Non-invasive determination of the systolic peak-to-peak gradient in children with aortic stenosis: validation of a mathematical model

Doppler derived systolic pressure gradients have become widely applied as n oninvasively obtained estimates of the severity of aortic valvar stenosis. There is little correlation, however, between the Doppler derived peak inst antaneous gradient and the peak-to-peak gradient obtained at catheterisatio n, the latter being the most applied variable to determine severity in chil dren. The purpose of this study was to validate a mathematical model based on data from catheterisation which estimates the peak-to-peak gradient from variables which can be obtained by noninvasive means (Doppler derived mean gradient and pulse pressure), according to the formula: peak-to-peak systo lic gradient=6.02 + 1.49*(mean gradient)-0.44*(pulse pressure). Simultaneou s cardiac catheterization and Doppler studies were performed on 10 patients with congenital aortic valvar stenosis. Correlations between the gradients measured at catheter measured, and those derived by Doppler, were performe d using linear regression analysis. The mean gradients correlated well (y = 0.67 x + 11.11, r=0.87, SEE=6 mm Hg, p=0.001). The gradients predicted by the formula also correlated well with the peak-to-peak gradients measured a t catheter (y=0.66 x + 14.44, r=0.84, SEE=9 mm Hg, p=0.002). The data suppo rt the application of the model, allowing noninvasive prediction of the pea k-to-peak gradient across the aortic valvar stenosis.