Circulation, Vol 52, 926-932, Copyright © 1975 by American Heart Association
Congenital heart malformations associated with disproportionate ventricular septal thickening
BJ Maron, JE Edwards, VJ Ferrans, CE Clark, EA Lebowitz, WL Henry and SE Epstein
Asymmetric septal hypertrophy, or ASH, is a genetically determined
myocardial disorder that is transmitted as an autosomal dominant trait. ASH
is characterized by a disproportionately thickened ventricular septum that
contains numerous hypertrophied, bizarrely-shaped and disorganized cardiac
muscle cells. Disproportionate hypertrophy of the ventricular septum has
also been observed in association with certain congenital cardiac
malformations. To determine whether such congenital cardiac malformations
are part of the disease spectrum of genetically determined ASH, cardiac
pathologic observations were made in eight patients with disproportionate
septal thickening (ventricular septal to posterobasal left ventricular free
wall thickness ratios of 1.5 to 2.5) and the following three categories of
associated lesions: 1) parachute deformity of the mitral valve (occurring
either as an isolated lesion or with ventricular septal defect, coarctation
of the aorta, supravalvular ring of the left atrium, or double outlet right
ventricle); 2) complete interruption of the aortic arch; and 3) ventricular
septal defect. The arrangement of cardiac muscle cells in the
disproportionately thickened ventricular septum was normal in six of the
eight patients; in the other two patients (one with parachute deformity of
the mitral valve and one with ventricular septal defect) numerous bundles
of hypertrophied cardiac muscle cells were interlaced in a disorganized
fashion among more normally arranged bundles of cells. First degree
relatives of six of the eight patients were studied by echocardiography and
found to have normal ventricular wall thicknesses and septal-free wall
ratios. It is concluded that disproportionate ventricular septal thickening
may occur in patients with a variety of congenital heart malformations, but
that such a finding is not necessarily a manifestation of the disease
spectrum of genetically determined ASH.