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Review articles A Journal of Cardiological Society of India, Kerala Chapter Two dimensional Speckle Tracking Echocardiography An overview AK Abraham* One of the main demands on echocardiography was the evaluation of regional and global left ventricular function. In the early days of echocardiography the M Mode based ejection fraction was considered to be the main tool for this purpose. Eventually this was found to be totally inaccurate in most cases, so much so, no less a person than Feigenbaum declared publicly that he does not do ejection fractions any more. There haven attempts to identify other parameters for LV function assessment as time progressed. Ejection fractions based on 3 dimensional volume determinations added the accuracy, but was constrained by the increased time and effort needed. Doppler based tissue velocity based studies , especially the mitral annular velocities ,offered some relief. But this was again criticized as inaccurate because of the inherent problems of the insonation angle discrepencies. Strain and strain rate studies offered some hope, but this was also based on Doppler technology which was again not totally acceptable. In early 2000, the 2 D based speckle tracking concept gained prominence. This overcame the problem of Doppler velocities being used to measure displacement. Speckle Tracking Echocardiography (STE) is a unique imaging technique where the motion of ultrasonic interference patterns called “speckles”are monitored to derive strain patterns. Regional STRAIN is a dimensionless measurement of deformation , expressed as percentage change from the original dimension. (1) During a cardiac cycle , stretching and shortening occur in the myocardium during systole and diastole. Essentially this is a deformation from the original state. This is known as the Langrangian Strain, and is used by the speckle tracking technology. The end diastolic myocardial dimension is taken as the reference point against which the deformation is analysed (2) Studies of LV myocardial contraction, mainly by Partho Sen Gupta and Bijoy Khanderia from Mayo clinic, have shown twist or torsional deformation Long axis view and graph in normal LV function *Head, Dept of Cardiology, Indira Gandhi Co-op Hospital, Kochi KHJ Kerala Heart Journal 23 Review articles A Journal of Cardiological Society of India, Kerala Chapter the longitudinal direction. According to Choi et al, a strain value less than – 17.9 % was correlated with severe 3 vessel disease.(6) 2. Myocardial infarction Myocardial infarctions result in changes in LV functions like ejection fraction an regional wall abnormalities. STE studies have been shown abnormal strain patterns in such situations. These strain patterns have been found to be correlated to the severity and extent of infarcted areas. (7,8) . These results have been of prognosis value also. Long axis and graph in LV Dysfunction occurs during ejection, which when viewed from the apex appears as clockwise rotation at the apex and counterclockwise at the base. (3). To describe these movements, terms such as twist, rotation and torsion are used. But by convention, “rotation “ refers to the rotation seen in short axis vies of LV. The term “torsion” to the difference in rotation that occurs along the longitudinal axis. The ability to quantify these data was made possible with the application of speckle tracking technology. This has made a tremendous stride in the evaluation LV function especially in various stages of myocardial ischemia. The accuracy of speckle tracking has been compared with the existing techniques like microsonometry , tagged MRI and tissue Doppler strain measurements and has been found to correlate significantly with all these methods.(4,5) 3. Stress echocardiography One of the major difficulties faced in stress echocardiography was the problem of quantification of the ventricular deformation imaging. The inter observer values were notoriously variable. Attempts were made to use tissue velocity imaging , but was constrained by it's inability to study radial contractions. A beakthrough in stress echo quantification has been attempted with the use of STE in systolic and diastolic phases of the cardiac cycle, using longitudinal, radial and circumferential directional values. (9) In 2D speckle strain examinati ons, the commonly used parame ters are (i) Peak systolic strain, (ii))Strain rates, (iii) time to peak measurements, (iv) circumferential strains (v)diastolic measurements. Using these studies in various clinical states haven undertake. 1. Coronary artery disease In myocardial ischemia, the longitudinal strain values , especially in the endocardium shows evidence of hypoperfusion . This would be translated into attenuated values in Radial view and graph in LV Dysfunction 24 KHJ Kerala Heart Journal Review articles A Journal of Cardiological Society of India, Kerala Chapter all 3 directions, as expected. The vaues can be utilized to assess the beneficial effect of treatment or worsening, on repeated exams. (13) 8. Radial view in normal LV function 4. Revascularization The role of STE in revacularization is to identify the damages during balloon occlusion, viability of tissues and the impact of successful procedure. 