Listing Low-Weight or Ill Infants for Heart Transplantation: Is It Prudent?

Infants Who Require Total Parenteral Nutrition and Paralytics at Time of Heart Transplant Experience Inferior Post-Transplant Mortality

Background: Infants experience the worst one-year post-heart transplant (HTx) survival of any other pediatric group. Although mechanical ventilatory (MV) requirement at the time of transplant is an established predictor of post-transplant mortality, the impacts of commonly co-utilized support modalities such as total parenteral nutrition (TPN)-dependence and paralytics are understudied. Methods: All infant HTx recipients from 2003 to 2020 in both the United Network for Organ Sharing and Pediatric Health Information System databases were identified (n = 1344) and categorized depending upon support requirement at the time of transplant—none (59%), MV-only (10%), MV + Paralytics (2%), TPN-dependence-only (15%), MV + TPN (10%), and MV + Paralytics + TPN (4%). The primary study aim was to characterize the impact of TPN-dependence and paralytics on one-year post-transplant survival (PTS). Results: Compared to no-support, supported infants were generally at higher risk and more ill at transplant, with greater rates of congenital heart disease, renal and hepatic dysfunctions, and inotrope requirements. Post-transplant hospital outcomes were inferior among supported patients; all support groups experienced longer post-transplant MV, intensive care unit, and hospital lengths of stay (all P < .05 vs no-support). Upon multivariable analysis, each support modality independently predicted 1-year mortality (MV vs no-MV: 1.54 [1.10-2.14]; MV + Paralytics vs neither: 2.02 [1.25-3.27]; TPN vs no-TPN: 1.53 [1.10-2.13]; P < .01 for all), whereas no-support was protective (HR 0.66 [95% CI 0.48-0.91]). Conclusions: Infants who require paralytics and/or who are TPN-dependent at the time of HTx experience worse one-year PTS. Such knowledge can assist in risk-stratification, and the identification of patients who would benefit from pretransplant optimization.

Waitlist and posttransplant outcomes of critically ill infants awaiting heart transplantation managed without ventricular assist device support

BACKGROUND

Infants listed for heart transplant are at high risk for waitlist mortality. While waitlist mortality for children has decreased in the current era of increased ventricular assist device use, outcomes for small infants supported by ventricular assist device remain suboptimal. We evaluated morbidity and survival in critically ill infants listed for heart transplant and managed without ventricular assist device support.

METHODS

Critically ill infants (requiring ≥1 inotrope and mechanical ventilation or ≥2 inotropes without mechanical ventilation) listed between 2008 and 2019 were included. During the study period, infants were managed primarily medically. Mechanical circulatory support, specifically extracorporeal membrane oxygenation, was utilized as "rescue therapy" for decompensating patients.

RESULTS

Thirty-two infants were listed 1A, 66% with congenital heart disease. Median age and weight at listing were 2.2 months and 4.4 kg, with 69% weighing <5 kg. At listing, 97% were mechanically ventilated, 41% on ≥2 inotropes, and 25% under neuromuscular blockade. Five patients were supported by ECMO after listing. A favorable outcome (transplant or recovery) was observed in 84%. One-year posttransplant survival was 92%. Infection was the most common waitlist complication occurring in 75%. Stroke was rare, occurring in one patient who was supported on ECMO. Renal function improved from listing to transplant, death, or recovery (eGFR 70 vs 87 ml/min/1.73m² , p = .001).

CONCLUSION

A strategy incorporating a high threshold for mechanical circulatory support and acceptance of prolonged mechanical ventilation and neuromuscular blockade can achieve good survival and morbidity outcomes for critically ill infants listed for heart transplant.

Pediatric heart transplantation in infants and small children under 3 years of age: Single center experience - "Early and long-term results"

OBJECTIVES

We analyzed the early and long-term survival after ABO-compatible heart transplantation in children under 3 years of age from 1991 to 2021 at our center. This retrospective and descriptive study aimed to identify serious adverse events associated with mortality after pediatric heart transplantation.

PATIENTS AND METHODS

46 patients with congenital heart failure (37%) in end-stage heart failure have undergone a pediatric heart transplantation. Primary outcome of interest was survival at follow-up time.

