An experimental study of the determination of volumes of turbulent blood flows by doppler echocardiography

An experimental model is used to reproduce high-speed unsteady turbulent flows of small diameter (3 to 5 mm). The spectra of the simulated flows were recorded by the continuous Doppler method and their volumes were estimated as the product of the velocity-time integrals times the cross-sectional area of the tubes. The flow volumes were too high in comparison with the specified values in all cases, necessitating the use of correction factors. The factors were inversely proportional to the flow velocities, and thus to the turbulence (as is evident from the Reynolds turbulence equation). For the range of maximum velocities of turbulent intracardiac flows most frequently occurring in practice (140 to 500 cm/sec) the correction factors were 0.76–0.87. The method may be very helpful in developing noninvasive criteria of the severity of regurgitations, in differentiating these, and in determining the prognosis, particularly for borderline states and combined heart defects.