Cardiac structures in marine animals provide insight on potential directions for interventions for pediatric congenital heart defects.

Despite recent advances in pediatric diagnosis and surgical intervention, mortality and morbidity continue to be a prevalent issue in both tetralogy of Fallot (ToF) and hypoplastic left heart syndrome (HLHS). Therefore, novel approaches to studying both of these conditions are warranted. Investigating cardiac anatomical features of different species in the animal kingdom that are similar to the defects and complications present in ToF and HLHS (as well as others) could serve as a new avenue for improving the management of congenital heart diseases (CHD). This review reveals that although some structures found in HLHS and ToF are pathological, similar structures can be found in diving mammals and reptiles that are adaptive. Pathological aortic dilation in CHD resembles the aortic bulb present in diving mammals, but the latter is more elastic and distensible compared with the former. The unrepaired HLHS heart resembles the univentricular heart of non-crocodilian reptiles. Right ventricle hypertrophy is pathological in HLHS and ToF, but in contrast, adaptive in crocodilians and diving mammals. Lastly, the increased pulmonary resistance due to pulmonary stenosis in ToF is comparable with increased pulmonary resistance in crocodilians due to the presence of an active valve proximal to the pulmonary valve. Some of these anatomical structures could potentially be adapted for palliative surgery in children with HLHS or ToF. Moreover, further investigating the underlying molecular signals responsible for the adaptive tissue responses seen in other species may also be useful for developing novel strategies for preventing some of the complications that occur after surgical repair in both of these congenital heart diseases.