To evaluate left ventricular function in patients (pts) with right ventricular overload, exercise echocardiographic studies using a bicycle ergometer were performed for seven pts with pulmonary hypertension (PH), two with cor pulmonale (CP) and 16 with atrial septal defects (ASD), and the results were compared with those of 10 (control I) and 27 (control II) normal persons. These subjects were categorized in two study groups; study I consisting of PH, CP and control group I with an exercise workload of 25 watts for 3 min; and study II consisting of ASD and control group II with an exercise workload of 50 watts for 3 min. The results were as follows: M-mode echocardiography revealed that: During exercise, the stroke volume (SV) was increased with a significant decrease of left ventricular end-systolic dimension (LVDs), but without a change in left ventricular end-diastolic dimension (LVDd) in control groups I and II, with a marked increase of LVDd and a slight decrease of LVDs in the ASD group. By contrast, the SV in the PH group tended to decrease during exercise with a slight decrease of LVDd, but without a significant change in LVDs. Right ventricular dimension (RVD) was significantly increased during exercise in the PH group, but was decreased in the ASD group. In control groups I and II, RVD did not change during exercise. In ASD, and control groups I and II, the peak velocity of circumferential fiber shortening (Vcf) was increased during exercise, and the peak negative Vcf was significantly decreased. However, these parameters exhibited impaired responses during exercise in the PH group. Abnormal interventricular septal (IVS) motion at rest tended to become normal during exercise in 12 of 16 pts with ASD. In all pts with PH, however, IVS motion did not change substantially during exercise. There were similar parameter responses between the PH and CP groups. Two-dimensional echocardiography showed that: The left ventricular short-axis view demonstrated a diastolic left ventricular configuration which changed from oblique to relatively circular orientation during exercise in the ASD group. In four of five pts with PH, the diastolic configuration of the left ventricle was oblique because of a loss of the normal curvature of the IVS at rest and during exercise. The diastolic left ventricular configuration improved during exercise in only one pt with PH, with slightly elevated pulmonary arterial systolic pressure as in the ASD group.(ABSTRACT TRUNCATED AT 400 WORDS)