Ecg Interpretation

Front 1

What are the normal axis values?

Back 1

-30 to +90

Front 2

If there was left axis deviation, where would the axis lie?

Back 2

-30 to -90

Front 3

If there was right axis deviation, where would the axis lie?

Back 3

+90 to +180

Front 4

What does the electrical axis represent?

Back 4

Average direction of the heart's electrical activity during ventricular depolarisation

Front 5

What leads are used to determine the electrical axis?

Back 5

Leads:
I
II
III
aVr
aVl

Front 6

Describe the quadrant method

Back 6

On the basis of QRS deflection in lead I and aVf
Lead I shows whether the impulses are moving right or left
Lead aVf shows whether the impulses are moving up or down

Front 7

Describe the degree method

Back 7

1. Review all 6 leads, identify the one that contains either the smallest QRS complex/ complex with equal deflection above and below the baseline.
2. Use the Hexaxial diagram to identify the lead at 90 degrees to this lead
3. Is this lead mostly negative or positive?

Front 8

Name 5 factors the influence the location of the axis

Back 8

1. Heart's position in the chest
2. Heart size
3. Patient's body size/ type
4. Conduction pathways
5. Force of electrical impulses being generated

Front 9

In which direction does the electrical axis swing when there is damage or necrosis?

Back 9

Away from the damaged area, therefore that area of the heart will be the last to be depolarised.

Front 10

What kind of deviation will infants and children have?

Back 10

Right axis deviation

Front 11

What kind of deviation will pregnant women have?

Back 11

Left axis deviation

Front 12

Name 6 causes of right axis deviation

Back 12

1. RBBB
2. Left posterior hemiblock
3. Lateral wall MI
4. Emphysema
5. RV hypertrophy
6. NORMAL

Front 13

Name 8 causes of Left axis deviation

Back 13

1. LV hypertrophy
2. Inferior wall MI
3. Left anterior hemiblock
4. LBBB
5. Ageing
6. Mechanical shifts
7. WPW syndrome
8. NORMAL

Front 14

Name 3 causes of mechanical shifts

Back 14

1. Ascites
2. Pregnancy
3. Tumours

Front 15

Why is left axis deviation common in the elderly?

Back 15

From fibrosis of the anterior fascicle of the left bundle branch
From thickness of the left ventricular wall (increased)

Front 16

In which leads is the P wave always positive and negative?

Back 16

Always positive in Lead I and II
Always negative in aVr

Front 17

How many small squares should a P wave be in duration and amplitude?

Back 17

Less than 3 small squares in duration
Less than 2.5 small squares in amplitude

Front 18

In which lead is the P wave normally biphasic?

Back 18

Lead V1

Front 19

What happens to the P waves in right atrial enlargement?

Back 19

They become tall and pointed (P pulmonale)

Front 20

What happens to the P waves in left atrial enlargement?

Back 20

They become notched/ bifid (m shaped) (p mitrale)

Front 21

What is the normal PR interval?

Back 21

0.12-0.20ms (3-5 small squares)

Front 22

What causes the PR interval?

Back 22

Atrial depolarisation and delay in AV junction (AVN/ bundle of HIS)

Front 23

What does a long PR interval indicate?

Back 23

1st degree heart block

Front 24

What does a short PR interval indicate?

Back 24

Accessory pathway/ WPW syndrome

Front 25

Where might non- pathological Q waves present?

Back 25

I
III
aVl
V5
V6

Front 26

How big is a pathological Q wave?

Back 26

More than 2mm deep and more than 1mm wide
OR 25% the amplitude of the subsequent R wave

Front 27

What does a pathological Q wave suggest?

Back 27

Previous MI

Front 28

Name 4 conditions that have a tall R wave in V1

Back 28

1. Right ventricular hypertrophy
2. Posterior MI
3. Type A WPW syndrome
4. RBBB
(A tall R wave in children in lead V1 is NORMAL)

Front 29

In which leads can you recognise left ventricular hypertrophy?

Back 29

V1 = tall S wave
V5/6 = tall R wave
(more than 35mm)
aVl = R wave (more than 11mm)
BASICALLY: QRS voltage increases with LVH

Front 30

What happens to the QRS complex in bundle branch block?

Back 30

It widens (above 0.12ms)

Front 31

What happens to the QRS complex in RBBB?

Back 31

In leads overlying the right ventricle (V1 and V2) the QRS complex looks like RABBIT ears or an M

Front 32

What happens to the QRS complex in LBBB?

Back 32

In V1 and V2 there are broad, deep S waves
Looks like a W

Front 33

What is the acronym for RBBB and LBBB?

Back 33

RBBB= MaRRoW - M in V1 and W in V6
LBBB= WiLLiaM - W in V1 and M in V6

Front 34

What is the J point?

Back 34

Point between the QRS and ST segment

Front 35

What does an elevation of the ST segment represent?

Back 35

Acute MI
Greater than 1 small square in 2 leads

Front 36

Give 3 causes of ST depression

Back 36

1. Ischaemia
2. LVH with strain
3. Digitalis toxicity

Front 37

What does T wave inversion suggest?

Back 37

MI
Ischaemia

Front 38

What are the changes seen in MI/ Ischaemia?

Back 38

Q waves
ST segment elevation/ depression
T wave inversion

Front 39

What does the QT interval represent?

Back 39

The total duration of depolarisation and reploarisation

Front 40

What happens to the QT interval when heart rate increases?

Back 40

It decreases

Front 41

What should the QTc be?

Back 41

Less than 0.44s in males
Less than 0.46s in females

Front 42

What is the risk with a prolonged QT interval?

Back 42

Ventricular arrhythmia

Front 43

What is a U wave?

Back 43

They are related to after depolarisations which follow repolarisation

Front 44

What should the look like?

Back 44

Small, round and symmetrical
Positive in lead II with an amplitude of less than 2mm
(The direction should be the same as the T wave)

Front 45

When is the U wave more prominent?

Back 45

At slow heart rates