Strain presentation class presentatio - copy
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This document discusses the evolution and clinical applications of strain imaging using echocardiography. Strain imaging allows quantitative analysis of myocardial deformation and function beyond what can be seen with conventional echocardiography. It describes how speckle tracking can measure longitudinal, radial, and circumferential strain to assess different regions of the heart. Clinical uses of strain imaging include early detection of chemotherapy-induced cardiomyopathy and assessment of valvular heart disease before changes in ejection fraction occur.
Strain presentation class presentatio - copy
- 3. CASE 1 65 year old male is a K/C/O HTN (5 years), smoker with family history of CAD present presented with complaints of angina on exertion since 3 months. ECG- Normal Echo- normal study. CAG- Normal coronaries. CASE 2 65 year old male is a K/C/O HTN (5 years), smoker with family history of CAD present presented with complaints of angina on exertion since 3 months. ECG- Normal Echo- normal study. CAG- TVD.
- 4. INTRODUCTION • Echocardiogram is a standard procedure in evaluation of LV function. • Conventional echocardiography is considered to be reliable for regional wall motion analysis. • Visual estimation of wall motion is very subjective & therefore highly operator dependent. • High interobserver & intraobserver variability
- 5. • Also some patients had no visual segmental wall motion abnormalities at rest despite having significant CAD on angiography. • Strain imaging is a new tool to measure myocardial deformation and allow quantitative analysis of global and regional myocardial function
- 6. • Deformation- Any change in shape. • Strain - percentage change in myocardial deformation. ε= L-L0/L0 L - length of the object after deformation, L0 is the basal length of the object.
- 8. Depending on the direction :- • shortening/ thinning of segment- Negative strain, • thickening/ lengthening of segment- Positive strain
- 10. Strain Rate • Rate of change of deformation of a myocardial segment over time. • Strain rate- strain/ ∆ time • It is expressed as seconds−1; • Noisier and less reproducible & most clinical studies use strain measurements.
- 11. • At baseline • A) 10 cm • B) 10cm
- 12. • At 2 second • A) 20cm • B) 15 cm
- 13. • At 2 second A) 20cm • Strain -20-10/10= 100% • Strain Rate- 1/2= 0.5 per second At 4 second B) 20 c 20cm Strain -20-10/10= 100% Strain rate 1/4 = 0.25 per second
- 14. • Myocardial Tethering • Dysfunstional segment is pulled by active segment. • 2D echo cant differentiate b/w active and passive movement. • Strain/ strain rate can differentiate which is actually pulled and not contracting
- 15. Three aspects • Velocity- How fast/ slow myocardial segment is contracting. - cm/sec • Strain- Total amount of contarction that has occurred. - percentage • Strain rate- At what rate it is contracting - per second.
- 16. • Strain calculated in three orthogonal planes- representing • Longitudinal - negative (shortening) • Radial – positive (thickening) • Circumferential – negative (shortening)
- 18. Longitudinal Strain- • Shortening of LV along its long axis • Directed from the base to the apex, during systole. • Represented by negative trend curves on speckle tracking • Measured from 4-chamber, 2-chamber, and apical long-axis views, both regional (relative to each of the 17 LV segments) and global strain values (global longitudinal strain) can be obtained.
- 20. Radial Strain • Thickening of LV wall along its radius, during systole • Obtained in basal and apical LV short-axis views. • represented by positive trend curves on speckle tracking
- 22. Circumferential Strain • Reduction in the circumference of LV cavity, during systole • Circumferential strain represented by negative curves. • Measured from short axis view
- 24. Rotational strain • LV rotates around its long axis. • During systole, apex rotates in anticlockwise direction & base rotates in clockwise direction. • Measured from short axis view. • By convention, anticlockwise rotation is displayed above the baseline and is assigned a positive value whereas the opposite is true for the clockwise rotation. Thus, the normal apical rotation is positive and the basal rotation is negative.
- 26. Arrangement of myofibers in Myocardium • Inner subendocardial fibres are oriented parallel to the long axis of LV and hence predominantly help in longitudinal contraction. • Mid-myocardial & subepicardial fibers are arranged parallel to the circumference of LV & hence help in radial, circumferential & rotational movement.
