Subaortic Membrane in the Adult
A 47-year-old white woman with a history of congestive heart failure and aortic stenosis had been admitted to an outside hospital several times within the preceding few weeks with multiple episodes of congestive heart failure. An echocardiogram performed at the outside facility was reported to depict severe aortic stenosis. She was transferred to the University of Chicago for aortic valve replacement. On arrival, she had mild dyspnea on exertion, coarse basilar crackles, and a 4/6 systolic ejection murmur. A repeated echocardiogram showed a subaortic membrane with a 48-mm Hg gradient, moderate aortic insufficiency, and thickened aortic valve leaflets (Figure, A and B). Results of coronary angiography were normal. A transthoracic, 3-dimensional echocardiogram demonstrated a membrane with a single, slitlike opening that measured 12×5 mm. (Figure, C). In the operating room, a dense, muscular membrane was found covering the left ventricular outflow tract only 5 mm below the aortic valve (Figure, D). The morphology of the membrane was similar to that shown by 3-dimensional echocardiography. The membrane was easily dissected away from the walls of the outflow tract and was excised in 1 piece (Figure, D, inset). The valve was replaced with a 25-mm tissue valve, and the patient was discharged home without complications in 5 days. A follow-up echocardiogram showed a residual gradient of 13 mm Hg.