title: Myocardial infarct size measurement using geometric angle calculation.
abstract: BACKGROUND
  In basic cardiovascular research focusing on animal models of myocardial infarction (MI), the measurement of infarct size is performed by planimetry of histological sections of the heart. However, in the setting of chronic MI with ongoing changes in ventricular geometry caused by wall thinning and hypertrophy, the scar area tends to become smaller.
  
  
  METHODS
  Here, in this study we compared infarct measurements in tissue sections (of rat and porcine hearts) based on three different calculation approaches, that is, infarct area, infarct lengths and infarct angles utilizing the centroid of the left ventricle using a newly developed calculation approach.
  
  
  RESULTS
  Infarct sizes from all three measurement approaches showed significant correlation with parameters of cardiac function. However, results derived from area measurements were significantly smaller than those obtained using the other two measurement approaches due to scar thinning (infarct size area: 14·81% ± 1·27 SEM, length: 23·94% ± 2·04 SEM, angle: 24·75% ± 2·13 SEM, P < 0·0001, n = 30). Moreover, results from angle measurements evidenced a much better correlation with parameters of cardiac function in a small animal model of chronic MI (e.g. ejection fraction, angle: r = -0·73; length: r = -0·64; area: r = -0·59, n = 30) as well as in a large animal model of acute MI (angle: r = -0·82; area: r = -0·67, n = 10).
  
  
  CONCLUSIONS
  We concluded that area-, length- and angle-based measurements can be used to determine the relative infarct size in acute MI models, although an area-based measurement might be less accurate in the setting of chronic MI. Our new method of infarct angle measurement is a reliable and simple way to calculate infarct size compared with conventional measurement approaches.
authors.affiliation: Universitätsherzzentrum Thüringen, Clinic of Internal Medicine I, Department of Cardiology, Friedrich Schiller University Jena, Jena, Germany; Christian Doppler Laboratory for Cardiac and Thoracic Diagnosis and Regeneration, Vienna, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Lichtenauer
authors.forename: Catharina
authors.initials: C
authors.lastname: Schreiber
authors.forename: Christian
authors.initials: C
authors.lastname: Jung
authors.forename: Lucian
authors.initials: L
authors.lastname: Beer
authors.forename: Andreas
authors.initials: A
authors.lastname: Mangold
authors.forename: Mariann
authors.initials: M
authors.lastname: Gyöngyösi
authors.forename: Bruno Karl
authors.initials: BK
authors.lastname: Podesser
authors.forename: Hendrik Jan
authors.initials: HJ
authors.lastname: Ankersmit
mesh_terms: D000818:Animals; D002921:Cicatrix / Q000473:pathology; D004195:Disease Models, Animal; D005260:Female; D008297:Male; D009203:Myocardial Infarction / Q000473:pathology*; D015425:Myocardial Reperfusion; D017207:Rats, Sprague-Dawley; D034421:Sus scrofa; D013552:Swine
keywords: Animal models; infarct size; measurement; myocardial infarction