A simple, automatic method for morphometric analysis of the left ventricle in rats with myocardial infarction.

Induction of acute myocardial infarction in the rat is an established model for studying effects of therapeutic interventions. Images of sections of the rat left ventricle, stained with nitroblue tetrazolium, were digitized and several parameters estimated by dedicated software on an image analyzer (IBAS 2.0). The method was tested on 7 rats with 48-hr-old myocardial infarction and 4 sham-operated controls. Infarct size can be evaluated by two largely used methods, based on area or on angular extension of the lesion. Results of the two methods are linearly correlated, but area calculations give values half of those obtained from angular extension. Five minutes were needed for a complete evaluation of a section of the left ventricle. Estimates of the parameters showed a relatively low between- and within-operator variability and a good correlation with a classic, but time-consuming, planimetric method. The method simultaneously measures infarct size and left ventricular geometry in the rat. The advantages over previous nonautomatic methods are simplicity, good reproducibility, and speed of execution, which make it particularly useful in the evaluation of drug effects.