By P. Peronneau, B. Diebold, J. P. Guglielmi, O. Lanusel, R. Bele, J. Souquet (auth.), J. Roelandt MD (eds.)
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Additional info for Color Doppler Flow Imaging: and other advances in Doppler echocardiography
As stated in the theory section the maximal flow exists only in the core flow region, the volume of which is quite small. It might therefore be a problem to distinguish the signal eminating from this volume from the noise, especially at high flow velocities in small holes, since in this case the effects due to the limited volume are combined with the broadening of the frequency spectrum described above. Discussion The ultimate goal when using Doppler technique for the assessment of valve regurgitation must be the measurement of regurgitation volume.
The driving pressure difference over the leaking valve may vary from 3 kPa for tricuspid or pulmonary regurgitation to 25 kPa at mitral regurgitation. The diameter of the circular hole and thc width of thc slot orfice are both assumed to be larger than 2 mm for the regurgitant flow to be of clinical significance. For these restrictions the flow can be found to be turbulent . The regurgitant flow through a leaking valve can be described as in Fig. 1. At the entrance of the orfice the flow contracts.
The authors' group has confirmed the diagnostic effectiveness in acquired valvular disease [5, 6, 7], congenital heart disease [8, 9, 10], and aortic aneurysm . Furthermore, an intraoperative use for various cardiovascular lesions has been found effective [12, 13]. Since the introduction of commercially available 2-D Doppler systems in December of 1983, a number of vigorous studies on color flow mapping have been rapidly carried out in many cardiac centers [14-19]. Regarding the usefulness of a new modality '2-D Doppler', it may he now safely concluded that it provides a dynamic method for studying the spatial distribution of blood flow velocities in the beating heart, unlike any noninvasive or invasive technique previously available .