CHARACTERISTICS OF A MODEL OF MYOCARDIAL-INFARCTION PRODUCED BY CORONARY-ARTERY LIGATION IN THE RAT

The rat model of coronary artery ligation is widely used to study myoc ardial infarction, ventricular remodeling, and congestive heart failur e. Total infarct size and the relationship between endocardial and epi cardial infarction were characterized in 691 animals that survived per manent ligation of the left coronary artery. Infarct size was determin ed from serial histologic sections of the left ventricle (LV), followe d by planimetry of muscle and scar circumferences. Mean infarct size w as 34.5% +/- 13.3% of total left ventricular circumference. Rats survi ving longer durations to terminal study had a smaller mean infarct siz e. Infarct transmurality, as described by the ratio of epicardial-to-e ndocardial infarct sizes, was 0.78 +/- 0.01. The transmurality ratio i ncreased and its variability decreased as infarct size increased. Sube ndocardial infarcts were more frequent among small infarcts and had sm aller areas of endocardial infarction. Although infarct size was highl y variable, infarct size indexed to endocardial infarct size was less variable. Infarct size indexed to endocardial infarct size may therefo re represent a significantly more powerful method for assessing the ef fects of treatments to reduce infarct size.