Final answer:
In significant mitral regurgitation, the continuous-wave Doppler tracing typically shows a symmetrical shape of the flow velocity spectral display, indicating a high-velocity jet throughout systole.
Step-by-step explanation:
In patients with significant mitral regurgitation, the continuous-wave Doppler tracing of the regurgitant lesion may demonstrate a symmetrical shape of the mitral regurgitation flow velocity spectral display. Mitral regurgitation is a condition where the mitral valve does not close properly, allowing blood to flow backward into the left atrium when the left ventricle contracts. The symmetrical shape of the Doppler waveform in significant mitral regurgitation suggests a high-velocity jet throughout systole, which is different from the variations in jet velocity that might occur with less severe regurgitation or other valvular abnormalities.