[Treatment of membranous subaortic stenosis with balloon dilatation]

This study sought to evaluate the immediate and follow-up results of percutaneous balloon dilatation for the treatment of membranous subaortic stenoses.

Fourteen patients with mean age 11.4 +/- 5.2 years, were submitted to the procedure. They were selected when the echocardiogram showed a thin subaortic membrane that was far from the aortic valve, no fibro-muscular obstruction and only mild or moderate aortic regurgitation. After measuring the pressure gradient and analysis of the angiographic features, the balloon dilatation was made by applying a fast manual inflation until the balloon waist disappeared. The balloon diameter was the same as that of the outflow tract of left ventricle, immediately bellow the aortic valve. Pressure measurement, left ventriculogram and aortogram were repeated. Doppler echocardiogram was repeated in the following day, after 3 months and every 6 months thereafter.

All 17 procedures were successful. The mean gradient was 76.1 +/- 21.2 mmHg before and 29.8 +/- 8.8 mmHg after dilatation (p < 0.01). There was no increase in aortic regurgitation or death after the procedure or during the follow-up. Twelve patients were discharged 24h after the procedure. Surgical treatment for femoral artery thrombosis was performed in 2 patients. In the follow-up of 33.3 +/- 23.6 months, 4 patients developed restenosis and 3 of them were submitted to successful redilatation.

We conclude that in selected cases, the procedure is safe and effective, and restenosis may be treated by percutaneous balloon redilatation.