A reconsideration of Doppler assessed gradients in suspected aortic stenosis

To further define the clinical role of continuous wave Doppler echocardiography for determining aortic valve gradient, we studied 60 consecutive adult patients (age range 22 to 81 years, mean age 63) with suspected aortic stenosis within 24 hours of catheterization. Blind comparisons of Doppler peak and mean gradients by the simplified Bernoulli equation were made with catheterization peak-to-peak (r = 0.84), peak (r = 0.87) and mean (r = 0.84) gradients in a double-blind fashion. Despite these favorable correlations, Doppler peak gradient generally overestimated catheterization peak-to-peak gradient (1 to 53 mm Hg), making it impractical for clinical use. Doppler-catheterization correlations of peak and mean gradients were more favorable, with the least scatter noticed for mean gradient. The results of analysis of pooled data indicated that mean gradient may also be most specific for differentiating severe from less severe aortic stenosis. In this consecutive series where a full range of catheterization gradients was encountered, seven patients with predicted Doppler gradients were found to have none, which is best explained by the use of the simplified Bernoulli equation in patients with aortic insufficiency. These data indicate that prudence should be maintained when Doppler gradients alone are used for the assessment of aortic stenosis.