Pediatric Donor Hearts Research Articles

They Deserve to Live: Impact of the Berlin Heart EXCOR on Small Children's Heart Transplant Waitlist in Low-Resource Settings.

Background: In newly emerging economy countries, the shortage of pediatric donor hearts and poor healthcare infrastructure poses a significant challenge. Although mechanical circulatory support (MCS) has been proven effective in enhancing heart transplant waiting list outcomes, economic barriers hinder its widespread adoption. Methods: A single-center retrospective study reviewed children under 10 kg on the heart transplant (HTx) list from 2012 to 2023. Elective or priority status was assigned based on their clinical condition at the time of transplant. In cases of clinical decompensation, centrifugal pump and extracorporeal membrane oxygenation, transitioned to the Berlin Heart EXCOR (BHE) pediatric ventricular assist device (VAD) was employed. Pre- and post-HTx outcomes were analyzed with descriptive statistics, Cox regression, and competing survival risks. Results: Out of 81 infants on the HTx list, 61.7% (50/81) were in critical condition. The median wait time was 224 days, and 34% (28/81) died while waiting. Out of 37 transplanted patients, 6 (16%) had graft dysfunction, and 10 (27%) had acute renal injury. Survival to discharge was 84% (31/37). Patients who received the BHE exhibited higher chances of receiving a transplant (hazard ratio: 2.3; 95% confidence interval: 1.2-4.6; P = .01). Priority status or MCS use did not significantly impact mortality post-transplant. Conclusion: Advanced MCS technologies can potentially reduce the mortality risk on the pediatric HTx waitlist. The findings highlight the significant waiting time for HTx and the critical role of the BHE in improving outcomes in children, particularly those under 10 kg. The results advocate for the adoption of ventricular assist devices as a viable interim solution to bridge critically ill children to HTx, ultimately enhancing their chances of survival despite limited donor heart availability.

A comprehensive, multifaceted strategy to increase pediatric donor heart utilization

BACKGROUNDMany hearts offered for pediatric heart transplantation (HT) are not placed. In 2016, we initiated a quality improvement endeavor to increase heart offer acceptance. This study assessed the effect of these interventions at our center. METHODSEvaluation of pre-/post-implementation cohorts (1/1/2008-12/31/2016 vs. 1/1/2017- 7/1/2023) comparing donor heart utilization. Six interventions were iterated over time to increase offer acceptance (“extended criteria”): ABO-incompatible transplant, ex vivo perfusion for distanced donors, 3-dimensional total cardiac volume (TCV) assessment, acceptance of Hepatitis-C or SARS-COV-2 infected donors, and institutional culture change favoring consideration of donors previously considered unacceptable (Public Health Service Risk, long CPR duration, etc.). Outcomes studied included annual HT volume, median waitlist duration, sequence number at acceptance, and post-transplant clinical outcomes. RESULTSFrom 1/2008–7/2023 annual transplant volume increased from 16/year to 25/year pre-/post-implementation. Three hundred-thirteen/389 (80%) listed patients were transplanted. Waitlist duration shortened post-implementation (P=0.01), as did the percentage of accepted heart offers utilizing at least one extended criterion (P<0.001). Institutional culture change and TCV assessment had the largest impact on donor heart utilization (P=0.04 &P<0.001). There was no difference in post-HT intubation or cardiovascular intensive care unit (CVICU) days (P= 0.05-0.9), though post-transplant hospitalization duration (P<0.001) increased. Post-transplant survival was unaffected by use of extended criteria hearts (P=0.3). CONCLUSIONSWe report increased donor heart offer acceptance resulting from a longitudinal, multi-faceted effort to increase organ offer utilization, with institutional culture change and TCV assessments having the greatest impact. Use of extended criteria hearts was not associated with inferior survival.

"Take it or leave it": Analysis of pediatric heart offers for transplantation in Switzerland.

