Echocardiographic Estimation of a Left-to-right Shunt in Isolated Ventricular Septal Defects

35 infants and children with isolated ventricular septal defects (VSDs) had echocardiographic examination within 24 h of cardiac catheterization. Left atrial to aortic root (LA : Ao) ratio, left atrial internal dimension/meter square body surface area (LAID/m2) and left ventricular internal dimension in diastole/meter square body surface area (LVIDd/m2) were compared with the cardiac catheterization determined pulmonary-to-systemic flow (Qp : Qs) ratio. 35 children with normal cardiovascular findings served as controls. The LA : Ao ratio in the VSD group (1.38 +/- 0.13) was significantly higher than in the control group (1.01 +/- 0.05) (P less than 0.01). Similarly the LAID/m2 and LVIDd/m2 were significantly higher in the VSD group than in the control group (P less than 0.01). Additionally, echographic dimensions were increased in proportion to the elevation of Qp : Qs (r = 0.71--0.73). LA : Ao ratios higher than 1.4 : 1 were generally associated with Qp : Qs ratios greater than 2 : 1. All patients with Qp : Qs greater than 2 : 1 had LA : Ao ratios of 1.4 or higher. This study suggested that echocardiography is a useful noninvasive technique in estimating the Qp : Qs in patients with isolated VSDs, and may serve as an additional clinical parameter in the assessment of patients with VSDs.