Interventricular septal and free wall dynamics in hypertrophic cardiomyopathy

Two-dimensional echocardiography was used to analyze interventricular septal and free wall dynamics in eight normal subjects and eight patients with hypertrophic cardiomyopathy. Upper, middle and lower septal and corresponding free wall motion and thickening were analyzed using both fixed and floating reference systems. The lower and midseptal dynamics did not seem to differ significantly between the two groups and the lower septum seemed to move more than the corresponding free wall (probability [p] less than 0.05). The upper septum moved and thickened less than the rest of the septum in both groups (p less than 0.05), but was less dynamic in patients with hypertrophic cardiomyopathy than in normal subjects when the fixed reference system was used (p less than 0.05). It is concluded that the interventricular septum in hypertrophic cardiomyopathy is not akinetic. Previously reported hypokinesia of the septum in hypertrophic cardiomyopathy may be due to sampling of the upper septum by M-mode echocardiography and to the fixed system of reference used by M-mode echocardiography.