ECG Dr.Muntaser Omari ECG - PowerPoint Presentation

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ECG

Dr.Muntaser Omari

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ECG

Stands for electrocardiogram

( EKG ); it’s a record of the

heart’s

electrical activity

.

This activity recorded in a form of waves ,

each wave has its own characteristic Electrical activity means the depolarization and repolarization of the myocardium

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ECG contains 12 leads :

6

chest leads ( V1 , V2

,

V3

,

V4 ,V5

,

V6 )3 arm leads ( I ,II , III )3 augmented limb leads ( aVL ,

aVR

,

aVF

.)

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V1,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,V6

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V1, V2, V3, V4:

Anteriospetal surface

.V5,V6: Lateral surfaceIn a normal cardiac axis (about 60 degrees):

V1: Small R, Deep S

V2: R increases, S decreases

V3/V4: R=S

V5/V6: Large R, S disappears in normal people

If the R is poorly enlarging (poor progression R wave

= sign of ischemia)

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6 limb leads:

I between

right arm and left arm.

II between

right

arm and

left

leg.

III between left arm and left leg.aVR

: right arm,

aVL

:

left arm,

aVF

: left leg

I,

aVL

: Left lateral surface.

II ,III ,

aVF

: Inferior surface.

aVR

: Right surface.

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Positive deflection

: If a wave of depolarization passing through the heart is moving toward a surface electrode

Negative deflection: If a wave of depolarization passing through the heart is moving away from the electrode.

Biphasic wave

: If a wave of depolarization passing through the heart is moving

perpendicularly to the electrode.

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Cardiac axis Normally

, between -30 and +90

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6

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RIGHT axis deviation

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causes of right axis deviation

Normal finding in children and tall thin adults

Right ventricular hypertrophyChronic lung disease even without pulmonary hypertensionAnterolateral

myocardial infarction

Left posterior

hemiblock

??

Pulmonary embolusWolff-Parkinson-White syndrome - left sided accessory pathway ??

Atrial

septal

defect

ostium

secondum

Ventricular

septal

defect

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LEFT axis deviation

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Causes of left axis deviation

Left anterior fascicular block

Left bundle branch blockLeft ventricular hypertrophyInferior MIVentricular ectopic

Paced rhythm

Wolff-Parkinson White syndrome in

Rt

sided accessory pathway

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No Man’s land

Indeterminate Axis

Northwestern axis

Lead

I ,II , III : negatives

Causes : seen in ventricular rhythm ,

dextrocardia

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Extreme axis

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Standard ECG

The quality of an ECG is determined by the presence of

PATIENT’S NAME, DATE/TIME, the 12 LEADS and a RYTHEM STRIP at the bottom.The paper moves in a speed of

25mm/s (horizontal) =

And a calibration of 1cm or

10mm/mV (vertical).

1 small square = 1 mm, 1 large square = 5 small square = 5 mm.

So each small square represent time horizontally and voltage vertically

So the paper of the ECG move 5 large square /s = 25 small square/s = 300 large square / min = 1500 small square / min Each large square width

represents

=

.2

second = 200 ms

Each

small square width

represent

=

.04

= 40 ms

Each

small square

hight

represents

.

1

mv

,

So

1mv needs 2 large square

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Basics of the ECG

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6

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Electrical activity for each cardiac cycle ( systole and diastole ) makes :

P:

Atria Depolarization (<2.5 mm vertical)QRS:

Ventricular Depolarization

T:

Ventricular

Repolarization

U:

Repolarization of the papillary muscles follows the T wave. (Normal or Abnormal)PR interval: 120-220 ms (3-5 small squares)>220: Block,

<120: accessory pathway

QRS complex: 120 ms (3 small squares)

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Waves changes

P wave :

Absent p wave : not sinus rhythm P pulmonale

:

more than 3mm

hight

P

mitral : more than

3 mm width Inverted p wave : junctional

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QRS

Generally duration less than 120 ms ( less than 3 small square )

If > 120 it is bundle branch block either partial if it is < 160 or complete if it is > 160 Accepted Q waves: V1,

aVR

and III

Negative in V1 ,

aVR

. Normally

Pathological Q wave should be more than 1 small square height and width and / or more than 25 % of the corresponding R waveV1-V6: R increases and S decreases (disappears in V6)

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LVH sign

Sum of the S wave (-

ve deflection) in V1 and the biggest R wave in V5 or V6 >35mm = Left Ventricular Hypertrophy (LVH)

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LBBB

QRS > 3

SsqRSR (M shaped QRS complex) in V5, V6, I and

deep S in V1

Usually associated with LAD

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LBBB

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RBBB

QRS > 3 Ssq

RSR (M shaped QRS complex) in V1, V2 and deep S in V6.

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RBBB

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Pre-excitation

syndromes (WPW Syndrome):

Preexcitation is a condition characterized by an accessory pathway of conduction,

which allows the heart to depolarize in an atypical sequence.

