Usefulness of the doppler mean gradient in evaluation of children with aortic valve stenosis and comparison to gradient at catheterization

Abstract

To assess the usefulness of the Doppler mean gradient as a noninvasive indicator of the need for intervention, 33 children (ages 3 months to 20 years) with valvular aortic stenosis (AS) underwent a 2-dimensional and Doppler echocardiographic examination a median of 1 day before cardiac catheterization. The clinical decision for intervention was based on finding a catheterization peak-to-peak pressure gradient of >75 mm Hg or from 50 to 75 mm Hg in the presence of symptoms or an abnormal exercise treadmill test result. Of the 33 patients, 23 required intervention. The decision for intervention was compared to the Doppler mean gradient, and the Doppler peak and mean gradients were compared to the catheterization peak-to-peak gradient. All 12 patients with a Doppler mean gradient >27 mm Hg had intervention and had a catheterization peak-to-peak gradient of >75 mm Hg. All 3 patients with a Doppler mean gradient < 17 mm Hg had no intervention and had a peak-to-peak gradient < 50 mm Hg. The remaining 18 patients with Doppler mean gradients between 17 and 27 mm Hg comprised an intermediate group in whom the Doppler mean gradient alone did not predict the need for intervention. From a chi-square table, a Dopppler mean gradient >27 mm Hg predicted the need for intervention with 100% specificity (no false positives) and 52% sensitivity (11 false negatives). if a Doppler mean gradient >24 mm Hg was used to predict intervention, the sensitivity increased to 91% (2 false negatives) but specificity decreased to 70% (3 false positives). To improve the ability to predict the need for intervention in patients with a Doppler mean gradient between 17 and 27 mm Hg, the presence of symptoms or an abnormal exercise treadmill test result was combined with the Doppler mean gradient as criteria for intervention. When the criteria for intervention were a Doppler mean gradient >27 mm Hg or a Doppler mean gradient from 17 to 27 mm Hg in the presence of symptoms or an abnormal exercise test, sensitivity was 96% (1 false negative) and specificity was 80% (2 false positives). Catheterization peak-to-peak gradients correlated well with Doppler mean and peak gradients (r = 0.74 and 0.73, respectively). Thus, the Doppler mean gradient is a useful indicator of the need for intervention in children with AS. A Doppler mean gradient >27 mm Hg indicates the need for intervention with 100% specificity while a Doppler mean gradient < 17 mm Hg predicts mild AS. For patients with Doppler mean gradient between 17 and 27 mm Hg, additional noninvasive data are necessary to determine the need for intervention.