Speckle tracking echocardiography: Basic concepts and clinical applications

Abstract

Assessment of the mechanical performance of heart usually means evaluation of left ventricular function and this can be done most easily by echocardiography by measuring ‘ejection fraction’. However, ejection fraction tells us the story of myocardium as a whole. Deeper understanding of cardiac mechanics has shown that this is a multi-layered phenomenon, as LV wall is composed of three layers of fibers. A deterioration in the function of one layer is compensated by others so the numerical value of ejection fraction is not compromised in the beginning. Speckles are produced due to ultrasound scattering and movement of these can be recorded by 2D imaging, frame to frame. This tracking of speckles is done in three directions viz. longitudinal, radial and circumferential, so that drop in global longitudinal strain is ascertained much before any change in ejection fraction is noted, “subclinical LV dysfunction”. In this review, the basics of speckle tracking, acquisition of echocardiographic data and the clinical applications of this new modality have been discussed.