5. Valvular heart disease Even severe valve disease like aortic stenosis can remain asymptomatic for a long time. However , subclinical LV dysfunction can occur early in the disease.STE can identify these abnormalities if done serially and can be made use of in determining the time of surgery 6. LV hypertrophy One of unique advantages of STE is in the identification of the nature and causes of LV hypertrophy in different conditions. Though there are different opinions , it is generally agreed that in the LVH found in in athletes the strains are high. (10) In the LVH in hypertension the longitudinal strain shows reduction, probably due to the associated fibrosis. (11) This has to be evaluated in the light of radial strains which often are paradoxical. The other condition with LVH is hypertrophic cardiomyopathy. Here again the universal opinion is that the STE values are diminished reflecting the myocardial fibre disarray found in the pathology of the disease. (12) STE can also identify the coexisting diastolic dysfunction also which the hallmark of this condition. 7. Dilated cardiomyopathy In dilated cardiomyopathy , strain is reduced in KHJ Kerala Heart Journal Stress cardiomyopathy Cardiomyopthy , known as Takotsubo cardiomyopathy, is attributed to be stress related and is usually reversible. STE can play a significant role in the diagnosis , because of the regional strain patterns not related to any coronary distribution. STE also can be used to monitor the recovery patterns.(14) 9. Pericardial disease Specific STE patterns have been described in various stages of pericardial disease. In constrictive percarditis, the circumferential strain is impaired while the longitudinal might be preserved. Conversely, in restrictive conditions like amyloidosis, it is the longitudinal strain that is reduced. This feature can be of significant in doubtful cases.(15) 10. Evaluation of heart failure STE studies have played a major role in the understanding 0f myocardial mechanics in cardiac failure. Contrary to the older model of separation of systolic and diastolic LV dysfunction, the new insight is to take these as expressions of a continuum of events. STE studies have revealed overlapping values in diastolic and systolic hear failure syndromes.(16,17) 11. Resynchronization Therapy The increasing acceptance of resynchronization therapy sought newer modalities for the evaluation LV dysfunction. Since the technology was based mainly on the radial contractility STE with it's unique ability to evaluate radial and circumferential functions became the focus of intense interest. Newer indices were developed using STE to identify ideal candidates for CRT and responders. (18,19) STE was also used to monitor the prognosis as well. 12. Cardicac involvement in systemic diseases One of the major fallouts of STE was the identification of subtle cardiac involvement I n 25 Review articles A Journal of Cardiological Society of India, Kerala Chapter diabetes. Longitudinal and global strain changes have been noted (20,21) This would be of great importance in the context of concerns of the complications of drugs like glitazones which are incriminated in LV dysfunction, and which may lead on to cardiac failure , The other area of interest would be the cardiotoxicity induced by anthracycline like molecules while being treated for malignancy . Early detection using STE can be of help in altering treatment. Personal experience In the department of cardiology SRE studies have been undertaken for the past one year, using Philips iE 33 ultrasound machine. There was a learning curve and it continues. There was also the factor of regular software upgrades which contributed which have contributed to accuracy of results. 2. D' Hooge J, Heimdal A, Jamal F, Kukulski T, Bijnens B, Rademakers F, et al .Regional strain rate measurements by cardiac ultrasound : principles, implementation and limitations. Eur J Echocardiogr 2000; 1: 154-70. 3. Sengupta PP, Tajik AJ, Chandrasekaran K, Khandheria BK. Twist mechanics of the left ventricle: principles and application. JACC Cardiovasc Imaging 2008;1: 366-76. 4. Amundsen BH, Helle-Valle T, Edvardsen T, Torp H, Crosby J, Lyseggen E, et al. Noninvasive myocardial strain measurements by speckle tracking echocardiography: validation against sonomicrometry and tagged magnetic resonance imaging JAm Coll Cardiol 2006; 47:789-93 5. Notomi Y, Lysyansky P, Seter RM, Shiota T, Popovic ZB, Martin- Miklovic MG, et al. Measurements of ventricular torsion by two dimensional ultrasound speckle tracking Imaging. J Am Coll Cardiol 2005, 45:203-41 6. Choi JO, Cho SW, Song YB, Cho SJ,Song BG, Lee SC, et al. Longitudinal 2D strain at rest predicts the presence of left main and three vessel coronary artery disease in patients without regional wall motion ad normality. Eur J Echocardiogr 2009; 10:695-701. 