days, and CKD were ascertained. AKI was defined as an increase in creatinine greater than 1.5 times baseline, and CKD, as an eCrCl less than 90 mL/min/1.73 m² . The need for RRT was also analyzed. 10 patients were included, with an average age of 20 years and an average listing time of 130 days. Preoperatively, the median eCrCl was 91.12 mL/min/m² (IQR 70.51, 127.75 min/mL/m² ). 5 (50%) patients had CKD, with 4 at stage 2 and 1 at stage 3. AKI occurred post-operatively in 3 of 9 (33%) patients: 2 at stage 1 and 1 at stage 2. 2 (67%) resolved by 7 days. Of the 5 patients who reached their 1-year follow-up, 1 (20%) had stage 3 CKD. Among 2 patients, neither had CKD at 5 years. One patient required RRT 2 weeks after CHLT. Despite an increased prevalence of preoperative CKD, patients undergoing CHLT have a lower AKI prevalence than those receiving an isolated heart or liver transplant. Of those with AKI, early renal recovery is common, although at 1 year CKD remains present in 20%. Among long-term survivors, normal renal function is achievable.

A coordinated approach to improving pediatric heart transplant waitlist outcomes: A summary of the ACTION November 2019 waitlist outcomes committee meeting

The number of children needing heart transplantation continues to rise. Although improvements in heart failure therapy, particularly durable mechanical support, have reduced waitlist mortality, the number of children who die while waiting for a suitable donor organ remains unacceptably high. Roughly, 13% of children and 25% of infants on the heart transplant waitlist will not survive to transplantation. With this in mind, the Advanced Cardiac Therapies Improving Outcomes Collaborative Learning Network (ACTION), through its Waitlist Outcomes Committee, convened a 2-day symposium in Ann Arbor, Michigan, from 2-3 November 2019, to better understand the factors that contribute to pediatric heart transplant waitlist mortality and to focus future efforts on improving the organ allocation rates for children needing heart transplantation. Using improvement science methodology, the heart failure-transplant trajectory was broken down into six key steps, after which modes of failure and opportunities for improvement at each step were discussed. As a result, several projects aimed at reducing waitlist mortality were initiated.

Long-term complications of acute kidney injury in children

PURPOSE OF REVIEW

The current review will describe the current evidence and mechanisms of acute kidney injury (AKI) as a risk factor for long-term kidney complications, summarize the rationale for AKI follow-up and present an approach to monitoring children with AKI. Despite emerging evidence linking AKI with risk for long-term kidney and cardiovascular outcomes, many children who develop AKI are not followed for kidney disease development after hospital discharge. Better understanding of long-term complications after AKI and practical algorithms for follow-up will hopefully increase the rate and quality of post-AKI monitoring.

RECENT FINDINGS

Recent evidence shows that pediatric AKI is associated with long-term renal outcomes such as chronic kidney disease (CKD) and hypertension, both known to increase cardiovascular risk. The mechanism of AKI progression to CKD involves maladaptive regeneration of tubular epithelial and endothelial cells, inflammation, fibrosis and glomerulosclerosis. Many AKI survivors are not followed, and no guidelines for pediatric AKI follow-up have been published.

SUMMARY

Children who had AKI are at increased risk of long-term renal complications but many of them are not monitored for these complications. Recognizing long-term outcomes post-AKI and integration of follow-up programs may have a long-lasting positive impact on patient health.