TISSUE DOPPLER IMAGING

1. TISSUE DOPPLER IMAGING

2. Introduction • TDI uses Doppler shift data from the myocardium to obtain qualitative and quantitative information on myocardial wall motion. • Measures the velocity of myocardial wall motion • Low velocity • 5 to 20 cm/s • 10 times slower than velocity of blood flow • High amplitude • Approximately 40 decibels higher than blood flow IntJ of Card Imaging 2001;17::8

3. Doppler tissue Vs blood pool imaging

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

6. 2D Colour TDI • Colour-coded representation of myocardial velocities- superimposed on gray-scale 2-dimensional 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.

8. M-mode colour Doppler tissue imaging • Colour-encoded images of tissue motion along an M-mode interrogation line. • High temporal and spatial resolution.

9. Pulsed-wave TDI • Used to measure peak myocardial velocities • Mitral annular motion: Good surrogate measure of overall longitudinal left ventricular contraction and relaxation. • To measure longitudinal myocardial velocities, the sample volume is placed in the ventricular myocardium immediately adjacent to the mitral annulus

10. Pulse Wave Tissue Doppler

12. Diastolic components of myocardial velocities correlate with mitral inflow velocities

13. Normal Myocardial Velocities : Basal Segments (cm/s) J Am Soc Echo 2001;14:1143-52

14. Myocardial Velocity Gradient • Difference in myocardial velocity between the endocardium and epicardium divided by the myocardial wall thickness • Reflects rate of change in wall thickness • MVG is an indicator of regional myocardial contraction. • Determined in a single segment with the same angle of interrogation of the Doppler beam- relatively angle independent J Am CollCard 1995; 26:217-23

16. Clinical Applications of TDI

17. Assessment of LV Systolic Function • Sa- Correlated with LV ejection fraction. • Peak systolic velocities were measured at 4 different sites of the mitral annulus. • A cut-off point of ≥ 7.5 cm/s had a sensitivity of 79 % and a specificity of 88 % in predicting preserved systolic function or ejection fraction of ≥ 0.50. • Regional reductions in Sa - regional wall motion abnormalities. J Clin Basic Cardiol 2002; 5: 127

18. Regional Systolic Function • Pulse wave tissue Doppler after anteroseptalMI. • Decreased velocity in the septum (top). • Normal velocity in the lateral wall (bottom).

19. Diastolic Dysfunction Impaired relaxation Pseudonormal Restrictive

20. Transmitral flow velocities are dependent on LA filling pressures. • Psuedonormalizationoccurs as LA pressure increases. • Difficult to diagnose diastolic dysfunction from mitral flow velocities. • Myocardial velocities are persistently reduced in all stages of diastolic dysfunction. • TDI assessment of diastolic function is less preload dependent.

21. Diastolic Dysfunction

22. Diastolic Dysfunction

23. 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/E’) • E/lateral E’ ≥ 20 - elevated LV end-diastolic pressure. • E/E’ = 5-15 is correlated with a normal LV EDP • E/E’ > 20 predicted PCWP > 15 mm of Hg with 92% sensitivity and 82% specificity Nagueh et al

24. Constrictive Vs Restrictive Physiology • Constrictive pericarditis with normal LV function have normal or elevated Emvelocities. • Doppler Em velocity of 8 cm/s differentiates constriction and restriction. • Restrictive < 8 cm/s • Constrictive > 8 cm/s

26. Assessment of RightVentricular Function • Important prognostic indicator in patients with heart failure and in postinfarction patients • Reduced tricuspid annular velocities with TDI have been documented in Post inferior myocardial infarction, chronic pulmonary hypertension, and chronic heart failure.

27. Limitations • Accuracy of velocities dependent on angle of ultrasound beam. • Not all wall velocity obtainable from every view. • Wide range of normal values. • Even non contractile myocardium will be pulled by near by segments resulting in apparent velocity component.

28. Strain Rate Imaging

29. Introduction • Evaluation of a myocardial region with reference to an adjacent myocardial segment. • Deformation analysis- analysis of ventricular mechanics or shapes during cardiac cycle. • Myocardial strain, strain rate, torsion. • Strain- percentage thickening or deformation of the myocardium during the cardiac cycle. • Change of strain per unit of time is referred to as strain rate

30. Strain calculated in three orthogonal planes- representing longitudinal, radial, circumferential contraction. • Negative strain- shortening of segment. • Positive strain- lengthening of segment

32. Strain & Strain rate

34. Methods

35. Comparison of Two-Dimensional Speckle Tracking Echocardiography(2D STE) with Tissue Doppler Imaging (TDI)

37. SR- Doppler tissue imaging

38. Speckle tracking • ‘Speckles’ are small dots or groups of myocardial pixels that are created by the interaction of ultrasonic beams and the myocardium. • Considered as acoustic fingerprint for that region. • This enables to judge the direction of movement, the speed of such movement, and the distance of such movement of any points in the myocardium.

39. Speckle

40. Method • Track the endocardial and epicardial borders of the left ventricle • Correctly define the region of interest (ROI) in the long or short axis view • Post-processing software automatically divides the ventricle into six equally distributed segments • 2D or 3D data set is produced • Mathematical algorithms are applied to generate values

41. Strain is not uniform among all myocardial segments. • Radial strain-Magnitude of basal parameters are higher than the apical values. • Longitudinal strain- less variability fron apex to base. • Circumferential strain- higher in anterior and lateral walls compared to posterior and septal. • Normal longitudinal strain averages -20% • Normal radial strain about +40%

43. Normal Strain Displays Wave Forms ,Curved M-mode

44. Normal Strain Displays- bulls eye presentation

46. Normal pattern Dilated cardiomyopathy Dyssynchrony

47. Velocity vector imaging

48. Cardiac muscle • 3 layers- • middle transverse layer. • inner oblique layer(descending segment) • outer oblique layer( ascending segment)

49. VENTRICULAR TORSION • Similar to the winding and Unwinding of a towel. • Isovolumetric contraction -the apex and base rotates in counterclockwise direction. • Ejection phase apex rotates counterclockwise & base rotates clockwise when viewed from the apex • Diastole - relaxation of myocardial fibres - recoiling - clockwise apical rotation. • Isovolumetric relaxation- both apex and base rotates in clockwise direction.

50. Myocardial mechanics