[Spontaneous course towards pulmonary atresia of Fallot's tetralogy. Theoretical and practical aspects].

A case of severe Fallot's tetralogy is presented; there was angiographic evidence of progression towards pulmonary atresia. The relationship between Fallot's tetralogy and pulmonary atresia with open septum is discussed, as is the variability of the pulmonary circulation found in cases of pulmonary atresia with septal defect, and the treatment is also discussed.