Balloon dilation of the aortic valve: studies in normal lambs and in children with aortic stenosis.

To evaluate the risks of and optimal method for valve dilation in aortic stenosis, balloons of different sizes were used to dilate the normal aortic root in 16 lambs and then stenotic valves in 15 children. In the lambs, inflated balloon to aortic anulus diameter ratios ranged from 0.9 to 1.5. These hearts were examined immediately after the procedure. Ratios of 0.9 to 1.1 did not produce significant damage to the left ventricular outflow tract, whereas those of 1.2 to 1.5 produced tears or hematomas, or both, of the aortic valve leaflets (n = 3), mitral valve leaflets (n = 4) and interventricular septum (n = 4). The 15 patients, aged 10 days to 15 years, underwent 16 balloon aortic valvotomy procedures. The balloon-aortic anulus ratio ranged from 0.67 to 1.1 (mean 0.90). The average pressure gradient decreased 69% and, overall, the peak systolic gradient decreased from 86 +/- 21 to 28 +/- 14 mm Hg (p less than 0.01) and the aortic valve area increased from 0.44 +/- 0.11 to 0.73 +/- 0.22 cm2/m2 (p less than 0.01). Immediately after the procedure an increase in aortic regurgitation was noted in 8 (57%) of 14 patients, but was never greater than 3+ and has been well tolerated. Other early complications encountered consisted of transient left bundle branch block in two patients, temporary femoral artery occlusion in three and femoral artery rupture requiring operative management in one infant. Balloon valvotomy can reduce the transvalvular gradient in most patients with valvular aortic stenosis when a balloon less than 1.1 times the aortic root diameter is used.(ABSTRACT TRUNCATED AT 250 WORDS)