Truncus arteriosus with anterior origin of a hypoplastic main pulmonary artery.

A newborn with an unusual form of truncus arteriosus is described, whose clinical presentation and certain features of her anatomy were more typical of pulmonary atresia with a ventricular septal defect. The morphological differentiation of certain types of truncus arteriosus and pulmonary atresia with ventricular septal defect remains an area of speculation among cardiac pathologists, and research in this area is being done using animal models. The anatomic features of the heart described in this report may assist in this discussion as the application of observations made in animal models to human cardiac development may be problematic.