E lectro c ardio g ram ECG Liaoning Medical University Affiliated First Hospital

1. Electrocardiogram ECG Liaoning Medical University Affiliated First Hospital He Xin

2. 一、Basic knowledge of ECG

3. Content 1、Electrophysiology 2、ECG Waveforms andintervals 3、ECG Lead system

4. 1、Electrophysiology ---Depolarization and repolarization ---Vector and vectorcardiogram

5. 2、ECG Waveforms and intervals Pacing and conducting system of the heart Sinus node Internodal tractsAV node right bundle branch(RBB) Purkinje fibers Bundle of His anterior fascicle left bundle branch(LBB) Purkinje fibers posterior fascicle

6. Componcents of the conduction system SA Node Bundle of AV junction AV Node Bundle of AV Left BundleBranch Right BundleBranch

7. 3、ECG Lead system --bipolar leads（Standard leads）I, II, III --unpolar leads: aVR, aVL, aVF

8. 3、ECG Lead system --Chest leads: V1, V2, V3, V4, V5, V6

9. 二、 Measurement and Normal ECG

10. 1.Measurement of ECG ECG paper Paper speed：25mm/s；Standard calibration： 1mV=10mm

11. (1) Measuring heart rate (HR) 60 60 =75/min =HR R-R (S) 0.80S ---Measuring heart rate (HR) = 60/R-R (bpm) ---300/the number of large time units between R-R ---1500/the number of small time units between R-R

12. (2) Amplitude of waves or segment: P, QRS, S-T, T, U

13. (3) Width or duration of waves: P, QRS, T, U * Duration of intervals: P-R, Q-T * Shape of waves: P, QRS, T

14. (4) Mean QRS axis ---normal cardiac axis range from -3090 ---significant left deviation: -30-90 ---right deviation: 90180 ---significant right deviation: 180-90

15. V1V2 V3V4 V5V6 normal Clockwise rotation Counterclockwise rotation (5) Clockwise and counterclockwise rotation ---Clockwise rotation ---Counterclockwise rotation

16. 2、 Normal ECG (1) P wave: atrial depolarization ---Amplitude  0.20 mv ---Duration  0.11 sec ---Positive in I, II, aVF, V4-V6; Negative in aVR (2) PR interval: the time for intraatrial, --- AV nodal, and His-Purkinje conduction, --- Duration: 0.12 ~ 0.20 sec

17. (3) QRS complex: ventricular depolarization ---The width: 0.060.10 sec,  0.11 sec. ---From V1 to V6, the R waves gets bigger and bigger,the S waves gets smaller and smaller. --R/S < l in V1, but R/S > l in V5 --R in V5 and V6 < 2.5 mv, R in V1 < 1.0 mv ---R in aVR < 0.5 mv, R in aVL < 1.2 mv and R in aVF < 2.0 mv    R in I < 1.5 mv ---Q < 0.04 sec in width, < 1/4 R in the same lead.

19. (4) ST segment: it reflects Phase 2 of the action potential. ---ST elevation < 0.3 mV in V1、V2； < 0.5 mV in V3；< 0.10 mV in V4 V6 ---ST depression < 0.05 mV in any leads (5) T wave: repolarization of ventricles ---It is upright in all the unipolar leads except aVR, and occasionally V1. ---T wave > 1/10 R in the same lead, maybe < 1.21.5 mV in the precordial leads

20. (6) QT interval: the duration of depolarization and repolarizaion of ventricles The normal range is 0.320.44 sec (7) U wave: the wave following the T wave and is usually very smal ---Its cause is not completely understood ---Elevated U wave: low K+ in plasma

21. 三、Atrial Enlargement and Ventricular Hypertrophy

23. 1、Atrial Enlargement (1) Right Atrial Enlargement Lead II ---P wave is peaked (P "pulmonale"); ---Amplitude of P wave ≥0.25 mV in limb leads. Lead V1 ---upright and amplitude ≥0.15 mV; ---biphasic and amplitude ≥0.20 mV

26. (2) Left Atrial Enlargement Lead II ---Duration of P wave ≥0.12 sec ---P wave become bifid (P "mitrale") ---The distance of two peak ≥ 0.04sec Lead V1 ---P wave become biphasic ---Ptfv1 - 0.04 mm·sec

29. (3) Biatrial Enlargement Lead II P wave duration and amplitude both increased

30. 2、Ventricular Hypertrophy (1) Left Ventricular Hypertrophy A. Increased voltage ---Rv5 or Rv6 > 2.5 mV SV1 + R V5 >3.5mV (female) or > 4.0mV (male) ---RI >1.5mV；RaVL >1.2mV；RaVF >2.0 mV RI + SIII >2.5 mV B. Left axis deviation C. longer duration of QRS (0.10-0.11s) D. ST depression and T inversion in V5-6

33. (2) Right Ventricular Hypertrophy A. Increased voltage (adults over 30) ---R/S ratio in V1 ≥ 1.0; R /Rs ---R/S ratio in V5 or V6 ≤ 1.0 ---R/q or R/S ratio in aVR≥1 --R V1+ S V5 >1.05mV (severe>1.2mV) --RaVR>0.5mV B. Right axis deviation ≥ +900 (severe > +1100) C. ST depression and T inversion in V1-2

36. (3) Biventricular Hypertrophy ---Normal ECG. ---One ventricular hypertrophy. ---Biventricular Hypertrophy.

37. 四、Myocardial Ischemia and Myocardial infarction

38. 1、Myocardial Ischemia Subendocardial:Upright T wave Subepicardial: Inverted, diphasic, low T wave

39. 1、Myocardial Ischemia Subendocardial:ST segment depression Subepicardial:ST segment elevation( coronary spasm)

43. Summary ---ST segment depression ---ST segment elevation ---T wave tall positive ---T wave inversion These changes are transitory and mostly synchronous with symptoms

44. 2、Myocardial infarction (1) Basic changes ---Ischemic T Waves. Tall peaked T waves, often appear as the earliest ECG sign of acute MI ---Injuried ST-segment Elevations. The ST segment elevated in one or more leads and may be straightened and fuse with the T wave (mono-phasic curve) ---necrotic (Pathologic) Q Waves. the sudden developed Q wave may indicate an acute MI

46. (2) Progressive ECG changes ---Hyperacute changes ---Acute period ---Subacute period (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 ---Old myocardial infarct A definitive diagnosis of old myocardial infarct depends on the presence of a pathological Q wave

48. (3) Localization of the ECG patterns 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

49. LOCALIZATION OF MI inferior anterior anteroseptal lateral Extensive anterior

50. Anterior MI