Classification of the site of ventricular septal defect by 2-dimensional echocardiography

Sixty-three consecutive patients aged 2 months to 27 years with simple ventricular septal defect (VSD) or the syndrome of Fallot's tetralogy were prospectively investigated with 2-dimensional (2-D) echocardiography to assess the accuracy of the method in defining the anatomic site of the VSD. Twenty-two patients were referred for surgery without invasive investigation. The anatomy was confirmed in all patients at operation. Two-dimensional echocardiography was reliable in identifying subaortic, inlet, small, moderate, and large subtricuspid, large subpulmonary, and most large central and apical muscular VSDs. Mistakes were made initially in distinguishing doubly committed subarterial defects from subaortic VSD because of difficulty in imaging the right ventricular outflow in short axis at the aortic root level, small subpulmonary defects obscured by prolapsed aortic cusp tissue, and small apical or outlet muscular VSDs because of difficulty in distinguishing true "dropout" from trabeculations. Other VSDs particularly muscular, were sometimes overlooked after another large VSD had been identified. Thus, identification of the anatomic site of VSDs by 2-D echocardiography is a reliable method that can replace invasive investigation in assessing the uncomplicated VSD before operation. Ventricular septal defects are classified as muscular or subvalvular and subdivided according to the valve to which the defect is related.