ELECTROCARDIOGRAMELECTROCARDIOGRAM

Body is a volume conductor.Body is a volume conductor. The process of recording the electrical activity of The process of recording the electrical activity of

the heart from the surface of the body with the the heart from the surface of the body with the help of a pair of electrodes is known as help of a pair of electrodes is known as electrocardiography.electrocardiography.

The record is known as electrocardiogram.The record is known as electrocardiogram. The machine with which the recording is done is The machine with which the recording is done is

called electrocardiograph. called electrocardiograph.

ECGECGEinthoven TriangleEinthoven Triangle

The sum of potentials at the end point of an The sum of potentials at the end point of an equilateral triangle with a current source at equilateral triangle with a current source at

the center is always zero.the center is always zero.

A similar triangle can be created in our A similar triangle can be created in our body by choosing 3 points(2 Acromian body by choosing 3 points(2 Acromian

processes and pubic symphysis) putting the processes and pubic symphysis) putting the electrodes in RA,LA,LF as arm and leg act electrodes in RA,LA,LF as arm and leg act as conducting cables. So according to the as conducting cables. So according to the

convention Vconvention VLL+V+VRR+V+VFF=0. =0.

EINTHOVENS LAWEINTHOVENS LAW

At any given instance the sum of potentials in At any given instance the sum of potentials in Lead-I and Lead-III is equal to the potential of Lead-I and Lead-III is equal to the potential of Lead-II.Lead-II.

Lead-I-Records LA-RA = (VLead-I-Records LA-RA = (VLL-V-VRR))

Lead-II-Records LF-RA =(VLead-II-Records LF-RA =(VFF-V-VRR))

Lead-III-Records LF-LA =(VLead-III-Records LF-LA =(VFF-V-VLL))

So potential of Lead-I + potential of Lead-IIISo potential of Lead-I + potential of Lead-III

=VL-VR+VF-VL=VL-VR+VF-VL

=VF-VR=The potential of Lead II.=VF-VR=The potential of Lead II.

ECG LEADSECG LEADS A lead means a view point of heart made with the help of two A lead means a view point of heart made with the help of two

electrodes.electrodes. There are unipolar and bipolar leads. The unipolar lead consists of There are unipolar and bipolar leads. The unipolar lead consists of

one active electrodes and the bipolar lead contents two active one active electrodes and the bipolar lead contents two active electrodes.electrodes.

Unipolar recording is done with placing the active electrode on the Unipolar recording is done with placing the active electrode on the area of the body surface whose potential we want to know and the area of the body surface whose potential we want to know and the other is the indifferent electrode which is kept at zero potential.other is the indifferent electrode which is kept at zero potential.

The bipolar recording is done with two active electrode .By keeping The bipolar recording is done with two active electrode .By keeping the electrodes at different places different view points are created the electrodes at different places different view points are created and they are named as various leads. and they are named as various leads.

Contd.Contd.

The various leads used in ECG are The various leads used in ECG are A : Precordial leads A : Precordial leads 1.1. V1 4V1 4thth intercostal space to right of sternum intercostal space to right of sternum2.2. V2 4V2 4thth intercostal space to left of sternum intercostal space to left of sternum3.3. V3 midway between V2 and V4V3 midway between V2 and V44.4. V4 5V4 5thth intercostal space in mid clavicular line intercostal space in mid clavicular line5.5. V5 left 5V5 left 5thth intercostals space in anterior axillary line intercostals space in anterior axillary line6.6. V6 left 5V6 left 5thth intercostal space in mid axillary line intercostal space in mid axillary line

B : Unipolar limb leadsB : Unipolar limb leads1.1. VL left armVL left arm2.2. VF left footVF left foot3.3. VR right armVR right arm

C: Bipolar limb leadsC: Bipolar limb leads1.1. Lead I between right arm and left armLead I between right arm and left arm2.2. Lead II between right arm and left legLead II between right arm and left leg3.3. Lead III between left arm and left legafLead III between left arm and left legaf

Unipolar LeadsUnipolar Leads

ECG Recording PaperECG Recording Paper

ECG paper –Graph having ECG paper –Graph having horizontal &Vertical lines at 1mm intervalshorizontal &Vertical lines at 1mm intervalsHeavier line is present every 5mm.Heavier line is present every 5mm.Heated stylusHeated stylus write the graph on moving ECG paperwrite the graph on moving ECG paperConventional speed—25mm/secConventional speed—25mm/secEach small division=0.04secEach small division=0.04secVoltage measured in vertical line=mvVoltage measured in vertical line=mv10mm vertically=1mv10mm vertically=1mv

