Abstract: Background　Pre-excitation syndrome affects terminal QRS vectors，which has not achieved enough attention.Objective　To discuss the effect of antegrade accessory pathway （AP） conduction on terminal QRS vectors，the relationship of changes in terminal QRS vectors with AP location and clinical significance among pre-excitation syndrome patients.Methods　From the First Affiliated Hospital of Jinzhou Medical University between January 2008 and December 2012，we enrolled 158 cases of preexcitation syndrome with an AP with antegrade conduction cured by radiofrequency catheter ablation （RFCA），including 150 with a manifest AP （manifest group） and 8 with a concealed AP（concealed group） detected by preoperative electrocardiogram （ECG）．We analyzed the manifest group in terms of the features of ECG before and after RFCA，effect of antegrade AP conduction on terminal QRS vectors，relationship of changes in terminal QRS vectors with AP location and the delta wave，and the concealed group in respect of the features of ECG before and after RFCA，ECG features of atrioventricular reentrant tachycardia（AVRT），effect of antegrade AP conduction on terminal QRS vectors，and the relationship of target spot V wave with the earliest onset of QRS complex on the intracardiac electrogram （IEGM） if the terminal QRS vectors had changed.Results　In patients with a manifest AP，the prevalence of changes in terminal QRS vectors was 100%，which was associated with the AP location.Moreover，both the trend of terminal QRS vectors changes and delta wave polarity varied by leads of V1，Ⅰ，Ⅱ，Ⅲ，aVL，aVF （P<0.001），indicating that the changes of the two were almost the same in different leads.Correlation analysis revealed that there were strong correlations between the trend of terminal QRS vectors changes and delta wave polarity in leads V1，Ⅰ，Ⅲ，and aVL （rs=0.812，0.701，0.771，0.762，P<0.05） and there were moderate correlations between them in leads Ⅱ and aVF（rs=0.569，0.647，P<0.05）．Two patients with a concealed AP were found with changes in terminal QRS vectors，and the target spot V wave via AP on IEGM appeared almost simultaneously with the earliest onset of QRS complex via AV node on the ECG.Conclusion　Both the initial and terminal QRS vectors can be changed by the antegrade conduction of AP in pre-excitation syndrome patients The appearance of delta wave indicates that the conduction via AP is faster than via AV node.The change of terminal QRS vectors is a sign of conduction to ventricle via AP，which is valuable for the diagnosis of atypical pre-excitation including unconspicuous delta wave and incomplete concealed pre-excitation syndrome.

Key words: Pre-excitation syndromes, Catheter ablation, Electrocardiography

摘要： 背景　预激综合征影响QRS波终末向量，但尚未被关注。目的　探讨预激综合征患者旁路前传对QRS波终末向量的影响、与旁路位置的关系和临床意义。方法　选取2008年1月—2012年12月锦州医科大学附属第一医院经导管射频消融术治愈的、术前旁路有前传功能的单旁路预激综合征患者158例。根据术前心电图表现分为两组，显性组150例，隐性组8例。显性组分析经导管射频消融术前、后心电图，观察旁路前传对QRS波终末向量的影响和QRS波终末向量改变与旁路位置及预激向量的关系；隐性组分析经导管射频消融术前、后和房室折返性心动过速（AVRT）心电图，观察对QRS波终末向量的影响，QRS波终末向量有改变者分析靶点图靶点V波与QRS波最早起点的关系。结果　显性组150例均有QRS波终末向量改变，QRS波终末向量改变与旁路位置有关。V1、Ⅰ、Ⅱ、Ⅲ、aVL、aVF导联不同预激方向患者QRS波终末向量变化比较，差异均有统计学意义（P<0.001），说明不同部位显性组预激综合征患者经导管射频消融术前与术后QRS波终末向量变化与预激向量方向基本一致。相关分析显示：V1、Ⅰ、Ⅲ、aVL导联QRS波终末向量变化与预激向量呈高度正相关（rs=0.812、0.701、0.771、0.762，P<0.05），Ⅱ、aVF导联QRS波终末向量变化与预激向量呈中度正相关（rs=0.569、0.647，P<0.05）。隐性组8例中2例有QRS波终末向量改变，靶点图示靶点V波（旁路下传）与QRS波最早起点（正路下传）几乎同时出现。结论　预激综合征旁路前传不仅影响初始向量同时影响QRS波终末向量；δ波是旁路下传心室快于正路的表现，QRS波终末向量改变是旁路前传心室的标志，有助δ波不明显和不完全隐性预激综合征的诊断。

关键词: 预激综合征, 导管消融术, 心电描记术