Pediatric heart transplant waiting times in the United States since the 2016 allocation policy change

A prospective multicenter feasibility study of a miniaturized implantable continuous flow ventricular assist device in smaller children with heart failure

BACKGROUND

There is no FDA-approved left ventricular assist device (LVAD) for smaller children permitting routine hospital discharge. Smaller children supported with LVADs typically remain hospitalized for months awaiting heart transplant-a major burden for families and a challenge for hospitals. We describe the initial outcomes of the Jarvik 2015, a miniaturized implantable continuous flow LVAD, in the NHLBI-funded Pumps for Kids, Infants, and Neonates (PumpKIN) study, for bridge-to-heart transplant.

METHODS

Children weighing 8 to 30 kg with severe systolic heart failure and failing optimal medical therapy were recruited at 7 centers in the United States. Patients with severe right heart failure and single-ventricle congenital heart disease were excluded. The primary feasibility endpoint was survival to 30 days without severe stroke or non-operational device failure.

RESULTS

Of 7 children implanted, the median age was 2.2 (range 0.7, 7.1) years, median weight 10 (8.2 to 20.7) kilograms; 86% had dilated cardiomyopathy; 29% were INTERMACS profile 1. The median duration of Jarvik 2015 support was 149 (range 5 to 188) days where all 7 children survived including 5 to heart transplant, 1 to recovery, and 1 to conversion to a paracorporeal device. One patient experienced an ischemic stroke on day 53 of device support in the setting of myocardial recovery. One patient required ECMO support for intractable ventricular arrhythmias and was eventually transplanted from paracorporeal biventricular VAD support. The median pump speed was 1600 RPM with power ranging from 1-4 Watts. The median plasma free hemoglobin was 19, 30, 19 and 30 mg/dL at 7, 30, 90 and 180 days or time of explant, respectively. All patients reached the primary feasibility endpoint. Patient-reported outcomes with the device were favorable with respect to participation in a full range of activities. Due to financial issues with the manufacturer, the study was suspended after consent of the eighth patient.

CONCLUSION

The Jarvik 2015 LVAD appears to hold important promise as an implantable continuous flow device for smaller children that may support hospital discharge. The FDA has approved the device to proceed to a 22-subject pivotal trial. Whether this device will survive to commercialization remains unclear because of the financial challenges faced by industry seeking to develop pediatric medical devices. (Supported by NIH/NHLBI HHS Contract N268201200001I, clinicaltrials.gov 02954497).

Programmatic Palliative Care Consultations in Pediatric Heart Transplant Evaluations

Guidelines advocate for integrating palliative care into the management of heart failure (HF) and of children with life-limiting disease. The potential impact of palliative care integration into pediatric HF on patient-centered outcomes is poorly understood. The present study sought to assess the association of programmatic implementation of palliative care into the heart transplant evaluation process with hospital-free days (HFD) and end of life (EOL) treatment choices. The study included patients less than 19 years of age who underwent a heart transplant evaluation between February 2012 and April 2020 at a single center. Patients evaluated in the programmatic palliative care (PPC) era (January 2016-April 2020) were compared to patients evaluated in the pre-PPC era (February 2012-December 2015). The study included 188 patients, with 91 (48%) in the PPC era and 97 (52%) in the pre-PCC era. Children < 1 year of age at the time of the evaluation represented 32% of the cohort. 52% of patients had single ventricle physiology. PPC was not significantly associated with increased HFD (IRR 0.94 [95% CI 0.79-1.2]). PPC was however associated with intensity of EOL care with decreased mechanical ventilation (OR 0.12 [95% CI 0.02-0.789], p = 0.03) and decreased use of ionotropic support (OR 0.13 [95% CI 0.02-0.85], p =0.03). PPC in pediatric heart transplant evaluations may be associated with less invasive interventions at EOL.

The future of partial heart transplantation

Heart valve replacement in children is an unsolved problem in congenital cardiac surgery because state-of-the-art heart valve implants do not grow. This leads to serial repeat operations to replace outgrown heart valve implants. Partial heart transplantation is a new transplant that helps alleviate this problem by delivering growing heart valve implants. In the future, partial heart transplantation has the potential to complement conventional heart transplantation for treating children with congenital cardiac disease primarily affecting the heart valves.

