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Fig. 13. Integrating mitral inflow Doppler and Doppler tissue imaging. Pulsed wave tissue Doppler imaging spectral waveforms with simultaneous standard Doppler mitral valve inflow. In the normal heart, there is brisk early myocardial relaxation. With impaired relaxation, there is marked slowing of the early myocardial relaxation velocity. Sa, systolic myocardial tissue Doppler velocity; Ea, early myocardial relaxation velocity; Aa, myocardial velocity associated with atrial contraction.

Fig. 13. Integrating mitral inflow Doppler and Doppler tissue imaging. Pulsed wave tissue Doppler imaging spectral waveforms with simultaneous standard Doppler mitral valve inflow. In the normal heart, there is brisk early myocardial relaxation. With impaired relaxation, there is marked slowing of the early myocardial relaxation velocity. Sa, systolic myocardial tissue Doppler velocity; Ea, early myocardial relaxation velocity; Aa, myocardial velocity associated with atrial contraction.

apex in diastole. Thus, a cardiac cycle is represented by three waveforms (Fig. 12): (1) Sa, systolic myocardial velocity above the baseline; (2) Ea, early diastolic myocardial relaxation velocity below the baseline; (3) Aa, myocardial velocity associated with atrial contraca-tion, below the baseline. The subscripts "a" for annulus or "m" for myo- cardial (Ea or Em) or the superscript "prime" (E') are used to differentiate tissue Doppler velocities from the corresponding standard Doppler blood flow velocities.

The peak Ea velocity is used in the analysis of LV diastolic function. This can be measured from any aspect of the mitral annulus (lateral, septal, inferior, or anterior from the apical four- and two-chamber views, respectively), however the lateral and septal velocities are most commonly employed. Owing to intrinsic differences in myocardial fiber orientation, septal Ea velocities tend to be slightly lower than lateral Ea velocities. Ea reflects the velocity of early myocardial relaxation as the mitral annulus ascends from the apex toward the base in association with early rapid LV filling (E-wave). DTI has been validated against invasive measures of LV filling and has been found to correlate relatively well with tau, the time constant of isovolumic relaxation. E is also a somewhat more robust than mitral inflow patterns under different loading conditions. Reduction in lateral Ea velocity less than 8-10 cm/sec is an indication of impaired LV relaxation (Table 3). In contrast to standard mitral flow inflow patterns, Ea velocities tend to remain consistently reduced through all phases of diastolic dysfunction (Fig. 13).

Technical Issues in Performing Doppler Tissue Imaging

1. From the apical views, decrease the image depth to focus on the LV and mitral annular region (Fig. 12).

2. Adjust the image to orient the transducer beam as parallel to the motion of the wall as possible.

3. Using the color tissue Doppler mode, place the sample volume on the ventricular side of the annulus in a position where the myocardium stays within the sample volume for a maximum amount of the cardiac cycle.

4. Use a sample volume of 3-6 mm. A smaller size may be required if LV systolic function is poor (the spectral pattern will appear unfocused). Try to optimize frame rate.

5. Switch to pulse wave DTI and record during a held breath at the end of expiration.

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