There is a shortage of donor hearts in Switzerland, especially for pediatric recipients. However, the rate and reason for refusals of pediatric donor hearts offered in Switzerland has not been systematically analyzed. The national transplant database, Swiss Organ Allocation System, was searched for all hearts from Swiss and foreign donors younger than 16 years from 2015 to 2020. The numbers of accepted and refused hearts and early outcome were assessed, and the reasons for refusal were retrospectively analyzed. A total of 136 organs were offered to the three Swiss pediatric heart centers and foreign donor procurement organizations. Of these, 26/136 (19%) organs were accepted and transplanted: 18 hearts were transplanted in Switzerland, and 13 of these were foreign. Reasons for refusal were (1) no compatible recipient due to blood group or weight mismatch, 89.4%; (2) medical, meaning organ too marginal for transplantation, 7.4%; (3) logistic, 1.4%; and (4) other, 1.8%. Five organs were refused in Switzerland by one center but later accepted and successfully transplanted by another center. Hearts from outside Switzerland were transplanted significantly less than Swiss hearts (n = 16/120 vs. 10/16, p < .001). The most common reason for refusing a pediatric donor heart is lack of compatibility with the recipient. Few hearts are refused for medical reasons. A more generous acceptance seems to be justified in selected patients. Switzerland receives a high number of foreign offers, but their rate of acceptance is lower than that of Swiss donations.

Pediatric donor heart utilization variability among organ procurement organizations.

Organ procurement organizations (OPOs) are responsible for the medical management of organ donors. Given the variability in pediatric donor heart utilization among OPOs, we examined factors that may explain this variability, including differences in donor medical management, organ quality, and candidate factors. The Organ Procurement and Transplant Network database was queried for pediatric (<18 years) heart donors and candidates receiving pediatric donor heart offers from 2010 to 2019. OPOs were stratified by pediatric donor heart utilization rate, and the top and bottom quintiles were compared based on donor management strategies and outcomes. A machine learning algorithm, combining 11 OPO, donor, candidate, and offer variables, was used to determine factors most predictive of whether a heart offer is accepted. There was no clinically significant difference between the top and bottom quintile OPOs in baseline donor characteristics, distance between donor and listing center, management strategies, or organ quality. Machine learning modeling suggested neither OPO donor management nor cardiac function is the primary driver of whether an organ is accepted. Instead, number of prior donor offer refusals and individual listing center receiving the offer were two of the most predictive variables of organ acceptance. OPO clinical practice variation does not seem to account for the discrepancy in pediatric donor heart utilization rates among OPOs. Listing center acceptance practice and prior number of donor refusals seem to be the important drivers of heart utilization and may at least partially account for the variation in OPO heart utilization rates given the regional association between OPOs and listing centers.

Risk Index Predicts Pediatric Heart Allograft Non-Utilization.

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

Pediatric donor heart acceptance practices in the United States: What is really being considered?

Recent studies demonstrate high offer decline and organ non-utilization rates are associated with increased pediatric heart transplant waitlist mortality. We sought to determine which donor, candidate, and offer specific variables most importantly influenced these decisions using only data available at the time of each offer. Retrospective review of pediatric (<18 years) heart donor offers made to pediatric candidates in the United States between 2010 and 2020. In addition to standard donor, candidate, and offer data available in UNOS, we extracted objective and qualitative valvar and myocardial function data from all available donor echocardiogram reports. During the study period, 5625 pediatric donor hearts produced 30 156 offers to 4905 unique candidates, of which 88.7% of all offers were declined and 39.2% of organs were not utilized by pediatric waitlisted candidates. Of the 60.8% utilized hearts, 89.7% had a 'cumulatively' normal echocardiogram at the time of offer acceptance; 62.9% of hearts not utilized for a pediatric candidate also had a cumulatively normal final echocardiogram. Random forest and logistic regression modeling demonstrated good predictive performance (AUROC ≥0.83) of likelihood to accept when utilizing donor, candidate, and offer specific variables. SHAP variable importance scores demonstrated number of prior offer declines and candidate institution's prior year acceptance rates as the two most important variables influencing offer decisions. Behavioral economics appear to play a significant role in pediatric heart transplant candidate institutions' acceptance practices, even when considering the arguably healthier pediatric donor population. Removal of prior institution's decisions from DonorNet may help increase donor utilization.

