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目的:观察急性心肌梗死(AMI)极早期心电图的变化,并着重观察缺血性J波的发生情况及其与心律失常发生的关系,为临床早期诊断AMI提供依据。方法:杂种犬19只,开胸结扎前降支造成前壁急性心肌缺血,观察结扎前和结扎后2h内心电图变化。结果:超急性期约42%犬出现缺血性J波。T波高尖发生率为84%。ST段抬高发生率100%,全部累及胸前导联。巨R波发生率16%,出现晚于T波高尖和ST段抬高。以上心电图变化均出现在前壁,与梗死部位一致。AMI超急性期心电图变化中T波高尖和缺血性J波出现最早,ST段抬高次之,R波变化出现最晚。冠状动脉前降支结扎造成前壁心肌梗死后58%的犬至少有1次室性心动过速(VT)发生,26%发生心室颤动(Vf)死亡。前30min内发生的VT占总数的70%,与后90min比有显著性差异(P<0.01)。出现J波的犬中全部发生VT,37.5%出现Vf;未出现J波的犬中27%出现VT,2只出现Vf。J波组VT较非J波组明显增加(P<0.05)。结论:结扎前降支所致AMI超急性期心电图可出现缺血性J波、T波高尖、ST段抬高和巨R波型,缺血性J波是提示急性心肌缺血的心电图新指标,同时缺血性J波的出现常提示心电活动不稳定,易发生VT和Vf。
Objective: To observe the changes of very early electrocardiogram (ECG) in acute myocardial infarction (AMI) and to observe the occurrence of ischemic J wave and its relationship with arrhythmia, so as to provide basis for clinical diagnosis of AMI. Methods: Nineteen mongrel dogs were treated with thoracotomy and left anterior descending coronary artery. The changes of ECG were observed before and 2 hours after ligation. Results: In hyperacute stage, ischemic J wave appeared in about 42% of dogs. T-wave high incidence of 84%. ST segment elevation incidence of 100%, all involving the chest lead. Giant R wave incidence of 16%, appeared later than T wave tip and ST elevation. ECG changes above appear in the anterior wall, consistent with the infarction. AMI hyperacute ECG changes in T-wave tip and ischemic J wave appeared the earliest, followed by ST segment elevation, R wave changes appeared late. Coronary artery anterior descending artery ligation caused 58% of dogs with anterior wall myocardial infarction at least 1 ventricular tachycardia (VT), 26% of ventricular fibrillation (Vf) death. VT occurred in the first 30 min accounted for 70% of the total, and 90min after the significant difference (P <0.01). VT occurred in dogs with J waves, Vf appeared in 37.5% of dogs; VT appeared in 27% of dogs without J wave, and Vf appeared in 2 dogs. J wave group VT compared with non-J wave group was significantly increased (P <0.05). Conclusions: Ischemic J wave, T wave hyperintensity, ST segment elevation and giant R wave may appear in AMI hyperacute ECG caused by descending branch before ligation, and ischemic J wave is a new index of ECG that suggests acute myocardial ischemia , While the emergence of ischemic J wave often prompted unstable ECG activity, prone to VT and Vf.