1) Basic ECG

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THE

ELECTROCARDIOGRAM(ECG / EKG)

By: Dr Yasir Mansour i

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How To Interpret ECG?

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Highlights

Always interpret the ECG in clinical

context

Always read the ECG systematically

Put the data together & try to find pathology

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Objectives

To recognize the normal ECG of the heart

To recognize the most common ECG

Abnormalities

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The QRS Complex

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ECG ANALYSIS

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Normal ECG with normal QRS transition from V1V6

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ECG ANALYSIS

RATE

RHYTHM

AXIS

P WAVE

P-R INTERVAL

QRS COMPLEX

ST SEGMENT

T WAVE

U WAVE

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ECG Paper

Speed Amplitude and

Deflection

Calibration

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Standardisation

10mv

Paper Speed

1 small square

= 1mv (mm)

1 big square

= 5 small squares

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ECG ANALYSIS

RATE

Dividing

300 by the number of big squares,

OR

1500 by the number of small squares

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THE RATE

NORMAL (60100 beats / min)

FAST (>100 beats / min) = TACHYCARDIA

SLOW (< 60 beats / min) = BRADYCARDIA

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Pacemakers of the Heart

SA Node - Dominant pacemaker with an

intrinsic rate of 60 - 100 beats/minute.

AV Node - Back-up pacemaker with anintrinsic rate of 40 - 60 beats/minute.

Ventricular cells - Back-up pacemaker with

an intrinsic rate of 20 - 45 beats/minute.

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HR > 150/minNote Paper Speed12.5mm/sec

Same ECG: HR 75/minat Paper Speedof 25mm/sec

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THE RHYTHM

REGULAR or IRREGULAR

There may be a combination of :

Abnormal Rate + Abnormal Rhythm e.g.

Atrial Fibrillation (fast and irregular)

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REGULAR RHYTHM

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IRREGULAR RHYTHM

InspirationExpiration

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NORMAL SINUS RHYTHM

Regular P-P interval

Regular R-R interval ( Rate between 60100/m )

Each P wave is followed by a QRS complex

P T

R R R

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ECG ANALYSIS

RATE

RHYTHM

AXIS

P WAVE

P-R INTERVAL

QRS COMPLEX

ST SEGMENT

T WAVE

U WAVE

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Determination of Electrical Axis of the Heart

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NORMAL AXIS

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LEFT AXIS DEVIATION

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RIGHT AXIS DEVIATIONRIGHT

AXIS DEVIATION

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THE AXIS

LADEXTREME

RAD

RADNORMAL

I

aVF

I

aVF

I

aVF

I

aVF

0

-90

+90

180

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Normal AxisPositive R in I

Positive R in II

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Right Axis DeviationDeep S in I (Small R )

Tall R in II

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Left Axis DeviationTall R in I

Deep S in AVF

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ECG ANALYSIS

RATE

RHYTHM

AXIS

P WAVE

P-R INTERVAL

QRS COMPLEX

ST SEGMENT

T WAVE

U WAVE

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P Wave

- Duration

- Amplitude

- Shape

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P Wave

Duration: 0.080.12sec(2-3 small squares)Amplitude: 2 - 2.5mm(22.5small squares)

Shape:Roundedand upright, in Leads I, II, aVF, V4-V6.

Inverted in aVR.

Flat, inverted or biphasicin III, V1, V2

P

P

P

Normal

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ECG ANALYSIS

RATE

RHYTHM

AXIS

P WAVE

P-R INTERVAL

QRS COMPLEX

ST SEGMENT

T WAVE

U WAVE

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PR Interval

P

R

T

PR Interval

Normal - 0.120.20sec

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PR Interval

Normal Short Prolonged

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ECG ANALYSIS

RATE

RHYTHM

AXIS

P WAVE

P-R INTERVAL

QRS COMPLEX

ST SEGMENT

T WAVE

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QRS Complex

1. Duration ( Normal 0.060.11sec)

2. Components ( Q, R, S )

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QRS Complex - Duration

Narrow - Normal (0.060.11sec)