- 27. • Epicardial coronary artery stenosis is a/w reduction in the subendocardial to subepicardial flow ratio. • Subendocardium layer of the heart is most vulnerable to ischemic damage. • The subendocardial region consists of longitudinally directed fibers, significantly contributing to long axis function. • As a result; longitudinal function is impaired first in CAD. • Measurements of longitudinal motion and deformation are therefore, the most sensitive markers of CAD
- 28. • RS & CS remain preserved or may even be accentuated during the early stages to compensate for the loss of the longitudinal function. • As the disease becomes more extensive/ more transmural, RS & CS also get progressively impaired. • Thus, the impairment of RS & CS is a relatively late phenomenon and tends to reflect more extensive myocardial damage. • However, in certain pathological conditions that affect the heart from the outside, such as constrictive pericarditis, CS & RS may get compromised earlier than the LS.
- 29. Methods Doppler tissue imaging • Two discrete points are compared for change in velocity • Strain rate- primary parameter obtained • Strain –derived by integrating velocity over time. Speckle tracking • Actual location of discrete myocardial segments calculated. • Strain is the primary parameter. • Strain rate-derived by calculating change in distance over time.
- 30. SR- Doppler tissue imaging
- 32. Comparison of Two-Dimensional Speckle Tracking Echocardiography (2D STE) with Tissue Doppler Imaging (TDI) 2D STE TDI Deformation analysis in 2 dimensions . One-Dimension measurements Angle independent Measurement dependent on angle Better spatial resolution Limited spatial resolution Less time-consuming data acquisition and easy data processing. Time-consuming Lower temporal resolution High temporal resolution Dependent on high resolution image quality Image quality less important Lower interobserver variability Higher interobserver variability Lower optimal frame rate limits the reliability of measurements in patients with tachycardia
- 33. Speckle tracking • Analysis of the spatial dislocation (referred to as tracking) of speckles on routine 2-dimensional sonograms. • ‘Speckles’ are small dots or groups of myocardial pixels that are created by the interaction of ultrasonic beams and the myocardium. • Judge the direction of movement, the speed movement, & the distance of movement of any points in the myocardium.
- 34. Speckle
- 35. How to perform speckle tracking echocardiography Image acquisition • Obtain high quality gray scale image, wherein endocardial & epicardial border is well defined • Apical 4, 3 & 2 chamber for Longitudinal strain. • Short axis view at basal, mid & apical levels for radial, circumferential & rotational strain. • For LA strain, apical 4, 3 & 2 chamber view • For RV strain, RV focused apical 4 chamber view
- 36. • Optimal frame rate - 60 and 110 frames/ second. • High quality ECG signal for proper gating of images • Minimal 3 cardiac cycle should be acquired. • All images should be acquired in breath- hold to avoid any breathing artifacts.
- 37. Image Analysis • Begin with an apical 3 chamber view. In this AV movement help in timing the AVC, essential to perform deformation analysis. • When the image is opened in software, software automatically brings up end systolic frame. • In this, endocardial border is traced manually, beginning at one end of the mitral annulus and ending at the other end.
- 38. • The software then generates a region of interest (ROI) to include the entire myocardial thickness. • Width of ROI can also be manually adjusted. • Software then track the myocardial speckles frame by frame and generates moving images displaying the tracking. • Software then divides the LV myocardium into seven segments and generates segmental and global longitudinal strain & strain rates.
- 41. • Same process is repeated with apical 4 & 2 chamber images. • Strain values for all the segments are recorded & averaged to obtain the global longitudinal strain. • Also provide Bull’s eye display of the regional & global longitudinal strain.
- 42. Normal Strain Displays- bulls eye presentation
- 44. • Short axis is also analyzed in the same manner to get the segmental & global radial & circumferential strain & strain rate.
- 45. Interpretation • Among all the strain parameters, longitudinal strain is more reproducible than the radial & circumferential strain & rotation. • Similarly, global strain has much better reproducibility than the segmental strain. • The normal GLS is usually in the range of - 16 to -18% or more (i.e. more negative).
- 46. • The circumferential strain is usually greater than the longitudinal strain with average values in excess of -20%. • The average radial strain is in the range of +40 to +60%. • The rotation strain has much greater variability which makes it difficult to define the normal ranges for the same. However, it should be noted that the apical rotation is normally much greater than the basal rotation which is limited by the tethering effect of the mitral annulus
- 47. • The maximum LS, CS & RS during systole is termed as peak systolic strain (peak LS, peak CS & peak RS). • Average strain during systolic phase is termed as mean LS, mean CS & mean RS
- 48. Normal Strain Displays Wave Forms ,Curved M-mode
- 52. Clinical application 1. Detection of subclinical myocardial dysfunction Fall in the LVEF represents a relatively late stage when sufficient myocardial damage has already occurred. Detection of the myocardial dysfunction in subclinical stage may have significant diagnostic and therapeutic implications .
