Myocardial Infarct Size Measurement in the Mouse Chronic Infarction Model: Comparison of Area- and Length-Based Approaches
Junya Takagawa1, Yan Zhang1, Maelene L. Wong1, Richard E. Sievers1, Neel K. Kapasi1, Yan Wang2, Yerem Yeghiazarians1, Randall J. Lee1, William Grossman1, and Matthew L. Springer1
1University of California, San Francisco, Department of Medicine, Division of Cardiology, San Francisco, California, U.S.A
2FivePrime Therapeutics, Inc., San Francisco, California, U.S.A
UJ Appl Physiol., March 8, 2007





Brief Summary:
  • > Efficacy of potential treatments for myocardial infarction (MI) is commonly assessed by histological measurement of infarct size in rodent models. In experiments involving an acute MI setting, measurement of the infarcted area in tissue sections of the left ventricle (LV) is a standard approach to determine infarct size. This approach has also been used in the chronic infarct setting to measure infarct area several weeks post-MI. We tested the hypothesis that due to wall thinning that is known to occur in the chronic setting, the area measurement approach would be less appropriate. We compared infarct measurements in tissue sections based on (1) infarct area, (2) epicardial and endocardial infarct arc lengths, and (3) midline infarct arc length. Infarct size from all three measurement approaches correlated significantly with LV ejection fraction (LVEF) and wall motion abnormality. However, the infarct size values derived from area measurement were significantly smaller than those from the other measurements, and the range of values obtained was compressed 0.4-fold. The midline method was able to detect the expected size differences between infarcts of variable severity resulting from proximal vs. distal ligation of the coronary artery. Segmental infarct size was correlated with segmental wall motion abnormality. We conclude that both area- and length-based measurements can determine relative infarct size over a wide range of severity but the area-based measurements are substantially more compressed due to wall thinning, and that the estimation of infarct midlines is a simple, reliable approach to infarct size assessment.

    NOTE: All cardiac assessments in this study were performed using a Vevo 660 micro-ultrasound system (VisualSonics Inc, Toronto).