Background: The Fontan procedure encompasses a variety of surgical techniques employed in patients with single ventricle congenital defects that would otherwise prove fatal.1 As an increasing number of individuals with Fontan physiology survive to adulthood, many will require either orthotopic heart transplant (OHT) or combined heart-liver transplant (CHLT) as a final therapeutic option.1OHT/CHLT in adults with congenital heart disease is a complex transplant procedure owing to multiple factors including prior cardiac surgeries, complex cardiac physiology, multiple organ involvement, and immunological sensitization.2 While recent publications indicate improved post-transplant outcomes, questions remain as to how to properly size donor organs as well as predictors of survival and morbidity for those undergoing OHT/CHLT.1

Methods: Retrospectively, 30 adult patients with failing Fontan physiology who underwent OHT or CHLT at UCLA from 2010-2020 were identified for a descriptive analysis of clinical data. Data collected included patient history, donor/recipient organ listing details, and transplant details. PHM and PHM ratios were calculated using the Calculate by QxMD Calculator and the UNOS PHM Match Calculator. 

Results: Previous work by Kransdorf et al. (2018) found that a donor to recipient PHM ratio as low as 0.83 results in acceptable post-transplant outcomes. We found that when using our current selection factors (donor to recipient height ratios, weight ratios, age, cross-sectional imaging to directly measure donor and recipient cardiac and liver dimensions), the donor to recipient PHM ratio would be considered “moderately oversized.” Despite concern for oversized donor livers, the mean donor to recipient PHM ratios in our patient population were comparable for OHT versus CHLT. 

This study was limited by a relatively small sample size given the small number of individuals undergoing OHT/CHLT for failing Fontan physiology, rendering it difficult to draw conclusions about factors impacting survival. Furthermore, differences in surgeons, technique and approach to risk modification in the Fontan patient are important confounders.