Inaccurate assessment of Doppler-derived mean pressure gradients by commercially available computer programs

Summary form only given. Computer programs incorporated with Doppler echocardiographic machines and other available programs for offline analysis provide estimation of mean pressure gradients. The accuracy of three programs in the assessment of mean gradients was evaluated. A linear relationship was found between program-derived mean pressure gradients and false gradient calculated as 4×(mean velocity)² (r=1). Digitalization of the envelope of the Doppler signal and calculation of the mean of the (4×velocity ²) function (the true Doppler-derived pressure gradient) did not correlate with program-calculated false pressure gradients. Errors in mean pressure gradients were sizeable, especially in patients with aortic stenosis. It is concluded that the assumption that mean of squares=square of means may be inaccurate in the assessment of mean pressure gradients and that commercial computer programs should be carefully evaluated before the provided estimate of mean gradients is accepted