Thirty-seven patients with ventricular septal defect (VSD) and twenty-seven patients with atrial septal defect (ASD) were examined echocardiographically for changes in left atrial(LA) size in relation to the size of the left-to-right (L to R) shunt. The LA size was expressed as a ratio of the left atrial to aortic root dimension (LAD/AoD) and the size of the L to R shunt was expressed in terms of pulmonary-to-systemic flow ratios (Qp/Qs).
In VSD, LA size was enlarged when L to R shunt was more than 1.5.In ASD, the size was enlarged at end systole, exclusively in large L to R shunt (＞2.0).
The correlation between LAD/AoD and Qp/Qs in VSD was relatively good (r=0.74) but poor in ASD (r=0.57) with much scatter.
The echo derived LAD/AoD is a useful method for detecting the LA enlargement and may be helpful in the evaluation of L to R shunt size in patients with VSD.