Aortic valve stenosis in children is due to a congenital anomaly of the aortic valve. Congenital anomalies include commissural underdevelopment, myomatous thickening of the valve leaflets, annular hypoplasia or a combination of these elements.
As a result of commissural underdevelopment, the aortic valve may be unicuspid (when only one commissure, usually the left-non coronary commissure, is well formed), bicuspid (when one commissure is underdeveloped and the other two are well formed), trileaflet (all three commissures are well developed) or rarely, quadricuspid (when an extra commissure is present).
An interrogation for aortic regurgitation is also important when evaluating aortic stenosis as this is a common association. A full assessment of all left heart structures should occur, given the known association with other left sided obstructive lesions (mitral stenosis, subaortic stenosis, coarctation) and with post-stenotic dilation of the proximal ascending aorta.