The Effect Of Myocardial Ischemia To Tpeak-Tend Interval

Objective The present study is to identify the effects of myocardial ischemia to Tpeak-Tend interval (TpTe) and approach the relation between transmural dispersion of repolarization(TDR) and TpTe.Method The objects include 25 coronary artery disease(CAD) patients in whom myocardial ischemia are induced by treadmill exercise test (TET) .30 normal people without myocardial ischemia in TET are regarded as the control group.All the people are validated by coronary angiography investigate(CAG) later.The 15 leads resting electrocardiogram (ECG) before TET and the 15 leads ECG at 3th minutes in stage of recovery are recorded. TpTe is measured on every precordial leads on which T wave is identified easily and variation seldom appears-except V1 because of difficult identification.TpTe/ RR^1/2 are worked out as corrected TpTe according to heart rate. TpTe and TpTe/ RR^1/2 are analysed by different groups, different leads in succession or at the same time.Result 1. On resting ECG before TET ,the TpTe of CAD group without myocardial ischemia is significantly longer than that of controlled group on V2 and V6 lead(P<0.05). Compared with the controlled group, the CAD group is not different for the TpTe/ RR^1/2 on V2-V6 leads(P>0.05).2.On V2-V5 leads, the TpTe is significantly longer in the CAD group in which myocardial ischemia are induced than the controlled group(P<0.05) after TET.At the same time, TpTe/ RR^1/2 is significantly longer in the CAD group than the controlled group on V2-V4 leads(P<0.05). 3.Because of heart rate increasing, TpTe is shorten (P<0.05) but the TpTe/ RR^1/2 is not different(P>0.05) after TETAThe effect of myocardial ischemia to TpTe/ RR^1/2 is to prolong it on V2-V5(P<0.05). The effect of myocardial ischemia to TpTe is to preventit's shorten by heart rate increasing on V3-V5 leads(P<0.05).Conclusion 1. Both TpTe and TpTe/ j^RR can be taken as electrocardiological indexes of TDR. TpTe represent the actual value of TDR. TpTe/VW represent characteristic of TDR.2.Bazett's formula is effective to correct TpTe according to heart rate.3.The increasing of TDR can be caused by myocardial ischemia,which may be the groundsubstance of ventricular arrhythmias (VA) during the period of myocardial ischemia for human.4.During TET, increasing of TpTe/ ^RR can be regarded as an index of myocardial ischemia.