Wide - Abnormal (> 0.11sec)

Causes of Wide QRS Complex

1. PVC

2. Intraventricular Conduction Delay (IncompleteBBB)3. BBB

4. Paced Beat

5. W-P-W Syndrome

6. Aberrant Conduction

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Premature Ventricular Contraction (PVC)

PVC

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Intraventricular Conduction Delay -

(Incomplete) Bundle Branch BlockQRS = 0.11sec

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Left Bundle Branch

Block QRS > 0.12 QRS 4x0.04

= 0.16

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(Complete) Right Bundle

Branch Block QRS > 0.12 QRS 4x0.04

= 0.16

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RBBB - Wide QRS complex Deep wide S in I, II, V5, V6

Prominent R / RsR in V1, V2

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Paced Beat

Pacemaker Impulse

Paced Ventricular Beat

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Type A W-P-W: Short PR Interval Wide QRS complex (Delta Wave)

Prominent R in V1, V2

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QRS Complex - Components

Q Wave

R Wave

S Wave

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Q WAVE

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Normal Q Wave

Narrow (1mm duration)

Amplitude less than of the accompanying R wave

Q wave

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Abnormal Q Wave

Wide (> 1mm duration) and / or

Amplitude > than of the accompanying R wave

Q

R

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R WAVE

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R Wave

Normal R Wave

R wave

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R Wave -Amplitude

Abnormal R Wave:

Low - Causes: i. Emphysemaii. Pleural Effusion

iii. Pericardial Effusion

iv. Dilated Cardiomyopathy

Tall - LVH- RVH

- Biventricular Hypertrophy

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LVH

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RVH - Prominent R in V1 and V2

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Biventricular Hypertrophy ( LVH + RVH )

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Differential Diagnosis of Prominent

R or rsR in V1

RVH

RBBB

True Posterior Myocardial Infarct

Type A Wolffe Parkinson White (WPW)

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RVH

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RBBB - Wide QRS complex Deep wide S in I, II, V5, V6

Prominent R / RsR in V1, V2

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True Posterior MI - Prominent R / Rsr in V! and V2

Rsr

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Type A W-P-W Short PR Interval Wide QRS complex (Delta Wave)

Prominent R in V1, V2

ECG ANALYSIS

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ECG ANALYSIS

RATE RHYTHM

AXIS

P WAVE

P-R INTERVAL

QRS COMPLEX

ST SEGMENT

T WAVE

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S-T Segment Changes

ST segment Elevation

ST Segment Depression

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May be due to -

i. Myocardial Infarction- Convexupwards

- Related to the area of infarct

- Abnormal Q wave may be present- Reciprocal ST depression may be present

ii. Early Repolarisation

(Elevated J Junction)

iii. Acute Pericarditis- Concave upwards

- Generalised ( in all the leads )

- No abnormal Q wave

Q

R

(i)

(ii)

J junction

(iii)

S-T Segment Elevation

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S-T Segment Depression

May be due to:

1. Myocardial Ischaemia

2. LVH with strain3. Unstable Angina

4. Non-ST segment Elevation Myocardial Infarction

5. Digoxin Effect / Toxicity6. Hypokalaemia

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QT Interval

Measured from the beginning of Q to the end of T

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QT Interval

QT Interval

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QT Interval


QTinterval < 50% preceding R-R interval

QTc( corrected QT interval)

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ECG ANALYSIS

RATE RHYTHM

AXIS

P WAVE

P-R INTERVAL

QRS COMPLEX

ST SEGMENT

T WAVE

T W

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T Wave

Normal T Wave

Abnormal T Wave - Tall T wave

- Inverted T wave

Tall T waveInverted T wave

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Normal ECG with normal QRS transition from V1V6

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Documents

1) Basic ECG