[Percutaneous dilatation with a balloon catheter in subaortic stenoses].

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.