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TISSUE DOPPLER BASICS

TISSUE DOPPLER BASICS. DR BIJILESH U. Tissue Doppler imaging (TDI) is a relatively new echocardiographic technique that uses Doppler principles to measure the velocity of myocardial motion. Assessment of myocardial motion. 2D imaging Poor delineation of endocardial borders

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TISSUE DOPPLER BASICS

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  1. TISSUE DOPPLER BASICS DR BIJILESH U

  2. Tissue Doppler imaging (TDI) is a relatively new echocardiographic technique that uses Doppler principles to measure the velocity of myocardial motion.

  3. Assessment of myocardial motion • 2D imaging • Poor delineation of endocardial borders • Inter observer variability • Qualitative than quantitative • Poor regional function assessment • Diastolic function assessment limited

  4. TDI • TVI obtain data even in suboptimal 2D windows • Less inter observer variation • Quantitative than qualitative • Important in diastolic function assessment • Better regional assessment

  5. Principles of TDI Doppler Effect Frequency of a reflected ultrasound wave is altered by movement of the reflecting surface away from or towards the source

  6. Doppler tissue Vs blood pool imaging

  7. RBC s - relatively weak reflectors and fast moving • Conventional doppler -filters adjusted to exclude highly reflective objects and to maximize less reflective & high velocity objects

  8. TDI- target is tissue rather than red blood cells. • Tissue has a greater reflectivity and slower motion, • Filters set to exclude high velocities and low-intensity reflectors. • Filters are set to parameters opposite

  9. Limitations • TDI measures only the vector of motion that is parallel to the direction of the ultrasound • Incident angle between the beam and the direction of target motion varies from region to region • Limits the ability to provide absolute velocity • Unable to discriminate passive motion from active motion

  10. Tissue Doppler –imaging modes • Pulse wave Doppler • Color 2D imaging • Color M- Mode

  11. Pulsed-wave TDI • Used to measure peak myocardial velocities • Suited to the measurement of long-axis ventricular motion • Longitudinally oriented endocardial fibers are most parallel to the ultrasound beam in the apical views.

  12. mitral annular motion :good surrogate measure of overall longitudinal left ventricular (LV) contraction and relaxation • To measure longitudinal myocardial velocities, the sample volume is placed in the ventricular myocardium immediately adjacent to the mitral annulus

  13. Wave forms • The cardiac cycle is represented by 3 waveforms • Sa - systolic myocardial velocity above the baseline as the annulus descends toward the apex • Ea - early diastolic myocardial relaxation velocity below the baseline as the annulus ascends away from the apex • Aa - myocardial velocity associated with atrial contraction.

  14. PARAMETERS OF TDI

  15. Normal Doppler pattern • Septal Systolic velocities lower than free wall Sm • Em / Am more than one, similar to E/ A in mitral flow • Peak velocities at base and decrease towards apex • Age related reduction in peak velocities Sm and Em • Em/ Am reversal after age of 50

  16. Color TDI • Color-coded representation of myocardial velocities is superimposed on gray-scale 2-dimensional or M-mode images • indicate the direction and velocity of myocardial motion • increased spatial resolution and the ability to evaluate multiple structures and segments in a single view.

  17. M-mode color Doppler tissue imaging • Color -encoded images of tissue motion along an M-mode interrogation line • Represents a combination of M-mode echocardiography, color Doppler imaging, and quantitative Doppler tissue imaging • High temporal and spatial resolution • Determining velocity gradients between adjacent points or more recently for strain rate imaging

  18. Endocardial-epicardial gradient • DTI sample volume in the subendocardium, & subepicardial • Difference between velocities -endocardial-epicardial gradient. • Alterations ,with a selective decrease in the subendocardial velocities --very sensitive marker of ischemia • determined in a single segment with the same angle of interrogation of the Doppler beam- relatively angle independent

  19. Strain • Deformation of the myocardium on application of stress • Change in distance between two points divided by the initial length (L0). • expressed as percentage L-Lo • Lo • Strain rate :- rate of deformation • Integration of Strain Rate gives strain

  20. Strain rate • Derivative of DTI provides a high-resolution evaluation of regional myocardial function • sensitive and earlier indicator of regional dysfunction

  21. With DTI simultaneously determine velocities in two adjacent points & relative distance in between • Defined as the instantaneous rate of change in the two velocities divided by the instantaneous distance between the two points. • Positive strain rate represents active contraction and negative values, relaxation or lengthening between the two points.