Risk Index Predicts Pediatric Heart Allograft Non-Utilization

BACKGROUND

Children listed for heart transplantation face the highest waitlist mortality among all solid organ transplant patients (14%). Attempts at decreasing donor allograft non-utilization (41.5%) could potentially decrease waitlist mortality for pediatric heart transplant patients. Our aim was to quantify the non-utilization risk of pediatric donor heart allografts at the time of initial offering.

METHODS

Using the United Network of Organ Sharing (UNOS) database, we retrospectively analyzed 8823 deceased donors (≤18 years old) data through univariable and multivariable analysis and logistic regression models. These factors were divided into a training (n = 5882) and validation set (n = 2941). Donor clinical characteristics and laboratory values were used to predict non-utilization of donor hearts. The multivariable analysis used factors that were significant from the univariable analysis (p-value < .05), and the pediatric non-utilization risk index (pDRSI) included significant factors from the multivariable analysis, producing an overall risk score for non-utilization. With these data, we created a non-utilization risk index to predict likelihood of donor allograft non-utilization.

RESULTS

From the 24 potential factors that were identified from univariable analysis, 17 were significant predictors (p < .05) of pediatric heart non-utilization in the multivariable analysis. Low left ventricular ejection fraction (odds ratio (OR)-35.3), hepatitis C positive donor (OR-23.3), high left ventricular ejection fraction (OR-3.29), and hepatitis B positive donor (OR-3.27) were the most significant risk factors. The phDSRI has a C-statistic of 0.80 for the training set and 0.80 for the validation set.

CONCLUSION

Using over 8000 donors, the phDSRI uses 17 significant risk factors to predict risk of pediatric heart donor allograft non-utilization.

Myocardial recovery in children supported with a durable ventricular assist device-a systematic review

OBJECTIVES

A small percentage of paediatric patients supported with a ventricular assist device (VAD) can have their device explanted following myocardial recovery. The goal of this systematic review is to summarize the current literature on the clinical course in these children after weaning.

METHODS

A systematic literature search was performed on 27 May 2022 using Embase, Medline ALL, Web of Science Core Collection, Cochrane Central Register of Controlled Trials and Google Scholar to include all literature on paediatric patients supported by a durable VAD during the last decade. Overlapping study cohorts and registry-based studies were filtered out.

RESULTS

Thirty-seven articles were included. Eighteen of them reported on the incidence of recovery in cohort studies, with an overall incidence rate of 8.7% (81/928). Twenty-two of the included articles reported on clinical outcomes after VAD explantation (83 patients). The aetiologies varied widely and were not limited to diseases with a natural transient course like myocarditis. Most of the patients in the included studies (70; 84.3%) were supported by a Berlin Heart EXCOR, and in 66.3% (55/83), only the left ventricle had to be supported. The longest follow-up period was 19.1 years, and multiple studies reported on long-term myocardial recovery. Fewer than half of the reported deaths had a cardiac cause.

CONCLUSIONS

Myocardial recovery during VAD support is dependent on various contributing components. The interactions among patient-, device-, time- and hospital-related factors are complex and not yet fully understood. Long-term recovery after VAD support is achievable, even after a long duration of VAD support, and even in patients with aetiologies different from myocarditis or post-cardiotomy heart failure. More research is needed on this favourable outcome after VAD support.

Characterization of Green Fluorescent Protein in Heart Valves of a Transgenic Swine Model for Partial Heart Transplant Research

A transgenic strain of pigs was created to express green fluorescent protein (GFP) ubiquitously using a pCAGG promoter. Here, we characterize GFP expression in the semilunar valves and great arteries of GFP-transgenic (GFP-Tg) pigs. Immunofluorescence was performed to visualize and quantify GFP expression and colocalization with nuclear staining. GFP expression was confirmed in both the semilunar valves and great arteries of GFP-Tg pigs compared to wild-type tissues (aorta, p = 0.0002; pulmonary artery, p = 0.0005; aortic valve; and pulmonic valve, p < 0.0001). The quantification of GFP expression in cardiac tissue allows this strain of GFP-Tg pigs to be used for future research in partial heart transplantation.

