SURGICAL-MANAGEMENT OF FIXED SUBVALVULAR AORTIC-STENOSIS - IMMEDIATE AND LONG-TERM HEMODYNAMIC-RESULTS

Forty patients operated on for fixed subvalvular aortic stenosis under went cardiac catheterization preoperatively, immediately after coming off! cardiopulmonary bypass and at long-term (1 to 14 years later, ave rage 7 +/- 3.9 years). The age range was 3 to 50 years (average 15 +/- 12 years) with 27 (68 %) aged under 18 years. Twenty-seven patients w ere male. The stenosis was the thin membranous type in 29, the fibromu scular collar type in 5, the tunnel type in 5 others and related to su pernumerary mitral tissue in the remaining patient. Significant other pathology was associated in 13 cases. In addition to excision of the m embrane or the fibromuscular ring, the surgeons performed myotomy In 6 cases, myomectomy in 12 cases, large resection of muscular and fibrou s tissue in tunnels, and aortic valve replacement in 3 cases. There wa s no operative fatality. Permanent cardiac pacing was required in 1 pa tient for complete atrioventricular block The peak systolic pressure g radient fell from 87 +/- 32 to 31 +/- 10 mmHg (p <0.0001) at the immed iate control : it remained >30 and even 50 mmHg in 3 patients (7.5 %), 2 of whom had tunnel types and the other the supernumerary mitral tis sue. The gradient increased in the long-term to 42 +/- 11 mmHg, 1 pati ent with a membrane developed a gradient of 40 mmHg and 4 others (10 % ) developed a gradient >50 mmHg (3 tunnels and 1 membrane). The 5 pati ents with tunnel types either had a residual stenosis or restenosis an d underwent aorto-ventriculoplasty by Konno's procedure 1 to 8 years l ater. This operation should be the procedure of first intention, even in small children : the large resection is only acceptable when it can not be performed or when aortic ring hypoplasia is mild. There is no r esidual stenosis and restenosis is rare (2.5 %) in the membranous and fibromuscular types, probably because of the widespread use of myotomy and myomectomy. In the absence of severe:associated malformations, su rgery in only justified when peak systolic pressure gradients are grea ter than or equal to 50 mmHg.