Background The treatment of babies with unrepairable heart valve dysfunction remains an unsolved problem because there are no growing heart valve implants. However, orthotopic heart transplants are known to grow with recipients. Aim Partial heart transplantation is a new approach to delivering growing heart valve implants, which involves transplantation of the part of the heart containing the valves only. In this review, we discuss the benefits of this procedure in children with unrepairable valve dysfunction. Conclusion Partial heart transplantation can be performed using donor hearts with poor ventricular function and slow progression to donation after cardiac death. This should ameliorate donor heart utilization and avoid both primary orthotopic heart transplantation in children with unrepairable heart valve dysfunction and progression of these children to end‐stage heart failure.

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.

Pediatric valvar heart disease continues to be a topic of interest due to the common and severe clinical manifestations. Problems with heart valve replacement, including lack of adaptive valve growth and accelerated structural valve degeneration, mandate morbid reoperations to serially replace valve implants. Homologous or homograft heart valves are a compelling option for valve replacement in the pediatric population but are susceptible to structural valve degeneration. The immunogenicity of homologous heart valves is not fully understood, and mechanisms explaining how implanted heart valves are attacked are unclear. It has been demonstrated that preservation methods determine homograft cell viability and there may be a direct correlation between increased cellular viability and a higher immune response. This consists of an early increase in human leukocyte antigen (HLA)-class I and II antibodies over days to months posthomograft implantation, followed by the sustained increase in HLA-class II antibodies for years after implantation. Cytotoxic T lymphocytes and T-helper lymphocytes specific to both HLA classes can infiltrate tissue almost immediately after implantation. Furthermore, increased HLA-class II mismatches result in an increased cellmediated response and an accelerated rate of structural valve degeneration especially in younger patients. Further long-term clinical studies should be completed investigating the immunological mechanisms of heart valve rejection and their relation to structural valve degeneration as well as testing of immunosuppressant therapies to determine the needed immunosuppression for homologous heart valve implantation.

Many young adults require heart valve replacements. Current options for valve replacement in adults include mechanical valves, bioprosthetic valves, or the Ross procedure. Of these, mechanical and bioprosthetic valves are the most common options, although mechanical valve usage predominates in younger adults due to durability, while bioprosthetic valve usage predominates in older adults. Partial heart transplantation is a new method of valvular replacement that can deliver durable and self-repairing valves and allow adult patients freedom from anticoagulation therapy. This procedure involves transplantation of donor heart valves only, permitting expanded utilization of donor hearts as compared with orthotopic heart transplantation. In this review, we discuss the potential benefits of this procedure in adults who elect against the anticoagulation regimen required of mechanical valve replacements, although it has not yet been clinically established. Partial heart transplantation is a promising new therapy for the treatment of pediatric valvular dysfunction. This is a novel technique in the adult population with potential utility for valve replacement in young patients for whom anticoagulation therapy is problematic, such as women who wish to become pregnant, patients with bleeding disorders, and patients with active lifestyles.

Objectives. Heart transplantation (HT) is a definitive therapy for refractory heart failure, making it the gold-standard treatment for recipients with end-stage disease. Heart allocation policy (HAP) in the United States was changed on October 18th, 2018. The aim of this study was to assess the effect of the new policy on racial disparities in heart transplantation (HT) outcomes. Methods. The United Network for Organ Sharing (UNOS) registry was used to identify adult recipients undergoing isolated HT between 2010 and 2021. Recipients were stratified into pre-HAP (January 2010 to September 2018) vs. post-HAP (October 2018 to September 2021). Recipient race was classified as White, Black, Hispanic, or other. The primary outcome was post-HT mortality. Cox proportional hazard models were used for risk-adjustment in evaluating the independent effect of race on post-HT mortality. Results. A total of 27,403 recipients underwent HT in 143 centers during study period. The proportion of non-Whites undergoing HT increased in the post-HAP era: (pre-HAP: White 66.0%, Black 21.2%, Hispanic 8.2%, Other 4.6% versus post-HAP: White 62.5%, Black 23.2%, Hispanic 9.5%, Other 4.8%; p < 0.001 ). In risk-adjusted analysis, Black recipients were at higher risk of post-HT mortality in the pre-HAP era (HR 1.31, 95% CI 1.22–1.41; p < 0.001 ) but not in the post-HAP era (HR 1.12, 95% CI 0.03–1.34; p = 0.222 ) compared to White recipients. Other non-White recipients had comparable risk-adjusted post-HT mortality rates compared to White recipients both in the pre-HAP and post-HAP eras. Conclusions. Under the new heart allocation system, a higher percentage of recipients are non-White. In addition, racial disparities in HT outcomes have improved with Black recipients no longer having an increased risk-adjusted mortality following HT.