Effect of acute ischemia on global repolarization of the left ventricular endocarium in intact canine

Objective To investigate the effect of acute ischemia on global repolarization of the left ventricular endocarium.Methods Ventricular endocardium unipolar electrograms were recorded from 8 anesthetized canines using noncontact mapping system before and after the left anterior descending coronary artery(LAD) ligated.Activation time(AT),activation-recovery interval(ARI) and repolarization time(RT) of all domains were calculated and analyzed.Results Repolarization gradients exist over the left ventricular endocardium in normal.Because AT and ARI were negatively correlated,the dispersion of RT was small.After 30 min of acute ischemia negative correlation between AT and ARI disappeared,AT delayed and ARI deceased,repolarization dispersions increased significantly(P0.01) in ischemic zones.Conclusion The delayed AT and ARI are all important in increasing the dispersions of ventricular endocardium repolarization during acute ischemia.