ECGECG Dr. Mohammed Shaat Modified by : Dr. Amal Al Maqadma.

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

V1 & V2 Septum V3 & V4 anterior +Right

Ventricle V5 & V6 Lateral Left

VentricleII+III+AVF inferior border

: einthoven's triangle

ECG PaperECG Paper

12 lead ECG layout:

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

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