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1、李宁,心电图,Questions Why ECG could be served for the diagnosis of some diseases? What is ECG? What is normal ECG?,正常心电图,A. Basic knowledge of ECG,Depolarization and repolarization Single myocardial cell A muscle strip,心电生理,心脏传导系统接受迷走-交感神经支配,3. Pacing and conducting system of the heart,Sinus node Interno
2、dal tracts AV node right bundle branch (RBB) Purkinje fibers Bundle of His anterior fascicle left bundle branch (LBB) Purkinje fibers posterior fascicle,心率估算法,一个RR间期的大格数 心率 1 300 2 150 3 100 4 75 5 60 6 50 7.5 40 ,电轴,临床工作中很少测量P波和T波的电轴，而QRS波群的电轴变化常与心脏病变密切相关。 电轴的正常值在-30+90度，-30-90度电轴左偏，+90+180电轴右偏，-90
3、+180度电轴不确定,P 波 形态：在、aVF 、 V4-V6 导联中均向上， aVR 导 联向下 时间：正常人小于0.12s 振幅：在肢体导联小于0.25mv,胸导联小于0.2mv,P-R间期,成年人的P-R间期 为0.12-0.20S。 在老年人及心动过缓的情况下， P-R间期 可略延长但不超过0.22S。,ST段 在任一导联ST段下移不超过0.05mv，ST段上抬在V1-V2导联不超过0.3mv,V3不超过0.5mv V4-V6与肢体导联不超过0.1mv。 T波（1）方向：大多和QRS主波的方向一致。若V1的T波向上，则V2-V6导联就不应再向下。 （2）振幅：除、aVL、aVF、V1-
4、V3导联外，T波的振幅一般不应低于同导联R波的1/10。T波在胸导联有时可高达1.2-1.5mv尚属正常。 Q-T间期 正常范围为0.32-0.44S。Q-Tc就是R-R间期为1s(心率60次/分）时的Q-T间期。Q-Tc的正常上限为0.44S。 U波 U波方向大体与T波相一致。U波明显增高见于血钾过低。,Part III Atrial Enlargement and Ventricular Hypertrophy,(1) Left Atrial Enlargement,Lead II Duration of P wave 0.12 sec. ; P wave become bifid (P
5、“mitrale“); The distance of two peak 0.04sec. Lead V1 P wave become biphasic; Ptfv1 - 0.04 mmsec,Right Atrial Enlargement,Lead II P wave is peaked (P “pulmonale“); Amplitude of P wave 0.25 mV in limb leads.,Biatrial Enlargement,Lead II P wave duration and amplitude both increased.,Left Ventricular H
6、ypertrophy,A. Increased voltage SV1 + R V5 3.5mV (female), 4.0mV (male); Rv5 or Rv6 2.5 mV; RI 1.5mV; RaVL 1.2mV; RaVF 2.0 mV; RI + SIII 2.5 mV; B. Left axis deviation C. ST depression and T inversion in V5-6.,Right Ventricular Hypertrophy,A. Increased voltage (adults over 30) R/S ratio in V1 1.0; R
7、/S ratio in V5 or V6 1.0; R/q or R/S ratio in aVR1; R V1+ S V5 1.05mV (severe1.2mV); RaVR0.5mV; B. Right axis deviation +900 (severe +1100). C. ST depression and T inversion V1-2.,Part VI Myocardial Ischemia and Myocardial infarction,ECG of myocardial ischemia shows:,ST segment depression; ST segmen
8、t elevation( coronary spasm); Inverted, diphasic, low T wave.,Myocardial infarction,(1) Basic changes “Hyperacute” T Waves. Tall peaked T waves, often appear as the earliest ECG sign of acute MI. ST Elevations. The ST segment elevated in one or more leads and may be straightened and fuse with the T
9、wave (mono-phasic curve) Pathologic Q Waves. the sudden developed Q wave may indicate an acute MI.,T Wave Changes. The elevated ST segments return to the baseline, and deep symmetrical T waves appear in these leads. Tall, symmetrical, upright T waves will appear in reciprocal leads at the same time.
10、,(2) Progressive ECG changes,(3) Localization of the ECG patterns,Leads with Abnormal Q Waves in MI Leads with Abnormal Q Waves location of MI V1 V3 Anteroseptal V3 V5 Anterior I, aVL, V5 V6 Lateral V1 V6 Extensive Anterior II, III, aVF Inferior,(4) Old myocardial infarct,A definitive diagnosis of old myocardial infarct depends on the presence of a pathological Q wave,