Membranous Sub aortic Stenosis

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. 


 

Long axis view of the left ventricular outflow tract shows a discrete membrane which creates systolic turbulence and a mild pressure gradient.

Echo

Long axis view color doppler of the left ventricular outflow tract shows systolic turbulence and a mild pressure gradient at the subaortic membrane.

Echo

Apical 5 chamber view of the left ventricular outflow tract shows a discrete membrane just below the aortic valve.

Echo

Apical 5 chamber view of the left ventricular outflow tract shows a discrete membrane which creates systolic turbulence and a mild pressure gradient.

Echo