[Essence of the tetralogy of Fallot from the standpoint of conus arteriosus formation].

Morphogeometric study of 10 normal hearts and 10 hearts with tetrad of Fallot showed that this anomaly is marked by incomplete inversion of the conotruncus, as a result of which the aorta takes a position to the right of the pulmonary artery. In tetrad of Fallot, the supraventricular crista does not form, and the parietal end of the conal septum is displaced to the front and is attached to the anterior wall of the right ventricle. This displacement determines, for the most part, the constriction of the infundibulum of the right ventricle. The ventricular septal defect forms in this anomaly not because of lack of septal tissue, but because the planes of the conal and ventricle septa do not coincide.