Successful surgical correction of (la estenosis pulmonar en la tetralogía de Fallot), requires that the postoperative ratio between the (right ventricular pressure) and (left ventricular pressure) (PVD/PVI) be less than 0.70. By measuring the ring diameter and pulmonary branch on relation to the (superficie corporal) it is possible to predict the outcome of this ratio and therefore indicate whether or not it is necessary to increase (AP). This paper presents our experience with 24 patients subjected to total correction of (tetralogía de Fallot) from March of 1975 to the present using the above criteria. The average age was 7 years (ranging from 2 to 20). In all cases the (cresta supraventricular) was (resected). In 14 (58%) a (valvultomia pulmonar) was performed and in 9 patients (37) it was necessary to increase the ring and pulmonary branch of the pulmonary artery according to measurements taken. The post-operative relationship PVD/PVI was 0.2-0.3: 15%, 0.4-0.5: 60%, 0.6-0.7: 25% In no case was the ratio greater than 0.70. No significant difference was found between those cases requiring... (parche transanular) and those where such treatment was not necessary. Three patients (12%) died immediately following the operation. It is concluded that measurement of the diameter of the pulmonary ring in comparison to the (superficie corporal) is extremely useful in management during surgery of (estenosis pulmonar) in patients with (tetralogía de Fallot).