Interatrial septal aneurysms and atrial arrhythmias in infants.

Studies have suggested that interatrial septal aneurysms (IASAs) may be the initiating mechanism of supraventricular tachycardia (SVT) in newborns and infants. A retrospective study was performed to determine the incidence of IASAs in 30 infants with atrial arrhythmias (SVT, atrial flutter, or frequent premature atrial contractions) and their possible relation to the mechanism of atrial arrhythmias. An IASA was defined as dilation of the septum > 5 mm beyond the plane of the atrial septum and associated with redundant tissue and abnormal mobility. The study patients were compared with age and sex-matched control subjects. Four (13%) of the 30 study patients and 2 (7%) of 30 control subjects had an IASA (difference not significant). In contrast to previous reports, this study demonstrates that there is not a significant relation between the presence of IASAs and the onset and recurrence of atrial arrhythmias.