- 53. a) Chemotherapy induced cardiomyopathy • Impairment of GLS despite preserved LVEF in patients receiving cancer chemotherapy may warrant discontinuation of the treatment regimen. • One study found that reduction of LS by 10% predicts decline in LVEF in subsequent 6 month with sensitivity of 78% and specificity of 79%
- 55. b) Valvular heart disease • In MR/AR, LV respond to increase in volume overload by dilatation & in AS respond to pressure overload by hypertrophy. • This maintain LV sysytolic function & could mask subcliniacal LV dysfunction. • Evidence of early myocardial damage in patients with severe AS/MR may help in timing the surgical intervention in these patients & can prevent irreversible myocardial damage.
- 56. • Impaired LS is the first sign of myocardial dysfunction in chronic VHD f/b impairement of RS & CS as disease progressed. • Also strain have been shown to improve after surgical intervention.
- 57. Also helpful in documenting cardiac involvement in a variety of disorders such as HTN, DM, obesity, OSA, amyloidosis, Fabry’s disease, etc. • Varghese MJ et al. (2016, AIIMS), GLS was significantly reduced in patients with OSA (p < 0.01). • Segmental analysis revealed that the LS abnormalities are more pronounced in the apical and mid segments of LV.
- 59. Differentiating HCM from Athletes’ heart. HOCM - Decrease LS strain with preserved CS strain Athlete’s Heart • Increase LV hypertrophy lead to increase LV mass with preserved or increase LV systolic & diastolic function. • STE showed increase in LS. • Some study showed increase in RS & CS
- 61. 2) As a surrogate for LVEF • For estimation of LVEF from GLS using the in-built regression equation. 3) Monitoring response to treatment • GLS can be used for monitoring improvement in LV contractile function after myocardial revascularization / stem cell therapy /drugs etc.
- 62. 4) Role in acute coronary event • LS is reduced in infarcted segment proportional to the area of infarcted region. Hence predict infarct size • In subendocardial infarct, only LS is reduced with preservation/ accentuation of RS & CS, While in transmural infarct, CS & RS is also impaired.
- 63. • Becker et al. have shown that segmental RS < +16.5% & CS < -11.1% can differentiate nontransmural infarction from transmural infarction with sensitivity of 70% & specificity of 71.2%. • He also found that RS > +17.2% indicate good functional recovery after reperfusion.
- 64. 5) As a measure of myocardial ischemia and viability • LS, when combined with DSE, improves the accuracy of assessment of myocardial ischemia and viability. • Augmentation of strain & strain rate with dobutamine is a marker of myocardial viability. • The resting GLS has also been shown to be a predictor of myocardial viability.
- 65. • In one study, it is found that RS cut off value 17.2% could predict a viable myocardium with sensitivity of 72% & specificity of 85% (similar to CE-MRI). • Another study (Park et al.), found that LS value < -10.2% following reperfusion therapy aftetr MI predicts non viable myocardium with sensitivity of 90% & specificity of 85%. • In addition, impairment in CS also indicates lack of myocardial viability as it reflects greater transmural extent of the infarct.
- 66. DCMP • Impairement of all three directional strain(LS/RS/CS) Stress cardiomyopathy • Reduction in various LV strain that extend beyond the single coronary artery territory & improvement in these finding at recovery.
- 68. Heart Transplant patients • Marciniak et al. found significantly lower LV LS & RS strain rate in patients with acute rejection. • Fusaka sera et al. found that LS <11% could predict cellular rejection with sensitivity of 40% and specificity of 90%
- 69. 6) Role in cardiac resynchronization therapy • Radial strain has been shown to be a robust measure of intraventricular mechanical dyssynchrony & a reliable predictor of the response to CRT therapy. • Time to peak radial strain can also help in identifying the site of least activation and thus help in guiding the LV lead placement. 7) Assessment of LV diastolic function • Early diastolic strain rate, peak untwist velocity and time to peak untwist velocity have all been used as measures of LV diastolic function with variable results.
- 70. 8) Assessment of RV function • RV longitudinal strain has been shown to be a reliable measure of RV systolic function in a variety of clinical conditions such as pulmonary embolism, RVMI, pulmonary hypertension, RV cardiomyopathies, congenital heart diseases like TOF, pulmonary atresia with intact IVS & TGA, tricuspid atresia, DORV & AV canal defect etc.