ECG PAPERECG PAPER

ELECTROCARDIOGRAPHELECTROCARDIOGRAPH

CHEST ELECTRODECHEST ELECTRODE

THE ELECTRODESTHE ELECTRODES

RECORDING OF ECGRECORDING OF ECG

GraphGraph

WAVES OF ECGWAVES OF ECG The various waves of ECG are P, Q, R , S, T , U.The various waves of ECG are P, Q, R , S, T , U. P Waves- duration 0.1 sec,( Atrial depolarization ) , 0.5 mv SA node P Waves- duration 0.1 sec,( Atrial depolarization ) , 0.5 mv SA node

to atrial muscleto atrial muscle PR segment 0.04 sec , ( Isoelectric) PR segment 0.04 sec , ( Isoelectric) QRS complex , (ventricular depolarization)QRS complex , (ventricular depolarization) Q wave-Small –ve wave , duration < 0.04 sec , mid portion of IV Q wave-Small –ve wave , duration < 0.04 sec , mid portion of IV

septumseptum R wave – onset of VS ( both ventricles)R wave – onset of VS ( both ventricles) S wave – excitation of basal part , 0.08 to 0.12 sec S wave – excitation of basal part , 0.08 to 0.12 sec ST segment- 0.04 – 0.08 sec ( Iso electric )ST segment- 0.04 – 0.08 sec ( Iso electric ) T wave – 0.27 sec , 0.5 mv ( ventricular repolarization ), closer of T wave – 0.27 sec , 0.5 mv ( ventricular repolarization ), closer of

semilunar valves semilunar valves U wave – rarely seen , 0.08 sec , slow repolarisation of palpillary U wave – rarely seen , 0.08 sec , slow repolarisation of palpillary

musclemuscle

ContdContd

PR interval 0.13 -0.16 sec , ad+ PR interval 0.13 -0.16 sec , ad+ conduction of boh( Bundle Of His )conduction of boh( Bundle Of His )

QT Interval 0.4 – 0.43 sec vd + vr QT Interval 0.4 – 0.43 sec vd + vr ST interval 0.32 sec VR ST interval 0.32 sec VR TP segment 0.2 sec TP segment 0.2 sec J point Iso electric point between s wave J point Iso electric point between s wave

and ST segment.and ST segment.

Amplitude in mvAmplitude in mv

P waveP wave Q waveQ wave R waveR wave S waveS wave T waveT wave

0.1 to 0.1 to 0.120.12

0.1 to0.20.1 to0.2 1.01.0 0.40.4 0.30.3

Interpretation of ECGInterpretation of ECG Cardiac rate Cardiac rate

RhythmRhythm

Determination of Sequence of P,QRS.T waveDetermination of Sequence of P,QRS.T wave

Voltage, Duration, Polarity of each wave, Cause of WaveVoltage, Duration, Polarity of each wave, Cause of Wave

Duration of PR , QT, & ST intervalDuration of PR , QT, & ST interval

Relation of ST segment, to base lineRelation of ST segment, to base line

Instantaneous mean VectorInstantaneous mean Vector

Axis of the heart---Numerical / From ElectrocardiogramAxis of the heart---Numerical / From Electrocardiogram

Evidence of hypertrophyEvidence of hypertrophy

Evidence of heart blockEvidence of heart block

Evidence of IHDEvidence of IHD

Evidence of arrhythmiasEvidence of arrhythmias

Mechanism of Generation of +ve &-ve waveMechanism of Generation of +ve &-ve wave

Instantaneous mean vectorInstantaneous mean vector

VECTORVECTOR

Definition & measurementDefinition & measurement

Instantaneous mean vectorInstantaneous mean vector

Direction & degree of Vector in Bipolar/ Unipolar limb leadsDirection & degree of Vector in Bipolar/ Unipolar limb leads

Calculation of Instantaneous mean QRS vector Calculation of Instantaneous mean QRS vector

Normal axis & RangeNormal axis & Range

What is RAD/LADWhat is RAD/LAD

Vector cardiogramVector cardiogram

Determination of cardiac axisDetermination of cardiac axis

Vector cardiographVector cardiograph

HIS BUNDLE ELECTROCARDIOGRAMHIS BUNDLE ELECTROCARDIOGRAM

CARDIAC AXISCARDIAC AXIS

Hypertrophy patternHypertrophy pattern

RAHRAH LAHLAH RAH &LAHRAH &LAH

Tall Tall 3mm,Peaked3mm,Peaked

P wave in leadP wave in lead

IIII

Broad,>2.5mmBroad,>2.5mm

Bifid P waveBifid P wave

In lead IIIn lead II

P wave is bothP wave is both

tall &broadtall &broad

LVH &RVHLVH &RVH

LVH &RVHLVH &RVH

FIBRILLATIONFIBRILLATION

HEART BLOCKHEART BLOCK

Heart blockHeart block

Idioventricular RythmIdioventricular Rythm

AV NODAL BLOCKAV NODAL BLOCK

HEART BLOCKHEART BLOCK

EXTRASYSTOLEEXTRASYSTOLE

ATRIAL ARRHYTHMIASATRIAL ARRHYTHMIAS

VENTRICULAR ARRHYTHMIAVENTRICULAR ARRHYTHMIA

Current of injury in MICurrent of injury in MI

Elevation of ST segmentElevation of ST segment

MYOCARDIAL INFARCTIONMYOCARDIAL INFARCTION