Role of echocardiography in diagnostic and hemodynamic assessment of hypertrophic subaortic stenosis.

An abnormal sharp anterior motion of the anterior mitral leaflet has been previously described as a diagnostic abnormality in hypertrophic subacute stenosis (HSS). The present prospective study explored the diagnostic sensitivity and specificity of this finding in 26 patients studied without knowledge of clinical diagnosis. When the abnormality observed was complete and persistent, a correct diagnosis of HSS was made in every case. In the absence of systolic abnormality at rest and on provocation, the diagnosis of HSS could be excluded. When the abnormality was small and inconstant (nine patients) two thirds of the patients were shown to have a latent or labile form of outflow obstruction whereas the remaining third had no evidence of HSS. In an extended part of the study on 31 patients with known HSS, comparisons of resting pressure gradients across left ventricular outflow tract were made with the echocardiographic findings at rest. Those with persistently abnormal mitral valve movement had an average pressure gradient of 78 mm Hg, those with inconstant abnormality had an average gradient of 24 mm Hg, and those with no resting abnormality had no gradients at rest.