Disproportionate ventricular thickening in patients with systemic hypertension.

To determine the prevalence and characteristics of disproportionate ventricular septal thickening (septal-free wall ratio of greater than or equal to 1.3) in a population of patients with severe chronic hypertension, which was unassociated with coronary arterial disease, 33 patients were studied at necropsy. The overall prevalence of disproportionate septal thickening was relatively low, ie, two (6 percent) of the 33 patients. The septal-free wall ratio in both of these patients was 1.3. Disproportionate septal thickening appeared to be secondary to the left ventricular pressure overload, rather than to coexistent genetically transmitted hypertrophic cardiomyopathy. This conclusion was based on the following facts: (1) numerous disorganized cardiac muscle cells, characteristic of hypertrophic cardiomyopathy, were not present in the ventricular septum of either patient with disproportionate septal thickening; and (2) echocardiographic studies performed in first-degree relatives of one of the two patients did not disclose disproportionate septal thickening. Hence, disproportionate septal thickening may occur as a secondary manifestation of left ventricular pressure overload that is present in patients with systemic hypertension, but this association appears to be relatively uncommon.