Use of peak Doppler gradient across ventricular septal defects leads to underestimation of right-sided pressures in patients with "sloped" Doppler signals.

In patients with "sloped" appearance of the Doppler signal across a ventricular septal defect (VSD), the peak Doppler velocity seems to overestimate the catheterization-derived peak-to-peak gradient, resulting in underestimation of right-sided heart pressures. In 11 patients with sloped Doppler signals across the VSD, ventricular pressure tracings were compared with simultaneous recordings of the Doppler signal. The average peak Doppler gradient (40.2 +/- 19.2 mm Hg) overestimated the catheterization-derived peak-to-peak gradient (20.2 +/- 13.6 mm Hg) significantly (P < or =.001). Doppler mean gradient (20.2 +/- 11.3 mm Hg; P = ns) and end-systolic gradient (17.0 +/- 12.5 mm Hg; P < or =.05) were closer estimates of the catheterization peak-to-peak gradient. All Doppler gradients showed good correlation to the catheterization peak-to-peak gradient with r2 values of 0.77, 0.73, and 0.91. We conclude that Doppler mean or end-systolic gradients should be used for calculation of right-sided heart pressures in this patient population.