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5). By placement of the Doppler sample volume at the aortic outflow and integrating the Doppler trace over Osimertinib manufacturer one cardiac cycle, the velocity time integral (VTI) may be calculated. The product of VTI with the aortic valve area provides an estimate of stroke volume. Across the mitral valve, the magnitude of the ratio of early (E) to late (A, i.e. atrial) filling velocities and the deceleration time of the E wave are indicators of diastolic function. The time for the pressure/velocity to decrease by 50% (pressure half-time) across the valve is an indicator of valve area (Hatle et al. 1979), with pressure half-time increasing as valve area is reduced due to valve stenosis. Placement of the Doppler sample volume at the mid-left ventricular level enables temporal measurements, such as isovolumic contraction (time between mitral valve closure and aortic valve opening) and isovolumic relaxation times (time between aortic valve closure and mitral valve opening) to be measured, in addition to ejection time (Fig. 6). In addition, spectral Doppler is useful for determining whether blood flow within vessels is arterial or venous; in general, arterial blood flow is pulsatile and venous blood is not. Colour Doppler blood flow imaging In colour Doppler imaging, the mean velocity of scatterers is colour encoded in a preselected region of interest and superimposed on the 2-D B-mode image (Fig. 7). The technique enables rapid visualization of blood flow within vessels and easy localization of a pulsed Doppler sample volume if spectral Doppler data are required. Alectinib mw Usually, blood moving away from the transducer is colour-coded blue and that moving towards the transducer colour-coded red. Colour Doppler is especially useful for studying incompetent heart valves, where regurgitant jets can be visualized. Power Doppler In power Doppler imaging, the power of the Doppler signal is displayed on the image. As with colour Doppler, this tool is useful for the location of blood vessels in rodent echocardiography but does not display directional information or information on blood flow velocity. GPX4 It is, however, more sensitive to the movement of blood than colour Doppler so is generally used to determine the presence or absence of small blood vessels. Tissue Doppler techniques The Doppler principle can also be applied to quantify both myocardial and intramyocardial velocities (McDicken et al. 1992). Although myocardial velocities are generally much smaller (