Evaluation and surgical treatment of pulmonary atresia and intact ventricular septum in infancy.
The initial surgical approach to the infant with pulmonary atresia and intact ventricular (PA-IVS) is to establish an adequate source of pulmonary blood flow and, when possible, relieve right ventricular (RV) outflow obstruction. The selection of patients for pulmonary valvotomy, alone or in combination with a systemic-pulmonary arterial shunt, depends on the presence of an RV outflow tract and the adequacy of the RV chamber. To evaluate the size of the RV cavity in PA-IVS, an RV index (RVI) was developed using biplane angiographic measurements of the sum of the tricuspid valve annulus and the RV inflow and the RV outflow tracts. The RVI was normalized by relating it to the aortic diameter (Ao) at the diaphragm (RVI/Ao). The RVI/Ao was 13.5 +/- 1.4 in 20 control subjects and only 7.3 +/- 2.6 in 26 PA-IVS patients (p less than 0.001), and was within the normal range in only two of the 26. Since 1976, pulmonary valvotomy plus a Blalock-Taussig shunt has been performed in 10 infants, with one death. Serial cardiac catheterizations in five of nine survivors demonstrated substantial RV growth in all, with the RVI/Ao increasing from an average of 8.0 to 12.5. In contrast, patients who underwent a shunt alone had no change in RV cavity size. We conclude that pulmonary valvotomy may be performed successfully in most PA-IVS patients, but usually must be combined with a systemic-pulmonary shunt. In a small minority of patients, a normal RV cavity, as evidenced by an RVI/Ao greater than or equal to 11, appears to be sufficient to sustain adequate pulmonary blood flow after valvotomy alone. The RVI/Ao ratio is a simple method of quantitatively evaluating RV cavity size and is helpful in planning the initial surgical approach for these infants.