Expanding the frontiers of Doppler echocardiography for the noninvasive assessment of diastolic hemodynamics.

Clinical and experimental evidences of limitations of the simplified Bernoulli equation for assessing pressure difference across nonobstructive valves. Role of inertial forces. Doppler echocardiography has been validated extensively for the assessment of the magnitude and time course of the pressure difference across a stenotic valve using the so-called “simplified” Bernoulli equation: pressure difference (in mm Hg) 5 4 3 velocity (in m/s) squared that allows only for convective flow acceleration. An accurate estimate of the pressure drop by the simplified Bernoulli equation is possible because the contribution of the convective acceleration component to the transvalvular pressure difference is much greater than normal in patients with valve stenosis. However, in the absence of valve obstruction, the local acceleration effect (inertial forces) cannot be neglected, and considering only the convective forces, one introduces a substantial error in the evaluation of both magnitude and time course of pressure drop across nonobstructive valves.