Changes in renal function after left ventricular assist device placement in pediatric patients: A Pedimacs analysis

Improvement in patient selection, management and outcomes in infant heart transplant from 2000 to 2020

OBJECTIVES

The study's primary outcome was to evaluate if post-transplant survival has improved over the last 2 decades. Secondary outcomes were the infant's waitlist mortality, waitlist time and identifying factors that affected the infant's survival.

METHODS

United Network for Organ Sharing (UNOS) database was queried for infants (age ≤ 1) who were listed for heart transplantation between 2000 and 2020. The years were divided into 3 eras (Era 1 2000-2006, Era 2 2007-2013 and Era 3 2014-2020). Non-parametric tests, Chi-Squared, Log-Rank test and Cox-Proportional hazard ratio were used for analysis (α = 0.05).

RESULTS

4234 infants were listed for heart transplants between 2000 and 2020. At the time of listing, Infants in era 3 were more likely to be heavier [in kg (P < 0.001)] and had better renal function (P < 0.001). Additionally, they were less likely to be on dialysis (P < 0.001), on a ventilator (P < 0.001) and on extracorporeal membrane oxygenation (P < 0.001). There has been a significant increase in left ventricular assist device use (P < 0.001), though there was no difference in waitlist (0.154) or post-transplant survival (0.51). In all 3 eras, waitlist survival (P < 0.001) and post-transplant survival (P < 0.001) have improved significantly. Congenital heart disease and extracorporeal membrane oxygenation were associated with worse waitlist survival in all 3 eras (P < 0.05). Infants are now waiting longer on the waitlist (in days) (33 Era 1 vs 46 Era 2 vs 67 Era 3, P < 0.001).

CONCLUSIONS

Infant heart transplant outcomes have improved, but they are now waiting longer on the waitlist. Further improvement in increasing the donor pool, expert consensus on listing strategies and donor utilization is needed to improve outcomes.

International Society for Heart and Lung Transplantation Guidelines for the Evaluation and Care of Cardiac Transplant Candidates-2024

The "International Society for Heart and Lung Transplantation Guidelines for the Evaluation and Care of Cardiac Transplant Candidates-2024" updates and replaces the "Listing Criteria for Heart Transplantation: International Society for Heart and Lung Transplantation Guidelines for the Care of Cardiac Transplant Candidates-2006" and the "2016 International Society for Heart Lung Transplantation Listing Criteria for Heart Transplantation: A 10-year Update." The document aims to provide tools to help integrate the numerous variables involved in evaluating patients for transplantation, emphasizing updating the collaborative treatment while waiting for a transplant. There have been significant practice-changing developments in the care of heart transplant recipients since the publication of the International Society for Heart and Lung Transplantation (ISHLT) guidelines in 2006 and the 10-year update in 2016. The changes pertain to 3 aspects of heart transplantation: (1) patient selection criteria, (2) care of selected patient populations, and (3) durable mechanical support. To address these issues, 3 task forces were assembled. Each task force was cochaired by a pediatric heart transplant physician with the specific mandate to highlight issues unique to the pediatric heart transplant population and ensure their adequate representation. This guideline was harmonized with other ISHLT guidelines published through November 2023. The 2024 ISHLT guidelines for the evaluation and care of cardiac transplant candidates provide recommendations based on contemporary scientific evidence and patient management flow diagrams. The American College of Cardiology and American Heart Association modular knowledge chunk format has been implemented, allowing guideline information to be grouped into discrete packages (or modules) of information on a disease-specific topic or management issue. Aiming to improve the quality of care for heart transplant candidates, the recommendations present an evidence-based approach.

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.

The trajectory of renal function following mechanical circulatory support and subsequent heart transplantation

Aim

Patients with advanced heart failure (HF) frequently suffer from renal insufficiency. The impact of durable mechanical circulatory support (MCS) and subsequent heart transplantation (HTx) on kidney function is not well described.

