Membranous Sub-aortic Stenosis

Echo studies

Comments

Subvalvular stenosis occurs in about 10% of aortic stenosis, is more common in males and can be caused by either a discrete membrane or a diffuse fibrous ring in the LVOT ('tunnel).

Degrees of genetic predisposition are unclear but a pedigree of multiple family members with discrete subaortic membrane has been reported. Varying severities of obstruction occur. The obstructions can create turbulence thickening the aortic valve leaflets and predisposing to endocarditis.

Echo is diagnostically reliable, but careful technique is required since the membrane is often thin. Color doppler will show turbulence.

Transaortic resection of the subaortic membrane is associated with a high incidence of recurrence requiring reoperation (16%). It is reasonable to consider alternative therapies to prevent recurrence in selected cases. Non-surgically, an Inoue balloon catheter has been used retrograde to dilate the membrane, though rupture of a papillary muscle was reported.