Transaortic Resection oftheSubaortic Membrane* Treatment forSubvalvular Aortic Stenosis

Inanattempt tobetter understand congenital subaortic stenosis, wereviewed 19consecutive pediatric patients undergoing surgery forthis problem between 1973and 1984.Preoperative cardiac catheterization demonstrated subvalvular stenosis inallpatients andassociatedanomalies in11patients. Allpatients underwent transaortic resection ofthesubaortic membrane. Five patients underwent concurrent additional cardiac procedures. An8-month-old infant withmultiple cardiac anomalies wastheonly operative mortality. Follow-up extended to16years, withameanof6.9years. Infive symptomatic patients, cardiac catheterization revealed ameansystolic pressure gradient of33.0 ±31.94 mm Hg 24.7 months (mean) after surgery. Twoofthese patients Congenital aortic stenosis represents 3to5percent ofallcongenital heart disease."12 Inapproximately half ofall cases, theaortic stenosis isvalvular, onethird issubvalvular, andtheremainder iseither supravalvular ormultilevel.34 Bothdynamic and fixed forms ofsubvalvular aortic stenosis havebeen described.5 Dynamicobstruction isproduced by myocardial hypertrophy; therefore, theoutflow orifice isvariable insize relating toleft ventricular volumeandcontractility. Fixed obstruction isproduced byaspecific anatomic malformation, andtheorifice size isunchanged byphysiologic variables. Fixed obstruction maybeoftwotypes. Type1ormembranous subvalvular aortic stenosis ismorecommon andiscaused byadiscrete subvalvular membrane. Lesscommonly, type2,fibromuscular, ortunnel subvalvular aortic stenosis, iscaused byadiffusely narrowed segment oftheleft ventricular outflow tract.5'6 We havereviewed theclinical, pathologic, and operative findings ofall patients undergoing surgery forthisproblem overa 12-year period atthe University ofMiamiSchool ofMedicine/Jackson Memorial Medical Center inorder tocompare our outcome withthat previously reported intheliterature.