[Noninvasive quantification of the severity of aortic defects using the Doppler method]

Using Doppler method (HPRF and CW regime), the authors assessed the peak velocity of flow in an aortal spurt in 41 patients with aortal stenosis. For calculation of the transaortal pressure gradient they used a modified Bernoulli equation. The values of the calculated gradients were compared with those obtained by direct manometric assessment during catheterization of the heart after an interval of several hours to five days. Combination of two Doppler techniques correlated closely with direct assessment (r = 0.811; p less than 0.001). By application of the continuity equation in the best records of spectral analysis of velocity curves the authors calculated in 8 patients the area of the reduced aortal orifice which was very close to the area calculated by means of Hakki's formula from direct haemodynamic indicators (r = 0.948; p less than 0.001). In 33 patients the authors quantified by Doppler method the severity of aortal regurgitation from the ratio of forward and backward flow in the descending portion of the aortal arch (expressed as the % regurgitation fraction--RF). The RF values correlated well with the angiographic semiquantitative scale of severity of aortal insufficiency (r = 0.805; p less than 0.001), although they enabled the authors only to make a partial differentiation of haemodynamically severe regurgitations and mild or insignificant ones. The authors conclude that the Doppler approach makes it possible to evaluate sufficiently accurately the severity of aortic valve disease (in insufficiencies the authors recommend a more comprehensive approach), which when correctly applied and interpreted, can make non-invasive clinical diagnosis more accurate and thus permits also more accurate indication of surgical treatment of these patients.