Ligating LAD with its whole length rather than diagonal branches as coordinates is more advisable in establishing stable myocardial infarction model of swine.

A reproducible and reliable myocardial infarction (MI) model with less inter-individual variation in ischemic size and ventricular function is essential in cardiovascular research. Little is known about whether the different ligation coordinates [whole length of left anterior descending artery (LAD) or diagonal branches] affect the inter-individual variation of ventricular function in the MI model. The present study compared the characteristics of the experimental swine MI model induced by surgical occlusion of LAD in two groups: group A (n=24), where ligation was performed below the second ventricular branch (D(2) branch), and group B (n=23), where ligation was performed at a distance one-third distal to the apex. Variation of ischemic size and left ventricular ejection fraction (LVEF) at 4 weeks after MI was compared between the two groups using the homoscedasticity F test and coefficient of variance (CV). Difficulty in identifying ventricular branches and the great variation of branching patterns encumbered the precise ligation of LAD in group A. The ischemic size and LVEF in group B were less variable than those of group A. There were significant correlations between the percentile of LAD ligation and infarct size or ventricular function. In conclusion, ligating LAD using its whole length rather than ventricular branches as coordinates may be more practical and advisable for establishing reproducible MI models, and this procedure may prove to help standardize the location of occlusion and infarct size.