An experimental study on isochronal ventricular mapping in acute myocardial infarction

Simultaneous epicardial (EP) and endocardial (EN) isochronal mapping during spontaneous ventricular arrhythmia was attempted in a experimental model of acute myocardial infarction. The left anterior descending artery (LAD) was ligated in 12 open-chest mongrel dogs. A total of 86 electrode terminals, 43 for EP and 43 for EN, were inserted over the infarction, border and normal areas, and connected to a computerized data acquisition system. Data for each ventricular arrhythmia were stored on disks for 3 hours following ligation and were analyzed to obtain isochronal EP and EN maps. Finally, the heart was sliced and stained by the TTC technique. In a comparison with TTC staining, the earliest activation sites of ventricular arrhythmias estimated from the isochronal maps 3 hours postligation were located in various areas but localized exclusively in the border zones. Moreover, the earliest activation sites tended to change their locations from EN to EP throughout the time course following ligation. In several spontaneous ventricular arrhythmias, findings suggestive of functional blocks and reentry circuits were also delineated in EP and EN maps.