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Experimental validation of left ventricular transmural strain gradient with echocardiographic two-dimensional speckle tracking imaging.

Research paper by Tomoko T Ishizu, Yoshihiro Y Seo, Yoshiharu Y Enomoto, Haruhiko H Sugimori, Masayoshi M Yamamoto, Tomoko T Machino, Ryo R Kawamura, Kazutaka K Aonuma

Indexed on: 09 Jan '10Published on: 09 Jan '10Published in: European journal of echocardiography : the journal of the Working Group on Echocardiography of the European Society of Cardiology



Abstract

To validate intramural strain measured by a speckle tracking imaging (STI) system against that measured by sonomicrometry crystals.In 11 anaesthetized sheep, six sets of three sonomicrometry crystals were implanted in endo-, mid-wall, and epimyocardium on the anterior and lateral walls. Circumferential strain (CS) was calculated at three layers from endo-, mid-wall, and epicardial speckle. Radial strain (RS) was assessed for inner and outer halves of the myocardium. We compared ultrasound-derived strain measurements against those by sonomicrometry at baseline and during pharmacological stress and coronary occlusion. Intraclass correlation coefficients at baseline and during coronary occlusion were as follows: endocardial CS 0.80, 0.97; mid-wall CS 0.58, 0.89; epicardial CS 0.71, 0.81; endocardial RS 0.50, 0.78; epicardial RS 0.35, 0.83; and total RS 0.33, 0.71; respectively. At baseline, endocardial strains were higher than mid-wall and epicardial strains, resulting in an inner/outer wall RS gradient and inner/mid/outer wall CS gradients. Ischaemia caused significant reduction in all strains and disappearance of the strain gradient.A newly developed STI system can accurately assess the intramural heterogeneity of CS distribution in normal and ischaemic myocardial segments and has the potential to become a non-invasive bedside tool for characterizing myocardial strain gradient.