Reversed septal curvature. Association with primary pulmonary hypertension and Shone syndrome

In the normal heart the interventricular septum is curved concave to the left and functions as a component of the left ventricular wall. We have studied the hearts of five patients at autopsy, after postmortem angiography and fixation in distention, in which the septum was concave to the right ventricle. These patients ranged in age from eight months to 25 years (average, 16 years); three had primary pulmonary hypertension, and two had coarctation of the aorta and congenital aortic stenosis. Catheterization studies in the latter two patients had demonstrated subaortic stenosis. At autopsy there was no evidence of asymmetric septal hypertrophy or of abnormal septal myocardial fiber disarray. The right ventricles were markedly hypertrophied. In each, the septal curvature was reversed leading to protrusion of septal muscle into the left ventricular outflow tract with marked narrowing of the outflow tract. Since the septal configuration is determined early in life, this abnormality of ventricular topography may develop primarily or it may develop in hearts subject to early as well as long-standing right ventricular overload.