Colour Visualization of Two-Dimensional Distribution of Intracardiac Flow Abnormalities by Multigate Doppler Technique

The detection of flow disturbances in the heart and great vessels by pulsed Doppler echocardiography has great potentials in the noninvasive assessment of valvular and shunt disease (1,2). Recent investigations (3-5) have suggested that the extent or the area of the flow disturbances may reflect the severity of the valvular abnormalities. Current advent of real-time, two-dimensional duplex Doppler echocardiography has provided a more exact localization of the sample volume in the heart and great vessels, and enabled us to evaluate the extent of the flow disturbances very accurately. However, it is sometimes difficult to determine the presence or absence of the flow disturbance from a representation of the audio spectrum, the time interval histogram, since this analysis is easily modified by improper setting and is sensitive to noise and signal amplitude. Although the multifilter soundspectrogram could express all information available in the pulsed Doppler signal, it is also qualitative. Thus, recent interest has focused on Fourier analysis as a possible method of quantitating flow disturbances from Doppler signals (7–10).