Neonatal heart transplant outcomes: A single institutional experience

Neonatal heart transplantation in the United States: Trends and outcomes

BACKGROUND

Heart transplantation in the neonatal period is associated with excellent survival. However, outcomes data are scant and have been obtained primarily from two single-center reports within the United States. We sought to analyze the outcomes of all neonatal heart transplants performed in the United States using the United Network for Organ Sharing (UNOS) dataset.

METHODS

The UNOS dataset was queried for patients who underwent infant heart transplantation from 1987 to 2021. Patients were divided into two groups based on age - neonates (<=31 days), and older infants (32 days-365 days). Demographic and clinical characteristics were analyzed and compared, along with follow up survival data.

RESULTS

Overall, 474 newborns have undergone heart transplantation in the United States since 1987. Freedom from death or re-transplantation for neonates was 63.5%, 58.8% and 51.6% at 5, 10, and 20 years, respectively. Patients in the newborn group had lower unadjusted survival compared to older infants (p < .001), but conditional 1-year survival was higher in neonates (p = .03). On multivariable analysis, there was no significant difference in survival between the two age groups (p = .43). Black race, congenital heart disease diagnosis, earlier surgical era, and preoperative mechanical circulatory support use were associated with lower survival among infant transplants (p < .05).

CONCLUSIONS

Neonatal heart transplantation is associated with favorable long-term clinical outcomes. Neonates do not have a significant survival advantage over older infants. Widespread applicability is limited by the small number of available donors. Efforts to expand the donor pool to include non-standard donor populations ought to be considered.

Surgical Protocol for Partial Heart Transplantation in Growing Piglets

Partial heart transplantation is a new approach to deliver growing heart valve implants. Partial heart transplants differ from heart transplants because only the part of the heart containing the necessary heart valve is transplanted. This allows partial heart transplants to grow, similar to the valves in heart transplants. However, the transplant biology of partial heart transplantation remains unexplored. This is a critical barrier to progress of the field. Without knowledge about the specific transplant biology of partial heart transplantation, children with partial heart transplants are empirically treated like children with heart transplants because the valves in heart transplants are known to grow. In order to progress the field, an animal model for partial heart transplantation is necessary. Here, we contribute our surgical protocol for partial heart transplantation in growing piglets. All aspects of partial heart transplantation, including the donor procedure, the recipient procedure, and recipient perioperative care are described in detail. There are important nuances in the conduct of virtually all aspects of open heart surgery that differs in piglets from humans. Our surgical protocol, which is based on our experience with 34 piglets, will allow other investigators to leverage our experience to seek fundamental knowledge about the nature of partial heart transplants. This is significant because the partial heart transplant model in piglets is complex and very resource intensive.

Partial heart transplantation: Growing heart valve implants for children

Heart valves serve a vital hemodynamic function to ensure unidirectional blood flow. Additionally, native heart valves serve biological functions such as growth and self-repair. Heart valve implants mimic the hemodynamic function of native heart valves, but are unable to fulfill their biological functions. We developed partial heart transplantation to deliver heart valve implants that fulfill all functions of native heart valves. This is particularly advantageous for children, who require growing heart valve implants. This invited review outlines the past, present and future of partial heart transplantation.

Partial Heart Transplantation - How to Change the System

Partial heart transplantation is the first clinically successful approach to deliver growing heart valve implants. To date, 13 clinical partial heart transplants have been performed. However, turning partial heart transplantation into a routine procedure that is available to all children who would benefit from growing heart valve implants poses formidable logistical challenges. Firstly, a supply for partial heart transplant donor grafts needs to be developed. This challenge is complicated by the scarcity of donor organs. Importantly, the donor pools for orthotopic heart transplants, partial heart transplants and cadaver homografts overlap. Secondly, partial heart transplants need to be allocated. Factors relevant for equitable allocation include the indication, anatomical fit, recipient clinical status and time on the wait list. Finally, partial heart transplantation will require regulation and oversight, which only recently has been undertaken by the Food and Drug Administration, which regulates human cellular and tissue-based products. Overcoming these challenges will require a change in the system. Once this is achieved, partial heart transplantation could open new horizons for children who require growing tissue implants.

