Instantaneous transmitral flow using Doppler and M-mode echocardiography: Comparison with radionuclide ventriculography

To improve the accuracy of Doppler echocardiographic indices of left ventricular filling, we derived two indices of instantaneous transmitral flow with the use of Doppler velocities and M-mode echocardiography. These indices were calculated from the product of pulsed Doppler mitral velocities and either the excursion of the anterior mitral leaflet or the separation of both mitral leaflets as measures of the changing mitral orifice area. The derived flow indices and the mitral velocities alone were compared to left ventricular filling as determined by radionuclide ventriculography in 24 patients. When compared as areas under the matched decile divisions of the derived filling sequences by linear regression analysis, the relationship for combined Doppler and M-mode versus radionuclide left ventricular filling was closer to the line of identity (slope = 0.98 and 0.94 using the anterior mitral leaflet and both mitral leaflets, respectively, both p = NS versus the line of identity) than was the relationship for mitral velocities alone versus radionuclide left ventricular filling (slope = 0.74, p < 0.05 versus the line of identity). The instantaneous mitral volume flow indices more closely resemble the time course and shape of radionuclide left ventricular filling curves than do mitral velocities alone, and the application of these indices should assist the quantitative description by Doppler echocardiography of left ventricular filling.