The relationship between subaortic membrane and aortic cusps evaluated by three-dimensional transthoracic echocardiography.

A discrete subaortic membrane is a rare cause of subaortic stenosis in adults. It may present in an isolated form as a fibrous or fibromuscular ring below the aortic valve. A 24 year-old male patient was admitted to our outpatient clinic with dyspnoea and palpitations. His physical examination was unremarkable except for an aortic 3/6 systolic murmur. Electrocardiography revealed normal sinus rhythm with signs of left ventricular (LV) hypertrophy. Two-dimensional transthoracic echocardiography demonstrated a subaortic stenosis. Full-volume three-dimensional transthoracic echocardiography (3-D TTE) showed a discrete membrane, and calcified right and non-coronary aortic cusps (Fig. 1A, B). 3-D colour TTE revealed moderate-to-severe aortic regurgitation with an eccentric jet (Fig. 1C). Full-volume 3-D TTE after cropping the left and right ventricle walls confirmed the relation between subaortic membrane and aortic valve cusps (Fig. 2). This condition may cause progressive LV outflow tract obstruction, LV hypertrophy and dysfunction, and aortic regurgitation due to damage to the aortic cusps because of the jet from the subaortic narrowing which may also render the aortic valve prone to infective endocarditis. 3-D TEE can provide visualisation of the subaortic membrane, as in this case. Detailed examination of the subaortic area can reveal the exact site and the extent of the subaortic membrane and which aortic cusps are influenced. Furthermore, the use of 3-D TEE is likely to be key in the spatial assessment of this complex lesion.