Methods and results

We studied patients with advanced HF who received durable MCS as bridge to transplantation (BTT) and underwent subsequent HTx at our centre between 1996 and 2018. Glomerular filtration rate (GFR) was measured by ⁵¹Cr‐EDTA or iohexol clearance during heart failure work‐up; 3–6 months after MCS; and 1 year after HTx. Chronic kidney disease (CKD) was classified according to KDIGO criteria based on estimated GFR. A total of 88 patients (46 ± 15 years, 84% male) were included, 63% with non‐ischaemic heart disease. The median duration of MCS‐treatment was 172 (IQR 116–311) days, and 81 subjects were alive 1 year after HTx. Measured GFR increased from 54 ± 19 during HF work‐up to 60 ± 16 mL/min/1.73 m² after MCS (P < 0.001) and displayed a slight but nonsignificant decrease to 57 ± 22 mL/min/1.73 m² 1 year after HTx (P = 0.38). The trajectory of measured GFR did not differ between pulsatile and continuous flow (CF) pumps. Among patients 35–49 years and those who were treated in the most recent era (2012–2018), measured GFR increased following MCS implantation and subsequent HTx. Estimated GFR displayed a similar course as did measured GFR.

Conclusions

In patients with advanced heart failure, measured GFR improved after MCS with no difference between pulsatile and CF‐pumps. The total study group showed no further increase in GFR following HTx, but in certain subgroups, including patients aged 35–54 years and those treated during the latest era (2012–2018), renal function appeared to improve after transplant.

Recent Era Outcomes of Mechanical Circulatory Support in Children With Congenital Heart Disease as a Bridge to Heart Transplantation

The objective of the study is to compare the clinical characteristics, risk factors, and overall survival (waitlist and posttransplant) outcomes in children with congenital heart disease (CHD) bridged to transplantation with either a ventricular assist device (VAD) versus extracorporeal membrane oxygenation (ECMO) versus no mechanical circulatory support (MCS) in the recent era. The study included 2,899 primary heart transplantations in patients <18 years with CHD between 2010 and 2019 from the United Network Organ Sharing database. Patients who had ECMO or VAD at listing or while listed were included, and their waitlist and posttransplant outcomes were compared with CHD patients who did not require MCS. Of all, 464 (16%) had ECMO and 200 (7%) VAD at the time of or during the listing. The VAD utilization increased over the last decade (4% in 2010 to 10% in 2019, p < 0.01). The 90 days post-MCS survival was better with VAD than ECMO (67 vs. 49%, p < 0.01). The transplantability rate at 90 days was decreased with younger age (odds ratio [OR], 0.91; 95% CI, 0.86-0.95), lower body mass index (BMI) (OR, 0.93; 95% CI, 0.89-0.98) and lower albumin <3g/dl (OR, 0.6; 95% CI, 0.53-0.7). The multivariate model predicted that lower BMI (OR, 1.12; 95% CI, 1.06-1.18), pretransplant ECMO (OR, 2.19; 95% CI, 1.39-3.45), and higher bilirubin (OR, 1.15; 95% CI, 0.97-1.36) decreased 1-year posttransplant survival. Patients transplanted with VAD had better 1-year survival than ECMO (88 vs. 70%, p = 0.01). Waiting list survival of children with CHD supported by VAD is better compared to ECMO. The 1-year posttransplantation outcome of CHD patients supported by VAD is similar to the no MCS patients and better than ECMO-supported patients. There is no significant difference in post-HT survival between patients transitioned from ECMO to VAD while listed and those with VAD-first.

Pediatric Heart Transplant Recipients Bridged with Biventricular Assist Device Have Worse 1 Year Graft Survival

There are little data on postheart transplant (HT) outcomes for pediatric patients that were supported to HT with biventricular assist device (BiVAD). The United Network for Organ Sharing database was queried for patients <18 years old at time of HT between January 2005 and March 2018, excluding patients bridged with total artificial hearts and right ventricular assist device (VAD). Of 4,904 pediatric HT recipients, patients were grouped by no VAD support (3,934; 80.2%), left ventricular assist device only (736; 15%), and BiVAD (234; 4.8%). Overall graft survival analysis indicates crossing hazard rates between groups over time with the BiVAD group having a significantly lower graft survival at 1 year post-HT. A Cox model adjusted for age, era, diagnosis, and time by group interaction demonstrated increased 1 year hazard ratio (HR) of 8.5 (95% confidence intervals [CI]: 6.15-11.79) comparing BiVAD to no VAD. Comparable hazard between BiVAD and no VAD groups were found at 5 years (HR 1.01; 95% CI: 0.67-1.51), while lower hazard for the BiVAD group was found at 10 years post-HT (HR 0.07; 95% CI: 0.03-0.18). Although pre-HT BiVAD support leads to worse graft survival 1 year post-HT, long-term survival is acceptable.