RESULTS

Median (IQR) follow-up time (y), age (y), body-weight (kg) and BMI (kg/cm²) were 13.2 (5.7-19.5), 0.9 (0.2-2.0), 6.8 (4.3-10.0) and 14.2 (12.3-15.7). Twenty-four (52%) patients were male. 15 patients (33%) had a single ventricle physiology. At 30- days survival rate was 94 ± 4%. Survival rate at 1, 5, 10 and 15 years post HTx was 87 ± 5%, 84 ± 6%, 79 ± 6% and 63 ± 8%. One child underwent re-transplantation after 4 years, and another one after 11 years - in both cases due to graft failure. Higher early mortality in patients under 3 months of age and in patients with single ventricle physiology. Transplant free survival at 15 years was in children with cardiomyopathy better (71 ± 10%) than in those with congenital heart disease (50 ± 13%). One or more previous heart surgeries prior to HTx (n = 21) were associated to more mortality.

CONCLUSION

Pediatric heart transplantation has acceptable long-term results and is still the best therapeutic option in children with end-stage cardiac failure. Underlying anomalies and single ventricle physiology, age below 3 months had a significant impact on survival.

The Genetically Engineered Heart as a Bridge to Allotransplantation in Infants Just Around the Corner?

BACKGROUND

Mortality for infants on the heart transplant wait list remains unacceptably high, and available mechanical circulatory support is suboptimal. Our goal is to demonstrate the feasibility of utilizing genetically engineered pig (GEP) heart as a bridge to allotransplantation by transplantation of a GEP heart in a baboon.

METHODS

Four baboons underwent orthotopic cardiac transplantation from GEP donors. All donor pigs had galactosyl-1,3-galactose knocked out. Two donor pigs had human complement regulatory CD55 transgene and the other 2 had human complement regulatory CD46 and thrombomodulin. Induction immunosuppression included thymoglobulin, and Anti-CD20. Maintenance immunosuppression was Rapamycin, AntiCD-40 and methylprednisolone. One donor heart was preserved with University of Wisconsin (UW) solution and the other three with del Nido solution.

RESULTS

All baboons weaned from cardiopulmonary bypass. B217 received a donor heart preserved with UW. Ventricular arrhythmias and depressed cardiac function resulted in early death. All recipients of del Nido preserved hearts easily weaned from cardiopulmonary bypass with minimal inotropic support. B15416 and B1917 survived for 90 days and 241 days respectively. Histopathology in B15416 revealed no significant myocardial rejection but cellular infiltrate around Purkinje fibers. Histopathology in B1917 was consistent with severe rejection. B37367 had uneventful transplant but developed significant respiratory distress with a cardiac arrest.

CONCLUSIONS

Survival of B15416 and B1917 demonstrates the feasibility of pursuing additional research to document the ability to bridge an infant to cardiac allotransplant with a GEP heart.

Heart Transplantation of a Preterm Infant With HLHS

A 33-week gestation, 1.75-kg female infant with mitral stenosis/aortic atresia variant of hypoplastic left heart syndrome and severe ventriculo-coronary connections underwent surgical septectomy and bilateral pulmonary artery banding at five weeks of age (2.10 kg). After separation from bypass, she developed hemodynamic instability requiring venoarterial extracorporeal membrane oxygenation support. She was listed for heart transplantation and transplanted after three days of support with an oversized heart (4.7:1 donor-recipient weight ratio).

The reality of limping to pediatric heart transplantation

OBJECTIVE

Improvements in surgical technique, critical care, and early repair for congenital heart disease (CHD) have led to improved outcomes with heart transplantation, often used as a salvage procedure after failed palliation, especially in infants. These patients, however, often have several risk factors for poor posttransplant survival. We aimed to identify the reality of survival after heart transplantation in patients "limping to transplant" with common risk factors.

METHODS

All heart transplant recipients younger than 18 years were identified from the UNOS data set from 2000 to 2017. Modifiable risk factors (MRFs) of mechanical ventilation, renal dysfunction, and liver dysfunction at transplant and nonmodifiable risk factors of infancy at listing or CHD were examined. One-year posttransplant survival was analyzed with logistic regression.

RESULTS

Of 4101 transplants, 1459 patients (36%) had 1 or more MRFs. There was a decrease in 1-year survival with additional MRFs up to a 9.1-times increased risk of death in an infant with CHD. A noninfant without CHD and no MRFs had a 95% 1-year survival, in contrast to an intubated patient with CHD without other end-organ dysfunction, who had 1-year survival of 76%, which decreased to 58% if they were an infant and also had renal dysfunction.

CONCLUSIONS

Patients "limping to transplant" with multiple risk factors demonstrates decreasing early survival relative to those without other end-organ dysfunction. It is imperative that we have transparent discussions about expected outcomes with these families and identify ways to optimize patients' conditions through other supportive avenues to improve posttransplant outcomes.