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. In conventional doppler we record the motion of blood…By adjusting gain and reject settings, the Doppler technique can be used to record the motion of the myocardium rather than the blood within it

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 All tehse are better with tdi , inter observer variability less as tdi is a aemi quantitive method. Better borders due to spatialresolution, regional function assessment better, stand alone tecniqe in diastolic fn

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

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

Doppler tissue Vs blood pool imaging returning signal contains a broad range of frequency shifts with low-frequency shifts being related to slowly moving targets and high-frequency shifts to more rapidly moving targets. There is also a broad range in the signal amplitude with low-amplitude targets being represented by red blood cells and high-amplitude targets by tissue.

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

blood motion imaging, low shifts and high-amplitude targets are filtered out, and a spectral display representing blood pool motion is presented. Opposite filtering of low-amplitude and high-frequency shifts results in selective registration of tissue motion.

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 With this technique, either the myocardium targeted and weaker reflections from the higher velocity blood cells relatively excluded.

blood motion imaging, low shifts and high-amplitude targets are filtered out, and a spectral display representing blood pool motion is presented. Opposite filtering of low-amplitude and high-frequency shifts results in selective registration of tissue motion.

blood motion imaging, low shifts and high-amplitude targets are filtered out, and a spectral display representing blood pool motion is presented. Opposite filtering of low-amplitude and high-frequency shifts results in selective registration of tissue motion.

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 One obvious limitation is that the incident angle between the beam and the direction of target motion varies from region to region. This limits the ability of the technique to provide absolute velocity

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

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. TDI can be performed in pulsedwave and color modes.

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 Because the apex remains relatively stationary throughout the cardiac cycle,

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.

Doppler tissue imaging using a spectral display and a single area of interest targeted to the lateral mitral valve anulus. The location of the sample volume is noted by the arrow and in this instance is in the lateral anulus. The systolic motion of the anulus (Sa) and the diastolic anular motion (Ea and Aa) are as noted.

Measurement of peak myocardial systolic (Sm), early diastolic (Em), and late diastolic (Am) velocities, as well as the time to peak systolic velocity in ejection phase (Ts) at basal septal and basal lateral segments by 2-dimensional color-coded tissue Doppler imaging in a normal subject (

PARAMETERS OF TDI

Normal Doppler pattern Sm (cm/sec) Em (cm/sec) Am (cm/sec) Septal 8.7 + 1.4 12.3 + 2.9 8.9 + 2.4 Lateral 10.3 + 1.8 16.3 + 2.9 7.8 + 3.0 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

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. Color TDI mode has the advantage of

septum moves posteriorly, it is encoded in blue, and as the posterior wall moves anteriorly in systole, it is encoded in red

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

individual with normal contraction individual with normal contraction. Note that motion toward the transducer is color encoded in red and that oriented away from the transducer is in blue. For this reason, normally contracting walls that move opposing directions are color encoded in opposite colors. Also note the excellent temporal resolution for determining the timing of contraction.

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 Derivation of doppler tissue velocity

Strain Lo Strain rate :- rate of deformation 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

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

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.

Clinical Applications of TDI

Assessment of LV Systolic 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

Note that in heart failure there is a reduction of Sm and Em Note that in heart failure there is a reduction of Sm and Em. Systolic dyssynchrony is demonstrated by the delay of Ts in the basal lateral segment when compared with the basal septal segment.

Assessment of Diastolic 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

Lateral annulus most commonly used 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 Because of intrinsic differences in myocardial fiber orientation

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

Em / Am < 1 Em <8 cm/sec

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

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 The technical difficulties of timely acquisition of both 2-dimensional and TDI data during exercise represent the major limitations to routine integration in stress testing.

Novel Applications of TDI A number of emerging applications for TDI are under active investigation

Estimation of LV Filling 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 Simultaneous cardiac catheterization and echocardiographic studies have shown that

Differentiation Between Constrictive and Restrictive 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. characteristic of restrictive cardiomyopathy result

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

Early Diagnosis of Genetic 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. Reduced Ea velocities have been similarly demonstrated in patients in the

Differentiation of Athlete’s Heart 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

Assessment of Cardiac Dyssynchrony 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

identify potential responders to cardiac resynchronization therapy

Assessment of Right Ventricular Function important prognostic indicator in patients with heart failure and in postinfarction patients Reduced tricuspid annular velocities with TDI have been documented in a variety of disease settings Post inferior myocardial infarction chronic pulmonary hypertension, and chronic heart failure The complexity of right ventricular anatomy and geometry challenges accurate assessment of right ventricular systolic function

TDI Consider complimentary to the std. Echo Important in diastolic function assessment TVI obtain data even in suboptimal 2D windows Less inter observer variation Quantitative than qualitative Better regional assessment Assessment of myocardial asynchrony

Strain rate imaging Better regional assessment than TVI Better predictor of LV function than TVI Better predictor of ischemia

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