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目的为了解急性心肌梗死(AMI)患者的QT离散度(QTd)。方法观察首次AMI患者发病后6h内接受静脉溶栓成功者30例的QTd,取其溶栓治疗前的心电图(ECG)对比观察其QTd的变化,所有ECG均用同一台12导ECG机,同一人测量。结果溶栓前为(43.6±13.2)ms,溶栓成功后为(37.1±10.2)ms,两组经配对t检验,P<0.05。由于AMI部位与正常心肌之间存在缺血区域,缺血区心肌细胞膜动作电位复极化延缓,ECG表现为各导联的QT间期差值增大,即QTd延长,所以心肌复极不均性显著的增加为折返激动的形成提供了条件,易于发生室速等心律失常。心室复极越不一致,电不稳定性就越大。成功的溶栓治疗后,随着冠状动脉的血流的恢复和维持左心室射血功能得到改善,QTd明显比治疗前下降,表明AMI后再灌流区与非梗塞区心肌的复极趋于一致,增加了心电的稳定性。AMI时QT间期变化的可能机制与局部低温、局部传导延迟、神经性作用及局部细胞处低钙等有关。结论因此,QTd可以用来评价心肌电活动状态和预测室性心律失常的发生。成功地容栓后,反映心室复极离散度的QTd下降可能是成功的溶栓治疗改善预后的一个重要机制。另一方面也可以用QTd作为溶栓成功与否的一个指标。作为一种预测心律失常的检查手段,QTd结合心率变异、晚点位检查,可提高AMI远期心律失常的预测准确性。
Purpose To understand QT dispersion (QTd) in patients with acute myocardial infarction (AMI). Methods The QTd of 30 patients who received intravenous thrombolysis within 6h after initial onset of AMI were observed. The changes of QTd were compared with those before electrocardiogram (ECG) of thrombolytic therapy. All ECGs were performed on the same 12-lead ECG machine, People measure. Results (43.6 ± 13.2) ms before thrombolysis and (37.1 ± 10.2) ms after successful thrombolysis. Paired t-test was used for the two groups (P <0.05). Due to the ischemic area between the AMI site and the normal myocardium, the repolarization of the action potential of the myocardial cell membrane in the ischemic area is retarded, and the difference between the QT intervals in each lead is increased, that is, the QTd is prolonged. Therefore, uneven myocardial repolarization A significant increase of sexual reentry excited to provide the conditions for the formation of prone to arrhythmia such as VT. The more inconsistent ventricular repolarization, the greater the electrical instability. After successful thrombolytic therapy, with the improvement of coronary blood flow and maintenance of left ventricular ejection function, QTd decreased significantly compared with that before treatment, indicating that the repolarization of reperfusion area and non-infarction area myocardium tend to be consistent after AMI , Increase the stability of ECG. The possible mechanism of QT interval changes in AMI is related to local hypothermia, local conduction delay, neurogenic effects and hypocalcemia in local cells. Conclusion Therefore, QTd can be used to evaluate the state of cardiac electrical activity and predict the occurrence of ventricular arrhythmias. After successful thrombolysis, a decrease in QTd reflecting ventricular repolarization dispersion may be an important mechanism for successful thrombolytic therapy to improve prognosis. On the other hand, QTd can also be used as an indicator of the success of thrombolytic therapy. As a means of predicting cardiac arrhythmia, QTd combined with heart rate variability, late check, can improve the prediction accuracy of AMI long-term arrhythmia.