Speckle-tracking echocardiography
The RALS was measured using STE, a relatively newer echocardiographic method for obtaining strain and strain rate measurements. For STE using 2D grey-scale echocardiography, apical four-chamber views were captured during breath holding at the end of expiratory phase for few seconds, and with electrocardiogram recording attached. A suitable image of myocardial tissue was obtained completely separated from surrounding structures. Three successive cardiac cycles were recorded and averaged. The frame rate was set between 60 and 80 frames per second. Analysis of speckle-based strain was done using Philips QLAB version 9.0 software. In four chamber RA focused views, the endocardial surface of the RA was traced manually by a three-point and-click approach. The system automatically generates an epicardial surface tracing. The region of interest (ROI) was therefore created, composed of 7 segments. The ROI was manually adjusted as needed to allow for enough speckle tracking. The software generates the longitudinal curves for each segment with its mean value. (20–22)(Figure 2)