Increase in diameter of ventricular septal defect and membranous septal aneurysm formation during the infantile period.

Serial changes in diameters of ventricular septal defect (VSD), and in the formation patterns of membranous septal aneurysm (MSA), were evaluated using two-dimensional (2-D) echocardiography during the infantile period. We studied 65 patients with VSD, who were classified into three groups by clinical feature. The patients with severe respiratory symptoms and significant failure to thrive were classified as group A (n = 15). The patients with no respiratory symptoms and mild or moderate failure to thrive were classified as group B (n = 38). Group C had no or trivial clinical symptoms and no need for surgical repair (n = 12). Group A showed rapid enlargement of VSD during early infancy. In this group, the mean diameter of VSD at age 5 months was 75% larger than the mean diameter at age 1 month (an increase of 5.5 to 9.6 mm; p<0.05). The other two groups (B, C) showed a slower enlargement as compared with group A. The rapid enlargement of VSD in group A seemed to induce the rapid increase in pulmonary blood flow with severe clinical symptoms. We suggest that careful observation of the changes in VSD diameters by periodic echocardiography is important in predicting the clinical course and in deciding the operation indication.