Donor supply for partial heart transplantation in the United States.

Congenital heart disease (CHD) is the most common cause of birth defects worldwide. Valvular defects are a common form of CHDs, and, at this time, treatment options for children with unrepairable valve disease are limited. Issues with anticoagulation, sizing, and lack of growth in valve replacement options can lead to high mortality rates and incidence of reoperations. Partial heart transplantation, or transplantation of fresh valve allografts, has recently been described as a strategy to provide a durable and non-thrombogenic alternative to conventional prostheses and provide growth potential in pediatric patients. The United Network for Organ Sharing (UNOS) database was queried to analyze the number of pediatric donor hearts that were not recovered but had viable valves (n=3565) between January 2010 and September 2021. Recoverable valves were grouped by donor age: infants (age<1year), toddlers (age ≥1 and <3years), and children (age ≥3 and <18years). Demographic characteristics of donors were analyzed between age groups. Infants, toddlers, and children had a total of 344, 465, and 2756 hearts with recoverable valves, respectively, over the study period, representing an average of 29, 39, and 230 hearts with recoverable valves per year. The results of our study identify the minimum donor supply for partial heart transplantation. The actual number is likely higher because it includes hearts not entered in the UNOS database and domino transplants from orthotopic heart transplant recipients. Partial heart transplantation is logistically feasible as there are recoverable valves available for all age groups, fulfilling a clinical need in pediatric patients with unrepairable valve disease.

Trends in pediatric donor heart discard rates and the potential use of unallocated hearts for allogeneic valve transplantation

ObjectivesAllogeneic valve transplantation is an emerging therapy that delivers a living valve from a donor heart. We reviewed the national discard rate of pediatric and young adult (aged 25 years or younger) donor grafts to estimate the number of hearts potentially available to source valve allotransplantation. MethodsWe queried the United Network for Organ Sharing database to identify pediatric and young adult heart donors from 1987 to 2022. Donor heart discard was defined as nontransplantation of the allograft. ResultsOf 72,460 pediatric/young adult heart donations, 41,065 (56.7%) were transplanted and 31,395 (43.3%) were unutilized. The average annual number of discarded hearts in era 1 (1987-2000), era 2 (2000-2010), and era 3 (2010-2022) was 791 (42.8%), 1035 (46.3%), and 843 (41.2%), respectively. From 2017 to 2021, the average annual number of discards by age was: 39 (31.8%) neonates/infants, 78 (38.0%) toddlers, 41 (49.4%) young children, 240 (38.0%) adolescents, and 498 (40.1%) young adults. High-volume procurement regions had the greatest proportion of nonutilization, with the national average discard rate ranging from 39% to 49%. The most frequently documented reasons for nonallocation were distribution to the heart valve industry (26.5%), presumably due to suboptimal graft function, poor organ function (22.7%), and logistical challenges (10.8%). ConclusionsWith ∼900 pediatric/young adult donor hearts discarded annually, unutilized grafts represent a potential source of valves for allogeneic valve transplant to supplement current conduit and valve replacement surgery. The limited availability of neonatal and infant hearts may limit this technique in the youngest patients, for whom cryopreserved homografts or xenografts will likely remain the primary valve substitute.

(397) Use of the SherpaPak Cardiac Transport System for Infant and Pediatric Donor Hearts: An Initial Experience

(397) Use of the SherpaPak Cardiac Transport System for Infant and Pediatric Donor Hearts: An Initial Experience

Rethinking status 1A criteria in pediatric cardiac transplantation: A case for the prioritization of patients with single ventricle anatomy supported by ventricular assist devices.

