e lectro c ardio g ram ecg liaoning medical university affiliated first hospital
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E lectro c ardio g ram ECG Liaoning Medical University Affiliated First Hospital He Xin. 一、 Basic knowledge of ECG. Content. 1 、 Electrophysiology 2 、 ECG Waveforms andintervals 3 、 ECG Lead system. 1 、 Electrophysiology. ---Depolarization and repolarization - PowerPoint PPT PresentationTRANSCRIPT
ElectrocardiogramECG
Liaoning Medical University Affiliated First Hospital
He Xin
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一、 Basic knowledge of ECG
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Content
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1 、 Electrophysiology2 、 ECG Waveforms andintervals3 、 ECG Lead system
---Depolarization and repolarization
---Vector and vectorcardiogram
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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
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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
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3 、 ECG Lead system
--Chest leads: V1, V2, V3, V4, V5, V6
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二、 Measurement and Normal ECG
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1. Measurement of ECGECG paper Paper speed : 25mm/s;Standard calibration : 1mV=10mm
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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
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(3) Width or duration of waves: P, QRS, T, U
* Duration of intervals: P-R, Q-T
* Shape of waves: P, QRS, T
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(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
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(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
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(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
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(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
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三、 Atrial Enlargement and Ventricular Hypertrophy
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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
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(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
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(3) Biatrial Enlargement Lead II
P wave duration and amplitude
both increased
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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
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(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
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(3) Biventricular Hypertrophy ---Normal ECG.
---One ventricular hypertrophy.
---Biventricular Hypertrophy.
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四、Myocardial Ischemia and
Myocardial infarction
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1 、 Myocardial Ischemia
Subendocardial: Upright T wave
Subepicardial: Inverted, diphasic, low T wave
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1 、 Myocardial Ischemia
Subendocardial: ST segment depression
Subepicardial: ST segment elevation( coronary
spasm)
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Summary ---ST segment depression
---ST segment elevation
---T wave tall positive
---T wave inversion
These changes are transitory and mostly
synchronous with symptoms
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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
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(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
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(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
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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
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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
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2 、 Electrophysiology---Automaticity
---Excitability
--Absolute refractory period (200ms)
--Effective refractory period (210ms)
--Ralative refractory period (50-100ms)
---Conductivity
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3 、 SINUS RHYTHM AND SINUS ARRHYTHMIAS
---Sinus rhythm features
---Sinus Bradycardia
---Sinus Tachycardia
---Sinus arrhythmia
---Sinus arrest
---Sick Sinus Syndrome (SSS)
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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
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Sinus Bradycardia(1) Sinus rhythm
(2) Heart rate <60bpm
(R-R interval or P-P interval >1.0 sec )
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Factors associated with sinus bradycardia
(1) Physiologic
Laborers and trained athletes
Emotional states leading to syncope
(2) Pathologic
-blocker
Hypothyroidism
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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
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Factors associated with sinus tachycardia
(1) Physiologic Exercise Strong emotion Anxiety states(2) Pathologic Fever Hemorrhage Anemia Myocarditis Hyperthyroidism
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Sinus arrhythmia
---Sinus rhythm and PR interval,
---Difference of P--P interval > 0.12sec
in the same lead
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Sinus arrest
The P wave missed for a short time
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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
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4 、 Premature contractions
--- Premature Ventricular Complex
--- Premature Atrial Complex
--- Premature junctional complex
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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
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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
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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
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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
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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
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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
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Ventricular Flutter
Ventricular flutter: It is impossible to separate the QRS complexes
from the ST segment and the T waves
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Ventricular fibrillation
Ventricular fibrillation: The ECG shows fine or coarse waves that are rapid, and irregular in size, shape, and width
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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)
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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
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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
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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
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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
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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
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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
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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
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