正常心电图一教材教学课件.ppt

R波：首先出现的位于参考水平线以上的正向波 Q波：R波之前的负向波 S波：R波之后的第一个负向波 R’波：S波之后的正向波 S’波： R’ 波之后的负向波 QS波：QRS波只有负向波 振幅小可称为q、r、s、r’、s’ QRS波群的命名原则 ECG各波段的组成与命名 （2） 心电图的测量 心率的测量 Heart Rate In normal sinus rhythm, a resting heart rate of below 60 bpm is called bradycardia and a rate of above 100 bpm is called tachycardia. 各波段振幅和时间的测量 平均额面心电轴 概念：心室除极过程中全部瞬间向量综合 测定方法： 查表法：分别测出Ⅰ导联和Ⅲ导联QRS波群电压差值(R波电压减Q波及S波)，查心电轴表 作图法 目测法 平均心电轴 平均心电轴的临床意义1 心脏解剖位置 横位心电轴可左偏，＜-30° 垂位心电轴可右偏，＞+120° 左右心室的对比 左室肥大，电轴偏左 右室肥大，电轴偏右 婴幼儿右室比例大，电轴右偏 平均心电轴的临床意义2 心室内除极顺序 下列除极顺序异常会导致心电轴方向改变： 激动起源于心室 室性心动过速 心室起搏心律 室内传导阻滞 心肌局灶纤维化，心肌梗死 （四）心脏循长轴转位 自心尖朝心底部方向观察 顺钟向转位： V3、V4波形出现在V5、V6导联 逆钟向转位： V3、V4波形出现在V1、V2导联 心脏循长轴转位 心脏循长轴转位的临床意义 顺钟向转位：可见于右心室肥大 逆钟向转位：可见于左心室肥大 钟向转位也可见于正常人 Lead aVF is the isoelectric lead.  The two perpendiculars to aVF are 0 o and 180 o.  Lead I is positive (i.e., oriented to the left).  Therefore, the axis has to be 0 o. Lead aVR is the smallest and isoelectric lead.  The two perpendiculars are -60 o and +120 o.  Leads II and III are mostly negative (i.e., moving away from the + left leg)  The axis, therefore, is -60 o. Bizarre QRS axis: +150o to -90o (i.e., lead I and lead II are both negative) Consider limb lead error (usually right and left arm reversal)  Dextrocardia  Some cases of complex congenital heart disease (e.g., transposition)  Some cases of ventricular tachycardia ST SEGMENT The ST segment is that portion of the ECG cycle from the end of the QRS complex to the beginning of the T wave. It represents the beginning of ventricular repolarization. The normal ST segment is usually isoelectric (i.e., flat on the baseline, neither positive nor negative), but it may be slightly elevated or depressed normally (usually by less than 1 mm). Some pathologic conditions such as myocardial infarction (MI) produce characteristic abnormal deviations of the ST segment. The very beginning of the ST segment (actually the junction between the end of the QRS complex and the beginning of the ST