Balloon dilation of discrete subaortic stenosis associated with other cardiac defects in children.

Balloon dilation (BD) is reported as an effective treatment for isolated discrete thin membranous subaortic stenosis (SAS). We asked if BD of SAS with associated cardiac defects: 1) is effective; 2) creates or worsens mitral insufficiency in the presence of valvar membrane attachment; and 3) creates or worsens aortic insufficiency. BD was performed on 13 patients (9 females, 4 males with a mean age of 5.8 years and an age range of 1-14 years old) for SAS with the following associated defects: VSD (6 patients), coarctation (4 patients), complete atrioventricular canal (1 patient), tetralogy of Fallot (1 patient), and abnormal mitral valve (4 patient). Prior intracardiac surgical procedures (3 for SAS resection) had been performed in 46% of the study group. Peak gradient was reduced from 53 +/- 40 mmHg to 31 +/- 25 mmHg (p < 0.01). The resulting gradient was related to the predilation gradient (r = 0.71; p =.006). Thin membranes (< 3 mm) were associated with lower initial gradient (p < 0.02), lower resulting gradient (p < 0.001) and a greater percent gradient reduction (76% versus 36%; p < 0.01). Aortic insufficiency, which was present predilation in 77%, did not change and was not created in any patient. Mitral valve membrane attachment was present in 69% and associated with a lower resulting gradient (p < 0.006). Mitral insufficiency was not created in 10 patients, was unchanged in 2 and was improved in 1 patient. Surgical procedures were ultimately required in 8 patients during follow-up. BD of SAS associated with other cardiac defects achieves the following: 1) reduces SAS gradient in selected patients without creating or worsening aortic insufficiency; 2) does not create or worsen mitral insufficiency when mitral valve membrane attachment is present; 3) improves preoperative hemodynamics; and 4) is unlikely to be effective in post-surgical recurrence.