Over the past 2 years advancements in the techniques and technology of pediatric heart transplantation have exponentially increased. However, even as the number of pediatric donor hearts has grown, demand for this limited resource continues to far outpace supply. Thus, lifesaving support in the form of ventricular assist devices (VAD) has become increasingly utilized in bridging pediatric patients to cardiac transplant. In the current pediatric heart transplant listing criteria, adopted by the United Network for Organ Sharing (UNOS) in 2016, all pediatric patients with a VAD are granted 1A status and assigned top transplant priority regardless of their underlying pathology. However, should this be the case? We suggest that the presence of a VAD alone may not be sufficient for status 1A listing. In doing so, we specifically highlight the heightened acuity, resource utilization, risk profile, and diminished outcomes in patients with single ventricle physiology supported with VAD as compared to patients with structurally normal hearts who would both be listed under 1A status. Given this, from a distributive justice perspective, we further suggest that the lack of granularity in current pediatric cardiac transplant listing categories may inadvertently lead to an inequitable distribution of donor organs and hospital resources especially as it pertains to those with single ventricle anatomy on VAD support. We propose revisiting the current listing priorities in light of improved techniques, technology, and recent data to mitigate this phenomenon. By doing this, pediatric patients with single ventricle disease might be more equitably stratified while awaiting heart transplant.

Abstract 14959: Mitochondrial Transplantation in Pediatric and Neonatal Porcine Hearts in a Model of DCD Heart Transplantation

Introduction: Heart transplantation in pediatric and neonatal patients is limited by the donor pool. Donation after circulatory death (DCD) could potentially expand the donor pool by offering an additional source of cardiac allografts. In this study, we investigated the efficacy of mitochondrial transplantation to enhance myocardial function in pediatric and neonatal DCD hearts. Hypothesis: Autologous mitochondrial transplantation enhances the viability and function of pediatric and neonatal DCD donor hearts. Methods: Circulatory death was induced by extubation in neonatal (25 - 50g heart weight, representing 4-16 month human) and pediatric (68 - 98g heart weight, representing 4-6 year human) swine model. Hearts were subjected to 20 min of warm ischemia and 10 min of cold cardioplegic arrest and then harvested. The aorta and pulmonary artery were cannulated, inferior and superior venae cavae ligated and a balloon was inserted in the left ventricle. The hearts were then mounted on the ex situ perfusion device. After 15 minutes of reperfusion, hearts received either vehicle alone ([VEH], 10 mL n = 6) or vehicle containing autologous mitochondria ([MT] 5x10 9 in 10 mL; n = 6). A Sham non-ischemic group (n = 4) did not undergo warm ischemia, mimicking donor after brain death (DBD). Hearts were machine perfused for 2 hours unloaded and 2 hours of loaded conditions. Results: Following 4 hours of reperfusion, neonatal and pediatric DCD hearts receiving VEH showed significantly decreased myocardial function and viability as compared to Sham non-ischemic control hearts. In contrast, in both neonatal and pediatric DCD hearts receiving MT, LVDP, dP/dt max, and fractional shortening were significantly increased (p &lt; 0.001 for each) and were equal or better than that observed in Sham non-ischemic hearts. Infarct size was significantly decreased in both neonatal and pediatric DCD hearts receiving MT as compared to VEH (p &lt; 0.001). Conclusions: Mitochondrial transplantation provides for significantly enhanced preservation of myocardial function and viability in neonatal and pediatric DCD hearts that is equivalent to or better than that observed in DBD hearts. Mitochondrial transplantation provides a possible option to expand the pediatric and neonatal heart donor pool.

