Aorto-pulmonary relationship, arterio-ventricular alignment, and ventricular septal defects in complete transposition of the great arteries.

A study of the conal anatomy of 36 specimens of complete transposition of the great arteries (TGA) is reported. The aim of the investigation was to verify if the two main anatomic features of the malformation, i.e. abnormal aorto-pulmonary and arterioventricular relationships, were strictly related to the maldevelopment of the conal structures. The findings indicate that in the cases with mitro-pulmonary fibrous continuity, there is a wide variation in subaortic conal development. and no correlation exists between the anterior position of the aorta and the length of the subaortic parietal conus. Therefore, differential conal absorption does not seem to play a role in the presumptive lack of rotation in TGA. TGA presenting with bilateral conus and biventricular pulmonary trunk origin are relatively frequent in this survey, but no correlation was observed between overriding of the pulmonary artery and development of the subpulmonary parietal conus. Consequently, in TGA the morphogenetic process of transfer of the pulmonary artery above the left ventricle does not seem to depend only on the absorption of the subpulomonary parietal conus. Ventricular septal defects (VSDs) in TGA are related frequently to conal pathology, either to some failure in conal septal growth or to malalignment of the normally developed conal and sinusal components of the ventricular septum.