Cross-sectional echocardiographic measurements of normalized septal curvature (NSC), systolic anterior motion of the center of the left ventricular cavity (CAM), and the M mode ratio of left ventricular posterior wall epicardial motion (PEM) to posterior wall thickening (PWT) were made in eight normal subjects, 16 patients with right ventricular volume overload (RVVO) and five with pressure overload (RVPO). Paradoxical M mode septal motion was confined to early systole in six patients with RVVO (group I) and was sustained in 10 (group II). Similar end-diastolic septal flattening was observed in RVVO group I (NSC 0.50 +/- 0.16 [SD]) and group II (0.49 +/- 0.23) when compared with the normal group (0.83 +/- 0.07, both p less than .005). NSC increased in both RVVO groups during the first one-third of systole (p less than .002) to values not significantly different from normal, but did not change significantly thereafter. CAM in RVVO group II (5.4 +/- 2.2 mm) exceeded CAM in both the normal group (1.8 +/- 1.9 mm, p less than .001) and group I (2.1 +/- 1.4 mm, p less than .005). Similarly, the PEM/PWT ratios in group II (mean 2.94; range 2.13 to 8.0) exceeded those in both the normal group (mean 1.59; range 1.11 to 2.13, p less than .01) and group I (mean 1.32; range 1.10 to 1.67, p less than .01). In the RVPO group, CAM was significant, the PEM/PWT ratios were lower than normal (p less than .01), and marked end-diastolic septal flattening was incompletely corrected during early systole, after which the septum was flattened further until end-systole (p less than .005).(ABSTRACT TRUNCATED AT 250 WORDS)