Percutaneous balloon dilatation of sub-aortic stenosis

Since 1987, percutaneous transluminal dilatation with a balloon catheter was performed in 4 patients with subaortic diaphragm. The patients' mean age was 13 years (range 6 to 22 years). Two of them were asymptomatic and all had mild to moderate aortic valve regurgitation. In all patients two-dimensional echocardiography showed the presence of sub-aortic stenosis. Following dilatation, 2D-echocardiography showed an image of membrane floating in the left ventricular outflow tract. The left ventricular systolic pressure fell from 194 ± 24 to 147 ± 16 mmHg and the intraventricular systolic gradient, from 92 ± 21 to 31 ± 3 mmHg. There were no changes in aortic regurgitation. No complication was observed.