Suitability of Infant Heart Transplant Recipients to Serve as Domino Partial Heart Transplant Donors

Partial heart transplantation is a new type of transplant that provides growing heart valve substitutes for infants with unrepairable heart valve dysfunction [1]. Partial heart transplants differ from heart transplants because only the part of the heart containing the necessary valve is transplanted, while the native ventricles are spared. Sparing the native ventricles has two important advantages. On the one hand, the risk of graft ventricular dysfunction is eliminated [2]. On the other hand, donor hearts with ventricular dysfunction can be used. This allows for domino partial heart transplantation using cardiectomy hearts from heart transplant recipients [3]. In the United States alone, there are over 100 infant heart transplant recipients per year [3]. However, it is unknown what proportion of infant heart transplant recipients are suitable domino partial heart transplant donors. Ethics approval was obtained from the Institutional Review Board at the University of Arkansas for Medical Sciences (protocol 298112). We retrospectively reviewed all heart transplant recipients at a single institution for their suitability as domino partial heart transplant donors. The inclusion criteria were all children who received a heart transplant between 2016 and 2024. Exclusion criteria were age older than 1 year at the time of the heart transplant, and absence of an echocardiogram within 2 weeks before the heart transplant. Suitability for domino partial heart transplantation was defined based on echocardiography reports as normal valve structure, no valve hypoplasia (z-score > −2), and no more than mild regurgitation or stenosis. A total of 17 consecutive infant heart transplant recipients were included. The cardiac diagnoses were complex single ventricle defects in 59% (n = 10/17), cardiomyopathy in 24% (n = 4/17) and critical aortic stenosis in 18% (n = 3/17) (Figure 1A). The total frequency of infant heart transplant recipients' valves that were suitable for domino partial heart transplantation was 71% (n = 24/34). Of those, two suitable valves were present in 35% of patients (n = 6/17). Based on the cardiac diagnosis, the frequency of suitable aortic and pulmonary valves was 80% (aortic/neo-aortic = 8/10) and 40% (pulmonary = 4/10) for complex single ventricle defects, 100% (aortic = 4/4) and 100% (pulmonary = 4/4) for cardiomyopathy, and 0% (aortic = 0/3) and 100% (pulmonary = 3/3) for critical aortic stenosis (Figure 1B). In summary, our data show that domino partial heart transplantation has the potential to contribute a substantial number of suitable valves. Heart transplant recipients with cardiomyopathy are universally suitable as domino partial heart transplant donors in this small cohort of patients. Many domino hearts can also be partitioned to provide separate aortic and pulmonary valve grafts. These new strategies amplify the benefit of each donor's heart to benefit a cascade of recipients [4]. The data that support the findings of this study are available from the corresponding author upon reasonable request.