An association between left axis deviation and an aneurysmal defect in children with a perimembranous ventricular septal defect.

Conspicuous left axis deviation was found in two thirds (27 patients) of 44 children with a perimembranous ventricular septal defect, echocardiographic signs of apposition of the septal tricuspid valve leaflet, and an aneurysm of the membranous septum. In 10 patients earlier electrocardiograms did not show left axis deviation; this feature appeared when the aneurysm of the membranous septum was first seen on the echocardiogram. None of the 44 controls with perimembranous ventricular septal defect but without an aneurysm had left axis deviation. This study suggests that the appearances of conspicuous left axis deviation in a patient with ventricular septal defect indicate a spontaneous reduction in the defect by apposition of the septal tricuspid valve leaflet and by the formation of an aneurysm of the membranous septum.