In Wolfe-Parkinson-White (WPW) syndrome, there’s a direct

atrioventricular

connection allows the ventricles to begin depolarization while the standard action potential is still traveling through the AV node.

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ECG Characteristics of WPW:

1. Short PR interval

2. QRS prolongation3. Delta Wave 4. Followed by tachycardia

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T - Wave

Peaked in young adult and hyper k

Inverted in ischemiaSmall in hypokalemia

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Intervals – PR

From the beginning of the P wave to the beginning of the QRS = 160 ms to 220 ms

It is the iso- electrical line for the ECG Shortened

in WPW syndrome or normally with tachycardia

Prolongation

= heart block ( 3 degrees )

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1st degree Heart block:

Prolongation of the PR interval, which is constant

All P waves are conducted

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2nd degree Heart block

(

Mobitz 1)/Wenckebach:Progressive prolongation of the PR interval until a P wave is not conducted.

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2nd degree Heart block

(

Mobitz 2):Constant PR interval with intermittent failure to conduct

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Mobitz 2 HB

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Third degree Heart block

(Complete):

No relationship between P waves and QRS complexes,Relatively constant PP intervals and RR intervals and Greater number of P waves than QRS complexes

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QT interval

From the beginning of the QRS to the beginning of the T wave

Variable duration in response to the heart rate Prolonged QT interval carries high risk of arrhythmia (torsades de pointes )

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Long QT syndrome causes

> 450 ms

Congenital ( romano ward syndrome , jervell

and Lang-Nielsen )

Drugs :

class 3 and class 1 a

antiarrhythmic

,

antimalrial chloroquine , tricyclic antidepressants , terfenadine , antibiotics ( macloride- erythromycin ,

floroquinilone

)

Hypo ( ca , mg , k )

Hypothermia

Myocarditis

Subarachnoid hemorrhage

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St segment

ST depression:

Downsloping or horizontal = abnormalIschaemia

(coronary

stenosis

):

Chest pain association

If lateral (V4-V6),

consider LVH with ‘strain’ or digoxin toxicity

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ST segment elevation

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Takotsubo cardiomyopathy

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Atrial and Ventricular

Arrythmias

Bradycardia : HR less than 60 Tachycardia : HR > 100 Supraventricular

arrythmia

: SA , Atria , AV

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SVT (Supraventricular

Tachycardia):

Narrow QRS, Rate >150, regular RR complexes, P wave may be superimposed on T wave or hidden inside the QRS complex

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Atrial Flutter:

Biphasic “

sawtooth” flutter waves at a rate of >250/minFlutter waves have constant amplitude, duration, and morphology through the cardiac cycle.

There is usually either a 2:1 or 4:1 block at the AV node, resulting in ventricular rates of either 150 or 75

bpm

Adenosine is used to unmask an unclear record (SVT or Flutter?) by showing the saw-tooth appearance.

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Atrial Fibrillation

Atrial

fibrillation is caused by numerous wavelets of depolarization spreading throughout the atria simultaneously, leading to an absence of coordinated atrial

contraction.

AF is important because it can lead to: Hemodynamic compromise, Systemic

embolization

and other Symptoms

On ECG

: Absent P waves , Irregularly irregular ventricular response and tachycardiac

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Causes of irregular pulse

Sinus arrhythmia

Atrial extra systole Ventricular extra systole Atrial fibrilation

Atrial

flutter with variable response

Second degree heart block with variable response

Multifocal

atrial tachycardia ( MAT )

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AF causes

HTN

IHD Mitral valve disease HF Thyrotoxicosis Alcohol

Infection : pneumonia

Pul

. Embolism

Post cardiac surgery

Idiopathic ( lone AF )

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Ventricular Tachychardia

(usually follows MI)

Broad bizzare QRS complex - Regular RR wavesRate >120 (less than the SVT)P waves are present, fused with T or on top of ascending QRS complexes

Captured beat & fusion beat

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Ectopic Beats

Abnormal early beat whether

atrial or ventricular within a normal ECGIn ventricular extrasystole

/ectopic beat : QRS would look broad and bizarre, not

preceeded

by P and followed by opposing ST-T changes and by a

compnesatory

pause.

In Atrial extrasystole/ectopic beat: QRS would look normal, abnormally looking P wave and with a compnesatory pause.

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Multifocal Atrial

Tachycardia:

Discrete P waves with at least 3 different morphologies. Atrial rate > 100 bpm

.

The PP, PR, and RR intervals all vary.

It’s very common

with COPD and Lung fibrosis patients.

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ECG and electrolytes

Potasium

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Interpretation

Name of the pt

Calibration Rhythm sinus or not Rate normal , brady ,

tachy

Regularity

Axis

P wave and PR interval best seen at lead II

QRS shape , width , progression , T wave : shape , inversion , Most important : ST segment for depression and elevation The presence of pathological Q wave Don’t forget the artifact changes in the ECG mainly the limb opposition

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