Transthoracic 3-dimensional echocardiography in the assessment of subaortic stenosis due to a restrictive ventricular septal defect in double inlet left ventricle with discordant ventriculoarterial connections

To evaluate the accuracy and clinical utility of three-dimensional echocard iography in the assessment of the size and shape of the ventricular septal defect in double inlet left ventricle. Methods. We validated the technique in an autopsy study, and then performed a clinical investigation. Six autop sied hearts were immersed in a waterbath and examined with 3-dimensional ec hocardiography. We identified the cross-section within the dataset which op timally displayed the ventricular septal defect "en face", and compared its smallest and largest diameters, as well as its area. The ventricular septa l defect was then filled with a silicone sealant and a section prepared for direct measurement. In patients, we measured the diameters and area of the ventricular septal defect in endsystole nad computed the aortic valvar are a in endsystole from the cross-section showing the aortic valve "en face". Ten patients with double inlet left ventricle, aged between 2 and 15 years, were studied using rotational or parallel scanning. All patients had under gone banding of the pulmonary trunk at a mean age of 7 (3-36) days, usually at the time of repair of the coarctation. Two patients had undergone surgi cal enlargement of the ventricular septal defect prior to echocardiographic examination. Results: The correlation between the areas of the ventricular septal defect in the specimens measured directly and by 3-dimensional echo cardiography was r = 0.98, with limits of agreement between -0.1 - 0.08 cm( 2). In the patients, the area of the defect was measured as 3.9 +/- 2 cm2, whereas the aortic valvar area was 2.6 +/- 0.9 cm(2). The ratio between the areas was 1.5 (0.5 - 2.3). Three patients with areas of the ventricular se ptal defect smaller than those of the aortic valve had resting Doppler grad ients between double inlet left ventricle and the aorta of 16, 20 and 30 mm Hgs, respectively. Conclusions: 3-dimensional echocardiography provides ac curate assessment of the area of the ventricular septal defect in double in let left ventricle, and is helpful in identifying patients with subaortic s tenosis caused by restrictive defects.