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Cardiac > ECG Made Easy > Flashcards

ECG Made Easy Flashcards

1
Q

What is a Q wave?

A

The first downwards deflection of the ECG

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2
Q

What is an R wave?

A

The first upward deflection of the ECG

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3
Q

What is an S wave?

A

Any deflection below the baseline, following an R wave

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4
Q

What does each large square (5mm) of an ECG represent?

A

0.2 s

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5
Q

What does each small square (5mm) of an ECG represent?

A

0.04s

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6
Q

What is a normal PR interval?

A

0.12 - 0.2s

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7
Q

What is a normal QRS duration

A

0.12s

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8
Q

What appearance does a QRS complex have if depolarization is moving predominantly towards the lead?

A

Predominantly upwards QRS

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9
Q

What appearance does a QRS have if depolarization is moving predominantly away from the lead?

A

Predominantly downwards QRS

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10
Q

What does a QRS with equal R and S waves indicate?

A

The depolarization wave is moving at right angles to the lead

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11
Q

What is a normal cardiac axis of the heart?

A

11 o’clock to 5 o’clock

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12
Q

What is the general deflection location in leads 1 - 3 in a heart with a normal cardiac axis?

A

Upwards in leads I - III

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13
Q

What ECG changes are seen in right axis deviation?

A

Negative deflection in lead I
Deflection in lead III becomes more positive

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14
Q

What are some common causes of right axis deviation?

A

Pulmonary conditions that put a strain on the right side of the heart and congenital heart disorders

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15
Q

What is a cause of left axis deviation?

A

LV hypertrophy or conduction defect (more common)
- commonly left anterior fascicle block

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16
Q

What is a left axis ECG with negative lead III indicative of?

A

Conduction defect (more likely than LVH)

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17
Q

What is the general rule for direction of cardiac axis?

A

It points towards any lead where R wave is larger than S wave

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18
Q

In degrees, what is the range of the normal cardiac axis?

A
  • -30 to + 90 degrees
  • with 0 being parallel to the horizontal
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19
Q

What 2 factors determine the shape of the QRS in the chest (V) leads?

A
  1. The septum between the ventricles is depolarized before the walls of the ventricles, and the depolarization wave spreads across the septum from left to right
  2. In normal heart, LV wall has more muscle than right LV wall
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20
Q

What area of the heart do leads V1 and V2 look at?

A

The right ventricle

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21
Q

What area of the heart do leads V3 and V4 look at?

A

The septum

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22
Q

What area of the heart do leads V5 and V6 look at?

A

The left ventricle

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23
Q

What directions are the first deflections in leads V5 and V6 and why?

A

RS wave (positive deflection first) and is because of the septum depolarisation

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24
Q

Why is S negative in leads V1 and V2?

A

The main muscle mass depolarized is the LV - which is spreading away from LV leads

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25
Q

What happens to the QRS as you transition from V1 - V6 in a normal heart?

A

QRS is predominantly negative in V1 and becomes gradually more positive towards V6 (R and S are opposite and equal size in V4)

26
Q

What is clockwise rotation on the ECG often indicative of?

A

Chronic lung disease

27
Q

What normal physiological characteristics can cause right axis deviation?

A

Being tall and skinny

28
Q

What does the PR interval indicate?

A

The time taken for depolarization to from SAN to ventricular muscle

29
Q

What is first degree heart block?

A

Long PR > 0.2s

30
Q

What is the significance of first degree heart block?

A

It is not important in itself
- but may be a sign of coronary artery disease, digitalis toxicity or electrolyte disturbances

31
Q

What is the difference between Mobiz 1 and Mobiz 2 (Wenkebach) heart block?

A

Mobiz 1 - PR gets progressively later and then dropped QRS
Mobiz 2 - Constant PR and then random dropped QRS

32
Q

What is 3rd degree heart block? (complete heart block)

A

Normal atrial contraction but not conducted to the ventricles
- slow escape mechanism

33
Q

What are some causes of complete heart block?

A
  1. Acutely following MI
  2. Chronic state - fibrosis around bundle of His
  3. Block of both bundle branches
34
Q

What is the significance of a RBBB pattern with normal length QRS?

A

Can be either problem with the right side of the heart or a common finding in normal people

35
Q

What is the significance of LBBB pattern?

A

Always an indication of heart disease, usually left side
- LBBB prevents any further interpretation of the ECG

36
Q

What are some ECG signs of RBBB?

A

McDonalds M in V1 and reversed in V6

MAINLY POSITIVE IN LEAD V1

  • wide QRS
  • deep S wave
  • first deflection is upwards
37
Q

What are some ECG signs of LBBB?

A

A wide W in lead V1 and this is reversed in V6
- first deflection is downwards

38
Q

How does a RBBB impact the cardiac axis?

A

It does not change it

39
Q

What other feature is associated with complete heart block?

A

Ventricular escape rhythms

40
Q

When is ventricular tachycardia diagnosed?

A

When the rate exceeds 120bpm

41
Q

What is the difference between extrasystole and escape beat?

A

Extrasystole comes early and escape rhythms come late

42
Q

What ECG features indicated SVE / pre-atrial complexes?

A

Abnormal P wave and a longer R-R interval following ectopic QRS

43
Q

What is bigeminy?

A

Every other beat is a pre-atrial complex (PAC)

44
Q

What is trigeminy?

A

Every 3rd beat is a PAC

45
Q

What is the difference between VEs and SVEs?

A

VEs do not have P waves - SVEs have abnormal p waves
VEs also generally have wider, uglier QRS

46
Q

What is another name for carotid sinus pressure?

A

Sympathetic vagal stimulation of SA and AV nodes

47
Q

What are promenant ECG features of junctional tachycardia?

A

Fast QRS complexes with no P waves

48
Q

What is a general rule for determining whether a QRS is of ventricular or supraventricular (e.g. with BBB)?

A

If QRS > 160 ms then is likely to be of ventricular origin
- if QRS complex is very irregular, is likely to be AF with BBB

49
Q

Can fibrillation occur within the ventricles?

50
Q

How is ventricular fibrillation identified?

A

Like atrial fibrillation but larger irregular deflections of baseline
- patient will likely have passed out - is how to distinguish from artefact

51
Q

How is WPW syndrome identified on ECG?

A

Delta waves and very short PR interval

52
Q

What can cause right atrium hypertrophy? and how is this identified on ECG

A

Tricuspid valve stenosis or pulmonary hypertension
- associated with peaked P waves

53
Q

What can cause left atrium hypertrophy? and how is this identified on ECG

A

Mitral valve stenosis
- associated with broad bifid P wave

54
Q

In a normal ECG, what are the approximate heights of the R waves?

A

Less than 25mm

55
Q

What ECG features can a PE show?

A

Those similar to right ventricular hypertrophy
- e.g. peaked p waves, right axis deviation, tall R waves, RBBB

56
Q

What is the general direction of ventricle depolarisation?

A

From the inside to out

57
Q

Which ventricle occupies the front of the heart anatomically?

A

Right ventricle

58
Q

In which ECG leads is the T wave inverted in normal physiology?

A

V1 (and sometimes V2 and V3)

59
Q

How can lead malposition be identified?

A

Completely inverted trace in certain leads

60
Q

How can you distinguish STEMI from WPW?

A

WPW has wide QRS complexes

61
Q

What is an ischemic cause of QRS fragmentation?

A

Abnormal ventricular repolarization
- due to fibrosis and scarring

Cardiac (7 decks)

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