title: Speckle-tracking echocardiography correctly identifies segmental left ventricular dysfunction induced by scarring in a rat model of myocardial infarction.
abstract: Speckle-tracking echocardiography (STE) uses a two-dimensional echocardiographic image to estimate two orthogonal strain components. The aim of this study was to assess sensitivity of circumferential (S(circ)) and radial (S(rad)) strains to infarct-induced left ventricular (LV) remodeling and scarring of the LV in a rat. To assess the relationship among S(circ), S(rad), and scar size, two-dimensional echocardiographic LV short-axis images (12 MHz transducer, Vivid 7 echo machine) were collected in 34 Lewis rats 4 to 10 wk after ligation of the left anterior descending artery. Percent segmental fibrosis was assessed from histological LV cross sections stained by Masson trichrome. Ten normal rats served as echocardiographic controls. S(circ) and S(rad) were assessed by STE. Histological data showed consistent scarring of anterior and lateral segments with variable extension to posterior and inferior segments. Both S(circ) and S(rad) significantly decreased after myocardial infarction (P<0.0001 for both). As anticipated, S(circ) and S(rad) were lowest in the infarcted segments. Multiple linear regression showed that segmental S(circ) were similarly dependent on segmental fibrosis and end-systolic diameter (P<0.0001 for both), whereas segmental S(rad) measurements were more dependent on end-systolic diameter (P<0.0001) than on percent fibrosis (P<0.002). STE correctly identifies segmental LV dysfunction induced by scarring that follows myocardial infarction in rats.
authors.affiliation: Department of Cardiovascular Medicine, Cleveland Clinic Foundation, Cleveland, OH 44195, USA.
authors.forename: Zoran B
authors.initials: ZB
authors.lastname: Popović
authors.forename: Carlos
authors.initials: C
authors.lastname: Benejam
authors.forename: Jing
authors.initials: J
authors.lastname: Bian
authors.forename: Niladri
authors.initials: N
authors.lastname: Mal
authors.forename: Jeannie
authors.initials: J
authors.lastname: Drinko
authors.forename: Kwangdeok
authors.initials: K
authors.lastname: Lee
authors.forename: Farhad
authors.initials: F
authors.lastname: Forudi
authors.forename: Rachel
authors.initials: R
authors.lastname: Reeg
authors.forename: Neil L
authors.initials: NL
authors.lastname: Greenberg
authors.forename: James D
authors.initials: JD
authors.lastname: Thomas
authors.forename: Marc S
authors.initials: MS
authors.lastname: Penn
mesh_terms: D000818:Animals; D003331:Coronary Vessels / Q000601:surgery; D004195:Disease Models, Animal; D004452:Echocardiography / Q000379:methods*; D005355:Fibrosis; D006352:Heart Ventricles / Q000000981:diagnostic imaging; D007090:Image Interpretation, Computer-Assisted; D008026:Ligation; D016014:Linear Models; D009203:Myocardial Infarction / Q000150:complications* / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D015588:Observer Variation; D011237:Predictive Value of Tests; D051381:Rats; D011917:Rats, Inbred Lew; D015203:Reproducibility of Results; D012107:Research Design; D012680:Sensitivity and Specificity; D013314:Stress, Mechanical; D013599:Systole; D018487:Ventricular Dysfunction, Left / Q000000981:diagnostic imaging* / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D020257:Ventricular Remodeling