Balloon dilatation for discrete subaortic stenosis: immediate and intermediate-term results.

Six children with subvalvar aortic stenosis underwent percutaneous balloon angioplasty over a 15-month-period ending October 1989. The mean systolic pressure gradient across the left ventricular outflow tract decreased from 56 +/- 19 (mean +/- SD) to 12 +/- 7 mmHg (p less than 0.001) immediately following valvuloplasty and the degree of aortic insufficiency did not significantly increase. Follow-up Doppler data (in all 6 patients) were available 3 to 16 months (mean, 11 months) after angioplasty and revealed a residual aortic subvalvar gradient of 21 +/- 5 mmHg, which continues to be significantly lower (p less than 0.001) than that prior to angioplasty. There was no increase in aortic insufficiency. The single infant with increase in gradient at followup was determined to have fibromuscular, tunnel type of subaortic obstruction. None of the five patients with discrete membranous obstruction had significantly increased their gradients. Use of balloons larger than aortic valve anulus did not produce any adverse effect, particularly aortic insufficiency. We surmise that the immediate and intermediate-term follow-up results of balloon angioplasty are encouraging and balloon angioplasty should be considered as a treatment option in the initial management of discrete subaortic membranous stenosis.