Ostium secundum atrial septal defect associated with balloon mitral valve in children

Eight children with an ostium secundum atrial septal defect and balloon mitral valve are described. Leftward-superior QRS forces, abnormal T waves and suggestive apical auscultatory findings (midsystolic click or a late systolic murmur of mitral insufficiency) were frequently observed and led to the erroneous diagnosis of ostium primum atrial septal defect in six cases. Lack of any or all of these manifestations did not preclude the presence of a balloon mitral valve. The prognostic importance of this valvular lesion indicates the need to perform left ventriculography in all patients with an atrial septal defect.