- 71. LA function • Reduced peak atrial LS is observed in:- -LV diastolic dysfunction - atrial septal device occlusion - who have undergone catheter ablation/ cardioversion
- 72. 10) RA Strain • Not much study. • One study showed that in DCMP patient with CRT for dyssynchrony, peak right atrial LS is much lower in non-responder (24+10%) in comparison to responder (40+8%). 11) Other uses • As mentioned earlier, early impairment of circumferential strain may help in differentiation between constrictive pericarditis and restrictive cardiomyopathy.
- 73. Limitation There are a number of factors that affect measurement of LV strain. These include physiological factors such as age, gender etc Other limitation are :- 1) image quality -Highly dependent on 2D image quality. -With suboptimal acoustic window, STE fail to quantitate strain correctly.
- 74. 2) Heart rate - Mismatch of temporal & spatial resolution at higher heart rate, leading to underestimation of strain & SR. 3) Vendor viability • - measurements obtained on one ultrasound system are not identical to the measurements obtained on another ultrasound system. • For these reasons, no universally accepted normal values are available for the different myocardial deformation parameters.
- 75. 3-D Speckle Tracking Echocardiography • 2D STE is based on the assumptions that speckles always confined within the 2D images. • This is not always valid because 3D motion of cardiac chambers. • 2D STE unable to measure one of three component of displacement vectors & this affect the accuracy of various derived strain. • In comparison, 3D STE result in more homogenous spatial distribution of various myocardial strain
- 76. • 3D STE estimated strains showed more interobserver, intraobsever & test-retest reproducibility. • Show greater correlation with MRI than corresponding 2D derived strain. • In addition, global deformation indices can be obtained in a shorter span of time by obtaining a single large 3D volume. • Finally, 3D strain exclusively allows for the measurement of “area strain (AS),” defined as longitudinal strain × circumferential strain, providing additional information on global myocardial function.
- 77. • Dillikar MV et al. (2017, Sri Satya Sai) found that the sensitivity of GLS for CAD was 80% for 2D versus 93% for 3D STE. • Similar findings were seen for global circumferential strain (sensitivity 87% for 2D vs. 100% for 3D). • However, the sensitivity of 3D global radial strain was lower (93% for 2D vs. 47% for 3D).
- 81. Flow chart Patients who meet the inclusion criteria for study admitted to BHMRC will be enrolled Eligible cases Routine demographic,clinical,biochemical and ECG assessment 2D echocardiography (Global peak LV strain,, LVEF,)
- 82. • All patients will undergo Coronary Angiography Statistical Analysis Outcome:whether 2Decho parameters of LV function helps in ruling out significant CAD Group 1 CAD present= Gensini score Group 2 CAD absent
- 83. Hypothesis With this study we hypothesized that global longitudinal peak systolic strain (GLPSS) correlates inversely with coronary artery disease severity and a reduced GLPSS may be able to predict high Gensini Score in patients undergoing coronary angiography, whose resting echocardiogram failed to detect any regional and/or global wall motion abnormalities.
- 87. Cardiac muscle • 3 layers- 1) middle transverse layer. 2) inner oblique layer(descending segment) 3) outer oblique layer( ascending segment)
- 88. 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.
- 89. • Rotation - Measure of the rotational movement of the myocardium in relation to an imaginary long axis line from apex to base drawn through the middle of LV cavity. • Twist (degrees) is the net difference between apical and basal rotation • Torsion - Twist divided by the vertical distance between the apex and base and is expressed as degrees/cm.
- 91. CAD- Myocardial ischemia, Myocardial infarction, Myocardial viability • Reduction in strain by 2D STE more objective and accurate than the traditional visual method of assessing WMA. • Post systolic thickening (deformation)by radial strain correlates with the severity of ischemia. • To differentiate transmural from subendocardial infarction- lower circumferential strain in the former
- 92. Applications • Heart failure with normal LVEF Reduced and delayed LV untwisting—at rest and exercise • Cardiac resynchronization therapy (CRT) Speckle Tracking and Resynchronization (STAR) study showed radial and transversal strain better than longitudinal and circumferential strain in predicting LVEF response and long term survival after CRT. Lack of dyssynchrony before CRT by 2D STE radial strain associated with death or hospitalization for heart failure
- 93. Twist in DCM Am J Cardiol 2008;101:1163–1169, 2008
- 94. Applications • Stress cardiomyopathy. • Restrictive cardiomyopathy. • Detection of subclinical diseases/early myocardial involvement. • Detection of rejection and coronary stenosis in heart transplant patients. • Early detection of chemotherapy induced cardiotoxicity. • Valvular heart disease- Decreased radial, circumferential and longitudinal strain in patients with severe aortic stenosis and normal LVEF. Long term follow up after valve replacement showed significant improvement in strain.
