The Change of the Tpeak-Tend Interval in Exercise Test Induced Myocardium Ischemia
|School||Dalian Medical University|
|Keywords||Tpeak-Tend interval Dispersion of ventricular repolarization Myocardial ischemia Exercise test|
Objective: Tpeak-Tend interval(Tpe)is defined as the time between the peak of the T wave to the end of the T wave. Many tests have concluded that the Tpe has close relationship with dispersion of ventricular repolarization, and a lot of tests have demonstrated the Tpe has a close relationship with the malignant ventricular arrhythmia, and it can be used as a predictor of life threatening arrhythmia. In recent years, there are more and more studies concerning on the relationship between myocardial ischemia and Tpe. This study aimed to evaluate the relationship between the Tpe and the dispersion of ventricular repolarization by exercise induced myocardium ischemia.Methods: Fifty positive and forty control patients in Exercise Test included, all patients have recorded the Electrocardiograph(ECG) of rest and at the peak of test; Measured the Q-Tpeak、Q-Tend of every record. Calculate the maximal Tpe (Tpe dispersion): the maximal Q-Tend interval minus the minimal Q-Tpeak interval of twelve leads; mean Tpe: the mean value of Tpe in 12 leads; QT dispersion: the maximal Q-Tend interval minus the minimal Q-Tend interval of twelve-lead ECG. Through heart rate correction; Compared the corrected maximal、mean and single-lead Tpe、the corrected QT dispersion between control and positive group before test and at the peak of test respectively; Compared the corrected maximal、mean and single-lead Tpe、the corrected QT dispersion before-test and at the peak of test in every group respectively.Results: 1.The comparison of the corrected maximal Tpe、mean Tpe、the corrected QT dispersion between two groups at rest is not significant(P>0.1); at the peak of test the corrected maximal、mean Tpe、the corrected QT dispersion is much longer in positive grou(p134±24ms vs 159±30ms, P <0.001; 86.1±14ms vs 103.9±23ms, P <0.05; 46.2±17ms vs 64.5±26ms, P <0.001);In control group, the comparison of the corrected maximal Tpe、mean Tpe、the corrected QT dispersion at the peak of test is not longer than at rest(P>0.2); but in positive group, the above three index at the peak of test are significantly longer than at rest(132±29ms vs 159±30ms, P<0.001; 94.3±14ms vs 103.9±23ms, P<0.001; 44±17ms vs 64.5±26ms, P<0.001).2.The comparison between the single lead: at rest, the Tpe in every lead is not significant between two groups, whereas the Tpe at the peak of test is longer in positive group, except the I、avL lead, (I lead: 92.4±13ms vs 86.3±22ms, P>0.1; II lead:96.3±28ms vs 112.3±43ms, P<0.05; III lead:101.3±24ms vs 120±46ms, P<0.05; avR lead:89.6±21ms vs 103.9±31ms, P<0.05; avL lead:94±10ms vs 83.3±5ms, P>0.1; avF lead:100.9±18ms vs 116.6±42ms, P<0.05; V2 lead:99.7±14ms vs 107.2±15ms, P<0.05; V3 lead:97.1±13ms vs 104.5±15ms, P<0.05; V4 lead: 93.3±20ms vs 104.6±24ms, P<0.05; V5 lead: 90.6±20ms vs 102.1±29ms, P<0.05; V6 lead:90.4±19ms vs 101.3±27ms, P<0.05);In control group ,the comparison of Tpe at rest and at the peak of test in every lead is not significant,however, in the positive group we can see the Tpe of every lead at the peak of test is much longer than at rest ( I lead:75±13ms vs 86.3±22ms, P<0.05; II lead:86.9±17ms vs 112.3±43ms, P<0.001; III lead:86.6±24ms vs 120±46ms, P<0.05; avR lead:77.2±9ms vs 103.9±31ms, P<0.001;avL lead:66.2±17ms vs 83.3±5ms, P<0.05; avF lead: 87.7±23ms vs 116.6±42ms, P<0.001; V2 lead: 98.4±23ms vs 107.2±15ms, P<0.05; V3 lead: 95.4±18ms vs 104.5±14ms, P<0.05; V4 lead: 91.3±23ms vs 104.6±24ms, P<0.05; V5 lead: 85.1±17ms vs 102.1±29ms, P<0.001; V6 lead:80.5±17ms vs 101.3±27ms, P<0.001).Conclusion: Through our test, we can conclude that the maximal Tpe、mean Tpe in positive group is significantly longer at the peak of exercise test, which may reflect the increasing of ventricular dispersion of repolarization, and it may indirectly reflect myocardial ischemia. At the same time, we can observe the Tpe in some lead is significantly longer at the peak of test by exercise test induced myocardial ischemia, which may reflect the local myocardial ischemia, Tpe may become one useful predictor in exercise induced myocardial ischemia and ventricular arrhythmia which is induced by myocardial ischemia.