ELECTROCARDOGRAPHY 2012

7/29/2019 ELECTROCARDOGRAPHY 2012

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ELECTROCARDOGRAPHYDewi Irawati MD, MS

Dept.of Physiology

FMUI


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ELECTROCARDIOGRAPH Recording of electrical activity of the heart

(depolarization and repolarization of themyocardial cells) through special electrodes

Human body: volume conductor ability toconduct electrical activity in all direction

Significancy:

Overview of spread of action potential (actionpotential summation of active cells), variateswith time, spread of impulse during one cycle.

Recording of electrical potential (voltage)difference between two electrodes


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ECG Recorder Galvanometer, sensitive to electrical

potential changes

Active/recording electrode at 2 differentpoints/site

Amplification of electrical potential difference

Recording apparatus - speed

Specific curve: amplitude (mV) and duration

(seconds)


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Technique of recording an ECG Special Graphic Paper:

Distance between 2 thin lines = 1 mm

Distance between 2 thick lines = 5 mm Paper speed 25 mm/sec. ( 1 mm = 0.04 sec.)

Sensitivity: , 1 and 2 (1 mV = 5, 10 or 20 cm)


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ECG Leads Bipolar:

Potential difference between 2 activeelectrodes

Einthoven: I, II and III

Unipolar: Potential diference between 1 active electrode

and indifferent electrode

Augmented extremity leads GOLDBERGER:aVR, aVL and aVF

Precordial leads WILSON: V1, V2, V3, V4, V5dan V6


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ECG Recordings (QRS Vector pointing leftward, inferiorly &

posteriorly)

LARA

LL

3 Bipolar Limb Leads:

I = RA vs. LA (+)


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LARA

LL


I = RA vs. LA (+)

II = RA vs. LL (+)


posteriorly)


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LARA

LL


I = RA vs. LA (+)

II = RA vs. LL (+)

III = LA vs. LL (+)


posteriorly)


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LARA

LL


I = RA vs. LA (+)

II = RA vs. LL (+)

III = LA vs. LL (+)

3 Augmented Limb Leads:

aVR = (LA-LL) vs. RA(+)


posteriorly)


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LARA

LL


I = RA vs. LA (+)

II = RA vs. LL (+)

III = LA vs. LL (+)

3 Augmented Limb Leads:


aVL = (RA-LL) vs. LA(+)

aVF = (RA-LA) vs. LL(+)

ECG Recordings (QRS Vector pointing leftward, inferiorly & posteriorly)


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V1 V2V

3

V4

V5

V6

6 PRECORDIAL (CHEST) LEADS

Spine

Sternum


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3 Bipolar Limb Leads

I = RA vs. LA(+)

II = RA vs. LL(+)

III = LA vs. LL(+)

3 Augmented Limb Leads


aVL = (RA-LL) vs. LA(+)

aVF = (RA-LA) vs. LL(+)

6 Precordial (Chest) Leads: Indifferent electrode (RA-LA-LL) vs.

chest lead moved from position V1 through position V6.

ECG Recordings: (QRS vector---leftward, inferiorly and posteriorly


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ECG Curve


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ECGAnalysis Normalrhythm:sinusrhythm

Every P wave is followed by QRS complex and Twave

All 12 lead


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Heart rate:60

P-P (R-R) interval (mm) X 0.04

ECGAnalysis


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ECG Analysis P wave Lead II

Amplitude: < 0.25 mV

Duration: < 0.11 sec.


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ECG Analysis P-R interval Lead II

Duration: 0.12 - 0.2 sec.


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ECGAnalysis QRS complex Lead V2 V3

Duration: < 0.12 sec.

QRS configuration: V1 V6 rS Rs

Transitional zone QRS interval

V2 V3 < 0.10 s


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ECG Analysis VAT (Ventricular Activation Time)

Spread of action potential fromendocardiumepicardium

Duration: V1-2 < 0.03 sec

V5-6 < 0.05 sec


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ECGAnalysis QRS electrical heart axis

QRS T angle: < 70I

III

Lead I: - 1 + 8 = +7

Lead III: - 2 + 12 = +10


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ECG Analysis Q-T interval

Onset of Q wave end of T wave Total ventricular activity

Varies with heart beat

QTc (corrected) nomogram


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ECGAnalysis S-T segment all leads

Iso-electric

Important clinical significance


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ECGAnalysis T wave configuration all leads

Positive deflection except aVR andsometimes V1


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ECGAnalysis U wave

Late Purkinje cells depolarization

Unknown significance


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ELECTROCARDOGRAPHY 2012

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