Differentiation of supravalvar aortic stenosis from valvular and subvalvular variety
Supravalvar aortic stenosis is often part of Williams syndrome, with associated elfin facies, hypercalcemia and often learning disability. Various points for differentiation of supravalvar AS from other varieties can be considered under the following headings:
Murmur of subvalvular AS is unlikely to radiate to the carotids. Murmur of supravalvar aortic stenosis may radiate more to the right carotid. Murmur of valvular aortic stenosis radiates to both carotids.
Ejection click is in favour valvular aortic stenosis.
Associated aortic regurgitation
Supravalvar AS is unlikely to be associated with aortic regurgitation, while it can occur in valvular and subvalvular variety. In fact aortic regurgitation may be seen in almost half of those with subvalvular membranous aortic stenosis. It may be noted that discrete subvalvular membranous aortic stenosis is different from dynamic subaortic obstruction seen in hypertrophic obstructive cardiomyopathy.
Pulse asymmetry or anisosphygmia
Anisosphygmia with right brachial pulse more prominent than left, may occur in supravalvar aortic stenosis, due to the direction of the jet towards the right brachiocephalic artery. There may be a corresponding difference of blood pressure more than 10 mm Hg between the two upper limbs. Anisosphygmia is not a feature of subvalvular or valvular aortic stenosis.