ElectrocardiogramECG

Liaoning Medical University Affiliated First Hospital

He Xin

1

一、 Basic knowledge of ECG

2

Content

3

1 、 Electrophysiology2 、 ECG Waveforms andintervals3 、 ECG Lead system

---Depolarization and repolarization

---Vector and vectorcardiogram

4

1 、 Electrophysiology

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

2 、 ECG Waveforms and intervals

5

Componcents of the conduction system

SA Node

Bundle of AV junction

AV NodeBundle of AV

Right BundleBranch

Left BundleBranch

3 、 ECG Lead system

--bipolar leads （ Standard leads ） I, II,

III

--unpolar leads: aVR, aVL, aVF

7

3 、 ECG Lead system

--Chest leads: V1, V2, V3, V4, V5, V6

8

二、 Measurement and Normal ECG

9

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

10

60R-R (S)

=HR60

0.80S=75/min

(1) Measuring heart rate (HR)

---Measuring heart rate (HR) = 60/R-R (bpm)---Measuring heart rate (HR) = 60/R-R (bpm)---300/the number of large time units between R----300/the number of large time units between R-

RR---1500/the number of small time units between ---1500/the number of small time units between

R-RR-R11

(2) Amplitude of waves or segment: P, QRS,

S-T, T, U

12

(3) Width or duration of waves: P, QRS, T, U

* Duration of intervals: P-R, Q-T

* Shape of waves: P, QRS, T

13

14

(4) Mean QRS axis ---normal cardiac axis range from -3090 ---significant left deviation: -30-90 ---right deviation: 90180 ---significant right deviation: 180-90

normal Counterclockwise rotationCounterclockwise rotationClockwise rotationClockwise rotation

V5V6V3V4V1V2

(5) Clockwise and counterclockwise rotation  ---Clockwise rotation ---Counterclockwise rotation   

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

16

(3) QRS complex: ventricular depolarization

---The width: 0.060.10 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.17

18

(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

< 1.21.5 mV in the precordial leads

19

(6) QT interval: the duration of depolarization

and repolarizaion of ventricles

The normal range is 0.320.44 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

20

三、 Atrial Enlargement and Ventricular Hypertrophy

21

22

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

23

24

25

(2) Left Atrial EnlargementLead 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

26

27

28

(3) Biatrial Enlargement Lead II

P wave duration and amplitude

both increased

29

2 、 Ventricular Hypertrophy(1) Left Ventricular HypertrophyA. 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 mVB. Left axis deviation C. longer duration of QRS (0.10-0.11s)

D. ST depression and T inversion in V5-6

30

31

32

(2) Right Ventricular HypertrophyA. 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

33

34

35

(3) Biventricular Hypertrophy ---Normal ECG.

---One ventricular hypertrophy.

---Biventricular Hypertrophy.

36

四、Myocardial Ischemia and

Myocardial infarction

37

1 、 Myocardial Ischemia

Subendocardial: Upright T wave

Subepicardial: Inverted, diphasic, low T wave

38

1 、 Myocardial Ischemia

Subendocardial: ST segment depression

Subepicardial: ST segment elevation( coronary

spasm)

39

40

41

42

Summary ---ST segment depression

---ST segment elevation

---T wave tall positive

---T wave inversion

These changes are transitory and mostly

synchronous with symptoms

43

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

44

45

(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

46

47

(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

48

LOCALIZATION OF MILOCALIZATION OF MI

II IIII IIIIII

aVRaVR aVLaVL aVFaVF

VV11 V V22 VV33 V V44 VV55 V V66

inferior

lateralanteroseptal anterior

Extensive anterior49

Anterior MI

Inferior MI

Lateral MI

五、 Arrhythmia

53

1 、 ClassificationAbnormal origin----sinus arrhythmia *

----ectopic rhythm ---passivity --escape

---initiative --premature contraction *

--tachycardia*

--flutter and fibrillation*

Abnormal conduction ----physiological block:

----pathological block: S-AB; A-VB*; LBBB; RBBB

----accessory pathway: pre-excitation syndrome

54

2 、 Electrophysiology---Automaticity

---Excitability

--Absolute refractory period (200ms)

--Effective refractory period (210ms)

--Ralative refractory period (50-100ms)

---Conductivity

55

3 、 SINUS RHYTHM AND SINUS ARRHYTHMIAS

---Sinus rhythm features

---Sinus Bradycardia

---Sinus Tachycardia

---Sinus arrhythmia

---Sinus arrest

---Sick Sinus Syndrome (SSS)

56

Sinus rhythm features(1) Every P wave is following by a QRS

complex

(2) P wave is upright in lead I, II, aVF, V4-V6, inverse in aVR

(3)  P-R interval ≥ 0.12sec

(4)  Normal rate is 60-100 beats/min

57

Sinus Bradycardia(1)  Sinus rhythm

(2)  Heart rate <60bpm

(R-R interval or P-P interval >1.0 sec )

58

Factors associated with sinus bradycardia

(1) Physiologic

Laborers and trained athletes

Emotional states leading to syncope

(2) Pathologic

-blocker

Hypothyroidism

59

Sinus Tachycardia

(1)Sinus rhythm, rate > 100 bpm

The R-R interval (or the P-P interval) <0.60 sec

(2)P-R and Q-T interval are shorter than usual

(3)S-T segment is slight depression, T waves may

be flattened

60

Factors associated with sinus tachycardia

(1) Physiologic Exercise Strong emotion Anxiety states(2) Pathologic Fever Hemorrhage Anemia Myocarditis Hyperthyroidism

