ECGECG

ElectrocardiographyElectrocardiography It is a voltage

difference, record the electrical activity of the heart as well as valuable information about the heart function and structure.

Willem Einthoven 1924

Leads (Leads (lead x electrodelead x electrode))LIMB LEADSIIIIII

AVFAVLAVR

CHEST LEADSV1V2V3V4V5V6

bipolar

unipolar

Limb leadsLimb leads

Limb leadsLimb leads

Both limb leadsBoth limb leads

Chest leadsChest leads

What chest lead represent What chest lead represent ??

ECG Leads - Views of the Heart

einthoven's triangle :

ECG PaperECG Paper

See video

ECG Cardiac CycleECG Cardiac Cycle

What is the isoelectric line؟

P waveP waveRepresent the

electrical activity of both atria ( atrial depolarization)

The depolarization slow within the AV node, there is a brief delay or PAUSE before the depolarization conducted to the ventricles

Normal duration <0.12 sec

Absent P wave:Atrial fibrillation SA BlockAV Rhythm

Peak P wave:Atrial hypertrophy

PR intervalPR interval

Normally :0.12-0.2sec

Prolonged in : heart block.

Short in : W-P-W syndrome.

QRS ComplexQRS ComplexRepresent the

electrical activity of both ventricles.

Ventricular depolarization( initiation of the ventricular contraction

QRS ComplexQRS ComplexQQ wave wave

RR wavewave::

SS wave : wave :

: : Normal QRS duration < 0.12 secNormal QRS duration < 0.12 sec

QRS ComplexQRS ComplexQQ wave wave

first first downward downward deflection deflection ..

septal septal depolarization.depolarization.

0.04sec0.04sec..

RR wavewave: : first upwardfirst upward deflection.deflection. height: 5-8 mm.height: 5-8 mm. early ventricular

depolarization

SS wave : late ventricular wave : late ventricular depolarization, depolarization,

Large QRS indicateLarge QRS indicate Ventricular hypertrophy.Ventricular hypertrophy.

ST - SegmentST - SegmentST segment: the

plateau phase of ventricular repolarization.

Isoelectric or> or<1mm.

If the ST segment elevated or depressed beyond the normal baseline this usually sign of serious pathology. (MI)

T- WaveT- WaveT-wave :represent rapid

phase of ventricular repolarization.

peaked T wave: early MI hyperkalemia Black races

Inverted : MI . Ventricular hypertrophy. Hypokalemia Digoxin

Q-T interval 0.4 sec in HR 70

Prolonged in :1. Hypocalcemia2. hypomagnesemia

U waverepolarization of the interventricular

septum. low amplitude Prominent: suspect hypokalemia,

hypercalcemia or hyperthyroidism

J wave represents the approximate end of

depolarization and the beginning of repolarization

camel-hump sign .Hypothermia hypocalcemia.

Low voltage ECG ObesityEmphysemaCOPDSevere hypothyroidism

RateRateNormal heart rate 60-

100/ min< 60 called bradycardia>100 called tachycardia

How To Calculate Heart How To Calculate Heart Rate ?Rate ?

300No. of Large box btw R-R

HR=

1500No. of Small box btw R-R

HR=

RHYTHMRHYTHM

Look For The Distance between Identical waves.

Most commonly used R-R

AXISAXISAt any point during depolarization

and repolarization electrical potential are being propagated in different directions.

Most of these cancel each other out and only the net force is recorded. This net is called AXIS or cardiac VECTOR

How To Check Axis in ECGHow To Check Axis in ECG

Principles of ECG recording

Explain the indication and the procedure for the patient. (assurance )

Ask the patient to take off any metals he/she wears.

Expose the wanted sites.Cleaning of skin and shaving if necessary. Place the electrodes in the correct

positions . Instruct the patient to remain still (should

not talk during the test ) and relax their shoulders and legs while the recording takes place (1 min)

See video

How to comment on ECG Name.Age ,Date and time.Calibration and Speed of paper RAWIHI :

RAWIHIR: rate, regularity,rhythm(sinus

or asinus),A: axis.W:waves.I :intervals.H: hypertrophy.I: ischemia

Normal Sinus RhythmRate = 60-100 beat / minute. The rhythm is regular All intervals are within normal limits There is a P for every QRS and a QRS

for every P. P : QRS ratio = 1 : 1.The P waves all look the same Presence of P, QRS, T in each cycle.Normal shape, time of waves,

segments and intervals

Interfering factors Inaccurate placement of the electrodes Electrolyte imbalances Poor contact between the skin and the electrodes Movement or muscle twitching during the test

Drugs that can affect results include digitalis, quinidine, and barbiturates

MIWhen myocardial blood supply is abruptly reduced toa region of the heart, a sequence of injurious eventsoccur :

Ischemia ( subendocardial or transmural)

InjuryNecrosis, and eventual fibrosis

(scarring) if the blood supply isn't restored in an appropriate period of time

Hyperacute T wave is the earliest sign of acute myocardial infarction

Precordial Septal Leads

◦V1 – V2

– Look at the Septum of the

heart

– The septal branch of the

LAD

Precordial Anterior Leads

◦ V3 – V4

–anterior wall of the left ventricle

–The LAD diagonal branch)

Anterior-Septal Terminology

Lateral Precordial Leads

◦I,AVL,V5 – V6

◦lateral of the left ventricle

◦The left circumflex

Inferior border leads

◦II, III and aVF◦the Inferior wall

of the RV◦ Posterior

Descending Branch of the RCA.

Posterior MINo leads look at the posterior wall.

usually associated with inferior and/or lateral wall MI. The changes of posterior myocardial infarction are seen

indirectly in the anterior precordial leads. Leads V1 to V3 face the endocardial surface of the posterior wall of the left ventricle. As these leads record from the opposite side of the heart instead of directly over the infarct, the changes of posterior infarction are reversed in these leads. The R waves increase in size, becoming broader and dominant, and are associated with ST depression and upright T waves. This contrasts with the Q waves, ST segment elevation, and T wave inversion seen in acute anterior myocardial infarction.

ST depression is considered reciprocal ECG changes in what should be ST elevation for acute posterior wall injury.

ECG Leads - Views of the Heart

lead border Arterial supply

V3 & V4 anterior Right Ventricle

RCA

V1 & V2 Septum LAD

a VL,V5 & V6

Lateral Left Ventricle

LCX

II+III+AVF inferior borderof right ventricle

RCA

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