- 95. Differentiation of Athlete’s Heart from Hypertrophic Cardiomyopathy Athlete’s Heart Hypertrophic Cardiomyopathy Normal longitudinal and other types of strain Decreased longitudinal strain Increased LVEDV Decreases after deconditioning for 3 months. Decreased LVEDV No change with deconditioning. Increased LV twist. Delayed LV untwisting. Increased early LA strain rate. Reduced LA strain and strain rate
- 96. 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
- 98. Why Global Longitudinal Peak Systolic Strain? • The subendocardium is often the earliest myocardial layer affected in many disease processes. • It is the furthest layer from epicardial coronary flow • It undergoes extreme fluctuations in pressure and compression in both systole and diastole • Appears prone to early structural microvascular architectural change
- 100. Measurement of GLPSS
- 101. Speckle tracking : Strain • Tissue imaging evaluation myocardial deformation • Good Quantitative assessment • Angle independence • Validated to CMR and Sonomicrometry • Minimal bias ( low intra and interobserver variability)
- 103. • Speckle tracking measures strain and strain rate. • Strain is defined as the percentage change in myocardial deformation and its derivative, • The strain equation (ε) is as follows: ε=L-L0/L0 • where L - length of the object after deformation, • L0 is the basal length of the object
- 104. Strain & Strain rate
- 105. • How to Obtain Strain Parameters • performed offline,. • The optimal frame rate - 60 and 110 frames/ second. • Begin with an apical 3 chamber view to select the frame corresponding to the aortic valve closure, followed by apical 4-and 2-chamber view acquisitions. • The endocardial surface of the myocardial segment analyzed is manually traced by a point-and-click approach. • An epicardial surface tracing is then automatically generated by the system, thus creating a region of interest.
- 106. • After manual adjustment, the software automatically divides the region of interest into 6 segments, and the resulting tracking quality for each segment is automatically scored as either acceptable or unacceptable, with the possibility of further manual correction. • Once the region of interest is optimized, the software generates strain curves for each selected myocardial segment. • From these curves, the operator can obtain regional and global peak and time-to-peak values.
- 107. • the software also automatically generates a topographic representation of all 17 analyzed segments (bull's-eye).
- 108. Application • Diabetes- detecting subclinical LV systolic dysfunction, which is unmasked by the alteration of longitudinal strain. • Valvular heart disease Inpatients with degenerative mitral regurgitation undergoing valvular surgery, speckle tracking showed post surgery LV dysfunction. In patients with AS/ AR immediately after AVR, there is a substantial increase in radial and circumferential strain, suggestive of how these myocardial deformation parameters critically depend on LV load conditions
- 109. • Heart failure LV longitudinal strain progressively deteriorates from NYHA I to class IV, with additional LV radial and circumferential systolic impairment occurring in NYHAclasses III and IV
- 110. • Other Application • Early detection of doxorubicin induced cardiac injury. • Useful in quantification of LV systolic function in athletes and the differentiation of physiologic hypertrophy in athletes’ hearts from asymptomatic nonobstructive hypertrophic cardiomyopathy, which is the major cause of sudden cardiac death in young competitive athletes.
- 111. • Also be used to differentiate physiologic cardiac hypertrophy (“athlete’s heart”) from hypertensive cardiac hypertrophy • Also useful for the evaluation of right ventricular (RV) function in pulmonary hypertension and RV diseases of different etiologies (RV infarction, arrhythmogenic RV dysplasia/ cardiomyopathy)
- 112. • Mean longitudinal LV strain is closely related to plasma BNP levels, in patients with both systolic and diastolic heart failure. • Sensitive indicators for sub-clinical diseases, including diabetes, systemic sclerosis, myocardial ischemia, arterial hypertension, isolated mitral regurgitation, aortic regurgitation and non- ischemic cardiomyopathies. • Useful for the assessment of myocardial damage after infarction, evaluation of myocardial revascularization efficiency and prediction of patient outcome with heart failure.
- 113. • Augmentation of strain and strain rate with dobutamine is a marker of myocardial viability and hence can improve the diagnostic and prognostic assessment of myocardial ischemia and post-infarction scars during dobutamine stress echocardiography. • In patients with chronic ischemic LV dysfunction it was shown that combined assessment of long-axis and short-axis function using 2Dstrain imaging may be used to identify the transmural extent of myocardial infarction
- 114. Following parameters of the left ventricle will be determined from apical two-chamber, three- chamber and four-chamber view: Global peak systolic longitudinal strain LV ejection fraction (LVEF) will be calculated using Simpson’s method.