Principles and potential application of 2D speckle tracking
Professor YU Cheuk-Man
MBChB, MRCP(UK), FRACP, FHKCP, FHKAM(Medicine), FRCP(Edin/London) , MD(CUHK)
Head of Division of Cardiology, Department of Medicine & Therapeutics, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong
Cheuk-Man Yu
2D Speckle tracking is a new echocardiographic technology that examines the speckles in greyscale 2-dimensional image on a frame-to-frame basis throughout the cardiac cycle to determine myocardial deformation. This technology is increasingly investigated by researches as it has the advantage of being angle-independent, as well as able to examine different components of cardiac function, such as left ventricular long-axis function, short-axis function, torsion (or twisting) as well as dyssynchrony.
The fundamental data obtained, through processing by dedicated software, provide the measurement of regional (or segmental) strain. Further processing of these data can determine the strain rate, regional displacement and even regional velocity. In apical views, they allow the measurement of longitudinal and transverse strain while the short-axis views allow the measurement radial and circumferential strain. Validation of strain measured by 2D speckle tracking with that measured by cardiac MRI has previously been performed, while validation of torsion with microsonometry in animals confirmed its accuracy.
Currently, investigators started to explore the potential clinical application of 2D speckle tracking in various disease models. Reduction of long- and short-axis 2D strain parameters is observed in heart failure, hypertrophic cardiomyopathy as well as in regions of previous myocardial infarction. Similarly, reduction of torsion has been observed in various disease models. In heart failure patients, dyssynchrony of short-axis motion has recently been described. Furthermore, in patients with advance heart failure received cardiac resynchronization therapy, the presence of baseline systolic dyssynchrony has been shown to be a predictor of both echocardiographic and symptomatic response.
In these patients, our study indicated that the relative preservation of short-axis function as reflected by the circumferential and radial strain predicted the occurrence of left ventricular reverse remodeling response. Further studies are needed to explore the role of this new tool in examining myocardial mechanics and its complementary role for assessing cardiac function on top of current echocardiographic facilities.
