Figure 21: A – The hypoplastic RV (‘RV’) in a heart with tricuspid atresia is demarcated by the LAD anteriorly and a posterior delimiting artery (PD) at the acute margin of the heart. B – The posterior aspect of the heart in another case of tricuspid atresia. In addition to the delimiting artery (PD) at the acute margin there is a large branch that descends from the crux (Cr) of the heart.