[Importance of echocardiography in the evaluation of surgical results in the tetralogy of Fallot].

M mode echocardiography was performed one year after surgical correction of Fallot's tetralogy in 32 patients (average age: 2, 7 years). All patients were asymptomatic without treatment and the average cardiothoracic ratio was 0,56 +/- 0,03. Echocardiographic indices of left ventricular function distinguished 4 patients with myocardial dysfunction (2 cases of poor myocardial protection and 2 double Blalock-Taussig anastomoses). Right ventricular diastolic internal dimensions were increased in 75 % cases. The ratio of right to left ventricular internal dimension was used to classify patients into three groups: Group I (ratio Less Than 0,70) 17 patients; Group II (ratio 0,70 Greater Than 0,80) 4 patients, and Group III (ratio Greater Than 0,80) 11 patients. This ratio was not related to the age of the patient of surgery or to the type of patch used on the right ventricular outflow tract but was related to the pressures recorded at operation after correction. A ratio Greater Than 0,80 was strongly suggestive of a significant residual abnormality which was often curable. Echocardiography has become an essential investigation in the follow up of Fallot's tetralogy after surgical correction: a right: left ventricular ratio Less Than 0,70 obviates the need of control catheterisation. On the other hand, a ratio Greater Than 0,80 is a strong indication for cardiac catheterisation even in the absence of clinical abnormalities.