Partial Heart Transplant in a Neonate With Irreparable Truncal Valve Dysfunction

Importance

The treatment of neonates with irreparable heart valve dysfunction remains an unsolved problem because there are no heart valve implants that grow. Therefore, neonates with heart valve implants are committed to recurrent implant exchanges until an adult-sized valve can fit.

Objective

To deliver the first heart valve implant that grows.

Design, Setting, and Participants

Case report from a pediatric referral center, with follow-up for more than 1 year. Participants were a recipient neonate with persistent truncus arteriosus and irreparable truncal valve dysfunction and a donor neonate with hypoxic-ischemic brain injury.

Intervention

First-in-human transplant of the part of the heart containing the aortic and pulmonary valves.

Main Outcomes and Measures

Transplanted valve growth and hemodynamic function.

Results

Echocardiography demonstrated adaptive growth and excellent hemodynamic function of the partial heart transplant valves.

Conclusions and Relevance

In this child, partial heart transplant delivered growing heart valve implants with a good outcome at age 1 year. Partial heart transplants may improve the treatment of neonates with irreparable heart valve dysfunction.

Partial heart xenotransplantation: A research protocol in non-human primates

Partial heart transplantation is a new type of transplant that delivers growing heart valve replacements for babies. Partial heart transplantation differs from orthotopic heart transplantation because only the part of the heart containing the heart valve is transplanted. It also differs from homograft valve replacement because viability of the graft is preserved by tissue matching, minimizing donor ischemia times, and recipient immunosuppression. This preserves partial heart transplant viability and allows the grafts to fulfill biological functions such as growth and self-repair. These advantages over conventional heart valve prostheses are balanced by similar disadvantages as other organ transplants, most importantly limitations in donor graft availability. Prodigious progress in xenotransplantation promises to solve this problem by providing an unlimited source of donor grafts. In order to study partial heart xenotransplantation, a suitable large animal model is important. Here we describe our research protocol for partial heart xenotransplantation in nonhuman primates.

Growing Heart Valve Implants for Children

The current standard of care for pediatric patients with unrepairable congenital valvular disease is a heart valve implant. However, current heart valve implants are unable to accommodate the somatic growth of the recipient, preventing long-term clinical success in these patients. Therefore, there is an urgent need for a growing heart valve implant for children. This article reviews recent studies investigating tissue-engineered heart valves and partial heart transplantation as potential growing heart valve implants in large animal and clinical translational research. In vitro and in situ designs of tissue engineered heart valves are discussed, as well as the barriers to clinical translation.

Survival After Intervention for Single-Ventricle Heart Disease Over 15 Years at a Single Institution

BACKGROUND

Children with single-ventricle (SV) heart disease possess a spectrum of heart malformations, yet progress through similar hemodynamic states, suggesting differences in outcomes are related to fundamental morphologic differences, patient characteristics, or procedural pathways. We sought to provide a holistic overview of survival after intervention for SV heart disease at our institution.

METHODS

SV heart disease was defined as patients born with a hypoplastic or dysfunctional ventricle with uncertain or unacceptable candidacy for a 2-ventricle circulation. Patients were stratified into 8 diagnostic groups and 11 procedural categories based on the initial interventional procedure.

RESULTS

Between 2005 and 2020, 381 patients born with SV heart disease underwent intervention at our institution. Ten-year survival was highest for patients with double inlet left ventricle (89% ± 7%) and lowest for patients with hypoplastic left heart syndrome (55% ± 5%). Initial palliation with less invasive procedures, such as ductal stent (4-year: 100%) or pulmonary artery banding (10-year: 95% ± 5%), demonstrated superior survival compared with more invasive procedures such as the Norwood procedure (10-year: 59% ± 4%). Survival of patients who achieved a biventricular circulation was superior to patients who remained with SV physiology (10-year: 87% ± 5% vs 63% ± 3%, P = .04). In a multivariable analysis, chromosomal/syndromic abnormality, lower weight, hybrid Norwood procedure, nonleft ventricular dominance, and earlier year of operation were risk factors for death.

CONCLUSIONS

Survival differences in patients with SV heart disease were related primarily to underlying cardiac anatomy, patient characteristics, and procedural complexity. Left ventricular dominance, more recent intervention, and attainment of a 2-ventricle circulation were associated with improved survival.