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, denned 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 < 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 < 0.001). These results suggest that an index of eccentric left ventricular shape which reflects abnormal motion of the interventricular septum can be defined. This index is easily obtained and allows separation of normal subjects, patients with right ventricular volume overload and patients with right ventricular pressure overload. © 1985, American College of Cardiology Foundation. All rights reserved.
Ryan, T., Petrovic, O., Dillon, J. C., Feigenbaum, H., Conley, M. J., & Armstrong, W. F. (1985). An echocardiographic index for separation of right ventricular volume and pressure overload. Journal of the American College of Cardiology, 5(4), 918–924. https://doi.org/10.1016/S0735-1097(85)80433-2