Impact of 2016 UNOS pediatric heart allocation policy changes on VAD utilization, waitlist, and post-transplant survival outcomes in children with CHD versus Non-CHD

AIMS

We analyzed the impact of the revised pediatric heart allocation policy on types of ventricular assist device (VAD) utilization, and waitlist (WL) and post-heart transplant (HT) survival outcomes in congenital heart disease (CHD) versus non-CHD patients before (Era-1) and after (Era-2) pediatric heart allocation policy implementation.

METHODS

We retrospectively reviewed the UNOS database from December 16, 2011, through March 31, 2021, for patients < 18 years old and listed for primary HT. We compared the differences observed between Era-1 and Era-2.

RESULTS

5551 patients were listed for HT, of whom 2447(44%) were in Era-1 and 3104(56%) were in Era-2. CHD patients were listed as status 1A unchanged, but the number of patients listed as status 1B decreased in Era-2, whereas the number of non-CHD patients listed as status 1A decreased, but status 1B increased. In Era-2 compared to Era-1, both temporary (1% to 4%, p < .001) and durable VAD (13.6% to 17.8%, p < .001) utilization increased, and the transplantation rate per 100-patient years increased in both groups. The median WL period for CHD patients increased marginally from 70 to 71 days (p = .06), whereas for non-CHD patients it decreased from 61 to 54 days (p < .001). Adjusted 90-day WL survival increased from 84% to 88%, p = .016 in CHD, but there was no significant change in non-CHD patients (p = .57). There was no significant difference in 1-year post-HT survival in CHD and non-CHD patients between Era-1 and Era-2.

CONCLUSIONS

In summary, after the revised heart allocation policy implementation, temporary and durable VAD support increased, HT rate increased, waitlist duration marginally increased in the CHD cohort and decreased in the non-CHD cohort, and 90-day WL survival probability improved in children with CHD without significant change in 1-year post-HT outcomes. Future studies are needed to identify changes to the policy that may further improve the listing criteria to improve WL duration and post-HT survival.

Outcomes of pediatric patients supported with ventricular assist devices single center experience

BACKGROUND

There has been a remarkable increase in the number of pediatric ventricular assist device (VAD) implanted over the past decade. Asian pediatric heart centers had not participated in the multicenter registries among the Western countries. This article aimed to report the outcomes of pediatric VAD in our hospital.

METHODS

The study enrolled all patients aged <18 years at the time of VAD implantation in our institution between 2008 and 2021.

RESULTS

There were 33 patients with diagnosis of acute fulminant myocarditis (n = 9), congenital heart disease (n = 5), dilated cardiomyopathy (n = 16), and others. Paracorporeal continuous-flow pump was the most frequently implanted (n = 27). Most of the devices were implanted in patients with INTERMACS profile 1 (n = 24). The median duration on VAD was 22 days (range 2-254). The proportion of patients attaining positive outcomes (alive on device, bridge to transplantation or recovery) was 72.7% at 1 month, 67.7% at 3 months, and 67.7% at 6 months. Most of the deaths on device occurred within the first month post-implant (n = 9), with neurological complications being the most frequent cause of death. All recovered cases were successfully weaned off the device within the first month of implantation.

CONCLUSION

We demonstrated a favorable outcome in pediatric patients supported with VAD at our institution.

Heart transplantation for pediatric foreign nationals in the United States

BACKGROUND

This study aimed to clarify survival outcomes, waitlist mortality, and waitlist days of heart transplantation of pediatric foreign nationals compared to pediatric United States (US) citizens.

METHODS

We retrieved data from March 2012 to June 2021 in the United Network Organ Sharing (UNOS) registry.

