Value and limitations of cross-sectional echocardiography of the aortic valve in the diagnosis and quantification of valvular aortic stenosis.

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Abstract
Few data are available regarding cross-sectional echocardiography (2-D) in the diagnosis and quantification of valvular aortic stenosis. Echographic measurements obtained by 2-D echo were compared with aortic gradient and aortic valve area and index calculated by the Gorlin formula in 20 normal subjects and 85 patients with clinical evidence of aortic stenosis. Technically adequate echograms were obtained in 72 patients (85%). Patients (46) with satisfactory echograms were classified as having critical aortic stenosis, while 26 were designated as having noncritical obstruction. Aortic leaflet separation (SEP) was measured as the maximal intercusp distance visualized in long, apical or short axis of the 2-D echo. SEP was less in critical aortic stenosis patients than in normal subjects and those with noncritical aortic stenosis (4.6 .+-. 0.4, 19.4 .+-. 0.5 and 10.0 .+-. 0.8 mm, respectively [mean .+-. standard error of the mean] [both P < 0.001] and was > 15 mm in all normal subjects and 11 mm or less in all patients in the critical group. SEP correlated poorly with peak systolic gradient and calculated aortic valve area and index in aortic stenosis patients. Of 46 patients in the critical group, 42 had SEP of 8 mm or less, yielding a sensitivity of 91%. Only 17 of 26 patients with noncritical aortic stenosis had a SEP of > 8 mm, for a specificity of 65%. The predictive value of SEP 8 mm or less on 2-D echo in the recognition of critical aortic stenosis was 82%. Two-dimensional echocardiography is a sensitive method to detect valvular aortic stenosis, and accurately separates patients with aortic stenosis from normal subjects, but the specificity of 2-D echo in distinguishing critical from noncritical aortic stenosis is limited.