Inter-Rater Reliability of Total Cardiac Volume Measurement for Heart Transplantation: An ACTION Collaborative Study

<h3>Purpose</h3> There is increasing evidence that size-matching pediatric donor hearts by direct measurement of total cardiac volume (TCV) is superior to traditional methods based on body size. Currently, there are no standardized protocols for assessing TCV or studies evaluating the inter-rater reliability of such measurements, both critical requirements to support a national TCV-based size-matching system. We sought to evaluate the inter-rater reliability of a standardized TCV measurement protocol across multiple pediatric transplant centers. <h3>Methods</h3> A total of nine pediatric transplant centers within the Advanced Cardiac Therapies Improving Outcomes Network (ACTION) performed TCV assessments in 12 test subjects. TCV was assessed from computed tomography (CT) or magnetic resonance imaging (MRI) files using a standard TCV measurement protocol that was reviewed with each center. Interclass correlation coefficients (ICC) were calculated between all centers and each center in relation to the primary center. <h3>Results</h3> Of the 12 test subjects, the median age was 9.5 years (range 18 days to 30 years), the median weight was 28 (2.5 to 89) kg; 3 had no heart disease (donors), 3 had cardiomyopathy (CMP); 6 had congenital heart disease (CHD) including 4 single-ventricle CHD (1 shunted newborn, 2 Glenns, and 2 Fontans) and 2 biventricular CHD (aortic stenosis, tetralogy of Fallot/pulmonary atresia). Imaging modalities included 7 contrast CTs (CCT), 3 non-contrast CT (NCT), and 2 MRI. TCV was performed by 7 cardiologists, 1 radiologists, and 1 biomedical engineer. Overall compared to the primary center, the ICC across all 8 centers for all 12 scans was 0.99 (95% CI 0.98-0.99), including in normal hearts 0.98 (0.95-1.0), in CMP 0.99 (0.96-1.0), in CHD 0.99 (95% CI 0.99-0.99) and single ventricle CHD 0.99 (95% CI 0.97-0.99). By imaging modality, ICC for NCT was 0.98 (0.94-1.0), CCT 0.99 (0.99-0.99), and MRI 0.79 (0.32-1.0). By age, infants ICC was 0.99 (0.95-1.0), children 0.99 (0.98-0.99), and adults 0.97 (0.81-1.0). <h3>Conclusion</h3> The inter-rater reliability for total cardiac volume assessment in healthy and diseased hearts appears excellent across a variety of age groups and diagnoses. ICC for MRI was modest compared to CT imaging albeit the small sample size. Further validation of a standardized TCV measurement protocol among ACTION transplant centers is warranted.

Assessing the Relationship Between Pediatric Donors’ Terminal Hospitalizations and Heart Acceptance Practices

<h3>Purpose</h3> Prior studies suggest half of all donor hearts offered to pediatric waitlisted patients are declined despite a nearly 20% waitlist mortality. We evaluated the association between a pediatric heart donor's terminal hospital course and pediatric recipient acceptance practices. <h3>Methods</h3> Retrospective UNOS database study of all pediatric (<18 years) donors offered to pediatric patients from 1/1/2010 to 12/31/2020, including the PDF versions of all echocardiogram (echo) results performed during the terminal hospital course. <h3>Results</h3> 5836 hearts were offered 34,078 times with a median initial offer occurring 8.9 (IQR 0.0, 13.4) hours post brain death (BD). Overall acceptance was 62.6%, though acceptance rates varied significantly by age, as seen in Table 1. Highest troponin values, vasoactive infusion (VIS) and PELD scores were significantly higher in rejected hearts. Thyroid repletion was uncommon but occurred significantly more often in rejected donors (8.8% (95% CI 4%, 13.6%) vs 6.8% (95% CI 3%, 10.5%), respectively, p=0.021). 5% of all donors did not have a documented echo, 62.4% had one, 25.3% had two and 7.1% had ≥3. Median time to first post BD echo was 15.7 (IQR 7.5, 21.9) hours at which time ≥50% of all rejected pediatric donor hearts demonstrated normal left ventricular (LV) function; right ventricular (RV) dysfunction occurred in less than 10% of all echos. Pre BD echos (median 36.4 (IQR 78.3, 11) hours pre BD) were much less common but exhibited more evidence of LV dysfunction. <h3>Conclusion</h3> Pediatric donor characteristics and management practices differed between groups and may have affected acceptance practices. Although approximately 1/3 of the Pre BD echoes on rejected donors showed moderate to severely depressed LV function, more than half of Post BD echoes on rejected donors demonstrated normal biventricular function. Assessment of the effects of hemodynamic status and current vs prior echo data on both acceptance practices and recipient outcomes is warranted and underway.

