Three children with big ventricular septal defects, large pulmonary blood flows, and pulmonary hypertension were catheterized at the ages of 3, 6, and 6 months. Pulmonary vascular resistance was low in two and slightly raised in the other. Recatheterization at the ages of 9, 16, and 26 months, respectively, showed increases of pulmonary vascular resistance in all, and the ventricular septal defects were successfully closed by open-heart operation soon thereafter. In the one child who was recatheterized only after there was clinical evidence of a raised pulmonary vascular resistance, postoperative catheterization showed a progressive rise in pulmonary vascular resistance indicating progressive pulmonary vascular disease. The other two children who were clinically well were recatheterized specifically to try and detect early pulmonary vascular changes and, in contrast, in both of these children pulmonary arterial pressures and vascular resistances have returned to normal after operation.
These patients demonstrate that in those at risk of developing pulmonary vascular disease (big ventricular septal defect with high pressures and flows), pulmonary vascular resistance can rise rapidly in early life. In these patients progressive pulmonary vascular disease could be prevented if surgery to lower pulmonary arterial pressure and blood flow is done early enough. Even in patients who appear to be improving, recatheterization is necessary to demonstrate a moderate rise in pulmonary vascular resistance, since a moderate rise is not detectable by current clinical techniques.