A new balloon for valvuloplasty (Trefoil balloon) was successfully used in a 12 year old boy with congenital aortic stenosis. The Trefoil balloon consists of three angioplasty balloons mounted in parallel on a single shaft. When they are inflated simultaneously they produce a rosette that allows blood flow to continue through the valve. The aortic pressure only dropped to 75 mm Hg during a 15 s balloon dilatation at 4 bar (400 kPa). The procedure reduced the transvalvar gradient from 45 to 15 mm Hg.