Diagnosis and quantitative evaluation of secundum-type atrial septal defect by transesophageal Doppler echocardiography.

Transesophageal echocardiography (horizontal sector scan) was performed in 11 patients with secundum atrial septal defect (ASD). In all 11 patients, transesophageal echocardiography presented the definite visualization of the defect and a clear laminar shunt flow that showed its 2 peaks in late systole and late diastole. We estimated the size of ASD and a shunt volume across the defect by using transesophageal echocardiography. The defect size determined by transesophageal echocardiography was correlated with the surgical measurement (horizontal width, r = 0.92, p less than 0.001; vertical length, r = 0.85, p less than 0.01). A significant high correlation was shown between the shunt volume measured by transesophageal echocardiography and that by Fick's method (r = 0.87, p less than 0.01). There was no significant correlation between the pulmonary to systemic flow volume (ratio) and the mean shunt flow velocity across ASD, although a high linear correlation was observed between the pulmonary to systemic flow ratio and the defect size in horizontal direction (r = 0.82, p less than 0.01). Transesophageal echocardiography used for diagnosis and quantitative evaluation of ASD could be performed easily and satisfactorily within 10 minutes. Thus, transesophageal echocardiography is a useful method in evaluation of the defect size and the shunt flow volume of ASD. The mean shunt flow velocity was not a reliable index for estimating the shunt flow volume. The defect size might be a valuable determinant of left-to-right shunt volume in ASD.