SUBAORTIC STENOSIS IN THE SPECTRUM OF ATRIOVENTRICULAR SEPTAL-DEFECTS- SOLUTIONS MAY BE COMPLEX AND PALLIATIVE

From July 1982 through September 1994, 19 children had operative treat ment of subaortic stenosis associated with an atrioventricular septal defect. Specific diagnosis were septum primum defects in 7, Rastelli t ype A defects in 6, transitional defects in 4, inlet ventricular septa l defect with malattached chordae in 1, and tetralogy of Fallot with R astelli type (3 defect in 1. Twenty-seven operations for subaortic ste nosis were performed, Surgical treatment of the outlet lesion was perf ormed at initial atrioventricular septal defect repair in 3 children a nd in the remaining 16 from 1.2 to 13.1 years (mean 4.9 years, median 3.9 years) after repair. Eighteen of the 19 children had fibrous resec tion and myectomy for relief of obstruction, Seven children had an ass ociated left atrioventricular valve procedure, One child received an a picoaortic conduit. Seven children (36.8%) required 8 reoperations for previously treated subaortic stenosis, Time to the second procedure w as 2.8 to 7.4 years (mean 4.9 years). Follow-up is 0.4 to 14.0 years ( median 5.6 years), Six-year actuarial freedom from reoperation is 66% +/- 15%. The angle between the plane of the outlet septum and the plan e of the septal crest was measured in 10 normal hearts (86.4 +/- 13.7) and 10 hearts with atrioventricular septal defects (22.2 +/- 26.0; p < 0.01), The outflow tract can be effectively shortened, widened, and the angle increased toward normal by augmenting the left side of the s uperior bridging leaflet and performing a fibromyectomy, Conclusion: S tandard fibromyectomy for subaortic stenosis in children with atrioven tricular septal defects leads to a high rate of reoperation, Leaflet a ugmentation and fibromyectomy may decrease the likelihood of reoperati on.