Effect of Donor Age on Posttransplant Mortality in Pediatric Heart Transplant Recipients: A 10-Year Nationwide Cohort Study

<h3>Purpose</h3> The French heart allocation system prioritizes pediatric over adult candidates. This policy seeks to address the shortage of pediatric donor hearts. Consequently, pediatric candidates frequently receive organ from adult donors. An association between donor age and posttransplant mortality has been shown in adult heart recipients. This study aimed to evaluate the effect of donor age on posttransplant mortality in pediatric heart recipients. <h3>Methods</h3> All candidates registered on the national waiting list before 18 years old between January, 1^st 2010 and December 31^st 2020 who underwent transplantation were included in this cohort study using the national registry Cristal. Recipient characteristics at transplant in addition to donor characteristics were analyzed. The main outcome was 1-year posttransplant survival estimated with Kaplan-Meier method. Relationship between donor age and 1 year mortality was assessed with a Cox proportional hazard model with donor age as a continuous variable transformed with restricted cubic splines. <h3>Results</h3> Of the 274 transplant recipients (148 males, <6 years n=69, 6-10 years n=47, 11+ years n=158, cardiomyopathy n=174, congenital heart disease n=46, retransplantation n=13, other n=41) 115 were on inotropic infusion, 32 on short-term mechanical support (MCS) and 45 on long-term MCS at transplant. Among donors, 129 were female, head trauma was the cause of death in 132, 101 had cardiopulmonary resuscitation and 159 (58%) were >17 years old. One-year posttransplant survival was 93%. Congenital heart disease and retransplantation were associated with posttransplant mortality. Donor age was not associated with hazard ratio for 1-year mortality (Figure). <h3>Conclusion</h3> Allocation of adult donor hearts to elective and urgent pediatric candidates through pediatric priority statutes can address the shortage of pediatric donor organs without affecting posttransplant outcomes.

Outcomes following use of pediatric and young adult donor hearts with bicuspid aortic valves: A single‐center case series

Valvular disease in pediatric and young adult donor hearts may be a relative contraindication to graft use. Outcomes following the use of donor hearts with bicuspid aortic valve (BAV) have not been previously reported in children. We describe 4 cases of pediatric heart transplantation (HTx) utilizing a donor heart with a BAV. Of the 469 HTx included in this study, 4 utilized a donor heart with a BAV. All recipients were female; median age was 11years (range 0.3 to 19years). In all cases, the BAV was not discovered until after HTx. All donors were less than 30years old. The patients were followed for a median of 6years (range 2 to 9years) with all patients alive at last follow-up. Two patients have transitioned to adult care, and 2 patients continue to follow in our clinic. In follow-up, no patient has required an aortic valve intervention or had infective endocarditis. At last review, no patient had greater than mild aortic insufficiency or more than mild aortic stenosis. Three patients developed mild-to-moderate left ventricular hypertrophy in the first year post-transplant that improved over time. One patient experienced a peri-operative embolic stroke at time of transplant unrelated to the BAV. On short- and intermediate-term follow-up, pediatric and young adult donor hearts with BAV demonstrated acceptable graft longevity and valvular function. A functionally normal BAV in a pediatric heart transplant donor should not be a contraindication to organ acceptance.

Center Donor Refusal Rate Is Associated With Worse Outcomes After Listing in Pediatric Heart Transplantation.

