The diagnosis of congenital subaortic stenosis; application of hemodynamic principles

Optically recorded subclavian pulse curves obtained with a simple cup-tambour system give graphic evidence of aortic valve mobility. Differentiation between congenital subaortic stenosis and aortic stenosis was aided by the demonstration in the former of a sharp incisura accompanied by a good aortic second sound; these two features were lacking or rudimentary in the latter. Despite marked auscultatory findings, there is usually little hemodynamic impairment in subaortic stenosis.