7. Bertini M, Mollema SA, Delgado V, Antoni ML, Ng AC, Holman ER, et al. Impact of time to reperfusion after acute mycordial infarction on myocardial damage assessed by left ventricular longitudinal strain. Am J Cardiol 2009;104:480-5. 8. Park YH, Kang SJ, Song JK, Lee EY, Song JM ,Kang DH, et al. Prognostic value of longitudinal strain after primary reperfusion therapy in patients with anterior wall acute myocardial infarction.J Am Soc Echocardiogr 2008; 21:2627. 9. Hanekom L, Cho GY, Leano R, Jeffriess L, Marwick TH. Comparison of two dimensional speckle and tissue Doppler strain measurements during dobutamine stress echocardiography: an angiographic correlation. Eur Heart J 2007;28:1294-9 In an analysis of 50 cases, these were our preliminary observations. 1. In a case of obvious global dysfunction all the STE values were very low. This denoted that STE can be an independent index of contractility. 2. In cases of myocardial infarction, the STE values ranged from normal to abnormal. Further studies are undertaken to identify the role of reperfusion. 3. There were cases of angiographically proven 3 vessel disease where the STE values were in the normal range. We are trying to correlate with prognosis . 4. Further studies are planned to to identify the patterns of STE in different states of LVH 5. Serial STE studies would identify the state of LV myocardium after medical or invasive revascularization. Conclusion A growing body of evidence suggests that the LV myocardial status can be assessed with STE to identify, the current contracitility, which would be correlated to myocardial micro and macro vascular blood flow independent of the angiographic scenery. STE hopefully can address this position apart from all the other tasks for which it can be employed. References 1. Abraham TP, Dimaano VL, Liang HY. Role of tissue Doppler and strain echocardiography in current clinicial practice. Circulation 2007; 116: 2597-609. 26 10. Knebel F, Schimeke I, Schroeckh S, Peters H, Eddicks S, Schattke S, et al. Myocardial function in older male amateur marathon runners: assessments by issue Doppler echocardiography, speckle tracking, and Cardiac biomarkers. J Am Soc echocardiogr 2009, 22: 8039. KHJ Kerala Heart Journal Review articles A Journal of Cardiological Society of India, Kerala Chapter 11. Kan SJ, Lim HS,Choi BJ, Choi SY, Hwang GS, Yoon MH, et al. Longitudinal strain and torsion assessed by two dimensional speckle tracking correlate with the serum level of tissue inhibitor of matrix metalloproteinase-1 a maker of myocardial fibrosis, in patients with hypertension J Am Echocardiogr 2008, 21:90711. 12. Sengupta PP, Mehta V, Arora R, MohanJC, Khandheria BK. Quantification of regional nonuniformity and paradoxical intramural mechanics in hypertrophic cardiomyopathy by high frame rate ultrasound myocardial strain mapping. Am Soc Echocariogr 2005;18:737-42. 13. Satio M, Okayama H, Nishimura K, Ogimoto A, Ohtsuka T, Inoue K et al. Determinants of left ventricular untwisting behavior in patients with dilated cardiomyopathy: analysis by two dimensional speckle tracking . Heart 2009, 95:290-6. 14. Mansencal N, Abbou N, Pillliere R, El Mahmond R, Farcot JC, Dubourg O Usefulness of two dimensional speckle tracking echocardiography for assessment of tako-tsubo cardiomyopathy. Am J cordial 2009; 103:1020-4. 15. Segupta PP, Krishnamoorthy VK, Abhayaratna WP, Korinek J,Belohlavek M,Sundt TM iii, et al. Disparate patterns of left ventricular mechanics differentiate constrictive pericarditis from restrictive cardiomyopathy. JACC Cardiovasc Imaging 2008 1:29-38 KHJ Kerala Heart Journal 16. Brutsaert DL. Cardiac dysfunction in heart failure: the cardiologists' love affair with time. Prog Cardiovasc Disc 2006; 49;157-81. 17. Cho GY, Marwick TH, Kim MK, Hong KS, Oh DJ. Global 2- dimensional strain as a new prognosticator in Patients with heart failure. J Am Coll Cordial 2009; 54:618-24. 18. Lim P, Buakhamsri A, Popovic ZB, Greenberg NL, Patel D, Thomas JD, et al. Longitudinal strain delay index by speckle tracking imaging: a new maker of response to cardiac resynchronization therapy. Circulation 2008; 118:1130-7. 19. Gorcsan JIII,Tanabe M, Bleaker GB, Suffoletto MS, Thomas NC, Saba S, et al. Combined longitudinal and radial dyssynchrony predicts ventricular response after resynchronization therapy. J Coll Cordial 2007; 50: 1476-83. 20. Ma H, Xie M, Wang J, Lu Q wang X Lu X, et al. Ultrasound speckle tracking imaging contributes to early diagnosis of impaired left ventricular systolic function in patients with type 2 diabetes mellitus. J Huazhong Univ Sic Techno log Med Sci 2008; 28:719-23. 21. Ng AC, Delgado V, Bernini M, van der Meer RW, Rijzewik LJ, Shanks M, et al. Findings from left ventricular strain rate imaging in asymptomatic patients with type2 diabetes mellitus. Am J Cardiol 2009, 104: 1398-401. 27