The dynamic characteristics of the area of the atrial septal defect (ASD) were evaluated using the technique of real-time three-dimensional echocardiography (RT 3DE),the potential factors re sponsible for the dynamic characteristics of the area of ASD were observed,and the overall and local volume and functions of the patients with ASD were measured,RT 3DE was performed on the 27 normal controls and 28 patients with ASD.Based on the three-dimensional data workstations,the area of ASD was measured at P wave vertex,R wave vertex,T wave starting point,and T wave terminal point and in the T-P section.The right atrial volume in the same time phase of the cardiac cycle and the motion displacement distance of the tricuspid annulus in the corresponding period were measured.The measured value of the area of ASD was analyzed.The changes in the right atrial volume and the motion displacement distance of the tricuspid annulus in the normal control group and the ASD group were compared.The right ventricular ejection fractions in the normal control group and the ASD group were compared using the RT 3DE long-axis eight-plane (LA 8-plane) method.Real-time three-dimensional volume imaging was performed in the normal control group and ASD group (n=30).The right ventricular inflow tract,outflow tract,cardiac apex muscular trabecula dilatation,end-systolic volume,overall dilatation,end-systolic volume,and appropriate local and overall ejection fractions in both two groups were measured with the four-dimensional right ventricular quantitative analysis method (4D RVQ) and compared.The overall right ventricular volume and the ejection fraction measured by the LA 8-plane method and 4D RVQ were subjected to a related analysis.Dynamic changes occurred to the area of ASD in the cardiac cycle.The rules for dynamic changes in the area of ASD and the rules for changes in the right atrial volume in the cardiac cycle were consistent.The maximum value of the changes in the right atrial volume occurred in the end-systolic period when the peak of the curve appeared.The minimum value of the changes occurred in the end-systolic period and was located at the lowest point of the volume variation curve.The area variation curve for ASD and the motion variation curve for the tricuspid annulus in the cardiac cycle were the same.The displacement of the tricuspid annulus exhibited directionality.The measured values of the area of ASD at P wave vertex,R wave vertex,T wave starting point,T wave terminal point and in the T-P section were properly correlated with the right atrial volume (P＜0.001).The area of ASD and the motion displacement distance of the tricuspid annulus were negatively correlated (P＜0.05).The right atrial volumes in the ASD group in the cardiac cycle in various time phases increased significantly as compared with those in the normal control group (P=0.0001).The motion displacement distance of the tricuspid annulus decreased significantly in the ASD group as compared with that in the normal control group (P=0.043).The right ventricular ejection fraction in the ASD group was lower than that in the normal control group (P=0.032).The ejection fraction of the cardiac apex trabecula of the ASD patients was significantly lower than the ejection fractions of the right ventricular outflow tract and inflow tract and overall ejection fraction.The difference was statistically significant (P=0.005).The right ventricular local and overall dilatation and end-systolic volumes in the ASD group increased significantly as compared with those in the normal control group (P=0.031).The aRVEF and the overall ejection fraction decreased in the ASD group as compared with those in the normal control group (P=0.0005).The dynamic changes in the area of ASD and the motion curves for the right atrial volume and tricuspid annulus have the same dynamic characteristics.RT 3DE can be used to accurately evaluate the local and overall volume and functions of the right ventricle.The local and overall volume loads of the right ventricle in the ASD patients increase significantly as compared with those of the normal people.The right ventricular cardiac apex and the overall systolic function decrease.