Study on mechanism of ECG change during myocardial ischemia-reperfusion process

[Objective]To investigate the relationship between oxygen free radicals and myocardial apoptosis and arrhythmia during myocardial ischemia-reperfusion injuries.[Methods]Duplicated myocardial ischemia-reperfusion models of rats,and analyzed incidence rate and duration of arrhythmias,changes of ST segment,malondialdehyde(MDA) value,the activity of superoxide dismutase(SOD) and the state of myocardial apoptosis between ischemic and reperfusion process.[Results]The incidences of atrioventricular block,ventricular premature beat and ventricular tachycardia were 7.5%,15% and 10% respectively.After reperfusion,the above indicators increased to 30%,67.5% and 32.5% respectively.The duration of the ventricular tachycardia increased form(40±14) s to(495±103) s after reperfusion.In reperfusion the duration of ventricle fibrillation was(198±22) s.The content of MDA in the reperfusion group is more than that in ischemia group(P0.01),and revealed the increasing trend.At the same time,the activity of SOD decreased during reperfusion.After 120 min reperfusion,the descending speed became slower.Myocardial apoptosis is obviously increased in the reperfusion group.During MIRI,the variations of arrhythmia had positive correlation with SOD change,and negative correlation with MDA and apoptosis changes.[Conclusion]The oxygen free radicals and myocardial apoptosis may be the important factors inducing arrhythmias inreperfusion.