RESULTS

Of 5857 pediatric patients newly waitlisted, 133 (2.27%) patients were non-US citizen/non-US residents (non-citizen non-resident [NCNR]). Patients with congenital heart disease were higher in the US citizen group than in the NCNR group (51.9% vs. 22.6%, p < .001); 76.7% of patients in the NCNR group (102/133) had cardiomyopathy. Of the 133 NCNRs, 111 patients (83.5%) underwent heart transplantation, which was significantly higher than that in the US citizen group (68.6%, p < .001). The median waitlist time was 71 days (IQR, 22-172 days) in the NCNR group and 74 days (29-184 days) in the US citizen group (p = .48). Survival after heart transplant was significantly better in the NCNR group than in the US citizen group (n = 3982; logrank test p = .015).

CONCLUSIONS

Heart transplantation for pediatric foreign nationals was mostly indicated for cardiomyopathy, and their transplant rate was significantly higher than that in the US citizen group, with better survival outcomes. The better survival outcomes in the NCNR group compared to the US citizen group can likely be attributed to the differing diagnoses for which transplantation was performed.

Late airway complications following pediatric liver transplantation: A case series

BACKGROUND

Late airway complications, as consequence of immunosuppression following pediatric liver transplantation are uncommonly reported.

METHODS

In this retrospective case series, we describe two young children presenting with symptoms of airway obstruction, secondary to differing pathologies in the supraglottic airway, as a result of immunosuppression following liver transplantation.

RESULTS

Case 1, a 2-year-old girl who presented with stridor 12-months following liver transplantation, was found to have a proliferative soft tissue mass involving the supraglottic larynx. Biopsies were consistent with infiltrative eosinophilic laryngitis and associated eosinophilic esophagitis. Case 2, a 12-month-old female who presented with stridor 5-months following liver transplantation, was found to have an exophytic soft tissue mass involving the supraglottis and hypopharynx. Biopsies revealed polymorphic Epstein-Barr virus (EBV) driven post-transplant lymphoproliferative disease (PTLD). Case 1 was managed with local resection and high dose oral corticosteroids. Case 2 responded to debulking of the necrotic supraglottic mass, reduction of immunosuppression and rituximab.

CONCLUSION

A high index of suspicion needs to be maintained for complications of immunosuppression for appropriate diagnosis of airway presentations following pediatric liver transplantation. Further research is necessary to improve early detection and consolidate management strategies for these airway lesions.

Impact of occurrence of cardiac arrest in the donor on long-term outcomes of pediatric heart transplantation

OBJECTIVE

The impact of cardiac arrest in the donor on long-term outcomes of pediatric heart transplantation has not been studied.

METHODS

The UNOS database was queried for primary pediatric heart transplantation (1999-2020). The cohort was divided into recipients who received a cardiac allograft from a donor who had a cardiac arrest (CA) versus a donor who did not (NCA). Univariable and multivariable analysis was done to compare recipient outcomes, followed by survival analysis using the Kaplan-Meier method.

RESULTS

A total of 7300 patients underwent heart transplantation, of which 579 (7.9%) patients belonged to the CA group. The CA group was younger (median 3 vs. 5 years, p < .001), male (51% vs. 47%, p = .03), and smaller in weight (13 vs. 17 kg, p < .001) and height (101 vs. 109 cm, p < .001) than the NCA group. The groups were similar in recipient heart failure diagnosis and blood type. The CA donors were younger (3 vs. 6 years, p < .001) versus nonwhite (48% vs. 45%, p = .003) and died from drowning and asphyxiation compared to blunt injury and intracranial hemorrhage in the NCA group. The left-ventricular ejection fraction was similar between the groups. There was no difference in VAD and ECMO use before the transplant. The listing status, waitlist days, and allograft ischemic times were similar. Posttransplant morbidity such as stroke, dialysis, pacemaker implantation, and treated rejection were similar. Donor cardiac arrest (hazard ratio = 0.93, p = .5) was not an independent predictor of mortality on multivariable analysis. There was no survival difference even beyond 20 years of follow-up between the groups (p = .88).

CONCLUSION

The occurrence of donor cardiac arrest has no impact on long-term survival in pediatric heart transplant recipients.