Discrete membranous subaortic stenosis. Report of 31 patients, review of the literature, and delineation of management.

Abstract

The presentation, management and follow-up to 31 patients with discrete membranous subaortic stenosis (DMSS) is presented. DMSS comprised 16% of 185 patients with congenital left ventricular (LV) obstruction. Only 1 patient was older than 40 yr. The rarity of DMSS in older patients in this population and in the literature is noted, and possible explanation are discussed. One quarter of these patients had dyspnea, chest pain or syncope combined with ECG left ventricular hypertrophy (LVH) and strain, and all had peak LV outflow gradients (PSG) greater than 85 mm Hg. One-quarter had neither symptoms nor ECG abnormalities, and all had PSG < 90 mm Hg. Bacterial endocarditis was found in 13%, and in 13% an immediate family member had congenital LV obstruction. Following surgical resection (25 patients), 18 were asymptomatic, 2 had residual fibromuscular obstruction and 4 developed new fibromuscular obstruction after from 1-6 yr (leading in 1 to late sudden death). Even after resection, these patients require continued re-evaluation for residual or new LV obstruction.