An 18 year old man was brought reluctantly 300 miles to the Groote Schuur Hospital in Cape Town, South Africa. His mother was concerned that he had developed chest pain when playing football. Examination revealed ejection systolic and early diastolic murmurs but the typical ejection click of congenital aortic valve stenosis was not heard. ECG showed features of left ventricular hypertrophy and strain pattern. Initial echocardiographic examination reported severe aortic stenosis with a peak instantaneous gradient of 90 mm Hg and possible membranous ventricular septal defect (VSD). At catheterisation, VSD was excluded, and a peak to peak gradient of 90 mm Hg across the aortic valve was recorded using a standard pigtail catheter (panel A). However, careful study with an end holed catheter revealed an intracavity gradient below the aortic valve (panel B). Subsequent repeat echo study clearly demonstrated a subaortic membrane (panel C).

This condition, which usually presents in childhood, is often associated with aortic incompetence as a consequence of subvalvar turbulence and trauma to the aortic valve leaflets. In congenital aortic stenosis, aortic incompetence is unusual; in addition, an ejection click is almost always audible. In young adults presenting with left ventricular outflow tract obstruction, non-valvar causes should be considered.