Abstract: Objective To study the changes of electrocardiograms(ECG)and myocardial ultrastructure in heroin dependence in rats,in order to reveal the mechanisms of the myocardial injury by heroin.Meth-ods Establish heroin addict model in SD mice,investigate the changes in electrocardiograms,HE staining and myocardial ultrastructure.Results The electrocardiograms of the addict group had prominently changes,main expressions:heart rate decreased,P wave and T wave amplitude reduced and duration in-creased,S-T reduced and duration increased,QT interval prolongation,these changes indicated that my-ocardium had been injured,myocardial ischemia,ventricle function declined.These difference was signifi-cant(P<0.05)between before inject heroin and after inject heroin.Transformations in the ultrastructure:nuclear concentrate,reduce,nuclear membrane shrink,chromatin agglutinate,mitochondria cristal had dis-order formation,disappeared or hollowed,these indicated that heroin could cause pathological changes in myocardial ultrastructure.Conclusion Above-mentioned changes indicated that heroin can injure myocardi-um,and the changes of myocardial ultrastructure suggested that myocardial apoptosis may be one of the mechanisms of the myocardial injury by heroin.

Key words: heroin addict, electrocardiogram, ultrastructure