The asymmetrically hypertrophied septum. Further differentiation of its causes.

Fifty-eight subjects with echocardiographic criteria for an abnormal septal to left ventricular posterior wall ratio were studied. Echocardiographic findings were related to clinical cardiac status. Abnormal ratios were found in normal children and in children with a variety of cardiac lesions, only one of which was obstructive or non-obstructive cardiomyopathy. In those without cardiomyopathy, the abnormal ratio usually resolved by one or two years of age. Persistence of abnormal ratio usually occurred in patients with increased right ventricular anterior wall thickness or idiopathic hypertrophic subaortic stenosis. The cause of abnormal ratio is multifactorial.