Left ventricular outflow tract blood velocity in hypertrophic subaortic stenosis.

ngiographic and echocardiographic studies A have demonstrated that subjects with hypertrophic subaortic stenosis display an abnormal systolic outflow tract narrowing brought about by apposition of a paradoxically moving anterior rnitral leaflet and a hypertrophic interventricular septum.' The hemodynamic consequence of such obstruction is the development of a fluctuant gradient between thc inflow and outflow tracts of the left ventricle with attendant changes in the contour of the pressure pulse.' In 1968, it was demonstrated that the measurement of phasic continuous arterial blood velocity, by means of Doppler flowmetry,%as useful for the