Atrial septal aneurysms in infants and children.

Interatrial septal aneurysm (IASA) has been detected with increasing frequency since the advent of two-dimensional echocardiography (2DE). In this study, we investigated the prevalence, characteristics, and predisposing factors in IASA formation in 724 infants, children, and adolescents undergoing 2DE. Among this group, 12 patients had an IASA (prevalence = 1.7%). Eleven of the 12 patients had abnormal atrial hemodynamics as a result of either structural heart disease or significant supraventricular dysrhythmias. Follow-up 2DE performed in 10 of 12 patients, 1 to 48 months (mean 16.5 months) after the initial diagnosis, demonstrated diminution or resolution of the IASAs in those patients who had normal hemodynamics following surgical or spontaneous closure of their intracardiac defect, or medical control of their dysrhythmias. In contrast, IASAs became more prominent in those patients with persistent hemodynamic abnormalities. The high prevalence rate and subsequent involution of many IASAs in infants suggest that in the presence of abnormal atrial hemodynamics, the neonatal atrial septum may be prone to aneurysm formation because of inherent structural weaknesses of the neonatal septal tissue. In the absence of continued hemodynamic stress., the majority of these IASAs in infants resolve with maturational changes in the septum and normal cardiac growth.