Pediatric donor heart acceptability differs among transplant centers. However, the impact of center donor acceptance on waitlist and posttransplant outcomes has not been investigated. The aim of our study was to investigate associations between transplant center refusal rate (RR) and outcomes after listing. Retrospective analysis was performed using United Network for Organ Sharing/Organ Procurement and Transplant Network pediatric (<18 y) heart transplant data from 2007 to 2017. Center RR was defined as the median number of refusals per listed patient. Associations between RR center quartile and waitlist time, waitlist removal for death or clinical deterioration, posttransplant survival, and survival after listing were investigated. There were 5552 listed patients in 59 centers who met inclusion criteria. The lowest quartile RR centers had a median RR of ≤1 per listed patient, and highest RR centers percentile had a median RR of ≥4. Highest RR centers had shorter time to first offer (19 versus 38 d; P < 0.001), with longer waitlist times (203 versus 145 d; P < 0.001), were more likely to remove patients from the waitlist due to death or deterioration (24.1% versus 14.6%; P < 0.001), less likely to transplant listed patients (63.1% versus 77.6%; P < 0.001), and had a lower likelihood of survival 1 year after listing (79.2% versus 91.6%; odds ratio, 1.6; 95% confidence interval, 1.2-2.0; P < 0.001) compared with low RR centers. Patients listed at high RR centers had worse survival from listing despite having shorter times to first offer.

UNOS Match Runs for Pediatric Heart Transplant Organ Allocation—How Well Do They Sequence Patients Based on Medical Urgency?

<h3>Purpose</h3> The match run is the automated mechanism by which UNOS prioritizes donor hearts to waitlist candidates for heart transplant (HT) based on medical urgency. We sought to determine how well match runs perform in sequencing patients according to their medical urgency after implementation of the 2016 pediatric heart allocation revisions. <h3>Methods</h3> OPTN data were used to identify all match runs between March 21, 2016 and June 9, 2020 for each pediatric donor heart offered through UNOS to US waitlist candidates. The rank-order of candidates on the match run was compared to the rank-order based on medical urgency alone defined as the probability of survival on the day of the match run using a risk prediction model developed and validated during the prior 6 years. <h3>Results</h3> Overall, 634 donors generated 2,524 unique match runs during the study period when a total of 2,608 candidates were listed for pediatric HT. The median age of donors was 5 years (Q1, Q3, 1, 13), median weight 21 (11, 54) kg with the most common cause of death natural causes (26%), non-motor vehicle accidents (MVA) (22%) and MVA (16%). The risk-prediction model for death or deterioration included 8 variables (age, weight, cardiac diagnosis and cardiac support). When the survival model was applied to the match run candidates within zone, 26% of candidates were ranked out of survival order (i.e. had a rank-reversal) (<b>Table</b>). Of these, 69% of rank-reversals involved candidates <i>within</i> the same UNOS status levels whereas 41% involved candidates spread across UNOS status levels. <h3>Conclusion</h3> There is evidence to suggest that the 2016 revision to the pediatric donor heart allocation system fails to sequence waitlisted candidates according to medical urgency, which affects a substantial fraction of match runs. Misclassification of patient risk by UNOS status level and within UNOS status levels each contribute rank-reversals. Rank-ordering patients based on a continuous survival probability model could address both problems.

Donor Bicuspid Aortic Valve: Double Trouble or No Problem?

<h3>Introduction</h3> Valvular disease in pediatric donor hearts may be a relative contraindication to graft use. Outcomes following use of donor hearts with milder forms of valvular disease have not been previously reported. We describe 4 cases of pediatric heart transplantation (HTx) in which the donor heart had a bicuspid aortic valve (BAV). <h3>Case Report</h3> Of the 469 HTx performed at our center since 1985, 4 donor hearts had a BAV. All recipients were female; median age 11 years (range 0.3 to 19 years). In all cases, the BAV was not discovered until after HTx. All donors were less than 30 years old. The patients were followed for a median of 6 years (range 2 to 9 years) with all patients alive at last follow up. Two patients transferred to adult care and 2 patients are followed by our clinic. In follow up, no patient required an aortic valve intervention or had infective endocarditis. At last review, no patient had greater than mild aortic insufficiency or more than mild aortic stenosis. Three patients developed mild to moderate left ventricular hypertrophy in the first year post-transplant that improved over time. One patient experienced a peri-operative embolic stroke at time of transplant unrelated to the bicuspid aortic valve. <h3>Summary</h3> On short- and intermediate-term follow up, donor hearts with bicuspid aortic valve demonstrated acceptable graft longevity and valvular function. A functionally normal bicuspid aortic valve in a pediatric heart transplant donor should not be a contraindication to organ acceptance.

