Abnormal motion of the interventricular septum has been described as an echocardiographic
feature of both right ventricular volume and pressure overload. To determine if two-dimensional
echocardiography can separate these two entities and distinguish them from normal,
geometry and motion of the interventricular septum in short-axis views of the left
ventricle were evaluated in 12 normal subjects and 35 patients undergoing cardiac
catheterization. Thirteen of the 35 patients had uncomplicated atrial septal defect
with associated right ventricular volume overload, but no elevation in pulmonary artery
pressure. The 22 remaining patients had a pulmonary artery systolic pressure greater
than 40 mm Hg and, thus, constituted the group with right ventricular pressure overload.
An eccentricity index, defined as the ratio of the length of two perpendicular minor-axis
diameters, one of which bisected and was perpendicular to the interventricular septum,
was obtained at end-systole and end-diastole. In all normal subjects, the eccentricity
index at both end-systole and end-diastole was essentially 1.0, as would be expected
if the left ventricular cavity was circular in the short-axis view. In patients with
right ventricular volume overload, the eccentricity index was approximately 1.0 at
end-systole, but was significantly increased at end-diastole (mean eccentricity index
= 1.26 +/- 0.12) (p less than 0.001). In patients with right ventricular pressure
overload, the eccentricity index was significantly greater than 1.0 at both end-systole
and end-diastole (1.44 +/- 0.16 and 1.26 +/- 0.11, respectively) (p less than 0.001).
These results suggest that an index of eccentric left ventricular shape which reflects
abnormal motion of the interventricular septum can be defined.(ABSTRACT TRUNCATED
AT 250 WORDS)