[Percutaneous balloon dilatation of membraneous subaortic stenosis in the adult].

We report a successful balloon dilatation for discrete subvalvular aortic stenosis in a 26-year-old, highly symptomatic patient. The intraventricular peak gradient was reduced from 140 mm Hg to 40-45 mm Hg; there were no complications. Two months after the procedure, the patient was asymptomatic and the gradient unchanged.