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Blood Flow Patterns in the Heart: Blood Flow Across Stenotic Sites
Blood flow across stenotic sites is often high velocity, and generally aliases. As the velocity increases, the likelihood of turbulence also increases. To visualize blood flow across a stenotic site, use any view that shows both the obstruction and the chamber distal to it. To estimate the severity of a stenotic lesion calculate the pressure gradient across the obstruction. CFI identifies blood flow characteristics and jet direction, but does not produce quantifiable numbers. The colors indicate only relative mean velocity estimates, so they are not useful in determining severity. However, you can use the blood flow spatial information CFI provides to quickly guide Doppler beam placement. Blood Flow Across Stenotic Sites: Mitral Stenosis Mitral stenosis (MS) visualizes as a flow jet from the apical and parasternal long-axis views. MS flow jets appear in diastole, as blood moves through the MV into the LV. The velocities present in stenotic mitral blood flow change throughout diastole. Therefore, frozen color images of the same MS flow jet can differ significantly, if taken from different points in diastole. This apical four-chamber view shows a MS flow jet in the LV in diastole. An enhanced velocity map is used. The MS flow jet moves toward the transducer and contains very high velocities, indicated by yellows and aliased blues. The blood flow is turbulent, represented by a mosaic pattern. As seen in the apical four-chamber view of a patient with MS, the position information provided by CFI facilitates PW Doppler sample volume placement. A mosaic, indicating high velocity and turbulence, represents the MS flow jet.