61

Sinus arrhythmia

---Sinus rhythm and PR interval,

---Difference of P--P interval > 0.12sec

in the same lead

62

Sinus arrest

The P wave missed for a short time

63

Sick Sinus Syndrome (SSS)

(1)   Sinus bradycardia (HR<50/min)

(2)   Sinus arrest or SA block

(3)  Tachycardia: Atrial tachycardia

Atrial Flutter

Atrial fibrillation

(4) AV block

64

4 、 Premature contractions

--- Premature Ventricular Complex

--- Premature Atrial Complex

--- Premature junctional complex

65

Premature Ventricular Complex(1) Ventricular complex (QRS) is not preceded by a

premature P' wave

(2) Premature QRS complex is the wider

and the bizarre , Duration of QRS> 0.12 sec

T wave in direction is opposite to QRS complex

(3) Complete compensatory pause

66

bigeminy

trigeminy

Premature Atrial Complex (1) The premature P' wave differs in contour from

the normal P wave in the same lead

(2) The P'-R interval >0.12s

(3) There may be a noncompensatory pause

68

Premature junctional complex

(1) A premature normal-appearing QRSpremature normal-appearing QRS complex

(2) The junctional P wave (P’) may be appear before in, and after the QRS

(3) Usually a complete compensatory pause

69

5 、 Tachycardia

Reentry Requires: ---Two conducting pathways

---Unidirectional block in one

---Slow conduction in the other

--Paroxysmal supraventricular tachycardia

--Ventricular Tachycardia

--Nonparoxysmal Tachycardia

--Torsde de pointes70

Paroxysmal supraventricular tachycardia (PSVT)

---Heart rate between 160 – 250 bpm

---A precisely regular rhythm with normal

QRS

71

Ventricular Tachycardia

---The rate is 140200/min and the rhythm is very

slightly irregular

---QRS complex is the wider and the bizarre,

Duration of QRS >0.12 sec

---P wave dissociated from QRS

The rate of P wave is less than The rate of QRS

---Ventricular capture

---Fusion beats are present74

Nonparoxysmal Tachycardia

---Nonparoxysmal junctional Tachycardia

The heart rate is 70130/min

---Nonparoxysmal ventricular Tachycardia

The heart rate is 60100/min

Torsde de pointes

6 、 Flutter and Fibrillation

--- Atrial Flutter

--- Atrial Fibrillation

--- Ventricular Flutter

--- Ventricular fibrillation

Atrial Flutter

---Absence of normal P waves

---P waves replaced by saw-tooth flutter wave (F waves)

---Flutter waves seen best in leads II, III,aVF

---F waves always uniform in size,shape and frequency

and absence of isoelectric line between F waves

---Regular atrial rhythm with a rate of 250-350 /min

---Ventricular response of 1:1,2:1,3:1,4:1 or higher

79

Atrial Fibrillation---Absence of clear P waves

---P waves replaced by f waves

---f waves: irregular in size, shape, best seen in lead V1

---Rate of f waves is 350 - 600/min

---Irregularly irregular ventricular rate

---Generally, duration of QRS complex <0.12sec

81

Ventricular Flutter

Ventricular flutter: It is impossible to separate the QRS complexes

from the ST segment and the T waves

84

Ventricular fibrillation

Ventricular fibrillation: The ECG shows fine or coarse waves that are rapid, and irregular in size, shape, and width

85

7 、 Conduction Disturbances---A-V Block

--- Complete Right Bundle Branch Block

--- Complete Left Bundle Branch Block

--- Wolff-Parkinson-White Syndrome(pre-excitation syndrome)

A-V Block First Degree A-V BlockProlonged P-R interval:

P-R interval > 0.20sec. in adults (varies with

heart rate)

 

87

Second Degree A-V BlockMobitz type I (Wenckebach phenomenon)

---The pattern is a progressive prolongation of

the P-R interval until a beat is dropped

---The first beat after the pause has the shortest

P-R interval, which may or may not be normal

88

Second Degree A-V BlockMobitz type II

There is a fixed numerical relationship between atrial

and ventricular impulses, which may be 2:1 (2 atrial

beats to one ventricular beat) or 3:1 or 4:1

90

Third Degree A-V Block (Complete heart block)

---The atrial and the ventricular rhythms are

absolutely, independent of one another

(There is no relationship of P to QRS.)

---atrial rate > ventricular rate

QRS is 0.12 sec. or greater

91

Complete Right Bundle Branch Block

---Right axis deviation

---QRS≥0.12 sec

---rsR’ pattern (M pattern ) in V1 or V2

---Wide and slurred S wave in leads 1, V5

and V6

---ST-T changes in leads V1 and V2

93

Complete Left Bundle Branch Block

---Left axis deviation

---A wide, slurred R in I,V5 ,V6.  The wide,

aberrant QRS , QRS≥0.12 sec

---The QRS in V1 may be QS or rS type

---ST-T changes

95

Wolff-Parkinson-White Syndrome(pre-excitation syndrome)

---P-R interval <0.12 sec

---QRS complex interval >0.12 sec

---Delta wave in the lower third of

theascending limb of the R wave

---ST-T changes

97

WPW Type AWPW Type A

characterized by dominantly upright QRScomplexes in the right precordial leads,resulting in tall delta-R waves in leads V1and V2

WPW Type BWPW Type Bcharacterized by dominantly negative QRScomplexes in the right precordial leads, withtall delta-R waves in leads V5 and V6

THANK YOU !