Study On The Changes Of Electrocardiogram In Early Stage Of Myocardial Ischemia

Objective: When patients with coronary heart disease(CHD)receiving percutaneous transluminal coronary angioplasty(PTCA),obstruction of blood flow results in definitive transient myocardial ischemia.In this study,we analyzed the changes of electrocardiogram(ECG)caused by balloon dilatation,that is,the changes of ECG indicators of hyper acute period of myocardial ischemia in patients with CHD,in addition to explore if there exists other ECG indicators for judgment of early myocardial ischemia except traditional ST segment changes.Methods: The study population consisted of 89 patients with CHD undergoing PTCA of the culprit coronary arteries.Culprit coronary arteries were judged by ECG of myocardial ischemia,Echocardiography and Coronary angiography.During the PTCA,continuous 25 mm/s 12-lead ECG was recorded using translucent ECG electrodes.Measurements were performed by comparing the baseline and PTCA-induced changes of ECG in 2 minutes.The differences were performed by statistical analysis.Cardiac depolarization indicators,such as QRS interval and QRS wave amplitude,and cardiac repolarization indicators including QT-,QTc-and Tp Te-intervals were measured,as well as PR-and RR-intervals.Results:1 Basic indicators:The difference of PR-intervals before and after balloon dilatation was not statistically significant(P>0.05).The difference of RR-intervals was of no statistical significance(P>0.05).2 Cardiac depolarization indicators:The difference of QRS intervals before and after balloon dilatation was statistically significant(P=0.001);The changes of R wave amplitude was statistically significant(P=0.012).The difference of S wave amplitude was of no statistical significance(P>0.05).3 Cardiac repolarization indicators: Changes of QTc interval was of statistical significance(P=0.039).Differences of T wave interval,QT interval,TpTe-interval and T wave amplitude were of no statistical significance(P>0.05).4 There were no significant differences in the number of lesion vessels about the indicators above(P>0.05).5 QT-interval and QTc-interval:The difference of QTc-interval before and after balloon dilatation was statistically significant(P=0.039),while the difference of QT-interval was not(P=0.071).6 Comparations among positive rates of ST segment,QRS interval,QTc-interval and R wave amplitude:Positive standards adopted in this study:ST segment elevated or depressed above 0.1mV;R wave amplitude elevated or depressed above 0.1mV;QRS interval prolonged more than 10ms;QTc-interval prolonged more than 10 ms.Each of the positive rates of QRS interval,QTc-interval or R wave amplitude was better than the positive rate of ST segment(P<0.05);Any two positive rates of the three new indicators(QRS interval,QTc-interval and R wave amplitude)were of no statistical difference(P>0.05).Conclusions:In this study,we find that there do exist other ECG indicators for judgment of early myocardial ischemia except traditional ST segment changes.QRS interval,QTc-interval and R wave amplitude will change obviously during the early period of myocardial ischemia.And we find that the positive rates of the three new indicators are better for judgment of early myocardial ischemia,that is to say,the new ones are more sensitive.We also find that QTc interval is better than QT interval for judgment of early myocardial ischemia.So medical workers should pay attention to QRS interval,QTc-interval and R wave amplitude besides ST segment and T wave,in order to diagnose myocardial ischemia early,so patients can receive treatment in time to improve prognosis.