Does pediatric heart transplant survival differwith variouscardiac preservation solutions?

Few studies directly compare outcomes between the most commonly used preservation solutions in pediatric heart transplantation in a large cohort of recipients. The purpose of this study is to investigate the effect of cardiac preservation solution on survival in pediatric heart transplant recipients. The United Network for Organ Sharing (UNOS) database was retrospectively reviewed from 01/2004-03/2018 for pediatric donor hearts. Saline, University of Wisconsin (UW), "cardioplegia," Celsior, and Custodiol preservation solutions were evaluated. The primary endpoints wererecipient survival at 30days, 1year, and long term. Afterexclusion criteria, 3012 recipients had preservation solution data available. The most common preservation solution used was UW in 1203 patients (40%), followed by Celsior in 542 (18%), cardioplegia in 461 (15%), saline in 408 (14%), and Custodiol in 398 (13%). Survival of recipients whose donor hearts were procured with UW was as follows: 97%-30day, 92%-1year; Celsior: 97%-30day, 92%-1year; cardioplegia: 97%-30day, 91%-1year; saline: 97%-30day, 91%-1year; and Custodiol: 96%-30day and 92%-1year. Analysis of Cox models for 30-day and long-term survival revealed no statistical differences when comparing UW to Celsior (p=.333), cardioplegia (p=.914), saline (p=.980), or Custodiol (p=.642) in adjusted models. There were no significant differences in 30-day or 1-year survival detected between commonly used preservation solutions in the pediatric heart transplant population.

A comprehensive strategy in donor acceptance: Impact on pediatric waitlist and heart transplant outcomes.

Significant inter- and intra-center practice variability is present in pediatric donor heart acceptability. This may contribute to variation in the donor refusal rate and may impact waitlist time, morbidity, mortality, and transplant rates. In order to reduce practice variability, our center developed and implemented a comprehensive strategy regarding donor acceptance in September 2017. The aim of this study was to assess the impact of this strategy on waitlist time and outcomes as well as early post-transplant outcomes. We performed a single-center, retrospective analysis of all pediatric (<18years) patients listed for single-organ heart transplant at our center from September 2015 to September 2018. Patients were divided into those listed before (Group 1) and after implementation of the comprehensive strategy (Group 2). The primary end-point was waitlist time. Secondary end-points included waitlist removal due to death or clinical deterioration, donor refusals per listed patient, early post-transplant outcomes (graft failure, mechanical ventilation time, inotropic support, length of hospital stay) and 1-year post-transplant survival. Of 78 listed patients, 54 were transplanted (29 in Group 1), 9 were removed due to death or clinical deterioration (7 in Group 1) and 15 were removed due to clinical improvement (12 in Group 1). The waitlist time was significantly shorter in Group 2 (17days, IQR 7-53) vs Group 1 (90days, IQR 14-162); P=.006. The number of donor refusals was lower in Group 2 (1, IQR 0-2.2) vs Group 1 (4, IQR 2-19); P<.001. The percentage of refused donors with normal function (Left ventricular ejection fraction>50%) was lower in Group 2 vs Group 1 (53% vs 84%; P<.001). Difference in removal from the waitlist for death or deterioration in Group 2 vs Group 1 (n=2, 7% vs n=7, 20%, P=.18) did not reach statistical significance. There was no difference in post-transplant outcomes between groups. The waitlist time and donor refusals significantly decreased after implementation of a comprehensive donor acceptance strategy without impacting transplant outcomes. This analysis supports the need for a comprehensive approach to donor organ acceptance within a pediatric transplant center.