Hemodynamic Predictors of Renal Function After Pediatric Left Ventricular Assist Device Implantation

Although renal function often improves after pediatric left ventricular assist device (LVAD) implantation, recovery is inconsistent. We aimed to identify hemodynamic parameters associated with improved renal function after pediatric LVAD placement. A single-center retrospective cohort study was conducted in patients less than 21 years who underwent LVAD placement between June 2004 and December 2015. The relationship between hemodynamic parameters and estimated glomerular filtration rate (eGFR) was assessed using univariate and multivariate modeling. Among 54 patients, higher preoperative central venous pressure (CVP) was associated with eGFR improvement after implantation (p = 0.012). However, 48 hours postimplantation, an increase in CVP from baseline was associated with eGFR decline over time (p = 0.01). In subgroup analysis, these associations were significant only for those with normal pre-ventricular assist device renal function (p = 0.026). In patients with preexisting renal dysfunction, higher absolute CVP values 48 and 72 hours after implantation predicted better renal outcome (p = 0.005). Our results illustrate a complex relationship between ventricular function, volume status, and renal function. Additionally, they highlight the challenge of using CVP to guide management of renal dysfunction in pediatric heart failure. Better methods for evaluating right heart function and volume status are needed to improve our understanding of how hemodynamics impact renal function in this population.

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.

Mechanical circulatory support in children: past, present and future

Rapid advances in the field of mechanical circulatory support (MCS) have dramatically changed the management of pediatric patients with heart failure. There is now emphasis on timely implantation of ventricular assist devices (VADs) to preserve or recover end-organ function, and increased focus on post-implant management to improve the stroke rate. Transplant waitlist mortality has significantly decreased in the era of VAD use. Devices approved for adults are being used off-label in children with excellent outcomes, allowing chronic therapy and discharge home to become part of pediatric VAD therapy.

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

BACKGROUND

The use of ventricular assist devices (VADs) in children with heart failure may be of particular benefit to those with accompanying renal failure, as improved renal function is seen in some, but not all recipients. We hypothesized that persistent renal dysfunction at 7 days and/or 1 month after VAD implantation would predict chronic kidney disease (CKD) 1 year after heart transplantation (HT).

METHODS

Linkage analysis of all VAD patients enrolled in both the PEDIMACS and PHTS registries between 2012 and 2016. Persistent acute kidney injury (P-AKI), defined as a serum creatinine ≥1.5× baseline, was assessed at post-implant day 7. Estimated glomerular filtration rate (eGFR) was determined at implant, 30 days thereafter, and 12 months post-HT. Pre-implant eGFR, eGFR normalization (to ≥90 mL/min/1.73 m² ), and P-AKI were used to predict post-HT CKD (eGFR <90 mL/min/1.73 m² ).

RESULTS

The mean implant eGFR was 85.4 ± 46.5 mL/min/1.73 m² . P-AKI was present in 19/188 (10%). Mean eGFR at 1 month post-VAD implant was 131.1 ± 62.1 mL/min/1.73 m² , significantly increased above baseline (P < 0.001). At 1 year post-HT (n = 133), 60 (45%) had CKD. Lower pre-implant eGFR was associated with post-HT CKD (OR 0.99, CI: 0.97-0.99, P = 0.005); P-AKI was not (OR 0.96, CI: 0.3-3.0, P = 0.9). Failure to normalize renal function 30 days after implant was highly associated with CKD at 1 year post-transplant (OR 12.5, CI 2.8-55, P = 0.003).

CONCLUSIONS

Renal function improves after VAD implantation. Lower pre-implant eGFR and failure to normalize renal function during the support period are risk factors for CKD development after HT.