title: Layer-specific strain analysis: investigation of regional deformations in a rat model of acute versus chronic myocardial infarction.
abstract: Myocardial infarction (MI) injury extends from the endocardium toward the epicardium. This phenomenon should be taken into consideration in the detection of MI. To study the extent of damage at different stages of MI, we hypothesized that measurement of layer-specific strain will allow better delineation of the MI extent than total wall thickness strain at acute stages but not at chronic stages, when fibrosis and remodeling have already occurred. After baseline echocardiography scans had been obtained, 24 rats underwent occlusion of the left anterior descending coronary artery for 30 min followed by reperfusion. Thirteen rats were rescanned at 24 h post-MI and eleven rats at 2 wk post-MI. Next, rats were euthanized, and histological analysis for MI size was performed. Echocardiographic scans were postprocessed by a layer-specific speckle tracking program to measure the peak circumferential strain (S(C)(peak)) at the endocardium, midlayer, and epicardium as well as total wall thickness S(C)(peak). Linear regression for MI size versus S(C)(peak) showed that the slope was steeper for the endocardium compared with the other layers (P < 0.001), meaning that the endocardium was more sensitive to MI size than the other layers. Moreover, receiver operating characteristics analysis yielded better sensitivity and specificity in the detection of MI using endocardial S(C)(peak) instead of total wall thickness S(C)(peak) at 24 h post-MI (P < 0.05) but not 2 wk later. In conclusion, at acute stages of MI, before collagen deposition, scar tissue formation, and remodeling have occurred, damage may be nontransmural, and thus the use of endocardial S(C)(peak) is advantageous over total wall thickness S(C)(peak).
authors: Faculty of Biomedical Engineering, Technion-Israel Institute of Technology, Haifa, Israel. noab@tx.technion.ac.il
authors: Noa
authors: N
authors: Bachner-Hinenzon
authors: Offir
authors: O
authors: Ertracht
authors: Assaf
authors: A
authors: Malka
authors: Marina
authors: M
authors: Leitman
authors: Zvi
authors: Z
authors: Vered
authors: Ofer
authors: O
authors: Binah
authors: Dan
authors: D
authors: Adam
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D002908:Chronic Disease; D004195:Disease Models, Animal; D004452:Echocardiography; D004562:Electrocardiography; D004699:Endocardium / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D005355:Fibrosis; D007090:Image Interpretation, Computer-Assisted; D016014:Linear Models; D008297:Male; D009200:Myocardial Contraction; D009203:Myocardial Infarction / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D009206:Myocardium / Q000473:pathology; D010496:Pericardium / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D011237:Predictive Value of Tests; D012372:ROC Curve; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013314:Stress, Mechanical; D013997:Time Factors; D014022:Tissue Survival; D016277:Ventricular Function, Left; D020257:Ventricular Remodeling