  22. Clinical Applications of TDI

  23. Assessment of LVSystolic Function • Systolic myocardial velocity (Sa) at the lateral mitral annulus measure of longitudinal systolic function • Correlated with LV ejection fraction • Mitral annular displacement Velocity reduced in LV dysfunction • Regional reductions in Sa - regional wallmotion abnormalities. • Advantage in suboptimal echo window

  24. Assessment ofDiastolic Function • Mitral inflow patterns are highly sensitive to preload • mitral valve inflow patterns to assess diastolic function remains limited • TDI assessment of diastolic function is less load dependent

  25. Ea - reflects the velocity of early myocardial relaxation as the mitral annulus ascends during early rapid LV filling. • Peak Ea velocity - measured from any aspect of the mitral annulus from the apical views • Lateral annulus most commonly used • Septal Ea velocitiy slightly lower than lateral Ea velocities

  26. Reductions in lateral Ea velocity to ≤ 8 cm/s in older adults indicate impaired LV relaxation • Differentiates normal from a pseudonormal mitral inflow pattern • Unlike conventional mitral inflow patterns, Ea is resistant to changes in filling pressure

  27. Em / Am < 1 Em <8 cm/sec

  28. CAD • Reduction in Sa velocity can be detected within 15 seconds of the onset of ischemia • Ischemia low systolic and diastolic velocities • <7.5cm./sec LV wall velocity - WMA • Em/ Am reversal

  29. TDI Stress Echo • Incorporation of TDI measures of systolic function in exercise testing to assess for ischemia • Peak Sa velocity increases with dobutamine and exercise and decreases with ischemia • Better identification of abnormal segments • Better reproducibility than standard Echo • Peak velocity < 5.5 cm/sec identify abnormal segments • 96% sensitivity, 81% specificity Katz et al

  30. Novel Applications of TDI

  31. Estimation of LVFilling Pressures • LV filling pressures are correlated with the ratio of the mitral inflow E wave to the tissue Doppler Ea wave (E/Ea) • E/lateral Ea ≥ 10 or E/septal Ea ≥ 15 -- elevated LV end-diastolic pressure, • E/Ea ≤ 8 is correlated with a normal LV EDP • E/Em > 10 predicted PCWP > 15 mm of Hg with 92% sensitivity and 82% specificity Nagueh et al

  32. Differentiation BetweenConstrictive andRestrictive Physiology • Constrictive pericarditis and restrictive cardiomyopathy -- abnormal LV filling • In the absence of myocardial disease, Ea velocities typically remain normal. • intrinsic myocardial abnormalities - impaired relaxation and reduced Ea velocities.

  33. Constriction Vs Restriction • Em < 8 cm/sec restriction >8 constriction • Garcia et al

  34. Early Diagnosis ofGenetic Disease • unexplained LV hypertrophy is typically required to diagnose hypertrophic cardiomyopathy (HCM) • degree of hypertrophy and age of onset are highly variable • Abnormalities of diastolic function-reduction of Ea velocities • Sarcomere gene mutation ;before the development of LV hypertrophy • Early stages of Fabry disease.

  35. Differentiation of Athlete’sHeart From HCM • Approximately 2% of athletes abnormal degree of LV hypertrophy • Discriminating physiological hypertrophy due to intense athletic conditioning from pathological • Athletes highly compliant ventricles with brisk Ea velocities • reduced Ea velocities in individuals with HCM

  36. Assessment of CardiacDyssynchrony • Identifying patients who will benefit from cardiac resynchronization therapy which can improve heart failure • TDI can be used to assess the relative timing of peak systolic contraction in multiple myocardial regions • standard deviation of the time to peak contraction represents a measure of overall ventricular synchrony

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